A static VAR compensator is a

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Voltage controlled shunt compensation device

Explanation: A Static VAR Compensator (SVC) is a power electronic device used to provide rapid reactive power compensation on high-voltage electricity transmission networks. It is connected in shunt with the transmission line to regulate the voltage at the point of connection by injecting or absorbing reactive power.

Working Principle: The SVC operates by controlling the amount of reactive power injected into or absorbed from the power system. It typically consists of a Thyristor-Controlled Reactor (TCR) and a Thyristor-Switched Capacitor (TSC). By adjusting the firing angle of the thyristors, the device modulates the effective reactive impedance, thereby maintaining the bus voltage at a desired set-point.

Key Formulas: $Q_{SVC} = \frac{V^2}{X_{SVC}}$ — Relationship between Reactive Power, Voltage, and SVC reactance; $X_{SVC}(\alpha) = X_L \frac{\pi}{\pi - 2\alpha - \sin(2\alpha)}$ — Effective reactance of TCR as a function of firing angle $\alpha$

Key Points: SVC is a member of the FACTS (Flexible AC Transmission Systems) family.; It provides voltage control through reactive power compensation without mechanical switching.; It responds very fast to system disturbances compared to mechanical compensators like synchronous condensers.; The shunt connection allows it to influence the node voltage directly.

Advantages: Fast voltage regulation; Improved transient stability; Reduced flicker and improved power quality; No moving parts, leading to low maintenance

Disadvantages: Generates harmonics (requires filtering); Limited overload capacity compared to synchronous machines; High initial cost of power electronics

Applications: Voltage support in weak transmission systems; Arc furnace power quality improvement; Reactive power compensation in industrial plants

Additional Info: SVCs are classified as shunt devices because they are connected in parallel with the transmission line to regulate voltage.. Option B, C, and D are incorrect because series compensation is typically achieved using TCSC or SSSC, and SVC is specifically a voltage-controlled shunt device.

Answer: A is correct — A Static VAR Compensator (SVC) acts as a shunt-connected device that controls voltage by injecting or absorbing reactive power.

Exam Tip: Always remember: SVCs are shunt-connected to regulate V, while series compensation (like TCSC) is used to control line impedance and power flow.

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