alstom testing

TestingProtectionDevicesB.doc

Testing Protection Devices

Dr. Michael Igel, ALSTOM Energietechnik GmbHIssue A, April 2001

Testing Protection Devices of 28

17. 04. 2001

ISSUE:TestingProtectionDevicesB.doc

1 Table of contents

1 TABLE OF CONTENTS ............................................................................................................ 2

2 OVERVIEW ............................................................................................................................... 3

2.1 ROUTINE TESTS ..................................................................................................................... 32.2 TYPE TESTS ........................................................................................................................... 4

3 MULTI-FUNCTION DEVICES REQUIRES SYSTEM TYPE TESTS....................................... 5

3.1 MULTI-FUNCTION DEVICES ................................................................................................... 53.2 TEST OF MULTI-FUNCTION DEVICES ..................................................................................... 6

4 METHODS TO TEST PROTECTION DEVICES ...................................................................... 6

4.1 STATIC TYPE TESTS............................................................................................................... 74.2 TRANSIENT TYPE TESTS ........................................................................................................ 8

5 ATP – A NETWORK SIMULATION SYSTEM ......................................................................... 9

5.1 LINE MODEL FOR SOLID GROUNDED NETWORKS................................................................ 105.2 LINE MODEL FOR INSULATED AND PETERSSON COIL GROUNDED NETWORKS..................... 11

6 ATPNET – A TOOL FOR TESTING PROTECTION DEVICES............................................. 12

6.1 REQUIREMENTS OF THE UNIVERSAL TEST NETWORK.......................................................... 136.2 DESIGN OF THE UNIVERSAL TEST NETWORK....................................................................... 136.3 ATPNET – GRAPHICAL USER INTERFACE FOR TESTING PROTECTION DEVICES ................... 156.4 TEST EQUIPMENT................................................................................................................ 15

7 TESTING PROTECTION DEVICES USING ATPNET ........................................................... 16

7.1 BASIC CONCEPT OF ATPNET ............................................................................................... 167.2 CONFIGURATION OF THE TEST NETWORK ........................................................................... 167.3 DEFINITION OF FAULT SITUATION AND FAULT TYPE ........................................................... 177.3.1 EXAMPLE: VOLTAGES AND CURRENTS IN CASE OF AN EVOLVING FAULT ........................... 197.3.2 EXAMPLE: VOLTAGES IN CASE OF A CVT ......................................................................... 207.3.3 EXAMPLE: INRUSH EFFECT .............................................................................................. 207.3.4 EXAMPLE: CT SATURATION ............................................................................................ 217.3.5 EXAMPLE: SINGLE-POLE FAULT WITH AUTOMATIC RECLOSING........................................ 227.3.6 EXAMPLE: FAULTS WITH ARC RESISTANCE....................................................................... 227.4 TEST PROCEDURES.............................................................................................................. 237.5 AUTOMATIC TEST................................................................................................................ 26

8 REFERENCES ......................................................................................................................... 28


17. 04. 2001


2 Overview

Tests of protection devices, which are performed by the device manufacturer, can be generally divided intwo different parts:

1. Routine Tests– of each manufactured device– as part of the production process– to ensure the quality and functionality of each delivered device

2. Type Tests– of devices manufactured in the series production– as part of the R&D process– to ensure the quality and functionality of all hardware and software components

The figure below shows duration, objectives, test location and targets of routine tests and type tests ofprotection devices.

Test Strategies

Routine Test Type Test

ýý 5..15 Minutes ýý Months .. YearsDuration

ýý Specified Standards ýý 100% of Relay FunctionsObjectives

ýý Production Site ýý R&D, CertificationTest Location

ýý Test of Assembled Hardware Components

ýý Selected Relay Functions

ýý Type Test of Hardware Variations

ýý Software Type Test: Function Groups

ýý System Type Test: Black Box Test as System Test

Targets

Figure 1: Test Strategies - Routine Test and Type Test

2.1 Routine Tests

Routine tests will be done as part of the production process. Each device has to be tested, before it willbe delivered out of the production. The main objective of the routine test is to ensure quality andfunctionality of each manufactured device.

The list below shows steps of the routine of protection devices. All steps will be executed as part of theproduction process.


17. 04. 2001


§ Heat soak test (burn-in-test of the fitted hardware components)§ Flash test (insulation test)§ Test of all binary input channels§ Test of all output relays§ Test of all analog output channels§ Test of all communication interfaces§ Calibration of all analog input channels§ Verification of calibration factors (gain, offset, phase)§ Verification of the accuracy of measuring data§ Verification of the accuracy of timers, thresholds, calculated impedances, etc.

Figure 2: Routine Tests

More steps can be added depending on the routine test strategy of the manufacturer. The results of theroutine tests have to be archived as test reports. The routine test reports shall be delivered together withthe protection device printed on paper or stored on a floppy disk.

2.2 Type Tests

Type tests of a protection device have to be done before the series production is started. Type tests haveto be performed as part of the R&D process to ensure the quality and functionality of all hardware andsoftware components. Only series produced devices have to be used for type tests.

