In an effort to solve voltage-disturbance problems in southwestern Connecticut, Northeast Utilities Service Co. (NU; Berlin, Connecticut) awarded ALSTOM a US$15 million contract to implement its STATCOM technology at NU's 115-kV Glenbrook Substation in Connecticut.

STATCOM, or static synchronous compensator, is one of a new family of Flexible AC Transmission System (FACTS) devices designed to be inserted into transmission grids to improve the delivery of power in weak areas of the grid. NU is taking this step to bolster its network in southwestern Connecticut, where faults on transmission lines caused by stressed equipment and high customer demand can sometimes occur. ALSTOM's STATCOM technology will help the network to recover quickly from such faults.

As the sole provider of major equipment on this project, ALSTOM, through its Transmission and Distribution Sector, will supply two 115-kV/14.6-kV high-voltage transformers from its manufacturing facility in the United Kingdom, 115-kV and 15-kV switchgear and two STATCOM units to NU. The equipment will be in service by the end of December 2003.

The STATCOM device prevents sudden voltage drops from affecting the network by temporarily injecting reactive power into the system and thereby maintaining the required voltage. At Glenbrook Substation, two STATCOMs of ±75 MVAR will be connected in parallel to provide ±150 MVAR to cope with anticipated surges or drops in voltage.

STATCOM requires a land area far less than that of the previous generation of static var compensation equipment, and works more quickly and efficiently without producing significant harmonic interference, thanks to the use of the latest power electronic switching devices. The technology is particularly suited to the North American environment, where long transmission lines and difficult weather conditions can cause significant voltage disturbances.
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