Presentation on theme: "August 14, 2003 Blackout Summary Based on Interim Report of the"— Presentation transcript:
1 August 14, 2003 Blackout Summary Based on Interim Report of the United States – Canada Power Outage Task ForceNovember 19, 2003
2 U.S.-Canada Interim Report Released November 19, 2003Result of an exhaustive bi-national investigationWorking groups on electric system, nuclear plant performance and securityHundreds of professionals on investigation teams performed extensive analysisInterim report produced by the teams and accepted by the bi-national Task Force
3 OverviewOverview of power system and reliabilityPre-outage conditions on August 14Trigger events and start of cascadeWide area cascadeRoot causesNext steps
5 Reliably operate the system you have! Reliability OverviewBalance generation and demandBalance reactive power supply and demandMonitor flows and observe thermal limitsObserve power and voltage stability limitsOperate for unplanned contingenciesPlan, design and maintain a reliable systemPrepare for emergenciesReliably operate the system you have!
9 Footprints of Reliability Coordinators in Midwest
10 NERC Immediate Response to Blackout First hoursWorked closely with NERC Reliability CoordinatorsIdentified what had tripped and extent of outageAssessed restoration effortsMaintained open line with DOE/FERCCommunicated with DHS, White House, and NRCFirst daysAssigned project managerEstablished Steering Group with industry executive expertsBegan organizing investigation teams90+ volunteers + entire NERC staff
11 Investigation Organization Overview Steering GroupU.S – CanadaTask ForceInvestigation Team LeadProject Planning and SupportRoot Cause AnalysisCooper SystemsInvestigation Process ReviewVegetation/ROW ManagementNERC & Regional Standards/Procedures & ComplianceSequence of EventsTransmission System Performance, Protection, ControlMaintenance & DamageMAAC/ECAR/NPCCCoordinating GroupMAACRestorationOperations - Tools, SCADA/EMS Communications Op PlanningGenerator Performance, Protection, ControlsMaintenance & DamageECARData Requests and ManagementFrequency/ACENPCCSystem Modeling and Simulation AnalysisSystem Planning, Design, & StudiesMEN Study Group
12 Data Gathering and Analysis Three fact-finding meetingsAugust 22September 8-9October 1-3Onsite interviews and inspectionsSecure database of outage informationExtensive corroboration of data to determine factsAnalysis by teams of technical experts
13 Root Cause AnalysisLogical structure for investigating complex problemsIdentifies changes, conditions, actions, or inactions at each causal stepStarts with final event and drills back through each branch of causal tree.Asks “why?” at each step.Accurate, reliable, defensible understanding of the root causes.Successfully used to investigate root causes of PJM voltage stability conditionin July and established history in nuclear and defense industries.
14 Root Cause Analysis Phases 16:15BLACKOUT16:06Sammis – StarStar – South CantonHanna – JuniperChamberlin - HardingInitial Focus15:05Pre-Existing ConditionsE.g. voltages, wide- area transfers,line and generator outages, etc.
15 August 14 Conditions Prior to Blackout Planned outagesCook 2, Davis Besse nuclear plantsEast Lake 4, and Monroe 1Transfers high to northeast U.S. + OntarioNot unusually so and not above transfer limitsCritical voltage dayVoltages within limitsOperators taking action to boost voltagesFrequencyTypical for a summer daySystem was within limits prior to 15:05, on both actual and contingency basis
20 Blackout was NOT Caused by Heavy wide-area transfersLow voltages, voltage collapseLack of IPP voltage/reactive supportFrequency anomaliesCinergy outages starting at 12:08East Lake 5 trip at 13:31Contributing factor to later events, but not by itself causal to the blackoutDPL Stuart-Atlanta trip at 14:02Contributing factor to loss of MISO real-time monitoring, but not electrically significant
22 East Lake 5 Trip: 1:31:34 PMONTARIOONTARIO21There were several incidents occurring earlier in the day on August 14. However, the investigation has not found any of them to be electrically related to the blackout. The first significant event setting the stage for the cascade is at 1:31:34 when the East Lake 5 generating unit trips while the unit operator is attempting to increase reactive output. The East Lake 5 forced outage causes increased flows into northern Ohio over transmission paths into the area.
