IEC 61850-9-2 conformance test and the required network bandwidth Smart Grid Testing department Woohyun Seo

Contents Merging Unit Tripping in Process Bus Conformance test Introduction, Advantages, Standards Tripping in Process Bus Conformance test Network Bandwidth for Process Bus Conclusion

1. Merging Unit - Introduction Busbar Analog Input Transformers Analog Measurement A/D conversion are moved away from the IEDs and “are placed” into the merging unit Conventional CTs/VTs Advantage . Good saturation curve Disadvantage . Signal level output . Noise influence Non-Conventional CTs/VTs Merging Unit Proprietary Link Controlled Ethernet Ports Line protection PIOC, PTOV, … Bay controller CSWI, CSYN, … Device control interface Process Bus Time synch Configuration

1. Merging Unit - Advantages Advantage of process bus with MERGING UNIT Reduce wiring cables and # of CTs/VTs In conventional scheme, every IED needs CT(s) and/or VT(s) for processing Improved measuring accuracy Short distance between CTs/VTs and signal processor Adopting high-performance eCT/eVT Small, Light, Broad dynamic range, Isolation between primary & secondary circuits, etc Unified platform for information sharing Merging unit broadcast the digitized measured data based on IEC 61850 standard

1. Merging Unit - Standards Signal processing interface Digital interface (Communication) IEC TC38 WG37 IEC TC57 WG10 IEC 61869-7, ADDITIONAL REQUIREMENTS FOR ELECTRONIC VOLTAGE TRANSFORMERS IEC 61850-9-1, Specific Communication Service Mapping (SCSM) – Sampled values over serial unidirectional multidrop point to point link IEC 61869-8, ADDITIONAL REQUIREMENTS FOR ELECTRONIC CURRENT RANSFORMERS Withdrawn IEC 61850-9-2, Specific communication service mapping (SCSM) – Sampled values over ISO/IEC 8802-3 IEC 61869-9, DIGITAL INTERFACE FOR INSTRUMENT TRANSFORMERS Implementation … Implementation Guideline for Digital Interface to Instrument Transformers using IEC 61850-9-2 IEC 61869-13, Stand Alone Merging Unit Conformance test procedure Test procedures for Sampled Values Publishers according to the "Implementation Guideline for Digital Interface to Instrument Transformers using IEC 61850-9-2" (9-2LE) Not published

2. Tripping in Process Bus GOOSE OUT

2. Tripping in Process Bus GOOSE IN GOOSE OUT SAMPLED VALUES Time requirement is more critical!!!

2. Tripping in Process Bus A/D signal processing time delay Primary condition for available protection Guideline : 3 ms (IEC 60044-8) Packet jitter and latency control Part of performance test Only the total number of packets in 1 sec existed Standard based syntax Following IEC 61850-9-2 and IEC 61869 series Network bandwidth Lack of bandwidth makes packet loss Out of range from conformance test

3. Conformance test Conformance test procedure Documentation : 2 test cases Configuration : 9 test cases Communication services : 17 test cases 50/60 Hz, 80/256 samples According to “Guideline”, Time master is based on “PPS”

3. Conformance test SV conformance test Conformity Verify conformity and performance Performance is very important for MU Accuracy test is not included Conformity Connecter and Link layer format verification 100Base-FX full duplex with ST, MT-RJ, LC fibers or Rj45 APDU or ASDU format verification Quality and Test bit verification

3. Conformance test Performance test SV maximum delay criterion : ~3 ms(3.3 ms) Verification # of messages per cycle PPS pulse SV with SmpCnt=0 SV delay Publisher(MU) Subscriber … … … PPS pulse PPS pulse 288000 messages for 80 samples of 60 Hz Jitter and latency control are required!

3. Conformance test Limitation of SV conformance test Not verifying focusing on packet treatment What if MU makes the signal processing delay? CT/VT or eCT/eVT Vo, Io PPS pulse SV delay Signal processing delay SV with SmpCnt=0 Vo, Io Real tripping time may be delayed

4. Network Bandwidth for Process Bus Background from IEC 61850-9-1 Telegram length : 888bit(packet) + 96bit(interFrame) BW : 80samples*60Hz*984bits < 5Mbps (per stream) Reliable?

4. Network Bandwidth for Process Bus Simple test Merging Unit 100Mbps, Max 2 streams, 80samples/Hz Time Synch 1 PPS from GPS Switch Separate network only for process bus with MU Switching latency : 7 micro second Switching bandwidth : 9.2 Gbps Testing tool Smart bit applications Packet size : 140 bytes(SMV packet : 128 bytes)

4. Network Bandwidth for Process Bus 1 stream Throughput Latency Packet Loss Passed Rate(%) (01,01,01) to (01,01,02) (pks/sec) 94.12 73529 Rate Tested(%) (01,01,01) to (01,01,02) (us)-CT 70.00 18.0 75.00 18.6 80.00 17.4 85.00 17.7 90.00 95.00 1512529.4 100.00 1502608.9 Rate Tested(%) (01,01,01) to (01,01,02) (%) 70.00 0.000 75.00 80.00 85.00 90.00 95.00 1.080 100.00 5.789 Network load : 5.88 Mbps Switching bandwidth(9 Gbps) is enough to handle this amount of traffic load (9,000 / 5.88 = 1,530 ports can be supported)

4. Network Bandwidth for Process Bus 2 streams Throughput Latency Packet Loss Passed Rate(%) (01,01,01) to (01,01,02) (pks/sec) 88.40 69061 Rate Tested(%) (01,01,01) to (01,01,02) (us)-CT 70.00 18.9 75.00 17.0 80.00 19.0 85.00 23.0 90.00 2649.6 95.00 1508004.1 100.00 1499575.3 Rate Tested(%) (01,01,01) to (01,01,02) (%) 70.00 0.000 75.00 80.00 85.00 90.00 1.906 95.00 7.156 100.00 11.577 Network load : 11.6 Mbps = 2*5.8 Mbps Network load for 2 streams is similar to twice one for 1 stream

5. Conclusion Expectation Network Bandwidth measurement in the real (simulated) process bus network Theoretically, 100 Mbps based network can handle more than 10 MUs But, need to check if how many MUs can implemented For more stable process bus implementation, the critical points will be Actual A/D signal processing time delay in device Packet jitter and latency delay from device

Thank you for listening Any Questions? Whseo@keri.re.kr 031-8040-4421