efficient energy automation with the iec 61850 standard...

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Efficient Energy Automation

with the IEC 61850 Standard

Application Examples

Energy Automation

Editorial

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Efficient Energy Automationwith the IEC 61850 Standard

The IEC 61850 standard has been defined in cooperation with manufactu-rers and users to create a uniform, future-proof basis for the protection,communication and control of substations. In this brochure, we presentsome application examples and implemented stations with the newIEC 61850 communication standard. IEC 61850 already has an excellenttrack record as the established communication standard on the worldwidemarket for the automation of substations.

Its chief advantages are:� Simple substation structure: No more interface problems.

With IEC 61850, protocol diversity and integration problems are a thingof the past.� Everything is simpler: From engineering to implementation, from ope-

ration to service. Save time and costs on configuration, commissioningand maintenance.� Reduction of costs: IEC 61850 replaces wiring between feeders, control

switches, and signaling devices.� More reliability: You only use one communication channel for all data –

in real time, synchronized via Ethernet.

Why use IEC 61850 technology from Siemens?

Siemens is the global market leader in this area. For you, that means:You benefit from the experience of projects for more than 1000 substa-tions and 140000 protection devices implemented in accordance with theIEC 61850 communication standard by the end of 2010. Siemens offersyou IEC 61850 technology that is certified as Class A by the independenttesting laboratory KEMA. Future-proof investment due to convincingmigration concepts: SIPROTEC 4 protection devices manufactured since1998 can be upgraded to make them IEC 61850-compatible without anyproblem. The solutions from the SICAM 1703 and SICAM PAS product linesoffer you flexible configurations for seamlessly integrating the latestIEC 61850 concepts into existing substations.

While reading this brochure, discover the diverse efficiency potential ofenergy automation with the IEC 61850 worldwide communication standard.

Choose a Powerful PartnershipEnergy Automation from Siemens

Ingo ErkensGeneral ManagerEnergy SectorPower Distribution DivisionEnergy Automation Products

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Efficient Energy Automationwith the IEC 61850 StandardApplication Examples Content Page

Switchgear Interlockingwith IEC 61850-GOOSE 3

Reverse Interlocking Usingthe GOOSE of IEC 61850 7

Beneficial Engineeringof IEC 61850 SubstationAutomation Systems 13

Innovative Solutions forSubstation Control withIEC 61850 21

Seamless Migration 27

Ethernet Topologies withIEC 61850 31

IEC Interoperability,Conformance andEngineering Experiences 37

IEC Browser –A Powerful Test Tool forIEC 61850 43

Siemens E D EA · Application Examples for IEC 61850 3

Switchgear Interlocking

Switchgear Interlockingwith IEC 61850-GOOSE

�1. IntroductionFast communication directly between protec-tion devices and bay control units accordingto IEC 61850-GOOSE can be used to imple-ment switchgear interlocking across bays(substation interlocking). GOOSE stands for“generic object-oriented substation event”and is an especially fast communication ser-vice that functions independently of commu-nication between the server (bay control unit)and client (centralized station controller).

And, as the system configurator softwareprovides a view across devices, simple engi-neering of the substation interlocking is possi-ble independent from the station level.

�2. TaskIn the simple example described here, thecoupler and the two feeders of a doublebusbar system exchange the informationitems necessary for substation interlocking(Fig. 1).

The information to be exchanged for substa-tion interlocking are the following:

1) From the coupler to the feeders:Information that the coupler is closed.

If this condition is met, the disconnectorsmay always be operated in the feeder bays(even if the circuit-breakers of the feedersare closed).

2) From the feeders to the coupler:Information that the busbars are connec-ted via the disconnectors. As soon as thetwo busbar disconnectors are closed in atleast one bay, coupler C02 can no longerbe opened because otherwise it would nolonger be permissible to operate the dis-connectors in the feeders. This functionis called a coupler switch blocking. Eachfeeder sends this information to thecoupler bay.

�3. Solution with SIPROTEC and DIGSIConfiguration of the substation interlockingis best performed in four steps:

1) Creation in the DIGSI matrix of the addi-tional GOOSE information items that arerequired

2) Preparation of the CFC charts for gener-ating the new messages and adding to theCFC charts for the switchgear interlocking

3) Creation of the IEC 61850 substation andconfiguration of communication (definingGOOSE subscribers, assigning IP addresses,creating the GOOSE application)

4) Routing of the GOOSE information itemsof the subscribers

In the first step, it is expedient to look at thesingle-line diagram (Fig. 1). This is the substa-tion view and definition of the informationtransmitted and received by the devices.In our simple example, the following informa-tion is required in the three bays:

C01: Transmitted information:Both busbar disconnectors inbay C01 closed

Received information:Coupler closed

C02: Transmitted information:Coupler closed

Received information:Busbar disconnectors in bay C01 closed

Busbar disconnectors in bay C03 closed

C03: Transmitted information:Both busbar disconnectorsin bay C03 closed

Received information:Coupler closed

These information items are created in a newgroup called “GOOSE” in the DIGSI matrix (seeFig. 2 on the following page, example of thecoupler unit in C02).

Fig. 1 Double busbar system with 2 feeders

Coupler

SS = Busbar

Siemens E D EA · Application Examples for IEC 618504


The GOOSE information items each have“CFC” as their source and the “system inter-face” as their destination. Placing a cross inthe “System interface” destination columncauses DIGSI to ask for the logical node namein the IEC 61850 designation. A meaningfulabbreviation can be entered at this point,e.g. “SI” for switchgear interlocking (Fig. 3).

If the simple CFC charts for forming the infor-mation items “Coupler closed” and/or “Busbardisconnectors in Bay C01/C03 closed” havebeen created, the CFC charts can also be addedfor the switchgear interlocking (second step).This is done by including the additional infor-mation in the release of the busbardisconnectors (bays C01 and C03) and/or thecoupler circuit-breaker (bay C02).

The third step is to close the DIGSI device en-gineering and create an IEC 61850 substa-tion. This is done in the DIGSI manager in thesame way as creating a device. A new “house”icon appears with the text “IEC 61850 substa-tion” (Fig. 4).

This icon can be used to start the systemconfigurator, which manages the IP addressesof the subscribers and permits configurationof GOOSE communication. First, the subscrib-ers of the GOOSE communication are defined.For this purpose, the substation is openedwith the right mouse button (via “Objectproperties”) and the “Subscribers” tab is se-lected (see Fig. 5 on the following page).

The upper area shows all available devicesthat can be moved into the lower area withthe arrow button. In this way, multipleGOOSE units can be defined in one DIGSI pro-ject to keep configuration of the connectionssimple. This is achieved by creating a newIEC 61850 substation several times.The IEC 61850 substation can then be openedwith a double click on the house icon. Thistakes you to the system configurator with thetwo views “Network” and “Connection”. Under“Network”, the IP addresses are assigned andunder “Connection” (Fig. 6), the GOOSE infor-mation items are connected, as in the DIGSI 4matrix.

Fig. 2 GOOSE information items in the DIGSI matrix (example of coupler C02).

Fig. 3 Query dialog box for newly created IEC 61850 information items

Fig. 4 “IEC 61850 substation” icon in the DIGSI 4 manager

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Bottom left and right, the GOOSE subscribersare listed in the two windows “Sources” and“Destinations”. In the “Name” column, theIEC 61850 structure of the objects is visibleand in the “Description” column, you can seethe SIPROTEC texts. Under the logical device“Control”, you will find in device C02 the logi-cal node “SFSGGIO1” with the element “C02coupler closed”. You insert this in the upper“Connections” table using the “Add source”button. In the bottom right window “Destina-tions”, you then choose the two correspond-ing information items that have the samename in devices C01 and C03 and movethese to the “Destination” column. The con-nection of these information items is now sto-red in the system.

In the same way, the information items“Busbar disconnector closed” from the feederunits are routed to the coupler. After this, thesystem configurator can be re-closed.As soon as the device parameter sets havebeen updated (triggered on the “Update” tabof the window in Fig. 5), the device parame-ter sets can be loaded. This update causes theGOOSE information to be written into theparameter sets.

After that, the parameters sets can be loadedinto the SIPROTEC devices in the usual way.Again using a right mouse click on the substa-tion, “Export IEC 61850 substation” can nowbe selected. The SCD file is then stored withall information for IEC 61850 communication.This can then be imported by a client, for ex-ample SICAM PAS. In our example, only theinformation report is routed to the client viathe interface; the information required for theinterlocking across bays is handled solelydirectly between the devices using GOOSE.

Fig. 6 “Connection” view in the system configurator

Fig. 5 Selection of the subscribers of a IEC 61850 substation

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�4. Monitoring conceptBecause GOOSE communication transmitssafety-relevant data for switchgear interlock-ing (and also for the reverse interlocking ofprotection devices), monitoring of the con-nection is necessary.This monitoring must

a) Reliably detect and report a failure of thecommunication line

b) Work selectively, i.e. only report infor-mation items as faulty that can really nolonger be transmitted.

For this purpose, monitoring is performed attwo points in the system: first, at eachEthernet channel, monitoring has the task ofchecking whether a connection to a switchexists. This also enables detection of failure ofone channel in redundant communication,while communication is running via the sec-ond channel. For example, it is possible totake remedial action in time and maintainavailability.

Second, the status of an information item canbe evaluated. If the required communicationchannel is interrupted, the bit “NV” for “notvalid” is set. This example illustrates this withthe assumption that the connection betweenC01 and C02 has been interrupted (Fig. 7).

In this case, the following information isinvalid:

• “Coupler closed” in device C01• “Busbar disconnector in bay C01 closed” in

coupler C02

Additionally, the interrupted connections areshown in devices C01 and C02 ("Channel 1faulty”).

The devices C02 and C03, on the other hand,can continue to communicate undisturbed.

In this fault case, it must be ensured thatthese interlocking conditions that process thenon-available information remain blocked.This is done by including the status in theseconditions. The status can be obtained fromthe information items with the status CFCblocks in DIGSI 4 and then evaluated in the in-terlocking conditions.

�5. SummaryThe use of IEC 61850-GOOSE enables imple-mentation of “substation wide switchgear in-terlocking” as a distributed application. Thishas the advantage of independence from acentralized station controller and increasedavailability. This example shows how wiringbetween bay control units is replaced easilyand reliably by GOOSE-telegrams. In variousprojects around the world, Siemens has suc-cessfully implemented this concept. Stan-dardization of the IEC 61850 interface alsomakes it possible to build up interoperable so-lutions. In the GOOSE network, informationcan be exchanged between equipment of dif-ferent manufacturers. This means that custo-mers can now build their substation withdevices from different manufacturers, whichwas previously only possible for the protec-tion equipment.