The objectives of type tests can be divided in three main parts.

1. Hardware Type Tests

Ä Test of all hardware modules and the complete device

– Accuracy tests– Functional tests– EMC type tests– Safety test– CE conformity– Environmental tests– etc.

2. Functional Type Tests

Ä Test of one function independent from other functions

– Protection functions– Control functions– Communication functions– Data acquisition functions– Measurement functions– Programmable scheme logic– HMI (Human Machine Interface)– etc.


17. 04. 2001


3. System Type Tests

Ä Test of the protection device as black box in case of realistic network situations

– Test of the interaction of functions– Test of the accuracy of the measurement system in case of transient phenomena– Test of the real-time behavior depending on different microprocessor load situations– Test with static and dynamic faults– Test with faults superimposed by transient phenomena– etc.

3 Multi-Function Devices Requires System Type Tests

3.1 Multi-Function Devices

Modern protection devices are designed as multi-function devices. All protection, measuring and controlfunctions are realized as independent software modules running on one microprocessor board.

Y VXT

Binary Signals / Measured Data / Commands Power SupplyCurrents / Voltages

µP

PC Interface Communication Interface

P

L A

B

GGC

GGG

G

G

TRIPALARMOUT OF SERVICEHEALTHYEDIT MODE= CLEAR

= ENTER= READ

C

MiCOM

NµC

Figure 3: Hardware Structure of Multi-Function Protection Devices

The figure above shows the typical structure of a microprocessor based multi-function device. The dataacquisition software samples voltages and currents and stores these data in ring buffers. All devicefunctions have a free access to the sampled and to the precalculated data independent from each other.Therefore it is very easy to integrate new protection functions in addition to an existing device software.


17. 04. 2001


A/D Frequency f 60 HzCurr. IP,max prim. 480 A

...

Metering

20 samples/

cycle

(P438/P436:

2 kHz)

Ring

Buffer

LIMIT

Nominal currents:

IP: 100 or 25 Inom

IN: 16 (2) Inom

V: 150 V

1 or 5 A

Dynamic ranges:

t>0I>

Fault Recording

<50 cycles prefault

<300 cycles per fault

<50 cycles postfault

Sampling:

Protection Functions

DIST, IDMT, ...

I>,... V>,...

Figure 4: Data Acquisition and Basic Data Processing

3.2 Test of Multi-Function Devices

The evolution from single-function protection relays to multi-function protection devices increasesdramatically the number of protection functions implemented in one device. Therefore the realization ofmulti-function devices has forced the development and the realization of new test concepts.

Functional type tests of one function only are not any more sufficient. It is necessary to test the protectiondevice as a system. System type tests have to be defined to stimulate several device functions in parallele.g. distance protection, auto reclosing and synchron check. The advantage of system type tests is, thatthe protection device can be tested during complex fault situations.

Customers wants to get more and more informations about the behavior of the protection device inspecific network situations. This can be e.g. the protection of a customer specific untransposed line orbasic researches about single-pole automatic reclosing in Petersson coil grounded networks. On othertypical example is to test the influence of a remanent magnetic flux in case of an automatic reclosing of acircuit breaker after a single-pole trip command.

This publication presents a realized concept to test multi-function devices. Methods and tools will bedescribed.

4 Methods to Test Protection Devices

In general two methods to test protection devices can be identified [9]:

1. Static Type TestsÄ as the conventional type test method

2. Transient Type TestsÄ as the improved type test method


17. 04. 2001


4.1 Static Type Tests

Static type tests stimulate protection devices using voltages and currents represented by sine variablesusing the fundamental frequency of the electrical power network only. Amplitude and phase angle ofvoltages and currents are defined for a fixed test period. Different test periods can be combined to a testsequence. Static type tests consist typically of pre-fault, fault and post fault periods.

Advantages of Static Type Tests

þ Static type tests can be executed using a simple 3-phase generator.þ Voltages and currents can be defined using amplitude and phase only.

Disadvantages of Static Type Tests

M Voltages and currents are calculated as sine variables only without transient signal components.M A sudden change of amplitudes will be realized using an absolute amplitude shift.M A sudden change of phases will be realized using an absolute phase shift.M The DC-component is calculated based on a mathematical equation, but not as the result of a

network simulation.M No transient signal components can be used e.g. for ground faults in insulated or Petersson coil

grounded networks.

It can be stated that static type tests calculate voltages and currents using linear mathematical equationsonly. Such equations can not take into account the transient behavior of electrical power networks.

Zq Zl-ZfZf

Monitoring Location u(t), i(t)Fault Location

Fault Location

Tri

pp

ing

Tim

e

80% LineLength

R

R

R

L

L

L

iA (t)

iB (t)

iC (t)

uA (t)

uB (t)

uC (t)

UA = ZA IA

UB = ZB IB

UC = ZC IC

Figure 5: Line Model for Static Type Tests

The figure above shows a line model typically used from static type test tools. The line model is a simplerepresentation of an overhead line or cable without any mutual coupling or capacities. The next figureshows the phase currents used for a static type tests. The phase currents were calculated based on thepresented line model.

