Operational Defense of Power System Cascading Outages

Transcription

1 Operational Defense of Power System Cascading Outages James D. McCalley Professor, Iowa State University Cascading Failures & Blackouts April, 008 IEEE PES T&D Conference and Exposition Overview. Summary of previous blackouts. Blackout attributes. Approaches to reduce frequency/severity of high consequence events. Emergency Response System. Triggering events. Simulator attributes. Final comments

2 . :0 Conesville Unit, MW. : Greenwood Unit, 8 MW. : Eastlake Unit, MW, overexcitation Weakening conditions. :0 Stuart Atlanta kv (brush fire) Triggering. :0 Harding-Chamberlain kv (tree) event. : Hanna-Juniper kv (tree). : Star-South Canton kv (tree) SLOW 8. :-:0 8 KV lines around Akron tripped PROGRESSION. :0 Sammis-Star kv (zone ) AUGUST, 00. :0 Conesville Unit, MW. : Greenwood Unit, 8 MW. : Eastlake Unit, MW, (overexcitation) WHAT HAPPENED ON AUGUST, 00??? Weakening conditions. :0 Stuart Atlanta kv (brush fire) Triggering. :0 Harding-Chamberlain kv (tree) event. : Hanna-Juniper kv (tree). : Star-South Canton kv (tree) SLOW 8. :-:0 8 KV lines around Akron tripped (overload PROGRESSION and failed). :0 Sammis-Star kv (zone, tree) 0. :08:8 Galion-Ohio Central-Muskingum kv (zone ). :0:0 East Lima-Fostoria Central kv (zone ). :0:-:0: Kinder Morgan (rating: 00 MW; loaded to 00 MW). :0 Harding-Fox kv. :0:0 :0: 0 generators along Lake Erie in north Ohio, MW. :0: West-East Michigan Kv (zone ) FAST. :0:8 Midland Cogeneration Venture, MW (reduction of 00MW) PROGRESSION. :0:8 Transmission system separates northwest of Detroit 8. :0:8 Perry-Ashtabula-Erie West kv (zone ) (cascade). :0:0 :0: lines disconnect between Pennsylvania & New York 0. :0: lines disconnect and gens trip in north Ohio,88MW. :0: :0: lines disconnect in north Ontario, New Jersey, isolates NE part of Eastern Interconnection, unit trips, 80 mw. :0: :0: New York splits east-to-west. New England and Maritimes separate from New York and remain intact. (power swing+ufls). :0:0 :: Ontario separates from NY w. of Niagara Falls & w. of St. Law. SW Connecticut separates from NY,blackout.(relay operation,ulfs)

3 IMPACT Location Date MW Lost Duration People affected Approximate cost US-NE // 0000 hours 0 million US-NE // 000 hours million 00 million France // hours West Coast //8 0 million Sweden //8 > 000. hours. million Brazil /8/8 Brazil 8/8/8 Hydro Quebec /8/ US-West // 00 Brazil // 80 US-West //. million Brazil // US-West //. million US-West // 00 small number US-West 8/0/ 08. million billion dollars MAPP, NW Ontario //8 0 hours 0. million San Francisco /8/ hours million Brazil // 000 hours million Brazil // 000 India // hours 0 million 0 million Rome //00 0. million US-NE 8// days 0 million - billion Denmark/Sweden // hours million Italy /8/ hours million Croatia //00 0 mwh. million Greece // hours million Moscow/Russia /-/00 00 > hours million European Blackout /00 > 00 Hour million PRE-EVENT CONDITIONS Location Date Weather Loading Topology US-NE // mild normal normal US-NE // Stormy normal weakened ( major tie feeder, major gen out) France //8 Heavy Normal West Coast //8 windy normal normal Sweden //8 Brazil /8/8 Brazil 8/8/8 Hydro Quebec /8/88 Freezing rain normal normal US-West // mild normal normal Brazil // US-West // cold Heavy normal Brazil // US-West // Hot 8C Heavy Normal US-West // Hot 8C Stressed Normal US-West 8/0/ Hot 8C normal weakened (three 00 KV line sections out of service MAPP, NW Ontario //8 stormy heavy normal San Francisco /8/8 normal normal normal Brazil // Brazil // India //00 Rome //00 Hot heavy weakened US-NE 8//00 heavy Weakened ( gens out of service) Denmark/Sweden //00 heavy Weakened ( nuclear unit out for maintenance) Italy /8/00 heavy Weakened (trip of Swiss 80 KV line Mettlen-Lavorgo) Croatia //00 wind,cold,ice, rain normal weakened Greece //00 Hot Heavy weakened( 0KV, a MW & 00MW unit out) Moscow/Russia /-/00 Hot Heavy Weakened (loss of a cogen plant) European Blackout //00 normal weakened as no of power plants shut down

