Automated Testing Of PMU Compliance

Richard Annell Moe Khorami Murari Mohan Saha

ABB AB, Substation Automation Products, SwedenE-mail of contact author: murari.saha@se.abb.com

Abstract: Validating a Phasor Measurement Unit (PMU) against the IEEE C37.118.1-2011 standardwith amendment C37.118.1a-2014 (from here on referred to as “the standard”) poses a challenge interms of the sheer number of measurements and calculations needed.This paper covers how ABB SA Products AB has accomplished this by designing a test-bench for theRES670 2.0 PMU product. The test-bench is capable of performing settings on the RES670 2.0 beingtested, controlling an Omicron GmbH CMC 256plus signal-generator with the CMIRIG-B interface (forapplying time-synchronized analogue input stimuli), receiving the C37.118 telegrams from theRES670 2.0 under test, calculating Total Vector Error (TVE), Frequency measurement Error (FE) andRate of change Frequency Error (RFE) and making pass/fail assessments.The test-bench is developed using Keysight VeePRO (formerly known as Agilent VeePRO) which is agraphical programming environment suitable for developing applications which involves control ofexternal instruments and network communication. The test-bench controls the signal-generator usingthe Omicron GmbH “CMEngine” interface which is a software interface which enables controllingOmicron GMBH equipment using third party software and communicates with the RES670 2.0 usingTCP/IP.

Index Terms: PMU, Synchrophasors, IEEE Std C37.118.1™-2011 standard, IEEE Std C37.118.1a™-2014 amendment, IEEE C37.242-2013 guide, Automated Testing, IEEE Std C37.118.1-2011™standard compliance

1. INTRODUCTION

The introduction of PMU’s to the power industry in the early 1990s helped revolutionize the way weanalyze and control power systems. All the measurements taken are synchronized and time-stampedby a precision timing device. Wide Area Systems are implemented allowing the networks to operatecloser to their capacity while maintaining the system security [1].

Wide Area Monitoring, Protection and Control System is a response to the "Smart Grid" concept ontransmission and sub-transmission level in order to increase network operator's awareness of gridperformance and security while making our power system smarter and more reliable. AccuratePhasor Measurement Units, fast and reliable communication infrastructure as well as smart wide areaapplications are the building blocks of wide area systems [2]. However verification of the PMU’saccuracy requires special test procedures, time sources and very accurate testing instrument [1].

The accuracy of synchrophasors (amplitude and angle) is expressed by a quantity called Total VectorError (TVE). According to the standard, TVE is an expression of the difference between a “perfect”sample of a theoretical synchrophasor and the estimate given by the unit under test at the sameinstant of time. The value is normalized and expressed as per unit of the theoretical phasor [3].

The PMU subjected to the described automated testing procedure in this paper is the ABB RES6702.0. During development of RES670 2.0, investigations were made regarding the possibility to havean external facility validate these requirements. However, at that point in time, this was not a feasibleoption because there was no external laboratory available that could certify the PMU’s compliancywith the standard.

Considering the amount and the complexity of the measurements that has to be performed in order tovalidate compliance with the standard, there is a lot to be gained by automating these tasks to thelargest extent possible. For this reason, ABB SA Products AB has developed an automated test-bench called “RES_ComplianceTests_C37.118-2011” (from here on referred to as “the test-bench”)which significantly facilitates the testing procedure. The test-bench is intended for internal ABB useonly. The paper continues with describing the hardware and software aspects of this test-bench.

2. TECHNICAL SOLUTION, HARDWARE

A basic requirement for performing these measurements is the possibility to generate analogue inputstimuli to the PMU which is synchronized to an absolute reference in time.Another basic requirement is that, in addition to the above, the generated analogue input stimuli haveto be generated with a sufficiently high accuracy.The signal-generator from Omicron GMBH, model CMC 256plus (from here on referred to as “thesignal-generator”), used in this solution is capable of this when used in conjunction with the externalIRIG-B time synchronization module.

Fig. 1. Schematic diagram of the test setup

Although it is possible to have the signal-generator act as a time reference in this application, anexternal station clock was selected for synchronizing both the signal generation and the RES670 2.0PMU under test.