Static type tests can be used to test the behavior of the protection device e.g. accuracy, operating times,etc. But transient phenomena can not be taken into account. On this point of view static type tests areonly a poor representation of electrical power networks.


17. 04. 2001


Figure 6: Pre-Fault, Fault and Post Fault of Phase Currents used for Static Type Tests

As conclusion it can be stated, that static type tests are not sufficient enough to test protection devices.

4.2 Transient Type Tests

Transient type tests are based on network simulation systems. A network simulation system calculatesvoltages and currents by solving the differential equations of the electrical network. This method takesinto account the dynamic characteristic of the electrical network. Transient phenomena e.g. mutualcoupling are taken into account, too.

þ Voltages and currents contain transient signal components.

þ Amplitudes and phases will be changed continuously.

þ Voltages and currents depend on the characteristic of the electrical power network.

A transient type test consists of voltages and currents using components of the power frequency and highorder frequencies experienced during system operating conditions. The signals used in these tests canbe calculated analyzing computer models of a electrical power systems using electromagnetic transientanalysis programs.

Different dynamic network and fault situations can be simulated depending on the structure of model ofthe electrical network:

§ Insulated and Peterson Coil Grounded Networks§ Networks with Two Infeeds§ CT Saturation with Hysteresis and Remanence§ Capacitive Voltage Transformers (CVT)§ Transformers with Overfluxing, Saturation, etc.§ Evolving Faults§ High Impedance Faults§ Faults with Arc Resistance§ EHV Lines with Series Compensation§ Underground Cables


17. 04. 2001


§ Untransposed Lines§ Double-Circuit Lines with Mutual Coupling in the Zero Sequence System§ etc.

First the protection engineer has to design a suitable model of the electrical network. The networksimulation software calculates voltages and currents for each network node. Voltages and currents haveto be used to stimulate the protection devices. Transient phenomena are taken into account dependingon the chosen network model.

It can be stated, that transient type tests have to be used to test protection devices in addition to statictype tests. Transient type tests give better informations about the behavior of the protection device incase of typical network disturbances.

5 ATP – A Network Simulation System

The network simulation system ATP (Alternative Transients Program) is designed and will be furtherdeveloped to simulate single- and multi-phase electrical power networks. ATP is very well prepared tocalculate voltages and currents of 3-phase electrical power networks. It can be used to simulate high-frequency transient phenomena as well as stationary short circuits.

ATP supports a lot of network elements, linear and nonlinear impedances and mathematical methods todesign a model of the electrical power network.

Linear Network Elements

§ Impedances (RLC)§ Overhead Lines (Single-Circuit Lines, Double-Circuit Lines, etc.)§ Transposed and Untransposed Lines§ Cables§ Transformers (2 Winding, 3 Winding, etc.)§ Circuit Breakers§ Generators§ Rotating Machines§ etc.

Non-Linear Network Elements

§ Static and Dynamic Arc Resistances§ CT Saturation with Hysteresis§ Overfluxing§ MOV (Metal Oxide Varistor)§ etc.

Further Properties

§ Transient Analysis of Control Systems (TACS)§ Filter Techniques§ Laplace Functions§ Free Programmable Interface (MODELS)§ etc.


17. 04. 2001


It can be stated that the use of the network simulation system ATP improves the testing of protectiondevices,

§ to calculate voltages and currents in electrical power networks depending on differentnetwork situations and using several network elements,

§ to test and approve protection devices in case of transient phenomena,

§ to calculate settings e.g. the reactive reach X1 for the protection device.

5.1 Line Model for Solid Grounded Networks

The figure below shows a line model using mutually-coupled RL elements. This line model can be used incase of solid grounded networks, where the influence of the capacities can be neglected.

Figure 7: Line Model based on Mutually-Coupled RL

The phase currents presented in the next figure were calculated in case of a 3-phase-to-ground fault. Therelation between reactance and resistance of the electrical network causes a DC-component.

Figure 8: Phase Currents with DC-Component

R

R

R

Ls

Ls

Ls

Lm

Lm

Lm


17. 04. 2001


The line model based on mutually-coupled RL elements can be used to calculate balanced lines using thepositive and zero sequence impedance only. Nevertheless it is possible to calculate voltages and currentsin case of an untransposed line too, based on the geometrical and physical data of the overhead line orthe underground cable.

5.2 Line Model for Insulated and Petersson Coil Grounded Networks

The figure below shows a line model designed to simulate insulated and Petersson coil groundednetworks. The model of insulated or Petersson coil grounded networks has to be taken into account thecapacities of the overhead lines and cables as well as the inductances of all transformers.

Figure 9: Distributed Line Taking into Account Parameters R, L and C

Figure 10: Phase-to-Ground Voltages in Case of a Single-Pole-to-Ground Fault

R

R

R

Ls

Ls

Ls

Lm

Lm

Lm

C C C


17. 04. 2001


Figure 11: Phase Currents Voltages in Case of a Single-Pole-to-Ground Fault

The figures above show the phase-to-ground voltages and the phase currents in case of a single-pole-to-ground fault. Voltages and currents were calculated using ATP.