24 Stuart Atlanta Trip: 2:02 PM In the Dayton Power & Light system about 2:02 pm, the Stuart-Atlanta 345 kV line trips and locks out due to a ground fault. The loss of Stuart-Atlanta is not electrically connected to the start of the cascade, but it is noteworthy later from an operational perspective.At 2:27:16, in a precursor of subsequent trips, the Star-South Canton 345 kV line trips on a ground fault and recloses.
25 MISO State Estimator and Reliability Analysis MISO state estimator and contingency analysis ineffective from 12:37 to 16:04State estimator not solving due to missing information on lines out in Cinergy then DPLHuman error in not resetting SE automatic triggerUsing Flowgate Monitoring tool to monitor conditions on previously identified critical flowgates
26 FirstEnergy Computer Failures 14:14 Alarm logger fails and operators are not awareNo further alarms to FE operators14:20 Several remote consoles fail14:41 EMS server hosting alarm processor and other functions fails to backup14:54 Backup server failsEMS continues to function but with very degraded performance (59 second refresh)FE system data passed normally to others: MISO and AEPAGC function degraded and strip charts flat-lined15:08 IT warm reboot of EMS appears to work but alarm process not tested and still in failed conditionNo contingency analysis of events during the day including loss of East Lake 5 and subsequent line trips
27 Phone Calls to FirstEnergy FE received calls from MISO, AEP, and PJM indicating problems on the FE system but did not recognize evolving emergency14:32 AEP calls regarding trip and reclose of Star-S. Canton15:19 AEP calls again confirming Star-S. Canton trip and reclose15:35 Calls received about “spikes” seen on system15:36 MISO calls FE regarding contingency overload on Star-Juniper for loss of Hanna-Juniper15:45 FE tree trimming crew calls in regarding Hanna-Juniper flashover to a treePJM called MISO at 15:48 and FE at 15:56 regarding overloads on FE system
28 Chamberlin-Harding (3:05:41) At 3:05 a sequence of three key events begins and sets the trigger for the cascade.First, at 3:05:41 the Chamberlin-Harding 345 kV line in FirstEnergy trips and locks out. The trip was caused by a high impedance ground fault.
29 Chamberlin-Harding Indication of Ground Fault Due to Tree Contact as Measured by DFR at Juniper
30 Hanna-Juniper (3:05:41) (3:32:03) At 3:32:03 the Hanna-Juniper 345 kV line in FirstEnergy trips and locks out. The Hanna-Juniper line trips due to contact with a tree, visually confirmed by a tree-trimming crew working a few spans away who saw the flash.
31 Hanna Juniper Confirmed as Tree Contact at Less than Emergency Ratings of Line
33 (3:05:41) (3:32:03) Star- S. Canton (3:41:35) At 3:38:48 the Star-South Canton 345 kV trips and recloses again.At 3:41:33-35 the Star-South Canton 345 kV line trips and recloses; then trips a final time and locks out. Each trip of the Star-South Canton line is caused by a short circuit to ground.
34 Situation after Initial Trips 3:05:41 – 3:41:35 ONTARIOWith the loss of the Chamberlin-Harding, Hanna-Juniper, and Star-South Canton 345 kV lines, three critical paths delivering heavy imports into northern Ohio are lost, aggravated by the prior loss of the East Lake 5 unit. The power that had been flowing over these 345 kV lines is now flowing over the underlying 138 kV lines in this area, and these lines quickly become overloaded. At 3:42, 36 minutes after the trip of Chamberlin-Harding, the cascade is electrically set to happen with no further triggers required, although intervening actions still appeared possible at this time.
35 Canton Central – Tidd (3:45:41) At 3:45:41 the Canton Central – Tidd 345 kV line trips and recloses. Several operations of a transformer circuit breaker at Canton Central cause low air pressure on the breaker. As a result, the 345/138 kV transformer is disconnected and remains open at Canton Central.At 3:39 a “local cascade” of 138 kV lines begins in the Akron area, resulting from line overloads. The lines are rapidly overheating and sagging into obstructions, with most tripping on ground faults.Following the trip of one 138 kV line at 3:59, a circuit breaker failure on the West Akron Transformer #1 causes a 138 kV bus trip and the five remaining 138 kV lines connected to West Akron are tripped.In a 30 minute period from 3:39 to 4:09, a total of sixteen 138 kV lines are lost in the Akron area. In this period, voltages are severely degraded in the area and about 600 MW of load is lost in Akron and areas to the south and west of Akron.Canton Central – Tidd(3:45:41)
37 138 kV Cascade Contributes Further to Overload of Sammis-Star 15:51:41 EDT15:05:41 EDT15:32:03 EDT16:05:55 EDT15:41:35 EDT
38 Sammis-Star(4:05:57.5)At 4:05:57, having become incrementally overloaded with the loss of underlying 138 kV lines over the prior 30 minutes, the Sammis-Star 345 kV line trips and locks out. The line trips in a steady state overload with the operation of a Zone 3 impedance relay. The Sammis-Star trip is a significant turning point for two reasons. First, this is the first 345 kV trip not caused by a ground fault. The line tripped due to an “apparent overload” – the impedance relay seeing a combination of increased current and sustained low voltage. Secondly, the trip of Sammis-Star is a turning point because it truly is the beginning point of a rapid, uncontrolled wide-area cascade. After Sammis-Star, there is likely nothing that could have been practically done to prevent the wide-area cascade with the electrical system and capabilities that were in place on that day .
