PROBLEMS

The thermal constraints associated with the outlying 500/230kV transformers are the primary constraints facing the Greater Bay Area. A single or overlapping outage involving a Metcalf 500/230kV transformer is considered the most limiting contingency. For example, an overlapping contingency such as the loss of Metcalf 500/230kV transformer #11 and the Pittsburg Unit #7 generator could reduce the available transmission capacity by over 1000MW.

Voltage and reactive power support to the Bay Area are also essential to the reliability of the transmission lines in the Bay Area, especially during emergency contingency conditions. If voltage and reactive power support is not sufficient during an emergency outage, low voltage and cascading blackouts could happen.

POSSIBLE SOLUTIONS

Installing additional transformer banks, reconductoring existing transmission lines, or re-rating the conductors of the transmission lines can solve thermal constraints. Installing capacitor banks or Static Vars Compensators can solve voltage and reactive power support problem.