Golden Valley Electric Association (GVEA), located in Fairbanks, Alaska, is operating a Static Var Compensator (SVC) in their 138 kV grid, supplied by Hitachi Energy in 2005 as a turnkey project. The SVC, located at Jarvis Creek in the Delta Junction region of Central Alaska, is rated at 8 Mvar (inductive) to 36 Mvar (capacitive) at 138 kV. In addition, it has a rated two-minute boosted capacitive output of 45 Mvar. The SVC was erected and commissioned on a turnkey basis in less than 12 months.
Also included in the Hitachi Energy undertaking were two 5 Mvar Mechanically Switched Capacitors (MSC) connected to the 138 kV system in the Jarvis Creek substation. The MSCs are used during annual maintenance, when the SVC is offline, or in the event of an unexpected trip of the SVC.
With the geographical conditions of the installation, large ambient temperature variations have to be accommodated. Thus, the equipment has been designed to operate over a temperature range of -52 to +35 degrees C.
Dynamic voltage control
The SVC is necessary for the operation of a recently electrically converted pump station in the Trans-Alaska Pipeline System, which transports oil from Prudhoe Bay to the south Alaskan coast. The purpose of the SVC is to yield dynamic control of the system voltage for various load conditions from steady state to load rejection situations in this remote part of the long radial, weak grid, and thereby to assure an uninterrupted flow of oil via the pipeline. The pump station comprises three pumps, each powered by a 6.6 kV, 5.4 MW VFD (Variable Frequency Drive). Also of importance is dynamic voltage support to a nearby ore processing plant.
|System fault level||84 MVA to 765 MVA|
|Ambient temperature range
||-52 to +35 degrees C|
|SVC rating||8 Mvar inductive to 36 Mvar
8 Mvar inductive to 45 Mvar
capacitive (2 minutes).
|Control system||Positive sequence voltage
control by means of a closed
|Thyristor valve||Water cooled, BCT type
thyristors, indirect light firing.
|MSC||138 kV, 2 x 5 Mvar|