Connecting an oscilloscope with one channel connected to the PPS (Pulse Per Second) output of thestation clock and one channel connected to the first voltage output of the signal-generator during themeasurements shows that it is possible to achieve a very high accuracy in terms of phase-shift inreference to PPS using this hardware setup. The technical specifications for the Omicron GMBHCMIRIG-B module states that the time error of time reference source to analogue outputs is typicallybetter than 1µs with a maximum error of 5µs (for CMC 256plus) [4]. Measurements performed asdescribed above showed that the voltage outputs stayed well within the typical limit of 1µs (with thepoint in time when the positive zero crossing of the output voltage passes through zero volts definedas zero degrees). According to the IEEE C37.242-2013 guide, general purpose test equipment thatcan be used to test PMU functions should be 4 to 10 times more accurate than the test tolerance, butthis will vary depending on the circumstance. This means a Test Uncertainty Ratio (TUR) equal to 4to 10. TUR is a quantity which describes how much better the test equipment is than the equipmentbeing tested [5].

Since the test-bench sets parameters for the signal generation via the “CMEngine” interface directlyon the signal-generator, technical specifications for the signal-generator can be used for determiningthe accuracy of the generated signals [6]. The technical specifications for the signal-generator specifymagnitude accuracy for the current outputs to be better than 0.04% of setting plus 0.01% of range(ranges are 1.25A and 12.5A). As an example of this, at the magnitude of 1A, the magnitude error isless than 0.000525A (0.0004A+0.000125A), which equals 0.0525%. Phase-shift error is specified tobe better than 0.02° (degrees). Even if adding a phase-shift error corresponding to 1µs (0.018° at

50Hz) to account for timing inaccuracy using the external IRIG-B timing module, the phase-shift erroris still better than 0.038°. In terms of TVE, the 0.0525% amplitude error and 0.038° angle errortogether will represent an error of less than 0.085% in the generated signal. TUR in this case whenvalidating against the 1% TVE limit commonly specified in the standard is higher than 11.8. At the setmagnitude of 0.1A (10% of 1A), the TUR still exceeds 5.6.

For voltage outputs, the technical specifications for the signal-generator specify magnitude accuracyfor the voltage outputs to be better than 0.04% of setting plus 0.01% of range (ranges are 150V and300V). As an example of this, at the magnitude of 110V, the magnitude error is less than 0.059V(0.044V+0.015V), which equals 0.054%. Phase-shift error is specified to be better than 0.02°. Even ifadding a phase-shift error corresponding to 1µs (0.018° at 50Hz) to account for timing inaccuracyusing the external IRIG-B timing module, the phase-shift error is still better than 0.038°. In terms ofTVE, this equates to an error of less than 0.086% in the generated signal. The TUR in this case whenvalidating against the 1% TVE limit commonly specified in the standard is higher than 11.7. At the setmagnitude of 11V (10% of 110V), the TUR still exceeds 5.3.

Using a separate signal source such as a plug in board for a PC combined with an external currentamplifier would most likely present a greater challenge in terms of achieving such a high TUR value.

3. TECHNICAL SOLUTION, SOFTWARE

From a software point of view, the main requirements on the test-bench performing thesemeasurements are the ability to:

· Perform settings on the PMU regarding rated frequency, performance class and report rate· Calculate and apply analogue input stimuli based on settings made and test at hand· Receive C37.118 telegrams from the PMU under test· Calculate TVE, FE and RFE· Calculate delay-time, response-time and over-/under-shoot when applicable· Calculate limits for the above based on current PMU settings and test at hand· Perform PASS/FAIL assessment· Logging of retrieved and calculated data, limits and results (for post-analysis)

If the above requirements are met and combined with the ability to loop through the settings and testtypes required, a high degree of automation is achieved.

Using the Omicron GMBH software option “CMEngine”, which enables controlling the signal-generatorfrom any third party software that is capable of utilizing ActiveX automation, it is possible to developan application that combines functionality like performing settings on the PMU with applying analogueinput stimuli and collecting data frames from the PMU under test. Keysight VeePRO constitutes adevelopment environment which is suitable for this and was chosen for the development of the test-bench [7].