4 TRIGGERING EVENTS US-NE // Faulty Relay setting N- US-NE // Lightening N- France //8 West Coast //8 00 KV Tr tower failed due to high winds N- Sweden //8 Disconector Failed N- Brazil /8/8 Xmer shutdown due to overload, and load increase N- Brazil 8/8/8 phase to grd short ckt+ in-advertent protection operation N- Hydro Quebec /8/88 Ice causes flashover N- US-West // Earthquake many Brazil // human error D.C. bipoles blocked US-West // Single phase to gnd fault, relay misop. N- (inadvertent of additional KV ckt) Brazil // human error+inadvertent prot. operation N- US-West // Tree Flashover followed by relay misop. N- US-West // Tree Flashover N- US-West 8/0/ Tree Flashover N- MAPP, NW Ontario //8 lightening N- San Francisco /8/8 human error no of lines Brazil // Bus Fault Multiple lines (> N-) Brazil // Inadvertent protection operation Many India //00 Rome //00 high load demand US-NE 8//00 Brush fire on a line (outage) N- Nuclear Plant trips (technical problem), double Denmark/Sweden //00 busbar fault N- Italy /8/00 Tree Flashover N- Croatia //00 Breaker failure N- Greece //00 Load Increasing N- Moscow/Russia /-/00 Load Increasing/Xmer bursting European Blackout //00 human error many PRE-COLLAPSE EVENTS Location Date Generation trip Transmission trip Time between initiating and secondary, precollapse events US-NE // no Four 0KV lines few minutes US-NE // Yes Yes occurred in a sequence between 0 to minutes after initial event France //8 yes > 0 minutes West Coast //8 No Yes Fast Sweden //8 No Yes 0 seconds Brazil /8/8 Xmer yes -0 minutes Brazil 8/8/8 No yes Hydro Quebec /8/88 Transformer yes - seconds US-West // Yes Yes Fast Brazil // yes yes US-West // No Yes 0- seconds Brazil // Xmer Yes US-West // yes yes 0 seconds US-West // No yes fast US-West 8/0/ yes ( generators) yes - minutes MAPP, NW Ontario //8 No yes minutes San Francisco /8/8 yes yes seconds Brazil // No Yes > 0 seconds Brazil // No Yes India //00 Rome //00 No No US-NE 8//00 yes yes more than hours Denmark/Sweden //00 yes yes minutes Italy /8/00 No Yes minutes Croatia //00 Yes Yes 0 seconds Greece //00 Yes No 0 minutes Moscow/Russia /-/00 No Yes > hours European Blackout //00 yes Yes 0 minutes 8

