real time contingency analysis practice at the...
TRANSCRIPT
Real Time Contingency Analysis Practice at the Ontario Grid
Control Centre
Yinhua Guo Jeff Penrice Vivian Cheuk
Ontario Grid Control Centre
Hydro One
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Hydro One Power System
• Major Transmission Company in Ontario
– 97% of Ontario transmission network, 29,000km high voltage circuits
– Interconnect with New York, Michigan, Minnesota, Manitoba, and Quebec (asynchronous)
• Largest Distribution Utility in Ontario
– 123,000km low voltage distribution network
– Serving 1.3 million rural customers
– Extensive distributed generation (wind & solar)
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Courtesy of WorldAtlas
Hydro One Real Time CA Sequence
• State Estimation (SE): every 30sec.
• Thermal Limit Calculation: limited time ratings
• SPS Basecase: arming status, tripped modules
• Contingency Analysis (CA): every 3min
– Contingency case redefinition (over 4100 ctgs)
– Extensive SPS simulation
– Contingency case screening (down to ~50 ctgs)
– Full processing for selected ctgs
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CA Redefinition
• Dynamically Expand CA Outages at CB Level
• Simulating Protective Relay Actions
– Interlock bypass switches considered
• Transfer Trip for LEO Protection
• SPS Remedial Actions Incorporated
• Cascading Outages: iterative simulations for interactions among SPS, LEO, overload, 59/27 voltage relays
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CA Redefinition
- Example of interlock bypassing & cascading
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SPS in Ontario Power System
• Rely Heavily on Special Protection Systems
– Stability concern, thermal limit, voltage violation
– ~400 modules, ~600 signals, ~3600 control actions
• SPS Remedial Action Examples
– Generation/load rejection
– Generation/HVDC runback
– Breaker (group) trip/close
– Equipment (group) rejection
– Capacitor/reactor switching
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SPS Simulation in CA
• SPS Contingency Detection Logic
– Status/topology based
– Analog value based
– Protective relay trip signals
• Arming and Conditional Arming
– Selection and blocking switches
– Trip supervision (voltage, status)
– Staged tripping
– Arming from OGCC and from IESO
– Selection from plant/station
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Transformer 2pu Protection
– Over current based: I > 2*I_rated
– Staged tripping of loads in 4.5”, 7.5”, 9.5”
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Line Backup Protection
– Not the classic zone 3 remote backup relay
– Loss of transfer trip communication on DESN
– Transformer back feeding
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CA Limits & Monitoring
• CA Branch Limit Violations
– Transformer/overhead line/cable thermal limits calculation in real time: IEEE standard based and expanded
– 15min or 2hr LTR used for CA monitoring
• CA Voltage Violations
• Transformer Back-feeding Condition
• CA Causing Islands
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Control Action Cancellation
• Manual Control Actions Developed
– Control action type CTG pre-defined for target CTG: with control actions reverted
– Enabled when target CTG cause violation
– Cancel control action when violations disappear for control action type CTG
• SPS Arming/Disarming Decision
– Target CTG cause violations -> arm SPS
– Control action type CTG with SPS disabled, when no more violations -> disarm SPS
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Detailed CA Post Flow
• CA Post Contingency Detailed Solution
– CA reports ctg violations/warnings only
– Postflow shows full CA solution for specified ctg
– Results shown on both tabular and one-lines
– Run in STNET, access from RTCA, STNET, STCA
• Different from Applying Ctg to Basecase
– Monitored limits: norm vs. emer, cont. vs. 15min
– Post ctg protective relay and SPS actions
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CA Solution Validation
• Verification of CA Solutions
– SE solution against SCADA measured values
– CA solution against SE/power flow solution
– Pre-outage CA solution against post-outage system state (real time or DTS Replay)
• CA Case Coverage
– Missing CA case definition? => monthly check
– Screen masking? =>periodical comparison of CA results with/without screening (off-line)
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CA Setup & Maintenance
• Solution Algorithms & Options
– Full Newton method (auto-enable)
– Fast Decoupled (default)
– MW only solution
– Separate control options for base and ctg cases
• Tuning & Trouble Shooting
– Model & solution must match system response
– Application parameters tuning
– Identifying ctg case causing crashing
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Performance Monitoring
• CA Solution Quality and Availability
– Invalid basecase
– Solution with extreme voltage (too high/low)
– Unsolved contingency cases
– Run every 3 minutes
• Monitoring Procedures and Tools
– Shift control engineer/officer (7x24), issuing tickets
– Application staff, 2nd level support
– Watchdog application, running in real time
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