lprf meters deployment in india rev2
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RF METERS DEPLOYMENT IN INDIA
A GUIDE LINE REPORT
Rev 2.0, Date 7 July 2012
BY
NARENDER RAO SAINENI, M.Tech(IIT)
VIJETHA TECHNOLOGIES PVT LTD.
CONSULTANTS AND DESIGN HOUSE
FOR ELECTRIC METERS AND OTHER EMBEDDED SYSTEMS
HYDERABAD,
INDIA-500062
Date: 17 Nov 2011
Please send your feedback to the given mail-id
Or discuss on the google sitehttps://sites.google.com/site/energymetersindia/home
mailto:[email protected]:[email protected]://sites.google.com/site/energymetersindia/homehttps://sites.google.com/site/energymetersindia/homehttps://sites.google.com/site/energymetersindia/homehttps://sites.google.com/site/energymetersindia/homemailto:[email protected] -
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INTRODUCTION
In India there are several states/provinces, each state has its own electric utility company (mostly
govt owned) and some states have more region wise. India has electric meter specification from two
standardisation bodies BIS and CPRI. Both these are national level bodies; duplication of standards
for the same product from two different bodies is creating some confusion to the utility companies
and suppliers. Regarding communication port and protocol there is no national standard so far,
every company is following its own protocol, so on the whole there are several hundreds of
variants of these meters.
Now India has started implementing the LPRF/ZIGBEE based electricity energy meters on trial basis.
Some states are going in a big way even without proper field trial.
This new technology allows the utility companies to read the meters staying outside the customer
premises, and going forward they can get the readings directly to their server on the internet.
Considering these advantages this technology is being adopted now. However compared to the
earlier method of manual reading /auto reading through optical port, zigbee is more complex.
To help the utility companies in preparing the specification of LPRF meters communication aspects,
this document is prepared.
In this document my effort is to clearly show a road map of implementation to the utility companies.
As we are not into manufacturing, we are not biased towards one or the other spec, our interest isto create good standards for every bodys sake.
THE DESIRED ROAD MAP:
It is possible to evolve the implementation in stages, protecting the investment of the utility
companies and insuring against costly mistakes of wrong decisions.
To evolve without loss to anyone, the required features in the system should be like these.
Meter should have the provision for doing the FOTA (FIRMWARE UPDATE OVER THE AIR).
Once the meter has this facility its firmware can be upgraded to enhance the features to meet the
evolving standards and requirements of the end customer. However the metrology engine should
run on a dedicated processor without FOTA facility, only the LPRF communication unit should have
its dedicated processor with FOTA facility, this way we will have both the flexibility and security of
the basic metering functionality against tampers.
FOTA is now part of the zigbee standard.
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When the meter is specified and designed as per the above architecture , the meter can not be
tampered in the field, however utility company investment is protected allowing the evolvement of
future communication needs by upgrading the firmware of the communication module over the air
without opening the cover.
Meter module though having its own firmware and non volatile memory, nothing should be
writable in it so that the metrology engine , the cumKWH reading on the display will be as reliable as
the present meters.
The communication module should have the full flexibility to evolve as per the new evolving
standards by having upgradability of its firmware over the air i.e qualified FOTA facility
as per zibgee standard .
The communication module reads some registers from the meter module and sends them to the
outside world i.e meter reader or another network node. Today the utility company may need to
read only 2 or 3 parameters like cuKWH , MD, Tampers. Tomorrow they may need to implement
different tariff rates in different time slots and inform the dynamic tariff rate to the customer
premises display. So by having firmware upgradability of the communication module they can
easily evolve towards the same without changing anything in the meter module.
The meter module allows the reading of certain registers ( like in modbus registers) , the
communication module may read those registers at any frequency as per its needs.
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Important Note
The communication module should have over the air firmware
upgrade facility as per zigbee cluster. This has to be tested to
qualify the vendor technically. Again this is a must wether you use
zigbee standard or some other LPRF standard.
If you are starting with zigbee then you need to allocate 64 bit
extended PAN Ids area wise. First obtain the most significant 24 bitorganizational part of the extended PAN ID from IEEE. Allocating
the least significant bits are in your control. Divide the available
addresses into geographical circles take the help of google maps.
The possible scenarios the utility companies are considering now are shown as phases of evolution
below.
