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Customer Success Story


SVC for voltage control and improvement of stability

To improve the voltage control and stability on the Central Southern 115 kV tie line the Electricity Generating Authority of Thailand (EGAT) is operating a Static Var Compensator (SVC) at Chumphon Substation.

This SVC was supplied by Hitachi Energy and has been in operation since 1987. The dynamic operating range is from 60 Mvar capacitive to 20 Mvar inductive.

The SVC is an addition at the Chumphon Substation located along the 115 kV tie line approximately half way between Surat Thani and Prachuap Khiri Khan.

The main purpose of the compensator is to control the voltage in the 115 kV busbar at Chumphon.

Before the advent of the SVC, conventional switched capacitor banks and reactors were used on the 22 kV level for reactive power control but no means for dynamic voltage control existed on the 115 kV level.

Main data
System SVC
Commissioning year 1985
Controlled voltage 115 kV
SVC rating

20 Mvar (inductive) to 60 Mvar (capacitive) 

Control system

3-phase voltage control by means of a voltage regulator

Thyristor valve Water cooled with outdoor dry type air/water heat exchanger

Chumphon: SVC for voltage control and improvement of stability