Fig. 7 Interrupted connection between 2 devices

Interrupted connection

�1. The principle of reverse interlockingReverse interlocking provides a low-cost wayof implementing busbar protection in conjunc-tion with time-overcurrent protection devices7SJ62 (Version 4.7 and higher) and 7SJ64.These devices have the performance requiredto execute time-critical protection applicationsusing GOOSE. The busbar is powered througha transformer feeder and the other feeders(Fdr.1 – Fdr.3) go to the loads (see Fig. 8).If very short tripping times of under 15 ms arerequired, a 7SS60 or 7SS52 busbar protectionsystem must be used.

In IEC 61850, a time-overcurrent protectionstage (DMT/IDMT) is described by the logicalnode “Protection Time Overcurrent” (PTOC).Pick-up of the stage is termed “Start” (str);tripping is termed “Operate” (Op). There is aparameterizable low-set or high-set currentstage (I> or I>>). If this is exceeded by theshort-circuit current, the stage is picked upimmediately (I> picked up / PTOC.str).After a parameterizable time delay T haselapsed, a trip command for the stage isissued (I> Trip / PTOC.Op).

On pick-up (I> picked up / PTOC.str) of thetime-overcurrent protection stage I> in fee-ders 1 – 3 (Fdr.1 – Fdr.3), the I>> stage of theincoming feeder is blocked via a binary input.The binary input is routed such that thisblocking is active without a voltage. The I>>stage of the incoming feeder is set with thedelay time T (70 – 100 ms) so that reliableblocking is ensured by a pick-up (str) in thefeeders before the time delay of this stageelapses in the incoming feeder. During nor-mal operation, a voltage is applied to the bi-nary input via a loop line through the closedcontacts. This means that the high-set I>>stage is not blocked and trips after the delaytime on pick-up of the I>> stage.

�2. Intended response of the interlockingto a short circuit

2.1 External short circuit on a feederAn external short circuit at position 1 (see Fig. 8)results in pick-up of the I> stage of the uniton feeder 1. This pick-up is routed to a nor-mally-closed contact and blocks the I>> stageof the incoming feeder via the binary input(BI) because the binary input is de-energizedwhen the contact opens. The short circuit iscleared by the time-overcurrent protectiondevice of the short-circuited feeder when itsdelay time has elapsed.

2.2 Short circuit on the busbarThe I>> stage of the incoming feeder is set toreliably pick up value in response to a busbarshort-circuit. A busbar short-circuit at posi-tion 2 does not result in pick-up by theI> stages of the devices in feeders 1 to 3.After the set delay time T has elapsed, a tripcommand is issued and the short circuit iscleared.


Reverse Interlocking

Reverse Interlocking Usingthe GOOSE of IEC 61850

Fig. 8 Simple busbar protection using reverse interlocking

Incoming feeder withtransformer

Infeed

Blocking of the I>> stage(active without voltage)

BI

Fdr. 1 Fdr. 2 Fdr. 3

Loop line

OvercurrentI> picked up





�3. Principle of GOOSE telegramtransmission (GOOSE messages)of IEC 61850

If a signal, e.g. the pick-up ”Overcurrent I>picked up”, is configured in a GOOSE message,the unit sends this message cyclically every0.5 seconds as a telegram over the Ethernetnetwork via Ethernet module EN100 at100 MBit/s. Such a telegram is just a fewmicroseconds long. The GOOSE message istransmitted with high priority in the network.The cyclic repeat time can be set in the sys-tem configurator and should be set with “highpriority” in protection applications. The con-tent of this telegram communicates the stateof pick-up (not picked up or picked up) to thesubscribers of the GOOSE message. The cyclictransmission enables each of the subscribersto detect a failure using a logic block when atransmitter has failed or a communicationschannel has been interrupted. This providesconstant monitoring of the transmission linebecause the subscriber expects to receive atelegram at several-second intervals. This isequivalent to pilot-wire monitoring in conven-tional wiring. On a pick-up, i.e. a signal chan-

ge, a GOOSE telegram is transmitted sponta-neously. This telegram is repeated after 1 ms,2 ms, 4 ms etc. before returning to cyclic ope-ration. The repeat time after a spontaneouschange is also configured in the system confi-gurator. If the pick-up drops off again withinthis time, the spontaneous transmission is re-peated. Fig. 9 shows the method as appliedto the pick-up signal. Each unit in the feedertransmits its GOOSE telegram to the unit inthe incoming feeder.

�4. Parameterization with DIGSI andsystem configurator

4.1 Station configuration in DIGSIFirst, a station is configured with the devicesin DIGSI (see Fig. 10). In addition to the devi-ces of the feeders and the incoming feeder,an IEC 61850 station is also required, whichwill later contain the system configuration.Using the time server, which may be integrat-ed into the PAS master unit, the time in thedevices is synchronized via the SNTP – proto-col via Ethernet. The devices only require thenetwork address (IP address) of the timeserver.

Fig. 9 How binary states are transmitted with GOOSE telegrams

Fig. 10 Station configuration in DIGSI

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Voltage at the BIof the infeed

Overcurrent: I> picked up = 0(contact close)

I> picked up = 0(contact close)

I> picked up = 1(contact opens)

Cyclic repeat time e.g. 0,5 s

Cyclic GOOSEI> picked up = 0

Transmittedtelegram

Spontaneous GOOSEI> picked up = 1

Spontaneous GOOSEI> picked up = 0


First repetition

1 2 ms 4 ms 8 ms 1 2 ms

12 μs


1

t

t



4.2 Settings in the devices of the feedersOnly settings that are necessary for this appli-cation are discussed here. In practice, therewill be further functions and routings to set.The IED name must be entered under the“Object properties” -> “Communication param-eters”. It is required in the IEC 61850 configu-ration to identify the device (see Fig. 11).The network parameters are later set in thesystem configurator.

The device must then be opened and savedagain to generate an IEC 61850 configurationfile (ICD file).

Under “Time Synchronization”, “Ethernet NTP”is selected (Fig. 12). Settings for the timezone and daylight-saving/standard time swit-chover can be set for a specific region. Withthis setting, the device queries the SNTP timerabout once a minute. The IP address of thetime server is set in a standardized way for alldevices in the system configurator and doesnot have to be configured separately in eachdevice.

In the network topology (see Section 5), thedevices works with an integrated switch inthe optical ring. Under “Communication” ->“Ethernet on device”, “Switch” mode must bechosen for the optical module (Fig. 13). Thissetting must be made in the optical ring foreach device. This dialog box also allows youto check the set IP address later.

In the routing matrix, the signals to be trans-mitted as the destination via the system inter-face S are configured. Because the I> pickedup indication is defined as a mandatory mes-sage in the IEC 61850 standard, it is alreadyrouted to S and cannot be unrouted by theuser. With a right-mouse click on the message,it is possible to view the IEC 61850 messagetext under “IEC 61850” (PROT/PTOC6/Str).This information is also seen as plain text inthe protocol and will later be required in thesystem configurator (see Fig. 14 on the fol-lowing page). After that, the unit is saved andDIGSI automatically creates all the data of thedevice that is necessary for IEC 61850 config-uration.

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Fig. 11 Setting of the communication parameters

Fig. 12 Time setting dialog box in DIGSI

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Fig. 13 Settings for the integrated switch

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4.3 Settings in the device in the incomingfeeder

Here, more extensive settings must be made.“Ethernet NTP” is selected as the time syn-chronization source and the integrated switchis set.A new information group is inserted in therouting matrix and named “GOOSE”. Here,new messages of the object type “Externalsingle point” from the information catalog arerequired. For each transmitted pick-up indica-tion of a feeder, a corresponding message isrequired with which the start message is fur-ther processed. A meaningful short text and

long text are edited for the message (DIGSItext). The message is routed to the systeminterface as a source and must be providedwith an IEC 61850 message text in a propertywindow (see Fig. 15). The structure of thetext is largely defined by the standard. Thistext is required in the system configurator.The messages are routed into the logic editor“CFC” as destination and further processedthere. Blocking of the I>> stage “>Block I>>”is routed to the CFC as the source because theblocking is mapped there by logic blocks. Mo-reover, a further message is created in theGOOSE group that generates an alarm ifthere is a disturbance in the GOOSE link(GO-alarm). This information can, for exam-ple, be routed to an LED, a contact, or the sys-tem interface as the destination and used asan alarm in the substation control unit.

4.4 Settings in the CFC in the device ofthe incoming feeder

With a little logic, the blocking and alarming isperformed in the CFC. Time-critical protectionapplications must be processed in the fastCFC charts. The new chart is named GOOSE.

Blocks of category “SI_Get_Status (Decoder)”are inserted and each is connected to thepick-up signals of the right-hand margin(sources) (see Fig. 16). Such a block has a“Value” output that indicates the ON/OFFstate of the message at the input. The “NV”output stands for “not valid”. If a GOOSE sig-nal is no longer received, this output is set.The pick-up signals are connected to an“OR block” whose output goes to the blockingof the I>> stage on the right-hand margin.The NV outputs are connected with the GOOSEalarm via an OR block. Depending on theoperator philosophy, this signal can also beused for other actions, e.g. blocking the stage.

Fig. 14 Routing of the pick-up message on system interfaceIEC 61850 message text in “Object properties” window

Fig. 15 Settings in the device of the incoming feeder in the routing matrix

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Fig. 16 Formation of the blocking I>> stage and the GOOSE alarm in the CFC

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Status-blocks OR gate

Left margin withpick-up signalsreceived viaGOOSE

Right marginwith DMT/IDMTI>> blk and GOOSEalarm

Configured IEC 61850 message text



4.5 Settings in the system configurator(Fig. 17)

First of all, all IEC 61850 devices of the stationare added to the system configurator. Thisalso adds the ICD files of the devices. This isdone in the “Station Manager” with aright-mouse click on the IEC 61850 stationunder “Object properties” -> “Communicator”.Then the system configurator is opened.

There, the first step is to set the IP addressesof the devices. DIGSI suggests networkaddresses, which are normally accepted. Notethat network addresses of other devices, forexample, the time server, the PAS, and theswitches must be set with the configurationsoftware of these devices. Only the IP ad-dresses of SIPROTEC units are configured withDIGSI. Moreover, the system configuratordoes not show all devices. To avoid networkconflicts due to duplicate IP addresses, it isadvisable to draw up a list of all network de-vices.

The next step is switchover to the connectionview. The system configurator offers a de-fault GOOSE application that is renamed inthe right-hand “Properties” window (ReverseInterlocking) and is set to high priority. Thismeans that the GOOSE messages are repeat-ed cyclically and spontaneously with highfrequency: every 0.5 s cyclically, starting with1 ms repetition on a spontaneous change to amessage.

The devices are listed with their signals on theleft-hand side below. For each device, theprotection pick-up must now be inserted asthe source signal in the connection view. It ishelpful if the familiar SIPROTEC texts are dis-played along with the IEC 61850 standardtext (e.g. Fdr1.PROT.PTOC6.str.general). Onthe right, the destination signals are availablethat have been configured as “External singlepoint indications” in the device of the incom-ing feeder. In the connection view, a “Source”is now connected to the “Target”. This is equi-valent to conventional wiring of a contact to abinary input. A source signal can also be con-nected to multiple destinations, although thisis not required in this case.