But my personal preference is to go for the phase-4 directly which is possible with the available
technology today and your investment will be fully protected.
PHASE-1: ( READING METERS FROM THE GATE)
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LPRF (ZIGBEE MESH) BASED ELECTRICITY METER NETWORK
REPEATER
HOME-MTR
APARTMENT-COMPLEX
FLAT
MTR
FLAT
MTR
FLAT
MTR
HOME-MTRREADER
Install the LPRF meters without dedicated head end/concentrator node.
Take a reader as is being done now, but now take a notebook/laptop/tablet-pc based CMRI/reader
to the site (in place of a proprietary hardware) to take the readings. On manual invocation the
reader becomes the co-ordinator node and forms the network and reads all the meters which are in
its radio range(limit to 2/3 hops), to get the meters out of range move the reader towards them , so
that until all meters are read.
The reader having big LCD display shows which are read and which are not read from the existing list
in easily understandable format (may be with a different colour).
Some utility companies can consider having the LPRF communication module as an upgradable unit
without affecting the basic metrology functionality (this will allow upgrade of hardware too)
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PHASE-2: ( READING METERS FROM TRANSFORMER)
LPRF (ZIGBEE MESH) BASED ELECTRICITY METER NETWORK
GPRS
Head End/ESP/
NET-COORDINATOR
ZIGBEE
REPEATER
HOME-MTR DISPLAY
INHOUSE
APARTMENT-COMPLEX
FLAT
MTR
FLAT
MTR
FLAT
MTR
HOME-MTR DISPLAY
INHOUSE
HOME-MTRREADER TABLET PC
Install a dedicated head end/concentrator node. And take the readings of all the meters in the
region from this node only, even during power failure.
To go from PHASE-1 to PHASE-2 , only the dedicated node with enough memory is to be added
which can collect and store data from all meters.
PHASE-3:( AUTOMATIC READINGS TO CENTRAL SERVER)
Upgrade the concentrator node such that it has uplink to the server on the internet through GPRS orany other available back haul network. The concentrator reads the meters and send the data
collected to a central server database. The GPRS application protocol in concentrator should reside
in GPRS-FOTA capable block. The meter FOTA should be possible from the central server.
Implement one gateway/concentrator per transformer and all the meters under this transformer
under the corresponding concentrator, this helps in easy audit of the power which is becoming
more and more scarce.
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PHASE-4 ( FULL AUTOMATION INCLUDING CONTROL)
Implement the protocol in the meters and concentrator node such that any end device will be visible
to the utility company/consumer to take reading or even control like disconnect/reconnect of
prepaid meters. And the visibility and control is through a web server.
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Some important specifications to ensure quality and avoid
confusion:
Frequency band
The frequency band to be considered to begin with, is 2.4 GHZ, which is as per the zigbee PRO
standard without any deviation. If this frequency is has any problem in PHASE-1, they can try sub
GHZ band( india has 865-867 MHZ free , earlier reserved for RFID purpose).
Application profile:The meters should implement smart energy 1.1 profiles upgradable to smart energy 2.0 soon. All the
parameters already defined in the smart energy profile should be available in the standard fashion,
in addition if the utility company wants more parameters which are not defined in the smart energy
profile, they can be provided from another end point with utility company specific profile.
Range of RF communicationThis should be specified in terms of allowed power output, and the antenna direction/gain.
Once these are fixed, it will have the range as specified in the standard in free air line of sight
conditions. But since zigbee gives us more range with mesh network, there is no point in
unnecessary pumping out more power from each and every node.
Range extendersThese have to be procured in some numbers ( may be one in 20 ). They are power operated totally
enclosed units to improve the reach ability of the meters.
Enclosure:Enclosure size and plastic weight should be mentioned in the tender to be more than a certain
minimum limit to ensure quality. And less than a certain maximum size to ensure easy installation.
TERMINALS:The terminals for power wiring should be big ( at least 6 mm hole dia), standard across all suppliers
to improve reliability of the joints.
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DisplayCBIP has to specify the size & segments of LCD to be uniform all across. The parameter list and
display sequence too. The no of LEDS and their purpose.
Super Cap/StdBy battery:They are better avoided, to lower the meter cost and increase the reliability.
RTC:RTC may be retained in the metrology block in PHASE-1, after successful PHASE-4, the RTC per
meter will not be required.
