New England grid operator looking at summer voltage reduction issues

By the OGJ Online Staff

HOUSTON, Oct. 30, 2001 – The New England grid operator said it will investigate why voltage reductions fell short of requirements during this summer’s record-breaking heat wave.

The ISO New England Inc. said it experienced problems when it called for a 5% transmission voltage reduction Aug. 9. An analysis of the 5%, 10-min. voltage reduction implemented Aug. 9 showed a reduction of only 0.6% or about 135 Mw.

ISO New England said the response fell short of NEPOOL standards requiring voltage reduction equipment to achieve at least a 1.5% reduction in load in 10 min. The grid operator said it relies on voltage reductions among other measures during capacity deficiencies to keep the system operating.

Tests performed in the spring resulted in a 1.9% load reduction. The grid operator said it will follow up with market participants and others to determine the causes of poor performance in this area. Initial conclusions of a staff study found several areas that “warrant” review for possible improvement, relating to thermal constraints and voltage performance, the ISO said.

It also said transmission constraints hampered transfer of hundreds of megawatts of electricity from Maine to other parts of New England. The bulk transmission system was “stretched” to its limits during peak periods in summer 2001, ISO New England said. New England set peak load records on five separate occasions during the summer.

The grid operator reported without the 2,870 Mw of new generation added since May it would have been impossible to serve all customers. But during the Aug. 9 peak load of 25,158 Mw, the grid operator reported 300-400 Mw was “locked in” and unavailable in Maine and the eastern Canadian provinces, while an additional 100-150 Mw was out of operation. Transmission bottlenecks also occurred in other parts of the system.

The Aug. 9 load eclipsed the 1999 peak of 22,544 Mw by 2,500 Mw and exceeded the forecasted summer peak load by nearly 2,000 Mw or 10%. ISO New England said the peak occurred despite load relief resulting from public appeals and other load reducing actions.

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