The test-bench is capable of validating the requirements specified in the following sections of thestandard for one voltage phasor and one current phasor simultaneously:

· Section 5.5.5 "Steady-state compliance"· Section 5.5.6 "Dynamic compliance-measurement bandwidth"· Section 5.5.7 "Dynamic compliance-performance during ramp of system frequency"· Section 5.5.8 "Dynamic compliance-performance under step changes in phase and magnitude"

The following 10 test types were defined in the test-bench in order to cover the requirements specifiedabove:

· MagnTest (section 5.5.5, Table 3, Influencing quantity: Signal magnitude)· PhaseTest (section 5.5.5, Table 3, Influencing quantity: Phase angle)· FreqTest (section 5.5.5, Table 3 & 4, Influencing quantity: Signal frequency)· InterfTest (section 5.5.5, Table 3 & 4, Influencing quantity: Out-of-band interference)· HarmTest (section 5.5.5, Table 3 & 4, Influencing quantity: Harmonic distortion)· ModMagn (section 5.5.6, Table 5 & 6, Amplitude modulation)· ModPhase (section 5.5.6, Table 5 & 6, Phase modulation)· FreqRamp (section 5.5.7, Table 7 & 8, Linear frequency ramp)· AmplStep (section 5.5.8, Table 9 & 10, Amplitude step)

· PhaseStep (section 5.5.8, Table 9 & 10, Phase step)

In the standard, table 3, 5, & 7 specifies TVE limits. Table 4, 6, & 8 specifies FE and RFE limits.Table 9 specifies phasor performance during step change in terms of response time, delay time andover-/under-shoot. Table 10 specifies frequency and rate of change frequency performance duringstep change in terms of response time [3].

Table 1 shows the supported settings in the RES670 2.0 in terms of rated frequencies (Fr),Performance Classes (PC) and Report Rates (RR):

Fr PC RR Fr PC RR

50 P M

10

60 P M

1012

25 1520

50 3060

100 120200 240

Table 1. Supported settings, RES670 2.0

The settings in Table 1 constitute 26 setting combinations to be tested. Combined with the 10 definedtest types in the test-bench, 260 different test cases have to be executed. Testing hardware withanother rated input current for example, requires all these 260 test cases to be repeated. Combinedwith the fact that every test performed requires a substantial amount of data to be collected andanalyzed, the need for automation of the task at hand becomes obvious.

3.1 TEST-BENCH, MAIN WINDOW

Figure 2 below shows an example of the main window of the test-bench during execution.

Fig. 2. Main window of the test-benchIn the test-bench, IP-address of the PMU, rated current, rated voltage and the phasor numbers for thevoltage and the current phasor is entered.

The operator can choose which rated frequencies to test at (50 Hz, 60 Hz or both), whichperformance classes to test (P, M or both) and which report rates to test for each rated frequency.The operator can also choose whether to execute one test type or all of the supported test types in theapplication.

Figure 3 below shows examples of selecting these parameters.

Fig. 3. Selecting rated frequency, performance class and report rate for Fr=50 Hz

Additionally, there are individual settings available for most of the test types. These settings areintended to enable executing only a specific test type with a reduced set of influencing quantitiesresulting in a much shorter execution time (for experimental purposes).

3.2 AUTOMATIC SELECTION OF APPLIED ENERGIZING QUANTITIES

The standard may specify different ranges of applied energizing quantities depending on for exampleperformance class used. Figure 4 below shows an excerpt from the standard (section 5.5.5, part oftable 3), specifying ranges of applied influencing quantities and TVE limits. Notice the differences in

the “Range”-column between P and M performance class for signal frequency and signal magnitudefor voltage.

Fig. 4. , Excerpt from the standard section 5.5.5, part of table 3

Since the test-bench is aware of the settings being applied during testing, the test-bench is alsocapable of automatically selecting the correct range of influencing quantities to use for the test athand.

Figure 5 below shows example code for selecting the voltage range to be used for the test type“MagnTest”.