The Surge Voltage Limit:
The surge voltage limit should be limited to 4KV as per 61000-4-5.
Magnetic tamper limits:
If either the ac/dc magnetic field is less than 10mTesla the meter should be immune.
Beyond 10milliTesla until it records the tamper it should be accurate to within 4% ( for 1 % meter).
While it records the tamper it should run at ( Imax*240V +/- 10%) . This will meet the field
requirement and ensure easy testing.
Power consumptionThe single phase meter with LPRF communication port , consumption during idle time (Tx off, Rx ON,
router mode) should be less than 2.5 Watts. VA rating less than 10VA.
Tamper records:Record of latest 6 tampers with time stamp are enough, there is no need to ask for big no of
tampers, the six are sufficient to analyse/penalise the customer as needed.
The storage location of the parameters:
The basic single record of cukwh, tamper, MD should be stored in the metrology block ( in which fota
will not be present).
The communication module should read from the metrology block and store records in its own
memory so that in future its firmware can be updated and more versatile form of data may be
collected and used.
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Note: The other specifications may be followed now as per CBIP-304.
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Introduction to ZIGBEE technology
GlossaryLPRF Low Power Radio Frequency
ZigBee the name of the wireless communication standard , which is based on zigzag dance of bees
to communicate among themselves.
Version History
ZigBee 2004, Original ZigBee version.
ZigBee 2006, Backward compatibility with ZigBee 2004 not required.
ZigBee 2007/PRO, Backward compatibility with ZigBee 2006 required.
Zigbee certified product
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Frequency Bands and Channels
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Frequency Bands available in India
Frequency Band: 865-867 MHz
Low power RFID equipments or any other low power wireless devices or equipments
Power: Maximum transmitter output power of 1 Watt ( 4 Watts Effective Radiated Power)Carrier
Bandwidth: 200 KHz
Reference: GSR 564 ( E) dated 30 July 2008
Frequency Band: 2.4-2.4835 GHz
Use : Low power equipments
Power: Maximum transmitter output power of 1 Watt ( 4 Watts Effective Radiated Power)
Carrier Bandwidth: spectrum spread of 10 MHz or higher
Reference: GSR 45E dated 28.1.2005
The ZigBee Network Description
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Device TypesZigBee networks include the following device types:
Coordinators
Routers
End devices
CoordinatorThis device starts and controls the network. The coordinator stores information about the network,
which includes acting as the Trust Center and being the repository for security keys.
RouterThese devices extend network area coverage, dynamically route around obstacles, and provide
backup routes in case of network congestion or device failure. They can connect to the coordinator
and other routers, and also support child devices.
End DevicesThese devices can transmit or receive a message, but cannot perform any routing operations. They
must be connected to either the coordinator or a router, and do not support child devices.
Mesh Network TopologyMesh topology, also called peer-to-peer, consists of a mesh of interconnected routers and end
devices. Each router is typically connected through at least two pathways, and can relay messages
for its neighbors.
As shown in the image above, a mesh network contains a single coordinator, and multiple routers
and end devices.
Mesh topology supports multi-hop communications, through which data is passed by hopping
from device to device using the most reliable communication links and most cost-effective path until
its destination is reached.
The multi-hop ability also helps to provide fault tolerance, in that if one device fails or experiences
interference, the network can reroute itself using the remaining devices.
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Benefits
This topology is highly reliable and robust. Should any individual router become inaccessible,
alternative routes can be discovered and used.
The use of intermediary devices in relaying data means that the range of the network can be
significantly increased, making mesh networks highly scalable.
Weak signals and dead zones can be eliminated by simply adding more routers to the network.
Addresses
Addressing within ZigBee includes all the following components
PAN ID ( MAC)
NwkAdr(NWK)
Endpoint(APS)
Profile ID(APS)
Cluster(APS)
Command and/or attribute(ZCL)
The application can configure and access the parameters of the network layer through the ZDO.
PAN ID ( Personal Area Network ID):
ZigBee Personnel Area Network identifiers (or PAN IDs) are used to logically
separate a collection of ZigBee nodes from other ZigBee nodes in the same vicinityor on the same physical channel. This allows nework A and network B to exist in
close proximity without interfering with each other, other than consuming over the
air bandwidth that they both share.