When configuration has been completed, it issaved and the system configurator is closed.A configuration file of the station (SCD file)is then generated automatically, which is inconformance with the IEC 61850 standardpart 6.

4.6 Loading of the configuration datainto the devices

Under “Properties” (right mouse click onIEC 61850 station) and “Update” the parame-ter sets of the devices are now updated withthe IEC 61850 relevant data. The devices onlyhave to be initialized once via the front serialinterface. Then they are assigned with net-work addresses and IEC 61850 configurationdata. Further updates can be performed viathe Ethernet interface (Fig. 18).

Fig. 17 Configuration of the signal connections in the system configurator

Fig. 18 Updating of the devices with the IEC 61850 configuration

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Sourcesignals

Destinationsignals



�5. Network topologyThe network is implemented as an opticalring that is terminated with a switch(see Fig. 19). At this point, a PAS master unitis connected. This unit is not involved in theGOOSE application but may, for example,read out messages and fault recordings fromthe devices and can pass on the GOOSEalarm. It can additionally monitor the topol-ogy of the network, which is implementedusing a special monitoring protocol SNMP.It also performs time synchronization in thenetwork with 1 ms accuracy via the SimpleNetwork Management Protocol (SNTP).

In the devices, an optical Ethernet modulewith an integrated switch is used. This achie-ves a maximum of electromagnetic immunityand fault-free data transmission. With con-ventional wiring, the signal wires can be pro-ne to high interference voltages. Except forthe SIPROTEC devices, few other networkcomponents are required, which reduces theconfiguration effort and increases the reliabi-lity of the system. The failure of one device istolerated in the optical ring because the net-work restructures itself into two chains in amatter of milliseconds and the devices cancontinue to intercommunicate. The data traf-fic is controlled by special filters on the opticalmodule to ensure that GOOSE telegrams areonly listened to in the devices that expect in-formation from a GOOSE telegram. This redu-ces the processor load on the Ethernetmodule, which is not constantly troubled withtelegrams with irrelevant content, as GOOSEtelegrams are always sent to all devices.GOOSE telegrams are also prioritized over re-gular data traffic, which is a special feature ofthe IEC 61850 GOOSE. A GOOSE messagepasses through the integrated switch of adevice in 4 s, so that it runs through the ringalmost without delay.

�6. SummaryUsing the peer-to-peer communication ofIEC 61850, parallel wiring between bay con-trol units can be replaced by GOOSE. This canalso be used for time-critical protection appli-cations. This requires the use of devices withhigh computing power, such as 7SJ64, 7SJ62as from Version 4.7, 7SA52/6, 7SD52/6,7UM62, and 6MD66. In place of hardwiring,the DIGSI software is now used for configura-tion according to the methods standardized inIEC 61850.

Optical links permit reliable operation. Due tothe ring topology of the network and exten-sive monitoring functions, component failurecan be detected in a matter of seconds. Thisresults in high availability because operationcan continue even if one component fails.These monitoring mechanisms are compara-ble with the constant pilot supervision of wireconnections, which is usually only implement-ed for tripping circuits because of the extracosts incurred for external components.Using the GOOSE mechanism of continual re-petition of telegrams and intelligent monitor-ing modules in the device, monitoring is im-plemented in the software, as is already thestate of the art in digital communication links,for example in differential protection.

Nevertheless, the method does require thor-ough commissioning that verifies correctfunctioning and checks the time response.This is supported by the internal logging ofthe devices and test tools. Test equipmentand software tools are now available thattrace the GOOSE messages on the bus andmake a record with millisecond precision, inthe same way as for binary signals that aregenerated via contacts.

Fig. 19 Structure of the Ethernet network as an optical ring

PAS master unit with timesynchronization (SNTP) andnetwork monitoring (SNMP)

Fdr. 1 Fdr. 2 Fdr. 3 Incoming Fdr.

Fiber-optic cable

ElectricalEthernet cableEthernet

switchMulti-mode fiberOperatingPC withDIGSI

62.5/125 μm or 50/125 μm


Beneficial Engineering

�1. IntroductionEngineering expenses dominate both the in-vestment costs of an SAS (Substation Auto-mation System). Consequently, the main wayto reduce these costs is to optimize the engi-neering process.

The process of engineering an SAS involvesseveral activities: system design and specifica-tion, device and system configuration,device parameterization, documentation,testing and diagnostics, and commissioning.Each activity includes several system levels,ranging from process interface, protection,and communication settings up to SCADAfunctionalities.

The current practice in engineering an SAS isto use vendor-specific tools, each of which isdesigned for a particular engineering activityand a particular system level. As a conse-quence, the engineer ends up using a chainof tools, especially in multi-vendor applica-tions, and expending a lot of effort on dataentry (often entering the same data multipletimes into various tools), data exchange, andmanual data conversion between tools. In ad-dition, these tools rarely support the reuse ofengineering data from existing installations innew or retrofitted projects.

The communication standard IEC 61850offers great hope for simplifying this process.With its object-oriented data model and for-mal description language, it promotes reusa-bility, data interoperability, and seamlessengineering.

In the pages that follow, the challenges in-volved in the process of engineering an SASare described. Then, the requirements for anefficient and comprehensive work flow bothin the project process and at the system levelare defined. Then, it is shown howIEC 61850’s intelligent methodologies canovercome these limitations and improve engi-neering efficiency.

�2. Engineering processEngineering an SAS to the point of systemcompletion and operation involves severalproject phases. Aside from commercial andproject management matters, all of theproject‘s technical concerns fall in the catego-ry of engineering. In the substation-automati-on domain, the term engineering includes alltechnical activities necessary for building andrunning an SAS over its complete life cycle –including modifications and extensions.These engineering activities include: systemspecification, device and system configura-tion, device parameterization, documenta-tion, testing, diagnostics, and commissioning.

2.1 Engineering roles and active partiesDuring the engineering of a substation auto-mation project, several parties are involved.Typically, the active parties include the utility,the consultant, the service provider, and thevendor. Depending on the project conditions,these parties can play different roles regard-ing engineering activities. With respect to theengineering phase of a project (commercialmatters are already clarified), the basic rolesinclude system owner, system integrator, andoperator. The role of the system integrator in-cludes all activities from system design andplanning through the commissioning stage.Thus it is not unusual for the role of systemintegrator in a project to be split amongmultiple parties.

In most projects, the utility specifies the SASand buys a turnkey system. In this case, theutility is usually the system owner and opera-tor, while the vendor or service provider is thesystem integrator.

In addition, various other arrangements arepossible, with the active parties playing differ-ent roles, see bibliography on page 19,reference [1].

Beneficial Engineering ofIEC 61850 Substation AutomationSystems



2.2 Engineering activitiesFig. 20 shows the engineering activities andsystem levels involved in erecting or retrofit-ting a typical SAS. The structure of the SASconsists of bay controllers and protectionrelays, which are connected to the primaryequipment via a process interface. TheseIEDs at the bay level communicate with eachother, and with IEDs at the station level, via acommunication infrastructure. Communica-tion to a remote control center is imple-mented by a WAN connection.

Due to these different system levels – rangingfrom process interface up to SCADA functio-nalities – engineering is carried out both inthe horizontal direction (activities) and in thevertical direction (system levels) in order tocomplete a system.

A short description of the engineering activi-ties is given below.

a) Design and specificationThis phase involves planning and specifyingthe layout, functions, and applications of anSAS. These tasks can be carried out by theutility, the service provider, the consultant orthe vendor.

Generally, the requirements of the primarysystem determine the design of the second-ary system. The functions and applications ofthe primary system regarding protection,operation, and monitoring are compiled andmapped to the secondary system according toeach application. Usually, the customer’s phi-losophy and requirements influence the spec-ifications of the functions and applications inareas such as the protection scheme, the con-

trol hierarchy, interlocking, and the HMI de-sign (including how all these functions aredistributed to IEDs). The design process in-volves defining details such as process param-eters (for example, current and voltagescaling), system parameters (for example,data exchanged for interlocking purposes),and setting values (for example, pick-up val-ues for the overcurrent protection). The resultis an application-specific data model that isrepresented by specifications typically docu-mented in the form of written requirementspecifications, including flow-charts and sig-nal lists.

Based on these specifications, a system con-figuration and appropriate IEDs meeting thefunctional requirements are selected.

b) Device and system configurationThis phase involves configuring the selectedSAS solution. A system integrator usually per-forms this task.

Configuration typically begins with devices.Starting from the requirement specifications,the desired functions and applications aretranslated into a device-specific data modeland operation code. These include protectionsettings, interlocking terms, CFC-Logic, HMImimics and diagrams. Device-specific toolsare used for configuring these items.

The communication infrastructure can beseen as the backbone of an SAS. Merging thedevices to a system by communication is thescope of system configuration. In system con-figuration, the communication parametersare set in order to determine what data is

Fig. 20 Engineering activities and system levels

Engineering Activities

Design &Specification

Device & SystemConfiguration

DeviceParameterization

Testing &Diagnostic Documentation

Commissioning& Operating

Application (HMI)

Communication (CC-Interface)

Communication (Station Bus)

Application (Protection & Control)

Process Interface

System LevelsHMI Station Unit

ControlCenter

StationLevel

BayLevel

ProcessLevel

Process

IEDs



exchanged – and how it is exchanged – be-tween devices, station unit, HMI, and remotecontrol centers.

c) Device parameterizationIn this phase, the system integrator deploysthe device-specific data models, settings, andoperation code to the appropriate devices.Naturally, device-specific tools are used fordownloading the data to devices.

d) Testing and diagnosticsTesting and diagnostics are crucial for con-firming proper operation of an SAS – or fortrouble-shooting, in case of malfunction.The testing and diagnostic tools are predomi-nantly vendor-specific, often functionallyintegrated within device configuration tools.Extensive testing takes place during FAT,commissioning, and SAT, usually with thesupport of monitoring and diagnostic tools.

e) DocumentationThe documentation is carried out by a systemintegrator and includes:

• Electric circuit diagrams of the completeSAS

• Signal lists• Communication address lists• Parameter settings (process, protection,

and communication)• Data lists for bit tests• Operational and technical manuals• Acceptance reports• Commissioning reports

f) Commissioning and operationCommissioning begins after the system is in-stalled and passes its acceptance tests. Thesystem integrator usually performs this task,together with the owner or the operator orboth. During the operation phase, periodic orcondition-based maintenance activities takeplace. In addition, modifications or evensystem extensions may requirere-engineering.