Fig. 5. Code snippet, selection of voltage magnitudes

Similar methodology is used for all test-types defined in the test-bench when applicable. For examplewhen selecting the amount of harmonic distortion to apply depending on performance class, whenselecting which interfering frequencies to apply and the magnitude of them and when selecting thestart and stop frequencies during frequency ramp testing etc.

3.3 AUTOMATIC SELECTION OF LIMITS

The standard may also specify different limits depending on for example performance class used.Figure 6 below shows an excerpt from the standard (section 5.5.5, table 4), specifying ranges ofapplied influencing quantities and FE and RFE limits. Notice that there are several differences in the“Error requirements”-column between P and M performance class. Additionally, there may be limitsthat are not applicable or suspended. Such as the RFE limits for harmonic distortion test and out-of-band interference test in the figure below. The test-bench is capable of detecting when this is the caseand sets these limits to “NA” (not applicable) for such tests. However, FE and RFE are still measuredand logged in those cases.

Fig. 6. Paragraph 5.5.5, table 4 from the standard

Again, since the test-bench is aware of the settings being applied during testing, the test-bench is alsocapable of automatically selecting the correct limits to use for the test at hand. Figure 7 below showsexample code for selecting the RFE limit to be used.

Fig. 7. Code snippet, selection of RFE limit

Figure 8 below shows example code for selecting the limits and the validity of the limits when testingwith harmonic distortion as the influencing quantity. Notice that the variable “RFELimitValid” is set to“0” (false) if the performance class is “M”, and that the FE limit is set depending on the set report rateif performance class is “M”.

Fig. 8. Code snippet, selection of limits and validity of limits

3.4 STEADY-STATE TEST-TYPES

The first five test-types defined in the test-bench which covers section 5.5.5 in the standard, “Steady-state compliance”, uses the predefined signal quantities available via the CMEngine interface for thesignal-generator in order to define the analogue input stimuli for the test at hand. For these test-typesthere is no need to calculate and download waveforms to the signal-generator.

3.4.1 MAGNTEST

Test type “MagnTest” sets frequency, phase shifts and magnitudes for the voltage and current outputsused on the signal-generator and applies them synchronized to the time signal from the station clock.The only quantity that varies during the test is the magnitude of the applied signals. For everymagnitude applied, C37.118 telegrams are received from the PMU under test, TVE, FE and RFEcalculated and compared to limits when applicable.

Figure 9 below shows an example of this test during execution. Notice the PASS/FAIL indicators onthe far right showing “NA” when the test-bench has determined that a limit is not to be applied (notspecified in the standard or suspended). However, as can be seen in figure 9 below, the test-benchwill still measure those quantities.

Fig. 9. Example of “MagnTest” in progress

3.4.2 PHASETEST

Test type “PhaseTest” sets frequency, phase shifts and magnitudes for the voltage and currentoutputs used on the signal-generator and applies them synchronized to the time signal from thestation clock. The only quantity that varies during the test is the phase-shift of the applied signals. Forevery phase-shift applied, C37.118 telegrams are received from the PMU under test, TVE, FE andRFE calculated and compared to limits when applicable.

Figure 10 below shows an example of this test during execution.

Fig. 10. Example of TVE measurements for the voltage phasor during “PhaseTest”

3.4.3 FREQTEST

Test type “FreqTest” sets frequency, phase shifts and magnitudes for the voltage and current outputsused on the signal-generator and applies them synchronized to the time signal from the station clock.Care has to be taken in this case when applying frequencies that are not evenly dividable. Forexample, if applying a frequency of 50.1 Hz, time synchronization is only possible every 10’Th secondin order to keep the signal uninterrupted in terms of avoiding sudden phase shifts. The only quantitythat varies during the test is the frequency of the applied signals. For every frequency applied,C37.118 telegrams are received from the PMU under test, TVE, FE and RFE calculated andcompared to limits when applicable.

Figure 11 below shows an example of this test during execution.