5 Location Date Causes of secondary, pre-collapse events US-NE // Proper protection operation (as designed) (overload protection) US-NE // Lightening, Proper protection operation (overload+gen protection) NATURE OF COLLAPSE France //8 Proper protection operation (overload protection,out of step relays) West Coast //8 Primary and secondary protection & communication failure Sweden //8 Proper protection operation (overload protection), underfreq LS failure Brazil /8/8 Simultaneous tripping of ckts and Xfmer Brazil 8/8/8 Protection failure (SPS setting) Hydro Quebec /8/88 Communication failure followed by load shedding protection failure US-West // Earthquake Brazil // Inefficient Protection, loss of synchronism US-West // Proper protection operation (overload protection) Brazil // Proper protection operation US-West // Proper protection operation (gen protection), relay misoperation US-West // Relay Misoperation US-West 8/0/ Trees, protection (relay) failure MAPP, NW Ontario //8 Lightening trip another kv line followed by proper ovrload protection San Francisco /8/8 No local protection, topology,delayed remote protection Brazil // Proper protection operation ( overload protection ) Brazil // Inadvertent Protection operation India //00 Rome //00 High Load, low generation, reduction in import US-NE 8//00 Proper protection operation Denmark/Sweden //00 Switching device breaks,proper protection operation (generator and overload protection) Italy /8/00 Unsuccessful reclosing, Tress, loss of synchronism, dynamic intercaction leading to voltage collapse Croatia //00 Protection failure Greece //00 Proper protection operation Moscow/Russia //00 lines from HV substation tripped due to faults and overloading European Blackout //00 Proper protection operation COLLAPSE TIME & NO. OF SUCCESSIVE EVENTS Location Date Collapse time #successive events US-NE // minutes Many US-NE // hour Many France //8 > 0 minutes Many West Coast //8 few minutes Many Sweden //8 > minute Many Brazil /8/8 > 0 minutes Topology Brazil 8/8/8 Topology Hydro Quebec /8/88 < minute Many US-West // minute Brazil // many US-West // substation topology Brazil // Topology US-West // seconds Several US-West // > minute Prevented by fast op. action US-West 8/0/ > minutes Many MAPP, NW Ontario //8 > minutes substation topology San Francisco /8/8 seconds many Brazil // 0 seconds substation topology Brazil // Topology India //00 Rome //00 US-NE 8//00 > hour Many Denmark/Sweden //00 minutes Many Italy /8/00 minutes Many Croatia //00 few seconds many Greece //00 minutes few Moscow/Russia /-/00 hours Many European Blackout //00 0 minutes Many 0

6 Summary of blackout attributes Impact: of largest blackouts occurred in last 0 years # of blackouts > 000 MW doubles every 0 years Pre-event conditions: Extreme weather Extreme conditions Weakened topology Triggering events: Various kinds of N- or N-k (k>) with fault + nearby protection failure Summary of blackout attributes Pre-collapse events: 0% involved generation, % involved transmission 0% had significant time between initiating & precollapse events 0% involved proper protection action Nature of collapse: Successive tripping of components and/or Voltage collapse Collapse time and # of events: 0% were slow 0% involved many cascaded (dependent) events

7 Scenario for 0% of blackouts. Weakened conditions: Heavy load, and/or one or more gen or cct outage possibly followed by readjustments. Initiating event: One or several components trip because of fault and/or other reasons;. Steady-state progression (slow succession): a. System stressing: heavy loading on lines, xfmrs, gens b. Successive events: Other components trip one by one with fairly large inter-event time intervals. Transient progression in fast succession: a. Major parts of system goes under-frequency and/or under-voltage. b. Components begin tripping quickly c. Uncontrolled islanding and wide spread blackout. Preventive/corrective action paradigm Probability>P (Class B events) Initiating event identification and probability calculation Emergency response system (ERS) Probability<P (Class C, D events) Highprobability events Assessment Lowprobability events Assessment Violation detection Determine preventive action and implement it Failure detection Determine corrective action and store it

8 Operational approach to blackout mitigation Preventive control is for high -probability events. Corrective control is for not-high (N-k) probability events. Blackouts typically result from the latter. Corrective control: operational solution to blackouts. Actions determined on-line, in anticipation of events, to be actuated through operator upon event occurrence Need new EMS Function ERS: decision support to unfolding events Operational approach to blackout mitigation The Emergency Response System: Continuously identifies catastrophic event sequences together with actions operators can take to mitigate them.. Intelligent selection of triggering events Uses current or forecasted conditions Based on mid-term (hours) simulation tool Must have protective relaying modeled Stores results for fast retrieval should event occur 8

9 High-Risk Triggering Events. Functional group tripping Proper relay tripping, may trip multiple components. Fault plus breaker failure to trip Breaker stuck or protection fail to send signal to open Two neighboring functional groups tripped. Inadvertent tripping of or more components Inadvertent tripping of backup breaker to a primary fault. Common mode events Common right of way, common tower.. Any of above together with independent outage of any other single component Contingency Selection Definition: A functional group is a group of components that operate & fail together as a result of breaker locations within the topology that interconnects them. Graph search identifies five types of initiating events:. Functional group tripping, ~ P Proper relay tripping, may trip multiple components. Fault plus breaker failure to trip, ~ P Breaker stuck or protection fail to send the signal to open Two neighboring functional groups tripped. Inadvertent tripping of two or more components, ~ P Inadvertent tripping of backup breaker to a primary fault. Common mode events, ~ P Common right of way, common tower.. Any of the above together with independent outage of any other single component in a selected set, ~ P ~ P 8