39 Sammis-Star Zone 3 Relay Operates on Steady State Overload
42 Major Path to Cleveland Blocked after Loss of Sammis-Star 4:05:57.5 PM RemainingPathsWith the 345 kV and 138 kV paths from eastern Ohio blocked, the still significant demand for imports in the northern Ohio area are met by lines along the southern shore of Lake Erie from Pennsylvania in the east and from Michigan and northwest Ohio in the west.
43 345 kV Lines Trip Across Ohio to West ONTARIOOver the next minute-plus, three more 345 kV lines in Ohio trip:4:08:59 – Galion-Ohio Central-Muskingum 345 kV line trips4:09:06 – East Lima-Fostoria Central 345 kV line trips4:09:07 – Harding-Fox 345 kV #2 line tripsWhen the Galion-Ohio Central-Muskingum and East Lima-Fostoria Central transmission lines disconnect, the transmission paths from southern and western Ohio into northern Ohio and eastern Michigan are disconnected. Thus the combined northern Ohio and eastern Michigan load centers are now connected only by the transmission lines from: 1) northwestern Pennsylvania along the southern shore of Lake Erie; 2) lines west and northwest of Detroit, Michigan; and 3) Ontario. Northern Ohio is connected to eastern Michigan by only three 345 kV transmission lines near the southwestern bend of Lake Erie.The reduced transmission capacity serving the northern Ohio load center results in the transmission voltage becoming severely depressed in that area as load exceeds the rapidly degrading power delivery capability.We begin to see signs of the grid ripping along natural seams where the system is less tightly connected.
44 Generation Trips 4:09:08 – 4:10:27 PM ONTARIOFrom 4:09:08 - 4:10: MW of generation is lost:MCV Plant drops 300MW from 1263 MW to 963 MW,Avon Lake #7 unit trips (82 MW),Two Kinder Morgan units trip (200 MW total),Berger #3, 4, & 5 Units trip (355MW total)Power flows into Michigan from Indiana become heavy in order to serve loads in eastern Michigan and northern Ohio. This reduces transmission capacity serving northern Ohio load centers resulting in depressed transmission voltage as load exceeds the rapidly declining power delivery capability over the remaining transmission lines.
45 345 kV Transmission Cascade Moves North into Michigan 4:10:36 – 4:10:37 PM From 4:10:36 to 4:10:37 three lines trip in rapid succession, continuing the ripping of the system through central Michigan.Argenta – Battlecreek 345kV line tripsBattlecreek – Oneida 345kV line tripsArgenta – Tompkins 345kV line tripsThese line outages interrupt the transmission paths into the Detroit area from south-central Michigan. Michigan lines northwest of Detroit then begin to trip, as shown on the next slide.
46 Northern Ohio and Eastern Michigan Served Only from Ontario after 4:10:37.5 – 4:10:38.6 PM From 4:10:37.5 – 4:10:38.4 a peninsula consisting of northern Ohio and eastern Michigan is formed as:the Hampton – Pontiac 345kV line trips;the MCV Plant is reduced in output by an additional 835MW;and the Thetford – Jewell 345kV line trips.
