end to end testing - umn ccaps · end to end testing • scott cooper • omicron •...
TRANSCRIPT
End-to-End Testing-Introduction
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What is it?• It’s the simultaneous injection of simulated fault quantities
into two or more interconnected devices in order to verify proper protection system operation
End to End Testing-Introduction
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Why do it?• Setting and communication errors represent nearly half of all
misoperations
End to End Testing-Introduction
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RelayElements
50G 50P
21P87L
...
Logic
Relay B
System Testing
Element Testing
Why do it?• Traditional functional testing cannot adequately test communication
assisted schemes
End-to-End Testing-Implementation
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Clock Accuracy Considerations
• Traditional communication-assisted distance protection• Only carries permissive and block signals• 1ms accuracy was acceptable
End-to-End Testing-Implementation
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Clock Accuracy Considerations
• Line/bus differential • 60hz->50usec/deg, therefore small time errors can introduce substantial
measurement inaccuracies• Newer applications require extraordinary precision (IEEE 1588)
End-to-End Testing-Implementation
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General Test Hardware Setup
• Positioning a GPS antenna in urban environments or around energized structures can be challenging
• For remote test sets not under remote control, voice communication is required
End-to-End Testing-Implementation
General procedure:1. Develop a list of desired test cases based on circuit design, logic
decisions, and potential scheme weaknesses
Variations in fault loop, fault location, system configuration, secondary faults, SOTF, LOPT, etc. should be tested to verify hardware, software, and settings.
End-to-End Testing-Implementation
General procedure:2. Develop test quantities for each desired test case
• Fault quantities can be obtained from a variety of modeling software
• Fault data format can be IEEE COMTRADE, a variety of proprietary formats, or a simple spreadsheet
End-to-End Testing-Implementation
COMTRADE Advantage:• Universal standard• Waveform includes
realistic DC offset and fault inception angle
• Waveforms easily scaled
C37-111-2013 COMTRADE (Common format for Transient Data Exchange)
End-to-End Testing-Implementation
COMTRADE format:• CFG file contains channel data• DAT file contains waveform data• HDR file optional info
C37-111-2013 COMTRADE (Common format for Transient Data Exchange)
End-to-End Testing-Implementation
General procedure:3. Isolate the equipment under test
• Common practice today is to take the protected object out of service
End-to-End Testing-Implementation
General procedure:4. Perform a metering test
• Carefully check all analog and binary signals5. Verify GPS or IRIG-B time synch
• Mixing test set manufacturers in the test
End-to-End Testing-Implementation
General procedure:6. Execute test cases
While the execution time is controlled by GPS, test cases are usually selected and armed via voice communication between the test locations.
End-to-End Testing-Implementation
General procedure:7. Evaluate results• Verify proper operation• Verify targets/SER
What is new for End to End testing?Testing Automatic Loop Restoration Schemes
Schemes are communication-based and can incorporate advanced recloser controls or traditional relaying.• Complex, but can dramatically affect system availability metrics
What is new for End to End testing?Testing Automatic Loop Restoration Schemes
Schemes require careful commissioning• Design vs. installation reality• Redundant communication channels and operating modes• Complex logic• Multiple test scenarios
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One PC controlling multiple test sets makes this easier
What is new for End to End testing?Testing Automatic Loop Restoration Schemes
Restoration schemes are difficult to test with conventional E2E methods.
What is new for End to End testing?Testing Automatic Loop Restoration Schemes
What is new for End to End testing?Testing Automatic Loop Restoration Schemes
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• Simple settings, but complex operation• Bench testing is good, but field installation will introduce variables
What is next for End to End Testing?Testing time Domain and travelling wave schemes
Why test Time Domain relays
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• 1nsec/ft propagation Time• TW pulses for currents must be simulated for first arrival and first reflected TW on both ends with
different TW polarities (current and voltage) and on different phases• Superimpose traveling wave pulses at 10kHz sampled current and voltage signals point-on-wave for
current and voltage traveling waves• End-to-end test with multiple time-synchronized test devices and high accuracy GPS clocks
What is next for End to End Testing?Testing time Domain and travelling wave schemes
Unique challenges for test hardware and software
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• Model topology of protected line (incl. non-homogenous segments, successor and predecessor line, parallel line, series capacitors, ...)
• Possibility to simulate faults on any location in the topology with different fault types, inception angles, arc resistances
What is next for End to End Testing?Testing time Domain and travelling wave schemes
Unique challenges for test hardware and software
What is next for End to End Testing?Testing time Domain and travelling wave schemes
• 100 km overhead line• Z1 = 7.8 Ohms @ 84 °• Z0 = 24.8 Ohms @ 81.5 °• Line propagation time:
340us (TWLPT)• Protected by 2 SEL-
T400L with TD21, TD32, TW32, TW87, POTT and DTT, TW (DE and SE) and Z-based (DE and SE) fault locators
What is next for End to End Testing?Testing time Domain and travelling wave schemes
What is next for End to End Testing?Testing time Domain and travelling wave schemes
Fault inceptionTravelling wave hits near endTraveling wave hit far end
Bewley’s Lattice Diagram of a similar fault
Conclusion
As relay systems become more complex, modern End to End testing tools provide the single most effective way to test communication based relay schemes.
Questions?
• Scott Cooper• OMICRON