IEC 61850-9-2 conformance test and the required network bandwidth
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Transcript of IEC 61850-9-2 conformance test and the required network bandwidth
IEC 61850-9-2 conformance test and the required net-
work bandwidth
Smart Grid Testing depart-ment
Woohyun Seo
1. Merging Unit• Introduction, Advantages, Standards
2. Tripping in Process Bus
3. Conformance test
4. Network Bandwidth for Process Bus
5. Conclusion
Contents
1. Merging Unit - IntroductionBusbar
- Analog Input Transformers
- Analog Measurement
- A/D conversion
are moved away from the IEDs and “are placed” into the merging
unit
Conven-tional CTs/VTs
- Advantage . Good saturation curve- Disadvantage . Signal level output . Noise influence
Non-Conventional CTs/VTs
Merging Unit
Propri-etary Link
Propri-etary Link
Controlled Ethernet Ports
Line protec-tion
PIOC, PTOV, …
Bay controllerCSWI, CSYN, …
Device control inter-face
Process Bus
Time synchConfigura-
tion
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 - StandardsMerging
UnitSignal processing interface
Digital interface(Communication)
IEC TC38 WG37
IEC TC57 WG10IEC 61869-7, ADDITIONAL REQUIRE-
MENTS FOR ELECTRONIC VOLTAGE TRANS-FORMERS
IEC 61869-8, ADDITIONAL REQUIRE-MENTS FOR ELECTRONIC CURRENT RANS-FORMERS
IEC 61869-9, DIGITAL INTERFACE FOR INSTRUMENT TRANSFORMERS
IEC 61869-13, Stand Alone Merging Unit
…
Not published
IEC 61850-9-1, Specific Communication Service Map-ping (SCSM) – Sampled values over serial unidirec-tional multidrop point to point link
IEC 61850-9-2, Specific communication service map-ping (SCSM) – Sampled values over ISO/IEC 8802-3
Withdrawn
Implementa-tionImplementation Guideline for Digital Interface to Instru-ment Transformers using IEC 61850-9-2
Conformance test procedure
Test procedures for Sampled Values Publishers according to the "Implementation Guideline for Digital Interface to In-strument Transformers using IEC 61850-9-2" (9-2LE)
GOOSE OUT
2. Tripping in Process Bus
GOOSE IN GOOSE OUT
SAMPLED VALUES
Time require-ment 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
2. Tripping in Process Bus
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– 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
Sm-pCnt=0
SV de-lay
Publisher(MU)
Subscriber
288000 messages for 80 samples of 60 Hz
… … …
PPS pulse
PPS pulse
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?
PPS pulse
SV with Sm-pCnt=0
SV de-lay
Vo, Io
Vo, Io
Real tripping time may be de-layed
CT/VT or eCT/eVT
Signal process-ing delay
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
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 17.7
95.00 1512529.4
100.00 1502608.9
Rate Tested(%) (01,01,01) to (01,01,02) (%)
70.00 0.000
75.00 0.000
80.00 0.000
85.00 0.000
90.00 0.000
95.00 1.080
100.00 5.789
Passed Rate(%)(01,01,01) to
(01,01,02) (pks/sec)
94.12 73529
Through-put
La-tency
Packet Loss
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
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 0.000
80.00 0.000
85.00 0.000
90.00 1.906
95.00 7.156
100.00 11.577
Passed Rate(%)(01,01,01) to
(01,01,02) (pks/sec)
88.40 69061
Through-put
La-tency
Packet Loss
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 imple-
mented
– For more stable process bus implementa-tion, the critical points will be• Actual A/D signal processing time delay in device• Packet jitter and latency delay from device