SOPD Voltage Control & System Reliability

Question 1

Which device injects or absorbs reactive power dynamically to support transmission‑level voltage?

Accepted Answer

Static VAR Compensator (SVC)

Answer

A Static VAR Compensator (SVC) is a flexible AC transmission system (FACTS) device that uses power electronics to rapidly inject or absorb reactive power into the transmission system. This dynamic reactive power compensation helps to maintain stable voltage levels, improve power transfer capability, and enhance system stability.

Question 2

Voltage stability margin refers to:

Accepted Answer

Distance to voltage collapse

Answer

Voltage stability margin quantifies how close a power system is to a state of voltage collapse, where the system can no longer maintain acceptable voltage levels. It represents the maximum additional load that can be served before the system experiences an uncontrollable and rapid decline in voltage, leading to a blackout.

Question 3

An on‑load tap‑changing transformer regulates voltage by:

Accepted Answer

Adjusting tap position to alter turns ratio

Answer

An on-load tap-changing (OLTC) transformer is equipped with a mechanism that allows its turns ratio to be adjusted while it is energized and carrying load. By changing the tap position, the transformer effectively alters the voltage transformation ratio, thereby regulating the voltage on the secondary side to maintain desired levels.

Question 4

Power factor correction improves reliability primarily by:

Accepted Answer

Reducing line current and voltage drop

Answer

A low power factor means that a larger apparent power (kVA) is required to deliver the same amount of real power (kW). Improving the power factor reduces the reactive power flowing through the lines, which in turn decreases the total current. This reduction in current minimizes I²R losses and voltage drops, enhancing the overall efficiency and reliability of the transmission and distribution system.

Question 5

Which fast‑acting device offers multilevel voltage support similar to an SVC but with IGBT technology?

Accepted Answer

STATCOM

Answer

A STATCOM (Static Synchronous Compensator) is a modern FACTS device that uses voltage-source converters (typically IGBT-based) to dynamically inject or absorb reactive power. Similar to an SVC, it provides fast and precise voltage support, but with superior dynamic performance and a wider operating range due to its active power electronics.

(SOPD) System Operator/Power Dispatching Practice Test

(SOPD) System Operator/Power Dispatching Practice Test

SOPD Voltage Control & System Reliability