In case of a single-pole-to-ground fault, voltages and currents contain a medium-frequent signalcomponent visible in both diagrams. The frequency of the medium-frequent signal component dependson the resistances, reactances and capacities of the complete electrical power network. A variation of onenetwork element or the network topology can change the frequency and the amplitude of the medium-frequent signal component. Protection engineers can calculate the voltages and currents using ATP andcan determine amplitude and frequency of the medium-frequent signal component.

As part of the network simulation system ATP, different line models are provided to take into accounttransient phenomena. In case of single-phase-to-ground faults in insulated or Petersson coil groundednetworks, it is sufficient to use the distributed-parameter line model.

The distributed-parameter line model can be used to calculate balanced lines using the positive and zerosequence impedance only as well as untransposed lines using the geometrical and physical data of theoverhead line or the underground cable.

Further line models take into account frequency dependent parameters e.g. the frequency dependence ofthe earth resistance.

6 AtpNet – A Tool for Testing Protection Devices

The network simulation system ATP is a very powerful tool to analyze electrical networks. But ATP wasnot designed to test protection devices. Additional tools will be needed, until protection engineers caneasily use ATP to test protection devices.

First it will be analyzed, which steps have to be executed, if a protection engineer has to test a protectiondevice using a network simulation system. The list below shows the steps to execute one test sequence.


17. 04. 2001


1. Definition PhaseDefinition of the test network

2. Test PhaseGenerating of the ATP input fileCalculation of voltages and currents using ATPConverting of the ATP output file e.g. to COMTRADETransfer of the sampled data to a test benchStimulation of the protection device using power amplifiersMeasuring the reactions of the protection device e.g. the operating timesWriting of the test report

3. Analyzing PhaseAnalyzing the measured reactions of the protection device

Table 6-1: Definition of a Test Sequence

The definition and the analyzing phases have to be carried out from a protection engineer. But in bothphases the protection engineer has to be assisted by suitable software tools to minimize time and costs.

The test phase has to be 100% automated using additional software tools running on a PC.

6.1 Requirements of the Universal Test Network

The main objective of the Universal Test Network is to assist the protection engineer during the definitionphase efficiently. “Efficiently” means to execute a maximum of test procedures with a minimum of timeand costs. The design of the Universal Test Network depends on the following basic requirements.

§ The network topology must be simple and clearly organized.§ The number of electrical network components must be limited.§ The electrical network must be configurable.§ It must be possible to simulate complex faults, evolving faults and complex fault sequences.§ The protection engineer must be able to define the tests using a graphical interface.§ The graphical interface must contain graphical symbols used by protection engineers.§ The network topology and the network components must permit the testing of all types of

distance protection, transformer differential protection, line differential protection, etc.§ The test equipment must consist of standardized hardware and software components.§ The test tools must assist the protection engineer to simulate electrical networks without a

deep knowledge about the simulation system ATP.

Table 6-2: Basic Requirements of the Universal Test Network

6.2 Design of the Universal Test Network

Basic researches have shown, that the Universal Test Network can be designed using a very smallnumber of network components only.

§ 2 Network Infeeds§ 2 Busbars§ 3 Lines (Single-Circuit Lines, Double-Circuit Lines, Cables)


17. 04. 2001


§ 4 Load Impedances§ 6 Transformers§ 14 Circuit Breakers§ Independent Fault Types and Fault Locations§ Some Additional Components e.g. Fault Impedances, Arc Resistances, CVT’s, etc.

Figure 12: Design of the Universal Test Network

The figures above and below show two different structures of the Universal Test Network using the samenumber of network elements. The left network structure can be used to test distance protection devices incase of transposed or untransposed double-circuit lines with mutual coupling in the zero sequencesystem. The right network structure can be used to test transformer differential protection devices.

Figure 13: Double Line Protection (left) and Transformer Differential Protection (right)


17. 04. 2001


6.3 AtpNet – Graphical User Interface for Testing Protection Devices

The last two figures have presented snap shots of the 32-bit-software AtpNet. AtpNet is a Windows

based graphical user interface for testing protection devices. The objectives to develop AtpNet were toassist protection engineers

§ to design test networks without having a deep knowledge about ATP,§ to configure electrical network components,§ to control the CMC test systems of Omicron via the CM Engine interface,§ to execute single test procedures or test procedure batches 100% automatically,§ to analyze the measured reactions of the protection device and§ to present the test results.

Compared with the phases of a test sequence presented in “Table 6-1: Definition of a Test Sequence”,AtpNet helps the protection engineer to automate the test procedure as far as possible.

The definition and analyzing phases have to be performed by the protection engineer. In both phases theprotection engineer gets an optimal assistance by AtpNet. Both phases can not be done 100% automatedby a software tool, because engineers need years of experience in protection to perform both steps.