Fig. 11. Example of TVE measurements for the voltage phasor during “FreqTest”

3.4.4 INTERFTEST

Test type “InterfTest” sets frequency, phase shifts and magnitudes for the voltage and current outputsused on the signal-generator and applies them synchronized to the time signal from the station clock.In this test-type, both the available signal definition memories per channel in the signal-generator areused. One for the applied fundamental frequency and the other one for the applied interferingfrequency. Care has to be taken in this case when applying interfering frequencies that are not evenlydividable. For example, if applying an interfering frequency of 50.1 Hz, time synchronization is onlypossible every 10’Th second in order to keep the signal uninterrupted in terms of avoiding suddenphase shifts. The only quantity that varies during the test is the interfering frequency added to theapplied signals. For every interfering frequency applied, C37.118 telegrams are received from thePMU under test, TVE, FE and RFE calculated and compared to limits when applicable.

Figure 12 below shows an example of this test during execution.

Fig. 12. Example of TVE measurements for the voltage phasor during “InterfTest”

3.4.5 HARMTEST

Test type “HarmTest” sets frequency, phase shifts and magnitudes for both the fundamental signaland the harmonic applied for the voltage and current outputs used on the signal-generator and applythem synchronized to the time signal from the station clock. The only quantity that varies during thetest is the number of the harmonic applied. For every harmonic applied, C37.118 telegrams arereceived from the PMU under test, TVE, FE and RFE calculated and compared to limits whenapplicable.

Figure 13 below shows an example of this test during execution.

Fig. 13. Example of TVE measurements for the voltage phasor during “HarmTest”

3.5 DYNAMIC TEST-TYPES

The five remaining test-types defined in the test-bench which covers section 5.5.6, 5.5.7 and 5.5.8 inthe standard, “Dynamic compliance”, calculates waveforms dynamically depending on the PMUsettings in use and the test at hand. The calculated waveforms are downloaded to the signal-generator via the CMEngine interface in order to define the analogue input stimuli. The magnitude ofthe outputs and the playback rate is set and the playback of the downloaded waveforms is startedsynchronized to the time signal from the station clock.

3.5.1 MODMAGN

Test type “ModMagn” calculates the waveforms used for modulated analogue input stimuli usingbasically the same mathematical algorithms as defined in the standard in paragraph 5.5.6.Figure 14 below shows an example of the waveform calculation used for modulated analogue inputstimuli. During modulation of magnitude, the phase angle modulation is set to zero.

Fig. 14. Code snippet, example of calculation of modulated waveforms

Where: Xm=amplitude, Kx=amplitude modulation factor, Ka=phase angle modulation in degrees,df=modulation frequency in Hz, f=fundamental frequency in Hz and t=time in s. A, B and C arecontainers for the result of the calculations for phase A (L1), B (L2) and C (L3) respectively.

For comparison, figure 15 below shows an excerpt from the standard, section 5.5.6, mathematicallydescribing the waveforms during modulation. The only tangible difference is the usage of radiansrather than degrees.

Fig. 15. Excerpt from the standard, section 5.5.6, mathematical representation of the waveformsduring modulation

The calculated waveforms are downloaded to the signal-generator. Playback rate and magnitudes forthe voltage and current outputs used on the signal-generator is set and playback is startedsynchronized to the time signal from the station clock. The only quantity that varies during the test isthe modulation frequency applied. For every modulation frequency applied, C37.118 telegrams arereceived from the PMU under test, TVE, FE and RFE calculated and compared to limits whenapplicable.

Figure 16 below shows an example of this test during execution.

Fig. 16. Example of TVE measurements for the voltage phasor during “ModMagn”

3.5.2 MODPHASE

Test type “ModPhase” calculates the waveforms used for modulated analogue input stimuli using thesame mathematical algorithms as test type “ModMagn”. During modulation of phase angle, theamplitude modulation factor is kept to zero.

The calculated waveforms are downloaded to the signal-generator. Playback rate and magnitudes forthe voltage and current outputs used on the signal-generator is set and playback is startedsynchronized to the time signal from the station clock. The only quantity that varies during the test isthe modulation frequency applied. For every modulation frequency applied, C37.118 telegrams arereceived from the PMU under test, TVE, FE and RFE calculated and compared to limits.

Figure 17 below shows an example of this test during execution.

