ISO New England Operations Significant Events December 2003 January 2004

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ISO New England OperationsSignificant Events

December 2003January 2004

NEPOOL Reliability Committee

February 3, 2004

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Significant Events

• 12/5 Declaration of OP4 Conditions

• 1/14 Declaration of OP4 Conditions

• 12/6 Loss of Salem Harbor Station

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Declaration of OP4 ConditionsDecember 5, 2003

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Dec. 5 OP4 Conditions

Initial Conditions (from morning report)

Installed generating capacity 33,024

Generation outages & reductions 5,362

External purchases 497

Operating reserve requirement 1,735

Peak load forecast for hour 18 19,375

Surplus 928

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Events Contributing to OP4

• 16:13 – Millenium tripped due to low boiler level.

• 16:42 – Lake Road #1 tripped.

• 16:53 – Mystic 7 tripped due to an ID fan problem.

• System load 500MW over forecast.

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OP4 Trigger

Maintenance crews at Yarmouth station were draining down the air system on breaker KG4/386 due to a compressor problem. At 17:25 low air pressure triggered a breaker failure lockout, transfer tripping the 391/386 and K386-4 breakers at Buxton, the KT1L breaker at South Gorham and the Yarmouth 4 generator.

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• Instantaneous Capacity deficiency about 500MW

• 17:30 - M/S#2 declared

• 17:30 - OP#4 actions 1&6 implemented.

• Total available relief from actions 1&6: 575MW

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Conditions improve

• 19:52 – The 386 line returned to service

• 20:00 – All actions of Op#4 are cancelled

• 21:00 – MS#2 cancelled

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Peak hour capacity analysis





Peak load for hour 18 19,822

Surplus -363

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Declaration of OP4 ConditionsJanuary 14, 2004

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Jan. 14 OP4 Conditions

Initial Conditions (from morning report)



External purchases -37


Peak load forecast for hour 18 21,975

Surplus 718

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Morning. events

• Multiple units reduced or OOS due to gas restrictions or freezing problems.

• Evening peak load forecast raised 500 MW.

• ISO anticipating 30 minute reserve deficiencies over the evening peak cancels all economic outages & recalls 342 line (Canal, Pilgrim, Auburn St.)

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Afternoon events

• 12:00 - M/S#2 declared for all Satellites

• 13:30 - New Brunswick, TransEnergie all forecast 30 minute reserve deficiencies over the evening peak.

• Restoration of 342 line delayed to difficulties reconnecting line leads. (550 Mw restriction on Canal generation)

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Evening events

• 17:00 – OP#4 actions 1&6 implemented.

• 17:34 – Generator posturing initiated to maintain total 10 minute reserves.

• 18:17 – 342 line restored.

• 18:33 – Posturing cancelled.

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Evening events

• 19:00 – All actions of OP#4 are cancelled.

• M/S#2 maintained until January 17th, 11:00.

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Peak hour capacity analysis





Peak load for hour 18 22,450

Surplus -108

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Loss of Salem Harbor StationDecember 6, 2003

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Dec. 5 L/O Salem Harbor

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20:27• Fault occurs on the 22-46 circuit breaker at Salem Harbor.

• T146 line & S145 terminal at Salem Harbor lock out.

• Close in fault caused #1&2 transformer & #1 bus

• differential relays to lock out all associated circuit breakers

• Salem Harbor 1&2 trip.

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• 20:37 - Salem Harbor 3 tripped, 33-54 & 33T CBs open. B154 now open ended and C155 radial to #2 bus.

• 20:44 - #2 bus de-energized.

• 21:37 - 22-46 CB isolated, T146 line shot & closed in.

• 21:41 - #2 bus energized & some SS load picked up.

• 21:53 – S145, B154, C155 closed in. Salem units receive permission to restart.

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Summary• 75 MW of area load lost.

• 313 MW of generation lost at Salem Harbor

• 23:44 - all area load restored

• No stability or thermal overloads occurred.

ISO New England Operations Significant Events December 2003 January 2004

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