Sunday, February 04, 2007

Queens Power Outage Update

DPS Staff Issues Draft Report
Since our prior post on the Queens power outage, the New York Department of Public Service (DPS) staff issued a Draft Report. The report, expected to be finalized by February 14, 2007, criticizes Con Edison for misoperation of its system, poor situational awareness, and inadequate communications with the public during the events and outages which began July 17, 2006, and recommends that the Public Service Commission commence a prudence proceeding.

A New York State Assembly Task Force on the outage issued a report critical of both Con Edison and the Public Service Commission on January 30, 2006.

PULP filed comments on the draft report on January 31. PULP identified ten matters needing further attention. Con Edison, as expected, did not agree with many of the Staff findings and recommendations. In particular, Con Edison opposed the Staff recommendation for a prudence proceeding, and opposed Staff's finding that it should have shut the network down completely for repairs instead of attempting to operate with several major feeders out of service, which Staff says exacerbated the crisis and damage when even more of the remaining overloaded feeders also failed. Con Edison's comments defend the decision not to shut down the network:
A shutdown of the entire network would have had an enormous impact on the people living, working or commuting through the neighborhoods covered by the LIC network. We preserved electric service to the many unaffected customers and the public by repairing and restoring feeders. . . .
Comments of other active intervenors in the investigation proceeding are at PULP's website page on the Queens outage.

Was there an Outage, Reactive Power Deficiency, or Grid Disturbance Just Prior to the Fire that began the Outage Events?
Discovery is still underway concerning a possible power plant outage on the afternoon of July 17, 2007 which may have occurred 25 minutes before the a distribution system feeder failed due to a fire at 3:50 PM. The substation serving the Long Island City network is located very near a number of power plants.
  • There are indications that voltage dropped in the Long Island City network at 3:25 PM on July 17, 2006. At about the same time
  • New York City load suddenly dropped by about 95 MW (even as temperatures were rising)
  • the NYISO declared a "large event reserve pickup" that required drawing upon generators to provide emergency spinning reserves of energy. (A "reserve pickup" is directed in cases where a major generator has tripped gone off line unexpectedly), and
  • NYISO real time spot market prices for energy quadrupled. (A sudden spike in spot market prices may also indicate that a generator has tripped off line).
At the time of the outage, a major Con Edison transmission line from Westchester to Queens was out of service, making New York City more reliant on local generators for both energy and reactive power. Reactive power deficiencies are sometimes manifested by lowered voltage and overheating of distribution system facilities. See "New FERC Rules to Impose Voltage Stability Obligations on Local Utilities."

On July 12, 2006, five days before the July 2006 Queens outage, FERC and NYISO grid officials testified that due to outage of two transmission lines from Westchester to New York City, the City was at increased risk of load shedding and blackouts in the event of hot weather or another outage.

It appears that both events may have occurred, and that the predictions of the grid officials were accurate. Minutes of the New York State Reliability Council indicate that "Indian Pt. 3 and Astoria Energy East each tripped twice at near full load" in the month of July. On July 17, 2006, a very hot day, the Con Edison distribution system cascaded into failure, shortly after the apparent disturbance in the bulk power grid.

The question remains whether there was sufficient reactive power (MVARs) at all times, and whether a reactive power deficiency -- or other disturbance -- in the bulk power grid may have caused or contributed to overheating of the distribution system wires and the fire that began the outage events. The reports of Con Edison and the draft DPS staff report do not discuss this. They begin their event time lines with the unexplained cable fire and feeder failure at 3:50 PM, without examination of grid conditions preceding the fire.

In the independent investigation report of the 1977 blackout, Con Edison was criticized at p. 28 for not having its transmission lines in good repair. In that incident on July 13, 1977, lightning hit major transmission lines importing power through Westchester while another major line connecting Con Edison with a New Jersey utility was not in service, making it unavailable to provide energy to support the system:
the system was not up to its designed strength. The Hudson-Farragut connection between New York City and PSE&G in New Jersey had been out of service since September 4, 1976. . . . Each of these outages significantly weakened the capacity of the system to withstand transmission emergencies. The availability of the Hudson-Farragut tie alone would have prevented the collapse of the transmission system on July 13.
The outage of the Hudson-Farragut transmission line was a factor mentioned by the state Court of Appeals in its decision affirming a lower court and jury finding that Con Edison had been grossly negligent in 1977.

In 2006, with import capability restricted, was Con Edison's system more vulnerable to disturbances flowing from an unscheduled outage of a local power plant?

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