2.3 Limitations and issuesIn practice, the engineering process describedabove is rarely seamless and straightforward– mainly because it requires vendor-specifictools designed for a particular engineering ac-tivity and system level, and the use of propri-etary data models. Projects with a homo-genous system platform (all devices from thesame vendor) involve relatively minor issues,as the tools are usually coordinated to cover

multiple system levels and activities. But inmulti-vendor applications – typically in highvoltage (> 110 kV), exchange, or extensionprojects – tool import and export qualitiesplay a major role.

The use of multiple tools in a project has thefollowing consequences:

• The engineer has to pass the processthrough a chain of tools, often with itera-tion loops.

• The same data must be entered multipletimes for different devices and systemlevels.

• System integrators and operators have tohandle a multitude of devices and tools (va-rying in type, manufacturer, technology,and modeling), each of which requiresappropriate training and know-how.

The data models of most tools are stronglysignal-oriented. As a result, mapping data toHMI applications requires extensive conver-sions to technology-oriented objects (e.g. cir-cuit breakers, disconnectors, transformers,and so on).

In addition, it is common in project activitiesthat most artifacts (requirement specifica-tions, documents, signal lists, data models,and so on) are neither standardized nor uni-form. These items are strongly influenced bycustomers’ and vendors’ work practices, tools,and philosophies. So, the following limita-tions and consequences occur:

• Extensive data conversions are requiredamong tools

• Reuse of engineering data is difficult



�3. RequirementsTo avoid the above-mentioned limitations andissues, an efficient engineering process needsto meet the following requirements regardingdata models and tools:

• Standardized and technology-oriented datamodel

• Unified interchange format for data-modelrepresentation

• Standard import and export interfaces forall tools

• Template support for easy reuse of engi-neering data in all types of cases, fromsimple system extensions up to delta engi-neering of complete systems

• An interface that hides complexity fromusers as a default, with expert mode avail-able on demand

• A single-tool model (covering a wide prod-uct range) in order to reduce the number oftools used in a project

• Integrated communication configurationcapabilities to further reduce the number oftools used per project

• Vendor-independent testing and diagnostictools

• Well defined interfaces between user roles

�4. Benefits of IEC 61850 engineering4.1 Key features of the IEC 61850 standardThe short abstract that follows provides a ba-sic understanding of IEC 61850 – its princi-ples, concepts, and methodologies.Unlike other applied communication stand-ards, such as IEC 60870-5-101 /-103 /-104,the IEC 61850 standard goes beyond justcommunications.

Key features are:

• An object-oriented and application-specificdata model focused on substation automa-tion, see bibliography on page 19, ref.[2-4]. This model includes object types re-presenting nearly all existing equipmentand functions in a substation – circuit-breakers, protection functions, current andvoltage transformers, waveform recordings,and many more.

• Communication services providing multiplemethods for information exchange. Theseservices cover reporting and logging ofevents, control of switches and functions,polling of data-model information, real-time peer-to-peer communication (GOOSE),sampled value exchange, and file transferfor disturbance recordings, see bibliogra-phy on page 19, ref. [5, 6].

• Decoupling of data model and communica-tion services from specific communicationtechnologies. This technology independ-ence guarantees long-term stability for thedata model and opens up the possibilityof switching over to successor communi-cation technologies, see bibliography onpage 19, ref. [7].

• A common formal description code, whichallows a standardized representation of asystem’s data model and its bindings tocommunication services, see bibliographyon page 19, ref. [8]. This code, called SCL(Substation Configuration DescriptionLanguage), covers all communicationaspects according to IEC 61850. Based onXML, this code is an ideal electronic inter-change format for configuration data.It provides for the following four types ofSCL files:

– SSD (Substation Specification Descrip-tion) files: these include primary equip-ment and topology information and itsbindings to basic application functions.The use of SSD files is optional.

– ICD (IED Capability Description) files:these include information about thefunctional capabilities of an IED.

– SCD (Substation Configuration Descrip-tion): these include the configured datamodels and communication settings ofall IEDs participating in an SAS

– CID (Configured IED Description)is an IED-specific subset of the SCD,which includes all relevant informationfor an IED. Its use is optional.

• A description of requirements of the systemand project management process and ofspecial tools for engineering, see bibliogra-phy on page 19, ref. [9]

With SCL, the IEC 61850 standard introducesa powerful and unique feature into the sub-station-automation domain. SCL allows a uni-form and vendor-neutral representation of asystem’s communication configuration to beused over the complete system life-cycle.



4.2 The SCL-centered engineering processToday vendors offer powerful tools which arecapable of handling SCL and meeting therequirements in terms of beneficial enginee-ring. These tools make the SCL-centered engi-neering process a reality. The sections thatfollow describe the SCL-centered engineeringmethodology and present its benefits. Fig. 21illustrates how the SCL files are passedthrough engineering activities.

a) Design and specificationSpecification data that is not relevant forcommunication is still in the form of draw-ings, tables, and CFC charts. The system spe-cification can be carried out with a dedicatedsystem specification tool in order to create anSSD file, but this method first may providereal benefits for substation to control centercommunication in the future.

However, all specification data directly appli-cable to communication can be covered bymeans of IEC 61850. Therefore it is importantto select suitable devices that provide speci-fied functionality and map the application-specific data to the IEC 61850 data model.The result of such device specification is thecollection of ICD files in accordance with theIEDs that are used.

Benefits:• Selection of conformance-certified IEDs.

With its standardized conformance testing,the standard allows selection of deviceswith conformance certificates. This ensuresa high degree of interoperability andperformance.

• Automatic creation of IED-specificIEC 61850 data models in the form of ICDfiles. In the case of device specification,

such tools offer the benefit of automatical-ly creating the 61850 data model. Forexample, in the case of a tool for controland protection devices, when the control ofa switch is required, the tool automaticallymaps it to the IEC 61850 domain by crea-ting appropriate instances of data objects(logical nodes XSWI, CSWI, CILO).

b) Device and system configurationThe detailed configuration of application func-tions – such as protection, control, interlock-ing, and so on – is within the scope of deviceconfiguration. With its uniform naming con-vention, the IEC 61850 data model allows theuse of seamless object and signal names intools. Object-oriented filtering offers distinctadvantages in configuration, especially duringconfiguration of the HMI and the controlcenter.

The system configuration includes all usecases for the configuration of communicationapplications. This configuration can be per-formed by the system configurator tool, whichis advantageously implemented in the deviceconfiguration tool. The system configuratortool imports all ICD files and sets basic commu-nication settings (e.g. IP addresses), reportconfigurations, and GOOSE configurations.In this manner, it creates the system’s SCDfile.

Benefits:• Seamless naming of data objects. Standard

naming conventions simplify data mappingto HMI and control-center applications.

• Simple handling of communication. Hidingcomplexity from users simplifies configura-

Fig. 21 The principles of SCL-centered engineering. ICDs = IED Capability Description files,SCDs = Substation Configuration Description files.

Engineering Activities

Design &Specification

Device & System-Configuration

DeviceParameterization

Testing &Diagnostic

Documentation Commissioning& Operating

Functional &operationalrequirements Tools Archive

Changes,extensions



tion and makes it easier to focus on the ap-plication itself.

• Built-in quality management. The built-insupport of revision tags in SCL allows moreeffective detection of changes in configura-tion files. In addition, the provided toolsvalidate the IED model against the standardand check its consistency.

c) Device parameterizationThe SCD file is deployed to all participatingIEDs. After importing the SCD file, the devicetools extract the relevant data subset anddownload the configuration data to the IED.

Benefit:• One common configuration file for all IEDs.

No additional device-specific communica-tion configuration is needed.

d) Testing and diagnosticsBased on Ethernet technology and on a stand-ardized protocol stack, the IEC 61850 stand-ard offers several advantages for testing anddiagnostics.

Benefits:• Simulation and testing of IEDs. With special

testing tools, it is possible to test communi-cation behavior by simulating heavy net-work traffic or special telegrams. Thesetools – and also the testing equipment forprotection functions – can import SCD filesfor simpler handling.

• Vendor-neutral testing and diagnostic toolsallow staff training to focus on fewer tools.Due to the standardized protocol stack ofIEC 61850-8-1, object browsers of IED ven-dors or test equipment manufacturers canbe used for all IEC 61850-compliant IEDs –and for network-traffic analysis tools thatare well established outside the substati-on-automation domain.

e) DocumentationThe SCD file represents the electronic docu-mentation of the communication configura-tion of an SAS. This file offers the followingadvantages for documentation purposes:

Benefits:• One common representation of the com-

munication configuration of a completesystem.

• Automatic creation of data lists for commu-nication tests.

f) Commissioning and operationThe standardized and technology-orienteddata model of the IEC 61850 standard, whencombined with a tool that supports object-oriented templates, opens various benefits forcurrent and future systems. In addition, thecomprehensive IED data models provide valu-able information for the utility.

Benefits:• Simple changes and extensions. When an

IED is modified, any changes in a templateare propagated to all instances of this tem-plate. Templates can also allow creation ofa new bay, including all necessary IEDs –a much more efficient method than usingcopy and paste.

• Access to maintenance data. During opera-tion, it is easy to read information neededfor asset management, including nameplates, switching operation counters,switching currents, and so on.

4.3 Delta engineeringDelta engineering is the most efficient way toengineer a new system. It involves taking anexisting configuration and applying changesand extensions in order to meet the newrequirement specification. This method isnot new, but with IEC 61850’s benefits –especially its data model – a higher level ofreusability is attainable.

�5. SummaryOptimizing the engineering process offersgreat potential for reducing investment andinstallation costs of substation automationsystems. The IEC 61850 standard providesseveral features that allow streamlining of allactivities from specification up to the opera-tion phase.

A promising lever for increasing efficiency ofengineering in substation automation is thevertical expansion of the IEC 61850 standard.By closing the gaps between substations andcontrol centers and between process and baylevel, the IEC 61850 standard’s seamless com-munication will overcome the last of the com-munication discontinuities.



Bibliography[1] K.-H. Schwarz “Impact of IEC 61850 on

system engineering, tools, peopleware,and the role of the system integrator”,Proceedings of Distributech, San Diego,USA, Feb. 2007.

[2] IEC 61850-7-1, "Communicationnetworks and systems in substations –Part 7-1: Basic communication structurefor substation and feeder equipment –Principles and models", Ed. 1, Jul. 2003.

[3] IEC 61850-7-3, "Communicationnetworks and systems in substations –Part 7-3: Basic communication structurefor substation and feeder equipment –Common data classes", Ed. 1, May 2003.

[4] IEC 61850-7-4, "Communicationnetworks and systems in substations –Part 7-4: Basic communication structurefor substation and feeder equipment –Compatible logical node classes and dataclasses", Ed. 1, May 2003.

[5] IEC 61850-8-1, "Communicationnetworks and systems in substations –Part 8-1: Communication ServiceMapping (SCSM) – Mappings to MMS(ISO 9506-1 and ISO 9506-2) and toISO/IEC 8802-3", Ed. 1, May 2004.