Fig. 17. Example of TVE measurements for the voltage phasor during “ModPhase”

3.5.3 FREQRAMP

Test type “FreqRamp” calculates the waveforms used for analogue input stimuli with a rampingfrequency. The calculation is divided into three parts; waveform before ramping of the fundamentalfrequency takes place, waveform during ramping of the fundamental frequency and waveform afterramping of the fundamental frequency. Ramp rate and ramp range is set automatically according tothe standard, paragraph 5.5.7, table 7.

The calculated waveforms are downloaded to the signal-generator. Playback rate and magnitudes forthe voltage and current outputs used on the signal-generator is set and playback is startedsynchronized to the time signal from the station clock. The only quantity that varies during the test isthe direction of the frequency ramp applied (positive or negative). C37.118 telegrams are receivedfrom the PMU under test, exclusion intervals is automatically calculated and applied, TVE, FE andRFE calculated and compared to limits.

Figure 18 below shows an example of this test during calculation of TVE, FE and RFE.

Fig. 18. Example of “FreqRamp” in progress during calculation of TVE, FE and RFE

3.5.4 AMPLSTEP

Test type “AmplStep” calculates the waveforms used for analogue input stimuli with a step change inamplitude. The calculation is divided into two parts; waveform before step change of the appliedamplitude and waveform after step change of the applied amplitude. In order to achieve the requiredaccuracy of at least one-tenth of the used report rate in response- and delay-time measurement, thewhole process is repeated ten times. Each time, the step-change is delayed one-tenth of the timecorresponding to the selected report rate. For example, if the report rate “10” is used, each iterationdelays the step-change 10ms compared to the previous iteration. The received C37.118 telegramsfrom the PMU are then correlated by subtracting the time stamps with the delay used in the currentiteration and finally interleaved, thus creating a set of data with 10 times higher resolution than theused report rate would provide in itself.

The calculated waveforms are downloaded to the signal-generator. Playback rate and magnitudes forthe voltage and current outputs used on the signal-generator is set and playback is startedsynchronized to the time signal from the station clock. The only quantity that varies during the test isthe direction of the amplitude step applied (positive or negative). C37.118 telegrams are receivedfrom the PMU under test, response and delay times, over-and under-shoot are determined andcompared to limits. After the final iteration, the final assessment is made.

Figure 19 below shows an example of this test after the final iteration.

Fig. 19. Example of “AmplStep” in progress during assessment of results

3.5.5 PHASESTEP

Test type “PhaseStep” calculates the waveforms used for analogue input stimuli with a step change inphase shift. The calculation is divided into two parts; waveform before step change of the appliedphase shift and waveform after step change of the applied phase shift. In order to achieve therequired accuracy of at least one-tenth of the used report rate in response- and delay-timemeasurements, the whole process is repeated ten times. Each time, the step-change is delayed one-tenth of the time corresponding to the selected report rate. For example, if the report rate “10” is used,each iteration delays the step-change 10 ms compared to the previous iteration. The receivedC37.118 telegrams from the PMU are then correlated by subtracting the time stamps with the delayused in the current iteration and finally interleaved, thus creating a set of data with 10 times bettergranularity than the used report rate would provide if the methodology described above wasn’t used.

The calculated waveforms are downloaded to the signal-generator. Playback rate and magnitudes forthe voltage and current outputs used on the signal-generator is set and playback is startedsynchronized to the time signal from the station clock. The only quantity that varies during the test isthe direction of the amplitude step applied (positive or negative). C37.118 telegrams are receivedfrom the PMU under test, response and delay times, over-and under-shoot are determined andcompared to limits. After the final iteration, the final assessment is made.

Figure 20 below shows an example of this test after the final iteration.

Fig. 20. Example of “PhaseStep” in progress during assessment of results

3.6 DATA LOGGING

The test-bench logs the results in multiple ways providing the possibility for different levels of postanalysis should so be desired. The first level is a simple summary of all tests that has been executedduring a session including information about test type, rated frequency, performance class and reportrate and whether the test at hand was assessed as passed or failed. This log can be viewed directlyfrom within the test-bench after concluding a test session. Figure 21 below shows an example of this.