10 Contingency Selection L0 TG0 G0 BUS-0 L0 BUS-0 T0 LOAD0 BUS-0 L0 L0 BUS-0 T0 L0 L08 L0 BUS-0 BUS-0 LOAD0 T0 L0 L L L0 L0 L0 BUS-0 L0 BUS-0 L L L G0 TG0 BUS-0 Number of contingencies of type N-k resulting from a single fault (Order P) for Bus System k No. L0 BUS-0 L0 L8 L BUS-08 0 T0 BUS-0 G0 L0 BUS-0 L0 TG0 0 0 LOAD0 BUS-0 BUS L0 L0 L0 8 L TG0 G0 L0 L08 L0 L8 L L G0 BUS-0 BUS-0 0 TG0 BUS-0 BUS-0 0 LOAD0 L0 8 0 L0 L 8 L L0 L0 LOAD0 8 0 L L L BUS-08 BUS TG0 BUS-0 L0 G0 LOAD0 L0 L0 L0 Number of contingencies of type N-k resulting from a fault/breaker failure (order P ) for Bus System k No. Number of contingencies of type N-k resulting from ITC (Order P ) for Bus System k No. 8 Testing on Large EMS Model Use graph-search to identify functional groups, and order P and P contingencies Number of components in the system Type Bus Line Xfmr Gen Shunt No. 80 Number of contingencies of type N-k resulting from a single fault (Order P) k 8 0 No Number of contingencies of type N-k resulting from a fault/breaker failure (order P ) k 0 No Searching Time to Identify Contingencies (.Ghz Pentium) System Scale (No. of Buses),000 0,000 Time (Second)

11 Simulator. Seamless interface with & simulation on node-breaker model for proper identification of initiating & successive events. Model full range of dynamics: Fast dynamics, including generator, excitation, governor Slow dynamics, including AGC, boiler, thermal loads. Model condition-actuated protection action that trips element Generator: field winding overexcitation, loss of field, loss of synchronism, overflux, overvoltage, underfrequency, and undervoltage Transmission: impedance, zone, out-of-step. Identifies islanded condition and continues simulation in each. Saves & restarts from conditions at any time. Failure detection and prevention. SPEED is essential: Adaptive time step using theta implicit integration method Intelligent Jacobian updating Sparsity-based coding and multi-frontal solver for Ax=b Deploying on an IBM BlueGene supercomputer Simulator is written in C++ ONE-LINE DIAGRAM OF DET TEST SYSTEM BUS-0 BUS-0 G0 (initiating generator trip at t=00s) Load ramping 0% from t=00s to t=00s L0 L0 L0 G0 G0 L0 L0 TG0 BUS-0 0 BUS-0 BUS-0 LOAD0 TG T0 BUS BUS-0 L0 L0 L0 8 BUS L L0 0 L0 8 L0 L08 L0 L8 L 8 L L0 L08 L0 T0 G0 BUS-0 0 BUS-0 8 TG0 BUS-0 LOAD0 L0 BUS L0 L0 LOAD0 T0 L0 L L L0 L0 L L L L BUS-08 L BUS-0 8 L LOAD0 8 0 L 0 BUS-0 0 L TG0 8 BUS-0 T0 TG0 8 BUS-0 G0 L0 BUS-0 G0 L0 8 L0 L0 LOAD0 BUS-0 L0 0 BUS L8 L 8 L BUS-08 8 LOAD0 L0 TG0 G0 L0 BUS-0

12 Initiating contingency: G0 Without Generator Protection First Control Action at 08. Second Control Action at 0.0 Final Comments on Operational Approach to Blackout Mitigation Number of major blackouts doubles every 0 years Various approaches to reduce frequency, mitigate severity Operators are last line of defense; they need better tools Preparing operators for rare events is fundamental to operating engineering systems having catastrophic potential; it has precedent in air traffic control, nuclear, & process control. Described approach is a generalization of already-existing event-based special protection systems, except here response continuously developed on-line actuation is done through a human