47 Power Transfers Shift at 4:10:38.6 PM At this point, the load centers in eastern Michigan and northern Ohio have little generation left available to them and the voltage is declining. The major connection between those load centers and the rest of the Eastern Interconnection is at the interface between the Michigan and Ontario systems.Line flows in Pennsylvania, New York and Ontario have now reversed direction and are flowing northeastward through Pennsylvania and into New York and Ontario before reaching Michigan by the remaining transmission path from Ontario. Power flows to serve eastern Michigan and northern Ohio loads, directly connected to Ontario, now all appear on the Pennsylvania – New York interface. This sudden large change in power flows drastically impacts the voltage and current levels on the transmission lines along the Pennsylvania – New York transmission interface.
48 Ontario – Michigan Interface Flow and Voltages Beginning 16:10:38 Eastern Eastern Michigan (Detroit) Unstable Voltage and Frequency Collapse and Pole SlippingOntario – Michigan Interface Flow and Voltages Beginning 16:10:38
51 Overloads on PJM – NY Ties 4:10:39 PM Responding to the surge of power flowing north out of Pennsylvania through New York and Ontario into Michigan, two 345 kV lines between Pennsylvania and New York disconnect within seconds of each other:4:10:39.5 – Homer City-Watercure Road 345 kV4:10:39.8 – Homer City-Stolle Road 345 kV
52 PJM – NY Separating 4:10:44 PM With the two 345 kV lines gone, several 230 kV lines quickly become overloaded and trip at 4:10:44:South Ripley - Erie East 230kVSouth Ripley - Dunkirk 230 kVEast Towanda-Hillside 230 kVAt this point, the northern part of the Eastern Interconnection (which still includes eastern Michigan and northern Ohio) remains connected to the rest of the Interconnection at only two locations:1) in the east through the 500 kV and 230 kV ties between New York and New Jersey, and2) in the west through the long and weak 230 kV transmission path in Ontario connecting it to Manitoba and Minnesota.Heavy power flows are now moving northward over the New Jersey to New York tie lines into what is now the great peninsula of northern Ohio, eastern Michigan, Ontario, New York and New England.
53 Cleveland – Toledo Island 4:10:39 - 4:10:46 PM Cleveland Blacks Out From 4:10:39 to 4:10:46 Toledo and Cleveland split off into a separate island. Frequency in this island collapses quickly. When the Beaver-Davis Besse 345 kV line trips, Cleveland and Toledo separate from each other. A race begins in Cleveland between under-frequency load shedding and generator trips on under-frequency. Load shedding of 1300 MVA is unable to arrest the frequency collapse and the Cleveland island blacks out. The Toledo island also experiences load shedding as portions of the Toledo area black out, but some loads are restored by automatic reclosures.
54 Northeast Completes Separation from Eastern Interconnection 4:10:43 – 4:10:45 PM North of LakeSuperiorAt 4:10:43, eastern Michigan is still connected to Ontario, but the Keith-Waterman 230 kV line that forms part of that interface then disconnects.At 4:10:45, the northwest Ontario system separates from the remainder of Ontario when the Wawa-Marathon 230 kV lines disconnect along the northern shore of Lake Superior. The portion of Ontario to the west of Wawa remains connected to the Eastern Interconnection through Manitoba and Minnesota.At this time, the Branchburg-Ramapo 500 kV line and underlying 230 and 138 kV lines are the last major transmission paths remaining between the Eastern Interconnection and the northeast. Branchburg-Ramapo trips at 4:10:45 taking the underlying 230 and 138 kV lines along with it. This leaves the northeastern part of New Jersey connected to New York. Pennsylvania and the remainder of New Jersey remain connected to the Eastern Interconnection.New York City, northern New Jersey, New York state, New England and the Canadian Maritime provinces, eastern Michigan, and the majority of Ontario are in a large island separated from the Eastern Interconnection. The areas outside this island were not significantly affected by the blackout.