Fig. 21. Example of viewing the summary log

The test-bench automatically generates screen shots of the complete operators interface afterconcluding each test. These screen shots are automatically named depending on the test type andsettings used including a user defined prefix. For example, the filename“110V1AMPS_Fr50_P_PhaseTest_Rr10.png” is a screen shot of the test type “PhaseTest” with theuser defined prefix “110V1AMPS”, executed with the rated frequency at 50 Hz, performance class setto “P”, report rate set to “10”. Figure 22 below shows an example of this.

Fig. 22. Example of automatically generated screen shot during execution

Additionally, a comprehensive log using the Keysight VeePRO [7] proprietary “dataset” format isgenerated automatically for each test executed. This log contains both calculated values in terms ofTVE, FE, RFE, measured times and the raw telegrams received from the PMU during each test. Thislog also contains the selected limits during the test and whether that limit is applicable or not for thetest at hand. The log is in text format and in a machine readable form making it easy to post process.This enables more complex post analysis to be performed. Figure 23 below shows a partial exampleof this.

Fig. 23. Partial example of automatically generated log during execution

4. DEGREE OF AUTOMATION

When using this test-bench during compliance testing of the RES670 2.0, the degree of automationachieved is to be considered very high. If executing what can be referred to as a “full test session”,meaning that both rated system frequencies, both performance classes, all supported report rates andtest types are included, the total unattended execution time can exceed 55 hours. During that time,more than 3.8 million C37.118 telegrams will be received from the PMU under test, more than 16million calculations in terms of TVE, FE, RFE, response time, delay time, overshoot and under-shootwill have been performed. PASS/FAIL assessments for all permutations of selected settings and test-types and logging of all data needed for post analysis and report creation performed. Or, to put itanother way, in less than three days, all supported test types will have been executed for both ratedsystem frequencies, both performance classes, all supported report rates and test types. Additionally,the repeatability achieved using this test-bench combined with the degree of automation achievedmakes it very useful for regression testing.

Figure 24 below shows an example of statistics shown in the operators interface after completion of atest session.

Fig. 24. Example of statistics shown in the operator’s interface of the test-bench

5. CONCLUSIONS

Testing a PMU in regards to compliance with the standard requires a great extent of automation.

By developing and using this test-bench, ABB SA Products AB has achieved a high degree ofautomation for compliance testing of the RES670 2.0 PMU.

This was achieved by including and combining settings functionality, generation functionality, datacollection functionality, result assessment functionality and data logging functionality in the same test-bench.

By eliminating solutions such as separate signal sources feeding external amplifiers, high accuracy interms of generated analogue input stimuli was achieved without the need to and the complexityinvolved in measuring the generated analogue input stimuli with external instruments or comparingthe PMU measurements with a reference PMU measuring the same analogue input stimuli.

6. REFERENCES

[1] M. Khorami, “Phasor Measurement Units (PMU) Applications in Power Systems” (EuroDobleColloquium, Barcelona, October 2013, Paper presentation D-4)

[2] M. Khorami, “Real Time Application of Synchrophasors for Improved Reliability” (EuroDobleColloquium, Barcelona, October 2013, Paper presentation A-3)

[3] IEEE Standard for Synchrophasors Measurements for Power Systems, IEEE Std C37.118.1™-2011 (Revision of IEEE Std C37.118™-2005) with amendment IEEE Std C37.118.1a™-2014

[4] Omicron GMBH CMIRIG-B, Technical Data:https://www.omicron.at/fileadmin/user_upload/pdf/literature/CMIRIG-B-Technical-Data-ENU.pdf(accessed 2015-05-07)

[5] IEEE Guide for Synchronization, Calibration, Testing, and Installation of Phasor MeasurementUnits (PMUs) for Power System Protection and Control, IEEE Std C37.242™-2013

[6] Omicron GMBH CMC 256plus, Technical Data:https://www.omicron.at/fileadmin/user_upload/pdf/literature/CMC-256plus-Technical-Data-ENU.pdf(accessed 2015-05-07)

[7] Keysight VEE, development environment:http://www.keysight.com/en/pc-1000003078%3Aepsg%3Apgr/agilent-vee?nid=-32809.0.00&cc=US&lc=eng(accessed 2015-05-07)