Question

What is the primary purpose of a FACTS device like a STATCOM?

• A. To break circuit arcs.
• B. To provide fast-acting reactive power compensation.
• C. To measure harmonic distortion.
• D. To convert AC to DC

Hint:

Think of STATCOM as a static, solid-state equivalent of a synchronous condenser.
Unlike traditional mechanical synchronous condensers, STATCOM has no rotating parts, responds much faster, and occupies a smaller physical footprint.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
The question asks for the primary operational purpose of a Static Synchronous Compensator (STATCOM), which is a Flexible AC Transmission Systems (FACTS) device.

Step 2: Detailed Explanation:

• STATCOM is a shunt-connected FACTS device based on a power electronics Voltage Source Converter (VSC).

• It acts as an alternating current voltage source behind a coupling reactance, synthesized from a DC capacitor link.

• By dynamically adjusting the magnitude of the VSC output voltage relative to the AC system bus voltage, STATCOM can instantly control the flow of reactive power:
- If the converter voltage is greater than the bus voltage, the STATCOM supplies lagging reactive power (acts as a capacitor).
- If the converter voltage is less than the bus voltage, the STATCOM absorbs lagging reactive power (acts as an inductor).

• Since this control is performed using solid-state power electronic switches (such as IGBTs or GTOs), the response is fast-acting (typically within milliseconds).

• This rapid compensation helps regulate transmission bus voltage, improves transient stability, dampens power oscillations, and increases the power transfer capability of the grid.

Step 3: Final Answer:
The primary purpose of a STATCOM is to provide fast-acting reactive power compensation.