In contrast to the definition and analyzing phases, the test phase can be 100% automated. AtpNet writesthe ATP input file, starts ATP as a background task, converts the ATP output data, transfers the sampleddata to the power amplifiers and controls the complete test procedure including the stimulation of theprotection device and the analyze of the reactions.

6.4 Test Equipment

The test equipment can consists of two main parts:

1. a high performance PC to execute the test software and

2. power amplifiers to stimulate and monitor the protection device.

The next figure shows the test equipment used since some years to test protection devices for type testsand application tests.

TYPE TEST PC WITH ATP NET

Supervision of TripCommands

Voltages and Currents

Communication andMeasurements

Windows Interface(CM Engine)

Figure 14: Test Equipment


17. 04. 2001


The PC shall consist of a high speed CPU and min. 256 MBytes RAM. ATP needs a lot of CPU powerand RAM to calculate voltages and currents efficiently. A Windows operating system is required toexecute ATP and the graphical user interface AtpNet. With Windows NT the best results of long termstability have been performed.

The test systems of OMICRON can be used as external amplifiers. OMICRON includes a software librarycalled “CM Engine” to control and program CMC test systems using Windows operating systems. Thetest software AtpNet communicates with the CMC test systems via the CM Engine DLL.

A typical test equipment consists of the basic device CMC156EP as a 3-phase voltage and 3-phasecurrent amplifier with extended precision. In addition one external amplifier as CMA156 with 2x 3-phasecurrent amplifiers can be connected. Using such a test equipment the protection engineer is able to testdistance protection devices including double-circuit lines with parallel line compensation. Transformerdifferential protection can be tested up to 3 windings, line differential protection devices up to 3 terminals.

An improved test equipment can consist of the basic device CMC256. This newer basic device contains a4-phase voltage amplifier and 2x 3-phase current amplifiers. It can be used in combination with oneexternal amplifier as CMA156 too. Using such a test equipment the protection engineer is able to testtransformer differential protection devices up to 4 windings and line differential protection devices up to 4terminals.

7 Testing Protection Devices using AtpNet

7.1 Basic Concept of AtpNet

AtpNet is designed to be the control center for testing protection devices. The protection engineer canperform all activities to test protection devices. Configuration dialogs will be presented depending on thenetwork elements or presented to configure the network topology.

It can be stated, that AtpNet assists protection engineers to define test networks and test procedures, toexecute test procedures and to analyze the test results.

The protection engineer can not design the test network using a drag&drop technology. He can onlyactivate or deactivate options in the configuration dialog. The graphical representation of the test networkdepends on the chosen configuration options and will be drawn automatically.

This restrictive design method has one important advantage: It is possible to check all implementednetwork configurations to maximize security and reliability. The protection engineer can define the testnetwork without a deep knowledge about ATP and directly will get an approved network.

In addition a lot of intuitive dialogs assist the protection engineer to configure the network elements or todefine fault types and fault situations. Complex network elements as CVT’s (Capacitive VoltageTransformers) or CT saturation can be activated or deactivated “by a click” only.

Depending on the activated network elements and the network definition, AtpNet chooses approvedmodels to simulate the network elements.

7.2 Configuration of the Test Network

As a first step defining a test procedure, the protection engineer has to configure the network topologyand the required network elements. The topology can be easily configured using the options of the dialog“Network Configuration” presented in the next figure (left side).


17. 04. 2001


The graphical network diagram will be drawn automatically depending on the activated network elementsand the chosen network topology.

Figure 15: Network Configuration and Definition of Line 1

The second snap shot (right side) in the figure above shows as an example the dialog to configure line 1.First the protection engineer has to choose the line model:

§ Single Line (Mutually-Coupled RL Impedances)§ Single Line (Distributed-Parameter Line)§ Single Line with Series Compensation§ Double-Circuit Line

The line impedances can be defined using the other dialog elements as the line impedance or the zerosequence system.

7.3 Definition of Fault Situation and Fault Type

A flexible definition of fault types and fault sequences is one of the most important functions. AtpNetassists the protection engineer with an intuitive dialog. The protection engineer can use up to threedifferent fault types for each line in parallel. Point on wave or start time and the end time can be definedseparately. The figure below shows the dialog to configure the fault situation.

As an example, the definition of an evolving fault will be explained.


17. 04. 2001


Figure 16: Definition of Fault Type and Fault Situation

The example presented in the figure above defines an evolving fault. After the pre-fault, a single-pole-to-ground fault AG occurs. The fault will be extended to a 3-pole-to-ground fault ABCG 20ms later. AtpNetrealizes the evolving fault with time programmable switches. In the lower part of the dialog, the protectionengineer can see the closing and opening times of the fault switches. He can check, that his definition ofthe evolving fault is correct. The figure below shows the definition of the evolving fault depending on thesimulation time.

FAULT ABCGFAULT AG

PREFAULT

FA

UL

T

TY

PE

TIME20 ms

Figure 17: Definition of an Evolving Fault


17. 04. 2001


7.3.1 Example: Voltages and Currents in Case of an Evolving Fault

Evolving faults shall be one of the standard tests for distance protection devices. A high percentage ofnetwork faults starts with a single-pole-to-ground fault and extends after a short time gap of somemilliseconds to a 2-pole or 3-pole fault. The protection device can detect the evolving fault as one or twoseparated faults. This depends on the time in between both faults. Therefore protection devices shall betested in case of an evolving fault using different time gaps.