55 Conditions at Niagara Indicate Progressively Worsening Stability Conditions with Prior Events
56 Island Breaks Up: 4:10:46 – 4:13 PM The voltage falls to 50 kV on the 230 kV system feeding eastern Michigan. Large units in Detroit appear to pull out of synch and slip two poles before tripping off. The remaining units in Detroit area are no match for the remaining loads and the frequency collapses at about 2 Hz/sec. High speed power swing oscillations occur on the lines feeding Detroit from Ontario. Two more system-to-system pole slips are observed in Detroit before the Keith line trips by zone 1 relay and eastern Michigan is blacked out.At 4:10:50, New York and Ontario separates an initial time, leaving New York and Ontario hydro generation at Niagara and St. Lawrence, along with some thermal generators and a tie to Quebec, connected to the western New York system, supporting the demand in upstate New York. A large portion of demand in Ontario is automatically disconnected by under-frequency load shedding. At 4:11:10, the three lines between New York and Ontario, which had reclosed after about 8 seconds, trip a second time west of Niagara, separating New York and Ontario a final time. Following this separation, the frequency in Ontario declines to 56 Hz by 4:11:57, resulting in an almost total blackout of most of Ontario, leaving 22,500 MW of demand lost out of a total demand of about 24,000 MW. The eastern New York island also blacked out with only scattered small pockets of service remaining. The western New York island continued to serve about 50% of its demand.Moments later, the southwest portion of Connecticut, which had been connected to the eastern New York island, separates and blacks out.As a result of the severe frequency and voltage changes, many large units in New York and Ontario have tripped. The eastern island of New York including the heavily populated areas of southeastern New York, New York City, and Long Island experiences severe frequency and voltage decline. At 4:11:29, the eastern island of New York splits into northern and southern sections. The small remaining load in the Albany area remains energized by local generation.
57 Frequency in Ontario and New York during Breakup Niagara Generation Stays with Western NY There were two very sharp frequency excursions to 63 Hz on the Upper State New York area and the IMO Beck and Saunders hydro-electric plants after this. This plot shows the frequency peaks and the separating moments as lines into Ontario tripped, successfully reclosed (accidentally), tripped again, and then separated for good. In between the two frequency peaks, the Ontario system and Upper State New York almost held it together, however, two 500 MW Nanticoke units tripped by negative sequence protective relays in rapid succession at this time and the resulting additional surge of generation into the deficient interior region of Ontario was too much for the weak three remaining ties at Beck. They tripped again by zone 2 distance relays. Definite-time reclose attemps after that were unsuccessful as the frequencies were widely separated.After this, the interior Ontario system frequency decayed, shed what remaining under frequency load shed locations at 58.8 Hz, and then fell, and fell some more until the total collapse of frequency (and simultaneously voltage collapse) at 16:11:56.The wild ride of frequency on the New York side shook several unit (especially the nuclear units) into tripping off with in-plant control limit violations.
59 Areas Affected by the Blackout Some Local Load Interrupted End of the CascadeAreas Affected by the BlackoutService maintainedin some areaSome Local Load InterruptedStarting at 4:10, and over the next 40 seconds, three more 345 kV transmission lines trip in Michigan, Ohio and Pennsylvania, as do twenty generators along Lake Erie, which had been producing 2,174 MW.The loss of this generation increased the power flows into the northern Ohio and eastern Michigan load centers on the remaining paths, which included the west-east transmission lines that cross Michigan.When the west-east Michigan 345 kV paths disconnected, it left eastern Michigan connected by only a circuitous path around northern Michigan that disconnected one second later, and the connections to Ontario and northern Ohio. Investigators are still studying the power flows that resulted.
60 Blackout Root Cause Group 1 FE Situational Awareness FE did not ensure a reliable system after contingencies occurred because it did not have an effective contingency analysis capabilityFE did not have effective procedures to ensure operators were aware of the status of critical monitoring toolsFE did not have effective procedures to test monitoring tools after repairsFE did not have additional high level monitoring tools after alarm system failed
61 Blackout Out Root Cause Group 2 Vegetation Management FE did not adequately manage tree growth in its transmission rights of way
62 Blackout Cause Group 3 Reliability Coordinator Diagnostics MISO’s state estimator failed due to a data error.MISO’s flowgate monitoring tool didn’t have real-time line information to detect growing overloadsMISO operators couldn’t easily link breaker status to line status to understand changing conditions.PJM and MISO ineffective procedures and wide grid visibility to coordinate problems affecting their common boundaries
63 Near-Term Industry Actions Responses from Control Areas and Reliability Coordinators Due December 15Voltage support/reactive supplyReliability communicationsComputer failure response & notificationsEmergency action plans and capabilitiesOperator training for emergenciesVegetation management
64 Next Steps U.S./Canada Power Outage TF hearings NERC next steps Public hearings to allow comment on report and input on recommendationsDecember 4December 5December 8 – TorontoIndustry technical conferenceDecember 10 – PhiladelphiaNERC next stepsNERC executive committees December 11NERC committees meet January 13-14Continue investigationNear term analysis and recommendations in support of U.S. Canada Task ForceLong term analysis and recommendations for NERC