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Customer Success Story


SVC to secure voltage control and network stability during severe disturbances

Since 1987 a Static Var Compensator, SVC, has been in operation at the Swedish National Grid‘s substation at Hamra west of Stockholm. The Mvar rating of the SVC ranges from 200 Mvar inductive to 200 Mvar capacitive. The SVC was supplied by Hitachi Energy on a turn-key basis.

Hamra is a major 400/220 kV substation supplying power to the Stockholm area and the SVC was installed to replace two synchronous condensers and two shunt reactors that were previously used for the voltage control at Hamra.

The SVC consists of two 100 Mvar blocks of thyristor switched capacitors (TSC) and two 100 Mvar blocks of thyristor switched reactors (TSR). One of the two reactor blocks can be controlled in two 50 Mvar steps. In this manner the total operating range of 400 Mvar can be controlled in steps of 50 Mvar.

The SVC is connected to the power grid through the 12 kV tertiary of a 750 MVA, 400/220 kV transformer. It is used for voltage control, which is accomplished mainly by absorbing reactive power from the 400 kV system and generating reactive power to the 220 kV system.

Main data  
System   SVC
Commissioning year   1987
 Controlled voltage   220 kV and 400 kV
SVC rating   200 Mvar inductive to 200 Mvar capacitive
 Control system   Three-phase voltage control by means of a voltage regulator
 Thyristor valves   Water/glycol cooled three-phase valves with magnetic firing