[6] IEC 61850-9-2, "Communicationnetworks and systems in substations –Part 9-2: Specific Communication ServiceMapping (SCSM) – Sampled values overISO/IEC 8802-3", Ed. 1, Apr. 2004.

[7] IEC 61850-7-2, "Communicationnetworks and systems in substations –Part 7-2: Basic communication structurefor substation and feeder equipment –Abstract communication service interface(ACSi)", Ed. 1, May 2003.

[8] IEC 61850-6, "Communication networksand systems in substations –Part 6: Configuration descriptionlanguage for communication in electricalsubstations related to IEDs", Ed. 1,March 2004.

[9] IEC 61850-4, "Communication networksand systems in substations –Part 4: System and project management",Ed. 1, Jan. 2002.


Innovative Solutions with IEC 61850

�1. IntroductionSince IEC 61850 was published as an interna-tional standard for communication in substa-tions, the standard has found broad accept-ance on the markets. In the first substationsto use it, the primary aim was successfulimplementation of existing concepts andsolutions using the new technology. Thispositive experience from the initial projectssecured the trust of the substation operators.However, these substations did not yet makeuse of the potential of IEC 61850.

With the rapidly growing number of imple-mented substations, confidence grew in theequipment and the first applications arosethat made specific use of the new technolo-gy. The most frequent control applica-tion was the decentralization of switchgearinterlocking using GOOSE messages.

The new communication standard containsmuch more comprehensive definitions thanother protocols and is primarily intended toimprove interoperability between devices

from different manufacturers, providelong-term investment protection and imple-ment efficient exchange of object-orienteddata models between engineering systems.In addition, IEC 61850 offers the possibility ofreplacing parallel wiring with Ethernet and ofimplementing fast information exchange be-tween devices. This article chiefly deals withthis aspect and contrasts these concepts withthe conventional approach.

Two practically proven examples demon-strate how modern solutions for digital substa-tion automation incorporating new functionsfrom IEC 61850 increase the benefit for users.

The application examples are2. Distributed synchro-check (page 22)3. Mash station automatic switching (page 24)

Innovative Solutions forSubstation Control with IEC 61850



�2. Distributed synchro-check2.1 The applicationThe synchro-check function checks beforeclosure of a circuit-breaker whether the elec-trical parameters of the two subnetworks arewithin the defined limits. This check is neces-sary to limit transient phenomena on connec-tion. For this purpose, the voltage of thefeeder to be switched is compared with thebusbar voltage for magnitude and phase an-gle, and frequency values.

For safety and cost reasons, a voltage trans-former is rarely mounted directly on a busbarin modern systems. To determine the voltageon the busbar, a reference bay is selected byapplication software. The bay control unit(BCU) in this reference feeder switches thevoltage to a ring line via a relay. This ring linedistributes the voltage to all bays and the BCUin the feeder to be switched picks off thevoltage from the ring line. Now, all necessaryinformation is available and the BCU autono-mously checks whether the synchro-checkconditions are fulfilled. If the voltage ampli-tude, angle, and frequency differences arewithin the defined limit values, release is per-formed by the synchro-check function andthe circuit-breaker closes.

2.2 Conventional conceptImplementation of the distributed synchro-check function with digital control technologyhas been state of the art for many years. Inmost substations with this functionality, thelogic for determining the reference bay is im-plemented centrally in the station controlunit. This means the control at station level is-sues a command to close the circuit-breakerof a bay A. This command is received in thestation control unit and the reference bay isselected in centralized logic that takesaccount of the relevant position indicationsand information items. Then the station con-trol unit sends a command to the selected BCUin the reference bay to close the ring line relay.The BCU of bay A can then run the synchro-check.

Fig. 22 Configuration for the distributed synchro-check

Reference bay

Ring line

CB ON

Fig. 23 Command sequence in the conventional concept

Station control unitcentralized logic

Station HMI

ON comCB in bay A

ON com-mand ringline

Reference bay Bay A

Bay A



2.3 Concept using peer-to-peercommunication

Since the introduction of IEC 61850, a newcommunication service has been available forefficient distribution of information betweendevices of the bay level. The applicationdescribed here shows how the GOOSE(generic object-oriented substation event)mechanism can be used to advantage.

This represents a decisive change as com-pared with the conventional, centralized con-cept. Having received the command from thecontrol point with switching authority, theBCU distributes the information “Referencebay search” to all other BCUs in a GOOSE tele-gram. The same logic to determine the refer-ence bay runs in parallel in all BCUs. As in theconventional concept, the logic considers theposition indications and additional informa-tion items in determining whether eachfeeder can be used as the reference bay. Thenon-bay-specific data that is required for se-lection is also exchanged among the BCUs inGOOSE messages. In typical substations, sev-eral bays are usually suitable for use as refer-ence bays.A single reference bay is selected by takinginto account a previously defined sequence inthe local logic.The BCU that is located in a reference bay dueto the topology information and is at thehead of the sequence sends the “Referencebay found” message to all other BCUs in aGOOSE telegram and connects the voltage viathe ring line relay.The ensuing test of the synchro-check condi-tions in the BCU of bay A and release of thecontrol command is performed in the sameway as in the conventional concept.

2.4 Benefit of the solutionMigrating the logic function from the BCU tothe bay level improves the availability of thesolution. Depending on the level of systemavailability required, redundant implementa-tion of the station control unit can be dis-pensed with. If one BCU fails, the BCU withthe next highest priority is used as the refer-ence bay. The synchro-check function is avail-able for switching via the remote interface,the station control, and also for switchingfrom the local control. This ensures reliableand synchronous switching in all operatingcases.

Fig. 24 Sequence when peer-to-peer communication is used

Reference bay Bay A

Station HMI

ON commandCB in bay A

Reference bayfound

Reference bay search

Connection ofthe control

centerSICAM 1703



�3. Mesh station automatic switching3.1 BackgroundA mesh station is a type of primary substationconfiguration that is economical in its use ofcircuit-breakers. Although there are manyvariants, the typical configurations are singleswitch and four switch meshes, the names in-ferring the number of circuit-breakers used toaccomplish the layout.

A mesh corner is where busbars connectcircuit-breakers, transformers and feeders –a four switch mesh has four mesh corners,whereas a single switch mesh has 2 corners.Feeders or transformers connect to mesh cor-ners via motorized disconnectors to provideindividual isolation and it is possible to havemore than one transformer connected to themesh corner. A mesh corner would typicallyhave a feeder and up to two transformersconnected – this means with four circuit-breakers, a station could be built with 4feeder and 8 transformer circuits. If a circuit-breaker requires maintenance, it may betaken out of the mesh without any loss ofsupply.

3.2 Mesh station automatic switching

Following a trip event for the mesh to ‘selfheal’, an automatic switching and delayedautomatic reclose (DAR) system is required.

For example, for a feeder fault, all circuit-breakers connected to the feeder's meshcorner must trip, including any transformerlow-voltage circuit-breakers and remote sub-station circuit-breakers through intertrip sig-nalling.

The mesh station circuit-breakers have priori-ties and dead timers, so after the fault a meshcircuit-breaker will attempt closure which, ifsuccessful, will result in all other circuit-breakers closing in a controlled sequence. Ifthe first circuit-breaker to automatically closetrips then the feeder is deemed to have a per-sistent fault and the mesh DAR system opensthe feeder disconnector at both ends of thecircuit – after the feeder has been removedfrom the mesh corners, the mesh circuit-breakers commence automatic reclosure.

For transformer faults, once circuit-breakershave tripped, the transformer is automaticallyisolated by opening its disconnector beforethe mesh circuit-breakers reclose in theirsequence.

Fig. 25 Mesh station = circuit-breaker= disconnector

Mesh corner 1

Transformer 1Transformer 2

Transformer 4Transformer 3

Feeder 1

Feeder 4Feeder 3

Feeder 2



3.3 The solutionA solution with one BCU per mesh corner wasdeveloped.

This gave the benefits of reduction of installa-tion costs and using a future proof industrystandard rather than a bespoke solution.

The automatic switching and delayed auto-matic reclosure functions were developedusing a graphical logic tool which was used todiagnose the bay control units.

A test system shows a single line diagramof the substation from which switchgearpositions can be manually changed, analogvalues controlled and protection events sig-naled. The visualization interfaces toPROFIBUS input/output devices which are inturn connected to the bay control units beingtested. The test system responds to events,i.e. simulates disconnector opening/closingand allows test sequences to be easily createdand replayed for repeatable testing.

Using this test system, the specific function-ing of the DAR function can easily be verifiedin the BCUs and there is no further obstacle tosuccessful commissioning of the substation.

�4. SummaryThe examples discussed show that IEC 61850offers a wide range of application possibilitiesexceeding by far current applications. A thor-ough analysis will reveal the advantages ofIEC applications. However, it is for the opera-tor of the substation and its supplier to decideon the degree to which alterations of existingconcepts and systems should be made.


Seamless Migration

�1. Migration strategies for connectingexisting substations to IEC 61850

Most substation projects are not new substa-tions but expansions or refurbishments. Useof IEC 61850 must therefore not be focusedexclusively on new substations; strategies forconnecting to existing technologies are alsorequired. This article describes methods andsolutions to achieve this.

�2. Migration into an existing environmentBecause of the large investments required,substation renewal is a continuous process.The long service life of the systems alsomakes heterogeneous solutions within onesubstation unavoidable. One of the most im-portant aspects of integrating old substationcomponents is the system’s flexibility withrespect to existing interfaces.

�3. Integration of devices with anIEC 60870-5-103 interface

The most frequent application is the couplingof protection units with IEC 60870-5-103-com-pliant interfaces. A rounded portfolio mustoffer flexible options to meet the differentrequirements of the applications andconfigurations. Basically two variants can beselected. Either devices are coupled with a-103 interface by means of serial hubs or mo-dems or direct coupling to a bay control unitis used. If a serial hub or modem is used,Ethernet is the communication medium forpacking the telegrams according toIEC 60870-5-103 into Ethernet containers andfor unpacking them again in the control sys-tem, allowing the control system to decodethe familiar -103 telegrams. If localcoupling via a bay control unit is used, theIEC 60870-5-103 addresses are assigned toa corresponding IEC 61850 address. In thiscase, Ethernet as the communication mediumis not only means of transport; data is alsoconverted.

Seamless Migration

Fig. 26 400 kV outdoor switchgear

LSP2

86

4.e

ps


Seamless Migration

�4. Coupling the control centerAnother important aspect of migration is theassignment of data models and communica-tion services of IEC 61850 to the telecontrolprotocol per IEC 60870-5-101/-104 or DNP3.0for communication with the network controlcenter. IEC’s technical committee TC 57 is cur-rently working on a technical specification todeal with this topic. The implementation ofthis recommendation in products and engi-neering systems enables an efficient ap-proach in each respective project and alsoavoids costly project-specific solutions.