The figure below shows the phase-to-ground voltages and the phase currents calculated for an evolvingfault AG ⇒ ABG in a solid grounded electrical power network using different time gaps DT.

The first two figures show phase-to-ground voltages and phase currents in case of an evolving fault withtime gap DT = 5 ms.

Figure 18: Voltages and Currents during an Evolving Fault with DT = 5ms

The next two figures show phase-to-ground voltages and phase currents in case of an evolving fault withtime gap DT = 25 ms.

Figure 19: Voltages and Currents during an Evolving Fault with DT = 25ms


17. 04. 2001


7.3.2 Example: Voltages in Case of a CVT

The figure below shows the transient signal components caused by an CVT (Capacitive VoltageTransformer). The fault location of the left diagram was defined at 0% of the line length for 3-pole-to-ground fault. Therefore the calculated voltages show only the transient behavior of the CVT after the faultoccurrence without the fundamental frequency.

The right diagram shows the phase-to-ground voltages for a fault location of about 10 km. The transientsignal components are damped by the line impedance in between the monitoring point of the protectiondevice and the fault location.

Figure 20: Phase-to-Ground Voltages in Case of CVT’s

7.3.3 Example: Inrush Effect

The energizing of a transformer causes harmonic signal components, if the transformer was not loaded.The reason is the magnetic characteristic of the transformer core. The figure below shows the phasecurrents after an unloaded transformer has been connected with an electrical power network. The phasecurrents consists of harmonics caused by the inrush effect.

Figure 21: Phase Currents in Case of a Inrush Effect


17. 04. 2001


7.3.4 Example: CT Saturation

The figure below shows the phase currents in case of a 3-pole-to-ground fault with CT saturation.CT saturation is the most complicated situation for a protection device especially for distance protection.The determination of the fault direction is possible in case of CT saturation. The calculation of the faultimpedance is complicated by the transient signal components caused by the non-linear inductance of thecurrent transformer.

Figure 22: Phase Currents in Case of a Transient CT Saturation

The next figure shows the magnetic characteristic of the current transformer including hysteresis. Themagnetic flux was calculated by integration of the voltage measured on the non-linear inductance.

Figure 23: Hysteresis Characteristic of a Current Transformer


17. 04. 2001


7.3.5 Example: Single-Pole Fault with Automatic Reclosing

80% of all faults in overhead line networks are single-pole-to-ground faults. After the fault clearance,distance protection devices tries to energize the overhead line again using the automatic reclosingfunction. The next two figures show the phase currents in case of a single-phase-to-ground fault withsuccessful fault clearance and a single-pole automatic reclosing of the circuit breaker. The diagram at theright is a zoom of the diagram at the left.

Figure 24: Clearance of a Single-Pole Fault using Automatic Reclosing

7.3.6 Example: Faults with Arc Resistance

The left figure below shows the phase-to-ground voltages in case of an fault with arc resistance. The faultlocation was defined at 0% of the line length. Therefore the phase-to-ground voltage consists only of thearc voltage caused by the dynamic behavior of the arc resistance. After the occurrence of the fault, thearc voltage increases, because the length of the arc increases.

The diagram at right shows the phase currents. According to the physic of the arc resistance, the phasecurrent does not contain harmonics.

Figure 25: Fault with Arc Resistance


17. 04. 2001


7.4 Test Procedures

If the test network and all network elements are configured, the protection engineer has to define the testprocedure. The test procedure consists of a sequence of single test steps. The protection device will bestimulated for each test step, the reactions will be measured and stored into a report file. After the testsequence is completed, the protection engineer can analyze the test results with assistance of AtpNet.

Figure 26: Definition of a Test Procedure

The figure above shows the dialog to define a test procedure. Test procedures can consist of up to 2 testlevels. Test level 2 will be automatically executed for each value of test level 1.

For example the figure shows the definition of a standard test procedure for EHV distance protectiondevices. AtpNet modifies as "Test Level 1” the “Fault Location Line 1 “ from 0% up to 90% of the linelength in 5% steps. As “Test Level 2”, AtpNet modifies the “Point on Wave” from 0° up to 330° in 30°steps for each fault location.

AtpNet can monitor the 10 binary inputs of the connected CMC test system. The measured operatingtimes will be compared with specified minimum and maximum operating times. Up to 4 monitoring rangescan be used. The supervision of trip command, starting signal and backward direction will be used asstandard configuration of the monitored binary inputs.

In this example, the test procedure consists of 260 different test steps. The protection device will bestimulated 10 times for each test step. In sum the protection device will be stimulated 2600 times.

For each test step, AtpNet transfers the calculated voltages and currents as sampling data to the CMCtest system. The CMC test system will then be programmed to stimulate and monitor the protectiondevice. AtpNet reads out the monitored data and calculates the operating times.