ZigBee PAN IDs are 16-bit numbers that range from 0x0000 to 0x3fff.
PanID - the same for all devices in a network, assigned by the network coordinator
This is the network ID ( 16 bit 0x0000 0x3fff) which uniquely identifies a set of nodes forming the
network. There can be multiple networks operating on the same channel. But there is should beonly one PAN ID across all the zigbee channels ( as per 2007 spec to ensure frequency agility of the
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network). This ID is randomly chosen by the coordinator ensuring that this ID is not being already
used. Some times this 16 bit alone is not sufficient to ensure conflict or fast selection of the suitable
network running required application. Hence 64 bit extended PAN ID is used, this is used during
initial joining, but once the network is formed the selected 16 bit PAN ID is used. The 64 bit PAN ID
will have organisational part in it.
Extended PAN IDsExtended PAN IDs are 64-bit numbers that uniquely identify a PAN.
ZigBee communicates using the shorter 16-bit PAN ID for all communication except
one. The beacon response issued as the result of a beacon request contains an
Extended PAN ID to allow a node that wishes to join a network to pick exactly the
right one.
Every time a ZigBee node wishes to join a network, it sends out a beacon
request. It then pays attention to all of the beacon responses, and picks the bestnetwork out of these responses.
Sometimes a PAN ID is just not enough. A particular application may want to only join a network that
has a particular (probably private profile) application on it. One way is to use a special PAN ID and
hope, but that's not a very sure way to join the right network. Another way is to join the network
and see if the application is on it, but this takes time to join the other network, and may require
special code to be implemented.
ZigBee thought of this and provided a mechanism to join only those PANs which are released by your
corporation, which leads us to extended PAN IDs.
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Network Address ( Short Address)Short Address (NWK) - unique for each device in a network, assigned when it joins the network
The network address, also called NwkAddr, short address, or node address, isa 16-bit number used to uniquely identify a particular node on a ZigBee
network. The ZigBee Coordinator is always NwkAddr 0x0000.
Two ZigBee coordinators can exist on the same channel with NwkAddr 0x0000,because they are on different PAN IDs. The 16 bit Network address uniquely
identifies a node in the network.
The network address to a joining node is assigned based on distributed assignment strategy. The
coordinator gives a block of addresses to a joining router, the router in turn assigns one from its pool
to a joining end device.
MAC Address ( Long Address )Long Address (IEEE) - unique for each device, usually assigned by a manufacturer at the factory,
never changes
The MAC address, also called IEEE address, long address, or extended address, is a64 bit number that uniquely identifies ZigBee device from all other ZigBee devices inthe world. The top 24 bits of this address consist of the Organizational UniqueIdentifier (OUI). The lower 40 bits are managed by the OEM producing the boards.The 64-bit MAC address has no direct relationship to the 16-bit Network address. If a
node leaves one ZigBee network and joins another, its MAC address will remain thesame, but Network address will likely change.
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Forming a new Network
The Co-ordinator is responsible for starting a ZigBee network. Network initialisation involvesthe following steps:
1. Search for a Radio Channel
The Co-ordinator first searches for a suitable radio channel (usually the one which has leastactivity). This search can be limited to those channels that are known to be usable - forexample, by avoiding frequencies in which it is known that a wireless LAN is operating.
2. Assign PAN ID
The Co-ordinator starts the network, assigning a PAN ID (Personal Area Network identifier)to the network. The PAN ID can be pre-determined, or can be obtained dynamically bydetecting other networks operating in the same frequency channel and choosing a PAN IDthat does not conflict with theirs.
At this stage, the Co-ordinator also assigns a network (short) address to itself. Usually, thisis the address 0x0000.
3. Start the Network
The Co-ordinator then finishes configuring itself and starts itself in Co-ordinator mode. It isthen ready to respond to queries from other devices that wish to join the network.
Joining a ZigBee Network
Once the network has been created by the Co-ordinator, other devices (Routers and EndDevices) can join the network. Both Routers and the Co-ordinator have the capability toallow other nodes to join the network. The join process is as follows:
1. Search for Network
The new node first scans the available channels to find operating networks and identifieswhich one it should join. Multiple networks may operate in the same channel and aredifferentiated by their PAN IDs.