Compliance with such an IEC technical specifi-cation ensures that all suppliers design the in-terface in the same way and that a systemcontrol center knows exactly what IEC 61850object is behind a 101/104 information item,irrespective of which manufacturer actuallyinstalled the switchgear. Siemens AG is alsoproviding decisive input for this standardiza-tion project and implementing it in productsearly on.

�5. Migration to company-specificprecursor systems

To achieve standardization, only solutions aredealt with that are based on communicationprotocols that comply with the IEC standard.Every manufacturer is required to provide mi-gration methods from the company-specificprotocols previously used for substation auto-mation or for the remote parameterizationinterface.

But solutions for each company’s own precur-sor systems are not the only requirement;flexible configurations that include proprieta-ry de-facto standards from the past must beincluded in the overall solution.

Only products and systems that support thedifferent protocol environments that arenecessary can permit efficient migration toIEC 61850 solutions in the retrofitting busi-ness.

�6. Step-by-step introduction of theIEC 61850 into a substation

The existing communication protocols are notthe only important constraint that applies inpractical use.

Above all, in refurbishment projects, wheresubstations are usually equipped with thelatest technology on a bay-by-bay basis, con-cepts are required to permit parallel, hetero-geneous operation of the substation.For example, let us take a case of a substationin which the interlockings in the existingequipment were conventionally implementedby wiring while the interlockings in the newequipment make use of the GOOSE mecha-nism.

To prepare the interlocking logic for the finalexpansion stage in the re-equipped bayswhile also providing the functionality of inter-locking across bays during the conversionphase, position indications from the hard-wired part of the substation must be takeninto account in the new substation part du-ring conversion. If a flexible coupling element

Fig. 27 Integration of IEC 60870-5-103 devices

AK 1703 ACP

SICAM PAS

Starcoupler

Serial hub

Serial hub

BC 1703 ACP

TM 1703 ACP

StarcouplerSerial hub

IEC 61850TCP/IP Ethernet

Serial connection tobay controllerIEC 61850 TCP/IP

IEC 60870-5-103


Seamless Migration

is used as a universal IEC 61850 server, thisinformation can be connected in parallel andmade available to the new part of the installa-tion in the form of a GOOSE message. Thispermits step-by-step conversion of conventio-nal substations to the latest technology andconcepts while retaining a maximum of sub-station functionality and therefore operatio-nal reliability.

�7. Complete upgrade of the bay controlunits to the IEC 61850 protocol

Alternately, it is possible to upgrade the in-stalled protection and control units by repla-cing the communication module and byupgrading the firmware to IEC 61850. Thismigration step provides solutions that arehomogeneous, high-performance, andfuture-proof (Fig. 28).

�8. Commissioning and testingIf commissioning is to be efficient, analyticaltools are indispensable. Products and systemsestablished on the market provide extensivediagnostic and analysis functions in their en-gineering tools. Now, with the more advan-ced features of IEC 61850 and the self-description of the devices, tools are availablethat are unparalleled in past solutions andmake analysis even more convenient for theuser. With a universal browser, the controlengineer is able to read out data models ofany IEC 61850 device, including all its attribu-tes, without needing to have the parametri-zing tool of the manufacturer. The additionaluse of web technologies provides further ex-tensive options for diagnostics and analysis.

�9. Benefit for the userProtection of investments is one of the primeobjectives of users when converting substa-tions. Concepts that permit seamless conver-sion from old systems to new solutions makean important contribution to achieving thisobjective. With the concepts described here,old systems can be converted to the latesttechnology step by step. This ensures the bestprotection for investments made andthe substations are prepared for furtherexpansion.

�10. IEC 61850 spreadsThe many substations now implemented(more than 1000 substations in 2010)are unequivocal proof that IEC 61850provides innovative substation solutions andis technically mature and reliable. The successso far with products and systems complyingwith IEC 61850 and the considerable demandon national and international markets showsthat previous investments in this field havepaid off.

Siemens E D EA will continue its commitmentto IEC 61850 both by contributing to the stan-dardization process and by implementing thestandard in devices and systems to further in-crease the benefit for users.

Fig. 28 Upgrading an existing IED with IEC 61850 communication

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Seamless Migration


Communication Possibilities with IEC 61850

Ethernet Topologies withIEC 61850

�1. IntroductionEthernet – which has been widespread incompany and office networks for a long time– is becoming more and more popular in allother parts of the industry. The IEC 61850standard specified this kind of network as thecommunication platform for the completestandard. Even if the bandwidth of theEthernet increases now and over the next fewyears, the protocol will run in every case.Ethernet is well known all over the world andno indication of any change to this protocol isimminent. Thus Ethernet will be the basis forIEC 61850 for many years to come.

This article shall give the reader an overviewof existing Ethernet technologies and com-mon topologies with IEC 61850.One of the most important topics in substa-tions is the reliability of the systems andtherefore also of the given communication in-frastructure. Reliability is provided by sever-al redundancy algorithms which are possiblein Ethernet networks.

For a very fast transmission of so-calledGOOSE messages for direct inter-bay commu-nication the IEC 61850 standard envisagedthe use of EtherType, which means that thesemessages run on a flat layer 2 network, with-out the need for layer 3 IP addresses. Othernon-time-critical communications, e.g. to sta-tion controller SICAM PAS, DIGSI configura-tion via IP or browsing the IEC 61850 modulehomepage are based on the TCP/IP protocol.

Not only the network itself can have redun-dancies, but connection redundancies arealso possible with the SICAM PAS station unitand all kinds of SIPROTEC 4 devices as well.Both IEC 61850 modules in the SIPROTEC de-vices, the electrical and the optical ones, have

redundant ports at the backplane. This meansthat each module can be connected to twodifferent switches. If a connection is interrup-ted, the standby connection will be activatedwithin some milliseconds. In the SICAM PASstation unit the same procedure is applicablewith the use of a dual network card, which isalso interconnected to two switches. And, ofcourse, system redundancy is also possible.

�2. Services in Ethernet networksWhat is the situation in existing substationstoday? Sometimes devices from different ven-dors are in use. The devices communicatewith each other in a simple way via contactsand binary inputs and additionally with thestation unit. This results in a number of ca-bling requirements in the substation. Everyvendor has its own bus for its configurationtools; for inter-bay communication you needhardwiring and binary inputs and outputs,etc. With Ethernet and IEC 61850 you nowhave the possibility of running all services onany device of any vendor on the same bus inparallel at the same time.Thus all devices only need two pairs of coppercables or one pair of fiber optic cables to exe-cute communication.



2.1 Layer 2 redundancy with RSTPThere are several redundancy algorithmsavailable for layer 2 networks. Some are dedi-cated and some are standardized in theEthernet world by IEEE. The most commonredundancy protocol is the so-called RSTP(Rapid Spanning Tree Protocol).This protocol provides the option of connect-ing all used Ethernet switches in a ring struc-ture; Siemens SIPROTEC devices with opticalIEC 61850 module can act in that manner dueto the integrated switch function.

To achieve network redundancy one requiresmore than one path from source to destina-tion. This will be achieved with the ring struc-ture which provides the physical loop in thenetwork design. However, if a true loop wereto occur in an Ethernet network, the firstbroadcast frame would circulate endlessly,consuming the entire available bandwidth.This results in a so-called “broadcast storm”.RSTP prevents this problem by quickly form-ing a logical tree network that spans allcomponents of the network, as the name ofthe protocol describes. In the case of the ringstructure, one of the physical interconnec-tions between two switches will be logicallyswitched off automatically. This backup linkwill be re-enabled as needed when networkproblems occur to restore the connectivity ofall attached devices. This will be done auto-matically and also works with any kind ofnetwork topology.

Not just redundancy in itself is very importantin substation automation systems. A fast re-covery time in the event of an error is also re-quired. The typical recovery time in a RSTPring configuration is some 100 millisecondsup to one second. This period lasts too longfor substation communication. For this rea-son Siemens made an extension to the RSTPalgorithm. So Siemens’ Ethernet modulesupports both versions automatically withoutthe need to change the configuration.

Recovery times between 20 and 30 millisec-onds are possible even in complex ring struc-tures with 30 devices. These comprehensivetests were made successfully together withthe Ruggedcom switches by the Siemens testlaboratory with the recommended switches(RuggedCom, Hirschmann and SiemensScalance).

2.2 Monitoring networks

As in the case of control centers, you alsohave the possibility of an online view of yourrunning Ethernet devices. This is implement-ed via the so-called Simple Network Manage-ment Protocol (SNMP).This common Ethernet protocol provides anonline monitoring view of all Ethernet swit-ches as well as the SIPROTEC devices. It is notjust possible to view network parameterssuch as performance data of the device andso on; it is sometimes also possible to confi-gure them.

2.3 Time synchronization with SNTPThe Simple Network Time Protocol (SNTP) isthe common protocol in Ethernet networksfor synchronizing the integrated clocks in net-work-connected devices. SNTP is also describ-ed in the IEC 61850 standard for distributionof time information to all participants. Thiswill be performed by an SNTP server which isalso connected to the Ethernet. This time serv-er has an external time source, for example aDCF or GPS receiver. All other connected de-vices act as SNTP clients and ask the server forthe right time at certain periods. All SIPROTEC 4devices support the SNTP protocol for timesynchronization. The configuration for thistopic can be done directly in DIGSI. Also possi-ble in the DIGSI Manager is a redundant clockmaster, so you have a higher availability ofyour SNTP time synchronization system.In the unlikely case of an error of the mainclock master, the secondary clock mastertakes over the time requests of all SIPROTECdevices.



2.4 VLAN and priority taggingWith VLAN (Virtual LAN) tags you can createdifferent sub-networks within your network.This will be performed by adding additionalbits to the Ethernet frame. In this way you canseparate devices in the network which are notto communicate with other devices of thesame network. This is just possible with a layer3 instance, e.g. a router. In theory, more than4000 different VLAN segments are possible.

The three priority bits tag an Ethernet frameto transmit the frame with a higher prioritythan a second frame, which shall be trans-mitted over the same network segment. Sothe frame with the highest priority will besent out first.

Both information tags, the VLAN and the Prio-rity, are common extensions in the Ethernetworld for separating and prioritizing Ethernettraffic. In the IEC 61850 standard there is alsothe definition that IEC 61850-compliant de-vices shall support this common Ethernetfeature.

These features are used especially for GOOSEmessages. GOOSE messages have to be trans-mitted very fast and with a higher prioritythan other types of Ethernet frames.

�3. Communication network designsSwitches can be seen as a short piece of anEthernet bus. They can be used to distributethis bus to different physical locations. Ifmanaged switches are used, they can also beconfigured to relieve the network traffic incertain segments of the Ethernet. Thus youcan implement collision-free data transmis-sion.