The operating times of the protection device will be written into a test report. An example of a test reportis presented in the text box below.


17. 04. 2001


-------------------------------------------------------------------------------------------

TYPE TEST REPORT : AtpNet - Test System for Protection Devices Copyright ALSTOM T&D AFS/T12 2001 Version 29.1 - 25.01.2001

------------------------------------------------------------------------------------------- Start of Type Test: 25.01.2001, 14:07:33-------------------------------------------------------------------------------------------

Output File : C:\Atp\TypeTestP437\BA602\Reports\TST_0200.TXT

-------------------------------------------------------------------------------------------

Device : 437

-------------------------------------------------------------------------------------------

F-Number : 0.007312.0 Software Version : 602.00 Software Date : 06.12.2000 dd.mm.yyyy Order No. : P437-0-08555490 Order Ext. No. : 301-401-451-912-602-801-801

Abbreviations-------------

Lev 1: Type test level 1 Lev 2: Type test level 2 Cnt : Count of measured tripping commands Min : Minimum value of measured tripping command time [ms] Mean : Mean value of measured tripping command time [ms] Max : Maximum value of measured tripping command time [ms] '+' : Specified signal state is equal to measured signal state '#' : Specified signal state is not equal to measured signal state 'ø' : Measured signal state is not relevant

Monitored Binary Inputs with Static Specified Level and Max. Operating Time---------------------------------------------------------------------------

Range 1 : [0.000000, 90.000000]

No. 01: 036.071 : General trip command Spec. Level : Not relevant Min.Op. Time: 0.0 ms Max.Op. Time: 40.0 ms No. 02: 036.000 : General starting Spec. Level : Not relevant Min.Op. Time: 0.0 ms Max.Op. Time: 40.0 ms No. 03: 036.019 : Fault direction backward Spec. Level : Not relevant Min.Op. Time: 0.0 ms Max.Op. Time: 1000.0 ms

Type Test : 0200----------------

Type Test Level 1 : Fault Location Line 1 Min. Value = 0 Max. Value = 90 Step = 5

Type Test Level 2 : Point on Wave Min. Value = 0 Max. Value = 330 Step = 30

Maximum Repetitions : 10 Relaxing Time : 100 ms


17. 04. 2001


Configuration File : C:\Atp\TypeTestP437\BA601\Pd_0200.net Network Description File : C:\Atp\TypeTestP437\BA602\Reports\NET_0200.TXT General Setting File : --- Reading Device Data File : --- Output Device : CMC156

Comments--------Metallic Short-CircuitFault Type AG

Results-------

Values | Binary Inputs No. | | 01 | 02 | 03 | Lev 1 | Lev 2 | Cnt Min Mean Max | Cnt Min Mean Max | Cnt Min Mean Max |-------------------------------------------------------------------------------------------- | | 036.071 : General tr 1| 036.000 : General st 1| 036.019 : Fault dire 1|-------------------------------------------------------------------------------------------- 0 | 0 | 10 17.4 18.8 19.7 +| 10 7.5 9.4 12.6 +| 0 ---- ---- ---- +| 0 | 30 | 10 15.4 18.2 20.6 +| 10 6.2 10.0 11.9 +| 0 ---- ---- ---- +| 0 | 60 | 10 17.8 18.3 19.0 +| 10 6.6 7.5 8.4 +| 0 ---- ---- ---- +| 0 | 90 | 10 16.0 17.1 18.0 +| 10 6.8 8.5 11.5 +| 0 ---- ---- ---- +| 0 | 120 | 10 14.8 15.7 16.7 +| 10 9.2 10.1 11.2 +| 0 ---- ---- ---- +| 0 | 150 | 10 18.9 19.8 20.8 +| 10 8.9 10.6 13.0 +| 0 ---- ---- ---- +| 0 | 180 | 10 18.4 19.4 20.2 +| 10 7.6 9.7 12.4 +| 0 ---- ---- ---- +| 0 | 210 | 10 19.6 20.3 21.1 +| 10 6.3 8.7 12.5 +| 0 ---- ---- ---- +| 0 | 240 | 10 17.5 19.3 20.9 +| 10 6.2 7.6 10.7 +| 0 ---- ---- ---- +| 0 | 270 | 10 16.3 18.3 20.3 +| 10 8.0 10.4 11.8 +| 0 ---- ---- ---- +|... 90 | 180 | 10 19.8 28.4 30.6 +| 10 15.2 16.4 17.0 +| 0 ---- ---- ---- +| 90 | 210 | 10 25.8 26.8 28.7 +| 10 14.8 15.2 16.2 +| 0 ---- ---- ---- +| 90 | 240 | 10 20.5 23.9 28.0 +| 10 14.6 15.0 15.5 +| 0 ---- ---- ---- +| 90 | 270 | 10 20.5 24.2 30.6 +| 10 13.7 14.5 15.0 +| 0 ---- ---- ---- +| 90 | 300 | 10 20.8 27.4 33.7 +| 10 13.7 15.9 18.0 +| 0 ---- ---- ---- +| 90 | 330 | 10 20.3 27.1 32.7 +| 10 16.3 17.0 17.5 +| 0 ---- ---- ---- +|

-------------------------------------------------------------------------------------------

Type test is completely finished. Result of Type Test: approved End of Type Test: 25.01.2001, 15:01:03

------------------------------------------------------------------------------------------- ALSTOM PCB Responsible | Customer Responsible Name/Signature: | Name/Signature: | | | | ------------------------ | ------------------------

-------------------------------------------------------------------------------------------

The test report contains informations

§ about the tested protection device e.g. the device identification or the software version,§ a short description of the test procedure,§ a description of the monitored signals,§ the measured operating times and§ the result of the type test.


