Bay Area T&D upgrade

In early December 2004, the Portrero substation received an early Christmas present. It was a shiny new static VAR compensator (SVC) from ABB (Raleigh, N.C.) that will improve the stability of the grid serving the San Francisco Bay Area.

The SVC, which was commissioned on December 10, will help stabilize the grid’s voltage during peak loading and network contingencies. Now there is less risk of a voltage collapse. The installation of the SVC at the Portrero substation also is important because it will enable the old synchronous condensers at the Hunters Point Power Plant in San Francisco to be shut down later this year.

In addition to installing the SVC at Portrero, ABB upgraded the series capacitor controls at the Vaca Dixon substation between San Francisco and Sacramento. The new automated system, which began operation on October 30, allows more precise control over the equipment, further improving the reliability and security of the Bay Area’s power grid. The SVC and upgrading of the series capacitor controls together represent $14 million in improvements.

Bob Fesmire, trade media relations manager at ABB, explained that the SVC consists of a number of building blocks. The most important are thyristor valves—stack assemblies of series-connected antiparallel thyristors designed to maximize controllability. Air-core reactors and high-voltage AC capacitors are the reactive power elements that work in concert with the thyristor valves. The equipment’s step-up connection to the transmission voltage is through an SVC power transformer. The thyristor valves and their auxiliary systems are located inside an SVC building, while the air-core reactors and capacitors and the power transformer are located outdoors.