With respect to the existing cabling infrastruc-ture, the cost situation and the need forhighly available networks, several networkdesigns are necessary and possible. This arti-cle cannot describe all the different variants;the three most common structures are de-scribed here. Different modifications of theseare possible, of course.The last one is only possible with the opticalEthernet modules. Each of these modulescontains an integrated switch function, withthe result that the SIPROTEC devices can beconnected to each other directly in a daisychain connection.

An optical fiber Ethernet ring with specialswitches (providing ring redundancy bymeans of ‘rapid spanning tree’ or similarmechanisms) is used for such cases. In thisway switches can be used to distribute the

Ethernet backbone (Ethernet bus) todifferent physical locations.

Such an Ethernet ring works on the n-1 basis.If there is a communication interruption, thenthe switches will automatically reconfigurethe ring in such a way that no communica-tion is lost.

To guarantee that all devices work togetherproperly we have tested in our system testdepartment a system with many IEC 61850IEDs to provide our customers with fast andreliable communication. In the meantimethere are more than 1000 substations run-ning with IEC 61850 worldwide. Somecustomers have systems with more than 200devices running well without interruptions.

3.1 Radial Ethernet connections(star structure)

Fig. 29 shows IEDs connected to two switcheswhich would also be possible for stationunits.This configuration can normally be used if allEthernet devices are physically relatively closeto each other; with fiber optical connectionslonger distances are also possible.This design can be chosen if electrical Ether-net modules are to be used. All SIPROTEC de-vices and station units can be connecteddual-armed to the network. Special redundan-cy mechanisms such as RSTP are not necessa-ry here, because no loop exists in thisnetwork. This offers redundancy if one of theswitches is off duty and connection redun-dancy for all attached devices as well. For thiskind of network design less effort is involvedfor the configuration of the Ethernetswitches.

Fig. 29 Station bus in a star structure

Station controller with IEC 61850time synchronization with SNTPand SNMP management

Managed Ethernet switches

Fielddevices

100 Mbit/s electrical



3.2 Ethernet ring with Ethernet switchesFig. 30 shows an Ethernet ring made withexternal switches. The layer 2 redundancymechanism opens the ring logically so thereare no circulating telegrams. In the event oferrors on one switch or a broken connectionbetween two switches the logically openedconnection will be established automaticallyin a few milliseconds so that communicationis still possible between all devices.The connections between the switches can berealized either with multi-mode fiber or withsingle-mode fiber, depending on theexisting cabling infrastructure and the usedswitches.

Also possible with this design are intercon-nections between different locations. All youneed is an adequate fiber connection to inter-connect the different locations. Thus distan-ces up to 100 km are possible.

In one ring up to 30 switches are possible.With proprietary enhancements of RSTP youcan build up rings with up to 80 switches.The amount of IEDs which can be connectedto one switch is just limited by the number of

physical connection ports (typically six IEDsor more per switch).

All SIPROTEC devices and station units can beconnected dual-armed to the network; bothelectrically and optically are possible. Thisoffers redundancy in case of malfunction ofone of the switches and connection redun-dancy for all attached devices as well. In thedual-armed design one of the two connec-tions is always active, the second is on stand-by. In case of link failures, the standbyconnection will be activated within less thanfive milliseconds, so that communication withthe device is still possible.Additionally the connections between theswitches can be realized with two separateconnections, these two connections will becombined via “link aggregation”, whichmeans you can double the ring bandwidthand also have an additional connectionredundancy.

A notebook for DIGSI configuration and alsoany other device can be attached to the net-work. The DIGSI-PC should be connected to aswitch port which does not generate a so call-ed “link loss” alarm while disconnecting thePC after the configuration process. This alarmcan be activated or disabled at every switchport within the switch configuration tool.

Fig. 30 Station bus in a ring structure with external switches

Station unit withIEC 61850 timesynchronization overSNTP.SNMP management fornetwork supervision

CorporateNetwork TCP/IP

Switch

Router to externalnetworks (optional)

Single-mode/Multi-mode fiber

Ring physically closedand logically open

Device 2

Device 1Device 3 Device 4

IEC 61850Interfaceelectrical/optical

Bay 1 Bay 2

Standby

Patch-cord

100 Mbit/s elekctrical

100 Mbit/s optical



3.3 Ethernet ring with SIPROTEC IEDsFig. 31 shows the preferred configurationwith the greatest benefits. Just one or two ex-ternal switches are necessary. This is possibleon account of the unique integrated switchfunction in the optical Ethernet module. Inthis way you can connect up to 30 SIPROTECdevices in one ring. If you need more youjust have to create a second ring, which canbe connected to the same switches (see alsoFig. 32).The optical module forwards all telegrams inwire speed without any delay; just the rele-vant frames for the receiving device will bepicked up from the station bus.

The optical Ethernet modules fully supportthe layer 2 redundancy mechanism RSTP, soyou have the same redundancy features aswith external switches. Additionally and espe-cially together with switches from Rugged-com the reconfiguration times after failureswere optimized. This design was tested byour system test and is applied for a reliableand user-friendly communication structure.

All SIPROTEC devices are connected dual-armed to the network in this way. Both con-nections are active at the same time.

All necessary components with electrical portscan be connected to the external switches.A notebook for DIGSI configuration can beattached to the network at the externalswitches (see Fig. 31).

Fig. 32 shows that not just one ring is possi-ble. This design allows you to create a systemwith up to 27 SIPROTEC devices. If more de-vices are in use, you can simply create a sec-ond ring with 27 additional devices, and soon and so on. This picture shows very clearlyone of the benefits of the optical Ethernetmodule: you just need two external switchesfor a highly available redundant IEC 61850Ethernet network.

This design provides you with cost advan-tages, a drastic reduction of external compo-nents, a simple configuration with fewercomponents in the network and a high avail-ability due to reduction of external compo-nents.

Fig. 31 Station bus with SIPROTEC devices in a ring structure

Fig. 32 Station bus with SIPROTEC devices in a double ring structure


100 Mbit/s optical

Ring physically closedand logically open

Multi-mode fiber

Bay 1 Bay 2

Station unit withIEC 61850 timesynchronization overSNTP.SNMP management fornetwork supervision

Device 4Device 3Device 2Device 1

Switch


100 Mbit/s optical



3.4 Connecting non-IEC61850 IEDswith serial interfaces

If non-IEC 61850 IEDs need to be connectedto the station unit, then it is advisable to use aserial hub. In the station unit these IEDs maythen be configured to the same interface (e.g.communication port 3). Even in redundantstation unit configurations serial hubs can beintegrated. In the master station unit this in-terface will be enabled and in the standby sta-tion unit this interface will be disabled. Onceswitchover occurs, these interfaces will betoggled. At first the interface of the masterstation unit will have to be switched off, sub-sequently the interface of the standby stationunit will have to be enabled. Communicationto the relevant IEDs will have to be inter-rupted for a short period of time. It will benecessary to use the automation and OPCinterface for this implementation.

Serial hubs can also be used if you want toconfigure a non-IEC 61850 SIPROTEC devicewith DIGSI via the Ethernet. In this case thepath of communication is implemented in theDIGSI PC with virtual COM ports. This virtualCOM port is assigned to the IP address of theserial hub in the network. In this way youhave a kind of point-to-point connection be-tween DIGSI and the SIPROTEC device. The bitstream of the serial connection will be wrapp-ed up in the Ethernet frames; every Ethernetframe acts as a container for transporting theinformation. At the receiver side, the informa-tion will be unloaded out of the Ethernet fra-mes and reorganized for a serial connec-tion to destination. All serial communicationwill be “tunnelled” through the Ethernet.

�4. SummaryHardware and software requirements for typi-cal redundancy architectures were discussedand advantages of the different design wereexplained. The described configurations arerecommended because they are successfullytested in comprehensive test scenarios by ourSiemens Test laboratory.

The highest benefit will be achieved with theoptical Ethernet modules when working inswitch mode in one or more ring structures.For this configuration just two or a few exter-nal switches are necessary. All SIPROTEC de-vices are automatically connected in a ringstructure to the network with both connec-tions in active mode.

The integrated switch function of the opticalEthernet modules in the SIPROTEC device re-duce the required number of external devi-ces, which decreases the configuration effortto a minimum and makes the configuration assimple as possible.

In the event of errors or failures in the ring,reconfiguration times are between a very fast20 and 30 milliseconds.

Fig. 33 Connecting non-IEC61850 IEDs to the station bus

Station unit

Switch100 Mbit/s electrical

RS485 serial

Serial hub

IEC 60870-5-103

Field devices


IEC 61850 Interoperability

IEC Interoperability,Conformance andEngineering Experiences

�1. OverviewThe interoperability tests carried out in thepast and the numerous customer projectshighlight the special importance of the stand-ardized configuration language SCL (Substa-tion Configuration Description Language).

IEC 61850 is the global communications stand-ard for station automation. The conditionsthat must be fulfilled so that the engineeringfunctions perfectly not only in equipmentfrom one manufacturer but also in so-calledmixed configurations can be identified in theinteroperability tests carried out in variousregions of the world.

�2. IntroductionThe last part of the IEC 61850 standard series,the part relating to the requirements for con-formity with the standard, was published inMay 2005. But even before this date, inNovember 2004, the first IEC 61850-compli-ant substation in the world with equipmentfrom Siemens went into service inWinznauschachen (ATEL Switzerland).By end of 2010, Siemens carried out projectsfor more than 1000 switching stations withIEC 61850-compliant communicationbetween devices.

The advantages of IEC 61850 were alreadyapparent in these first substations. It was alsoclear that certain preconditions had to bemet, for example conformity with standardsand standardized engineering.

Conformity of the communications interfacesof the individual device types with the stand-ard is checked and certified (Fig. 34) on be-half of the manufacturers by an independenttest laboratory, for example KEMA in theNetherlands, see bibliography on page 41,reference [1].

This tests laboratory was accredited by theinternational user organization of theIEC 61850, the UCA international, see biblio-graphy, ref. [2]. It works according to testplans that have been drawn up jointly withthe user organization. Valuable experiencehas been gathered in the first tests and certifi-cations of equipment with IEC 61850 inter-face which indicates an extremely high quality

of the products and of the certification pro-cesses.

Another step for ensuring interoperable solu-tions is the implementation of so-called inter-operability tests which are initiated, forinstance, by the user organization UCA inter-national or by individual users, that is to sayelectric utilities. Important tests included theinteroperability demonstrations at the CIGRE2004 and 2006 in Paris and in the exhibitionon the occasion of the Western ProtectiveRelay Conference in Spokane (USA) inOctober 2005; see Fig. 35 on next page.

Fig. 34 Conformity certificate for SIPROTEC 4 device 7SJ64

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�3. IEC 61850-6 engineering processPart 6 of standard IEC 61850 defines the Sub-station Configuration Description Language(SCL) for a station automation system (SAS)[3]. This is the core element of the engineer-ing according to IEC 61850. The SCL languageis not a programming language like Java, C++or Assembler but is a system description lan-guage based on XML . This means that a wayhas been found of describing the communi-cations and object model of a station auto-mation system in machine-readable formusing the XML instruction set, see bibliogra-phy on page 41, ref. [4].

