Static and Dynamic Tests of Digital Measurement Devices for Power System Protection

1. Static and Dynamic Tests of Digital Measurement Devices for Power System Protection M. Gurbiel P. Komarnicki, Z. A. Styczynski, J. Blumschein, A. Phadke CIGRE Actual Trends in Development of Power System Protection and Automation Moscow, Russia, 7-10 September 2009 Chair Electric Power Networks and Renewable Energy Sources

2. Table of Contents • Measurement devices supporting power network operation and protection • Phasor Measurement Unit (PMU) • Merging Unit (MU) • Test bench for measurement device testing • Accuracy scenarios • Accuracy calculation methods • Accuracy test examples • Summary Static and Dynamic Tests of Digital Measurement Devices for Power System Protection

3. Phasor Measurement Unit and Merging Unit • Phasor Measurement Unit measurement principle is defined in IEEE C37.118-2005 • Merging Unit: • [IEC 60044-8] Physical unit performing the time coherent combination of the current and/or voltage data coming from secondary converters. The merging unit can be a part of one of the transducers in the field or maybe a separate unit (e.g. in the control room) • [IEC 61850-9-1] Interface unit that accepts multiple analogue CT/VT and binary inputs and produces multiple time synchronized serial unidirectional multi-drop digital point to point outputs to provide data communication via the logical interface 4 and 5 IEC 61850-5 Static and Dynamic Tests of Digital Measurement Devices for Power System Protection

4. Accuracy Testing - Merging Unit’s Test Setup Test bench capable of testing two MUs simultaneously PPS and LAN-time source via GPS receiver PC with IEC-61850-9-2 protocol reader Arbitrary waveform generator allows for the execution of static and dynamic scenarios Programmable reference measurement device Static and Dynamic Tests of Digital Measurement Devices for Power System Protection

5. Accuracy Testing - Accuracy Calculation Methods Fourier based method Sample to Sample method Park's Transform method • Suitable only for static scenarios • Averaging random errors • Synchronization errors visible in phase displacements 1. Magnitude error 2. Phase difference 3. Total Vector Error 1. 2. 3. Static and Dynamic Tests of Digital Measurement Devices for Power System Protection

6. Accuracy Testing - Accuracy Calculation Methods Fourier based method Sample to Sample method Park's Transform method • Suitable only for static scenarios • Sample random errors preserved • Synchronization errors indistinguishable 1. Average value – DC error component 2. Standard deviation of a signal – AC error component 3. Maximum absolute value of the errors in the analysis window 1. 2. Static and Dynamic Tests of Digital Measurement Devices for Power System Protection

7. Accuracy Testing - Accuracy Calculation Methods Fourier based method Sample to Sample method Park's Transform method • Suitable for static and dynamic scenarios • Sample random errors preserved • Synchronization errors visible in phase displacements • One error for 3-phase system 1. Magnitude error 2. Phase difference 3. Total Vector Error Static and Dynamic Tests of Digital Measurement Devices for Power System Protection

8. Accuracy Testing - Test Scenarios Overview Static scenarios: Symmetrical and asymmetrical magnitude change Symmetrical and asymmetrical angle change Frequency change Flat curve test Over swing test Harmonic test Dynamic scenarios: Frequency step Frequency ramp Angle step Magnitude step DC step Miscellaneous scenarios Frequency response test Merging Unit’s noise test Anti-Aliasing filter test Static scenario definitions Static and Dynamic Tests of Digital Measurement Devices for Power System Protection

9. Merging Unit Test Examples – Static Tests 1 4.5 4 0.5 3.5 3 0 [%] [%] 2.5 maxerr DCerr -0.5 2 U U 1.5 -1 1 -1.5 Ph#1 Ph#1 Ph#1 Ph#1 0.5 Ph#2 Ph#2 Ph#2 Ph#2 Ph#3 Ph#3 Ph#3 Ph#3 0 -2 0 20 40 60 80 100 120 0 20 40 60 80 100 120 Magnitude level [%] Magnitude level [%] 1 2. 0.9 1. 0.8 0.7 [%] -0.04 0.6 ACerr U -0.06 0.5 Voltage error [%] 0.4 -0.08 0.3 -0.1 0.2 4. 0 20 40 60 80 100 120 3. Magnitude level [%] 20 40 60 80 100 120 Magnitude level [%] • Symmetrical magnitude change scenario • Fourier based method (4) • Sample to Sample method (1, 2, 3) Static and Dynamic Tests of Digital Measurement Devices for Power System Protection

10. Merging Unit Test Examples - Dynamic Tests Angle step scenario. (+90°) Step in 100µs • Angle-step test using Park transform • DC-step test shows the averaging method of MU measurement Static and Dynamic Tests of Digital Measurement Devices for Power System Protection

11. Merging Unit Test Examples – Miscellaneous Tests Static and Dynamic Tests of Digital Measurement Devices for Power System Protection

12. PMU Test Examples 2. • Dynamic Tests: • Frequency Ramp Test (1) • Static Tests: • Frequency Change Test (2, 3) Fourier based method 1. 3. Static and Dynamic Tests of Digital Measurement Devices for Power System Protection

13. Conclusions The digital measurement devices that may be used as a digital interface between power network and power network protection equipment need proper accuracy testing The static scenarios cover the uncertainty evaluation of both the merging unit and phasor measurement unit The dynamic scenarios test introduce MU and PMU to the situations such as short-circuits, voltage and current drops and increases, angle steps and step changes in frequency The special tests are developed for testing the equipment performance and equipment components. The accuracy methods should be chosen in respect to requirements of devices that use merging unit’s data The Fourier-based method is suitable for PMU accuracy analysis and covers requirements that comes from a standard IEEE C37.118-2005 The sample-to-sample method is another approach for testing the MUs and is designed to fulfill the accuracy requirements when small number of samples is available The test setup performance in respect to synchronization is a key issue for accuracy calculation using sample-to-sample method The Park's Transform method is suitable for dynamic test visualization Static and Dynamic Tests of Digital Measurement Devices for Power System Protection

14. Thank You for Your Attention