2. Select Parent
The node may be able to see multiple Routers and a Co-ordinator from the same network,in which case it selects which one it should connect to. Usually, this is the one with the bestsignal.
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3. Send Join Request
The node then sends a message to the relevant Router or Co-ordinator asking to join thenetwork.
4. Accept of Reject Join Request
The Router or Co-ordinator decides whether the node is a permitted device, whether theRouter/Co-ordinator is currently allowing devices to join and whether it has address spaceavailable. If all these criteria are satisfied, the Router/Co-ordinator will then allow the deviceto join and allocate it an address.
Typically, a Router or Co-ordinator can be configured to have a time-period during whichjoins are allowed. The join period may be initiated by a user action, such as pressing abutton. An infinite join period can be set, so that child nodes can join the parent node atany time.
Device Discovery
Device discovery is the process whereby a ZigBee device can discover otherZigBee devices. There are two forms of device discovery requests: IEEE addressrequests and NWK address requests. The IEEE address request is unicast to aparticular device and assumes the NWK address is known. The NWK address
request is broadcast and carries the known IEEE address as data payload.
Service Discovery
Service discovery is the process whereby the capabilities of a given device arediscovered by other devices. Service discovery can be accomplished by issuing aquery for each endpoint on a given device or by using a match service feature(either broadcast or unicast). The service discovery facility defines and utilizesvarious descriptors to outline the capabilities of a device.Service discovery information may also be cached in the network in the casewhere the device proffering a particular service may be inaccessible at the time
the discovery operation takes place.
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Endpoints and clusters
Devices are defined by profiles and implemented as application objects. Each application
object is connected to the rest of the ZigBee stack by an endpoint, which is an addressable
component within a device.
For example, a remote control might allocate endpoint 6 for the control of lights in the master
bedroom, endpoint 8 to manage the heating and air-conditioning system, and endpoint 12 for
controlling the security system. This allows the remote control to independently communicate
with these devices and identify which packets are intended for each application and device.
Communication is made from endpoint to endpoint through data structures called clusters.
Clusters contain a set of attributes that represent device state together with commands that
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enable communication between application objects. Each cluster is identified with a unique
ID.
Clusters used in a specific application are defined within its profile. For example, the Home
Automation profile contains a cluster dedicated to the control of lighting subsystems.
Each cluster has two ends:
The client/output requests and manipulates the data.
The server/input has the source data.
The ZigBee Cluster Library (ZCL)
All ZigBee application profiles are defined using clusters from the ZigBee Cluster Library.
This library allows common clusters to be reused across a number of different functional
domains, for example, the same lighting clusters can be used for any application that requireslighting control, such as home automation and commercial building automation.
Clusters within the ZCL are organized into a number of different functional domains,
including Lighting, HVAC (Heating, Ventilation, Air Conditioning), Measurement and
Sensing, Security and Safety, and General.
Each cluster specification within the ZigBee Cluster Library defines
mandatory and optional attributes
cluster-specific commands
functional description
Each device specification within an application profile defines
mandatory and optional cluster usage
values of free parameters in the ZCL
any additional functional description
Bindings
At a high level, binding is the process of establishing a relationship between two devices thatcan communicate in a meaningful way, for example, which switch controls which lights.
Each binding supports a specific application profile, and each message type is represented by
a cluster within that profile.
Bindings can be created between either individual or groups of endpoints, such as lights and
switches, that have matching input and output clusters (with the same cluster ID). ZigBee
devices can have up to 240 endpoints, so each physical device can support multiple bindings.
Conclusion
By providing the ZigBee Cluster Library and application profiles, the ZigBee Alliance hasalready done a lot of the hard work for you.
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If you need your device to perform a specific function or behave a specific way, there is no
need to create things from scratch. You can simply implement the ZigBee cluster that already
exists for that purpose.
Adherence to the application profiles and the ZCL also helps to achieve ZigBee certification
to ensure interoperability with other ZigBee devices.
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- Node A and B are given unique addresses when they joina Zigbee network
- Switch 1 and 2 would have unique endpoint numbers- Lamps 1, 2, 3 and 4 would have unique endpoint numbers
as well- Setup allows Switch 1 to uniquely address and control
Lamps 1, 2 and 3 using clusterIds
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Hope this helps the stake holders in india implementing this technology in the smart grid
infrastructure.