17. 04. 2001


An improved kind of presentation of the test results is presented in the next figure. AtpNet can read thepresented test report and draws automatically the tripping characteristic as a graphical diagram. Theprotection engineer is able to recognize the reactions of the protection device at first sight.

Figure 27: Tripping Characteristic as Graphical Diagram

The diagram shows the tripping characteristic of the EHV distance protection P437 for a line reactance of10Ω. The reactive reach of zone 1 was defined at 80% of the line length. The operating times are lessthen 25ms up to the line length of 65%. The execution of this standard test procedure takes about 1 hour.The protection device was stimulated 2600 times.

7.5 Automatic Test

One of the objectives of the AtpNet test software was to execute test procedure batches 100%automated. The figure below shows a snap shot of the AtpNet dialog to define an automatic test. Anautomatic test consists of a sequence of test procedures. AtpNet executes each test procedure step bystep and stores the test reports in a user defined directory.

The advantage of this concept is, that the protection engineer is able to create different test batchesbased on the same pool of test procedures.


17. 04. 2001


Figure 28: Definition of an Automatic Test

The protection engineer can analyze the test reports of an automatic test assisted by AtpNet. The testresults can be presented e.g. as operating times and deviations. The figure below shows the results of astandard automatic test for the EHV distance protection P437. The test results are based on 62400stimulations of the protection device.

Type offault

SIR Fault location Tmin Tmax Deviation

AG 0.25 ≤ 65 % 12 ms 23 ms -1.25% / +1.25%

1 ≤ 65 % 16 ms 22 ms -1.25% / +1.25%

5 ≤ 65 % 20 ms 27 ms -1.25% / +3.75%

10 ≤ 65 % 20 ms 30 ms -2.5% / 3.75%

AB 0.25 ≤ 65 % 12 ms 23 ms -1.25% / +1.25%

1 ≤ 65 % 17 ms 22 ms -1.25% / +1.25%

5 ≤ 65 % 20 ms 27 ms -1.25% / +1.25%

10 ≤ 65 % 20 ms 29 ms -2,5% / 2.5%

ABCG 0.25 ≤ 65 % 14 ms 25 ms -1.25% / +0%

1 ≤ 65 % 18 ms 24 ms -1.25% / +1.25%

5 ≤ 65 % 20 ms 27ms -1.25% / +1.25%

10 ≤ 65 % 20 ms 29 ms -2.5% / 2.5%

Figure 29: Test Results of an Automatic Test about Metallic Short-Circuits


17. 04. 2001


The EHV distance protection device P437 was tested for the fault types AG, AB and ABCG and the SIRfactors 0.25, 1, 5 and 10. The automatic test consists of 24 test procedures. The test reports would beanalyzed to identify the minimum and maximum operating times for fault locations up to 65% of the linelength.

The second aspect was the accuracy of the decision zone. The reactive reach of zone 1 was defined at80% of the line length. The column at the right shows the deviations of the decision zone.

8 References

[1] American EMTP User GroupATP Rule BookPortland, Oregon 1987-92, USA, 1995

[2] Mustafa Kizilcay / Laszlo PriklerATP-EMTP Beginner’s Guide for EEUG MembersEuropean EMTP-ATP Users Group e.V., June 2000

[3] American EMTP User GroupATP Rule BookPortland, Oregon 1987-92, USA, 1995

[4] ALSTOM Energietechnik GmbHPx30 Platform PresentationProduct Training, November 2000 ff.

[5] Michael IgelRoutine Test and Type Test of Protection DevicesProduct Training, November 2000 ff.

[6] Michael / Peter SchegnerPrüfung von SchutzeinrichtungenETZ 1995

[7] Michael IgelPrüfung von SchutzgerätenALSTOM Energietechnik GmbH, Seminar Selektivschutztechnik II, 1997 ff.

[8] Michael IgelProtection of Untransposed LinesMiCOM P437EHV Distance ProtectionALSTOM Energietechnik GmbH, 2001

[9] J.A. JodiceRelay Performance TestingA Power System Relaying Committee PublicationIEEE Power System Relaying Committee, Working Group I13

The following copyright notice applies to the software that accompanies this documentation:

Windows, Windows NT are trademarks of Microsoft Corporation

alstom testing

Documents

universal

testing protection

protection

software components

function devices

protection

routine test

type tests