Which of the following is the function of static var system in EHV transmission?

To provide reactive Var control in order to support the power supply system voltage and to filter the harmonic currents in accordance with Electricity Authority recommendations, which prescribe the permissible voltage fluctuations and harmonic distortions, reactive power (Var) compensators are required.

Static Var compensators: A static VAR compensator (SVC) is a set of electrical devices for providing fast-acting reactive power on high-voltage electricity transmission networks. It increases the active power transmission capacity of a line.

Advantages:

• It increases the power transmission capability of the transmission lines.
• It improves the transient stability of the system.
• It controls the steady-state and temporary overvoltage.
• It improves the load power factor, and therefore, reduced line losses, and improves system capability. 

The most commonly used SVC scheme are as follows:

• Thyristor controlled reactor (TCR)
• Thyristor-switched capacitor (TSC)
• Self Reactor (SR)
• Thyristor controlled reactor – Fixed capacitor (TCR-FC)
• Thyristor-switched capacitor – Thyristor controlled reactor (TSC-TCR)