The IED and the system configuration of astation automation system are implementedin the engineering process in accordance withIEC 61850-6.

The actual parameterization of the selectedIEDs (Intelligent Electronic Devices) is imple-mented with the vendor- and equipment-specific IED configuration tools (IED Configu-ration Tools). The DIGSI 4 tool is used forSIPROTEC bay controllers and protection de-vices. This tool is also used to create andadapt the ICD (IED capability description)files, see bibliography, ref. [5].

The description files of the IEDs are furtherprocessed by a system configuration tool inthe system engineering. The result of theengineering in the system configuration toolis a description file for the configuration ofthe station automation system (SCD -Substation Configuration Description).

1) XML- Extensible Markup Language, defined by theW3C (World Wide Web Consortium)

The file generated by the system configura-tion tool is then re-imported the IED configu-ration tools. The individual IED configurationtools read out the configuration parametersthat are needed for the particular device.

The advantage of the engineering proceduredescribed consists in the vendor-neutral andautomated exchange of the configurationdata of both the IEDs (importing of the IEDfile into the system configuration tool) andthe communication system (importing thesystem file back into the IED configurationtools). Since vendor-specific tools are usedhere as a general rule, it goes without sayingthat only SCL-compliant files can be process-ed without error.

Fig. 35 CIGRE in Paris

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�4. System planning andsystem integration

The system planner and the system integratorof a substation have a particular responsibil-ity. The station automation system is designedand developed during the system planning.The individual device types are selected in thisphase, which includes matching the datamodels (what data is available) and the nec-essary communication services (how the datais transmitted). That depends on the plannedapplication functions.

For example, all relevant data relating to theswitching states (e.g. circuit-breaker on/off,disconnector open/closed, grounding switchopen/closed) must be made available for thestation interlocking test.

This should also be carried out as promtlyas possible to each change of state. One trans-mission service that fulfils the time require-ments with a high degree of reliability is theGOOSE1) service of the IEC 61850.

This is a spontaneous/cyclical, object-orientedmulticast transmission at Etherlink level. Thisfirstly ensures a short transmission time to alarge number of recipients and secondly alsoguarantees that the latest message changesare transmitted to all GOOSE stations.

1) GOOSE – Generic Object-Oriented Substation Event

In order to enable the application functions touse the GOOSE service, the service must beimplemented in every participating device.The standard does not stipulate which serv-ices are implemented in the equipment of thevarious vendors. That is the decision of themanufacturers, and selection of compatibleequipment is the responsibility of the systemplanner.

The parameters of the special applicationfunctions are set during system integration.This process is implemented as describedabove with the aid of IED configuration andsystem configuration tools. Apart from thecommunication parameters, parameters mustalso be set for evaluating and using the indi-vidual data. In the examplary application de-scribed above (station interlocking test), it isnecessary to include not only the switchingstates of the disconnectors, earth groundingswitches and circuit-breakers in the evalua-tion logic but also the so-called quality of thisdata (valid, blocked, invalid, replaced, etc.).The actual implementation of the functionlogic of the interlocking test does not formpart of the contents of the communicationsstandard IEC 61850. That is the task of thefunction software of the individual devices.

Checking the communication capabilities andfunctionality of the equipment for theplanned applications is the responsibility ofthe system planners and system integrators.

Fig. 36 IEC 61850 system configuration tool in DIGSI 4 tool

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�5. Certification of standard-compliantdevices

A useful aid for the user of IEC 61850-compli-ant equipment is the check for conformitywith the standard which is confirmed by theKEMA certificate. As a precondition for thistest, the following documents and files docu-menting compliance with standard IEC 61850must be provided by the manufacturers:

> MICS – Model Implementation Conform-ance Statement (declaration by themanufacturer with respect to the imple-mented data model)

> PICS – Protocol Implementation Conform-ance Statement (declaration by themanufacturer with respect to the imple-mentation of the protocol and the trans-mission services).

> PIXIT – Protocol Implementation ExtraInformation for Testing

> ICD – IED Capability Description (engineer-ing process file relating to the capability ofthe IED).

These documents are important sources ofinformation for the system planners and sys-tem integrators of station automation sys-tems because they provide information aboutthe status and scope of implementation ofthe IEC 61850 standard.

There are a number of potential problemsthat can occur in the case of IEC 61850-com-pliant communication between devices.

• The engineering files provided for theequipment (ICD) are not valid.

The substation Configuration Description Lan-guage (SCL) is based on XML and thus displaysthe characteristic that files created with it canbe checked for compliance with the SCL rulesagainst a so-called XML schema. This is imple-mented with the aid of a validator, a softwareprogram that carries out these tests. If the ICDfile is not valid it naturally cannot be importedand processed in the system configurationtool and consequently communication be-tween the associated devices within the SASis also not possible. DIGSI operating programexports SCL: description files based on strictapplication of the IEC 61850 scheme.

• Implemented transmission services of differ-ent devices are not compatible.

The standard does not stipulate which trans-mission services are to be implemented in thebay devices (protection and control devices)and in the station control unit. However,there are mandatory rules as far as depend-ence between equipment is concerned, par-ticularly with regard to the interaction betweenstation control unit and bay controllers. Forexample, a protection device that wants todispose of its alarms, warnings and statusmessages per buffered reporting (bufferedmessage transmission via TCP/IP) in its capac-ity as server should be connected to a stationcontrol unit with the same client functional-ity. If the client of the station control unit“only” offers the unbuffered transmission serv-ice this causes a conflict in the engineering.Sound technical support by Siemens employ-ees during preparation and specification ofthe substation automation system ensuresthat only devices that have passed inter-operability tests are deployed.

• Use of private data objects.The use of non-standard-compliant data ob-jects is not forbidden by the standard. Theyare identified via a dedicated name space. Na-turally, it is not possible to achieve inter-operability in this way because only themanufacturer of the device concerned knowsthe designations and significance of the data.Full modeling of the data with the resourcesof IEC 61850 is a basic requirement for utiliz-ing the advantages of the standard. Only dataclasses from the IEC 61850 model are usedfor Siemens SAS, bay control units and pro-tection devices.



�6. Summary

Requirements for the implementation andapplication of IEC 61850 can be deduced asfollows:

• Interoperability tests will diminish the riskof interoperability problems between de-vices in the initial phase of the global rolloutof the standard in which a constant streamof new equipment types from the manufac-turers are equipped with IEC 61850. Thisapplies particularly when new equipmenttypes are connected together for the firsttime before they have been certified forcompliance with the standard.

• Engineering tools are not yet standardizedin the standard. An important aspect forgood user-friendliness is to restrict the dis-play of parameters for the user to thoseneeded for the solution of the problem inhand.

• Testing for standard validity (validation)of the engineering files (ICD, SCD, SSD andCID) will facilitate working with the datawhenever data is imported into a configu-ration tool. Errors are detected early on andconsequential faults can be avoided.

Bibliography and reference tips:[1] KEMA Netherlands –

http://www.kema.com

[2] UCA International Users Group –http://ucausersgroup.org

[3] IEC 61850-6 Communication networksand systems in substations –Part 6: Configuration descriptionlanguage for communication in electricalsubstations related to IEDs.Geneva/Switzerland: Bureau Central dela Commission Electrotechnique

[4] Etz-Report 34 “Offene Kommunikationnach IEC 61850 für die Schutz- undStationsleittechnik“ (Open communica-tion to IEC 61850 for protection devicesand station control systems) , 2004,K.-H.Schwarz et al., Article 11:Engineering und Konfiguration vonSchaltanlagen-Leittechnik (Engineeringand configuration of switchgear controltechnology), Dr. W.Wimmer,H.Dawidczak

[5] SIPROTEC. Siemens AG,Energy SectorPower Distribution DivisionEnergy Automation (E D EA),Nuremberg: http://siemens.siprotec.de


IEC Browser

IEC Browser – A PowerfulTest Tool for IEC 61850

�1. IEC Browser – A Powerful Test Tool forIEC 61850

The IEC browser was developed for SICAM PASas a test tool. The PC program acts as anIEC 61850 client and, in online mode, repre-sents all data objects of an IEC 61850 server,e.g. a SIPROTEC 4 device. Just like with anInternet browser, you can connect to theIEC 61850 server, which runs on an EN 100Ethernet module of a SIPROTEC 4 device, readall the data objects, and even change somedata objects. The left window shows the logi-cal devices and logical nodes of a server in atree structure. The right window shows thevalues of the data objects you have selectedin the left window.

For installation the IEC browser freeware isavailable free of charge on the DIGSI programCD (V 4.80 and newer).First import the ICD files of the individual de-vices of an IEC 61850 station. Then connectto the devices that are connected to the samenetwork. Even more conveniently, you canload the completely configured station, i.e. itsSCD files. Here, all IP addresses are stored, ofcourse, and clicking “Connect” is all you needto do to establish the connection.

It is easy to find what you are looking for: theIEC 61850 data objects are clearly organizedand displayed in a tree structure togetherwith their familiar descriptions from the de-vice context. In AutoRefresh mode, changesto the IEC 61850 object list are displayed im-mediately without manual triggering.

Furthermore, it is possible to configure dynam-ic reports that are then spontaneously sent tothe browser by the device, if data objectshave changed. These reports can be changedor deleted directly from the IEC browser with-out first having to create them in the systemconfigurator. But the reports and the GOOSEapplications that were configured in the sys-tem configurator are also displayed by thebrowser in online mode. You can change con-trollable data objects using the IEC browser:This makes it possible for commands to betransferred to the device as a test.

The IEC browser is a powerful tool for analyz-ing and testing the IEC 61850 client – servercommunication. This program is free ofcharge for every DIGSI user. It can be oper-ated in parallel to DIGSI so that changes tothe IEC 61850 parameterization are directlytraceable in the browser.

Fig. 37

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Appendix

Exclusion of liability

We have checked the contents of this manualfor agreement with the hardware and soft-ware described. Since deviations cannot beprecluded entirely, we cannot guarantee thatthe applications described will function cor-rectly in any system.

Copyright

Copyright Siemens AG 2010.All rights reserved

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All rights reserved.If not stated otherwise on the individual pages of thiscatalog, we reserve the right to include modifications,especially regarding the stated values, dimensions and weights.Drawings are not binding.All product designations used are trademarks or productnames of Siemens AG or other suppliers.If not stated otherwise, all dimensions in thiscatalog are given in mm.

Subject to change without prior notice.The information in this document contains generaldescriptions of the technical options available, whichmay not apply in all cases. The required technicaloptions should therefore be specified in the contract.

efficient energy automation with the iec 61850 standard...

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