SOPD Voltage Regulation 2

Question 1

A transmission line experiences a sudden load increase. What is the FIRST control action a system operator should take to restore voltage?

Accepted Answer

Dispatch reactive power from nearby generators or capacitor banks

Answer

Reactive power support from generators or switched capacitor banks is the primary and fastest method to restore depressed voltage from load increases.

Question 2

What does a negative voltage regulation value indicate about a transmission line?

Accepted Answer

Receiving-end voltage is higher than sending-end voltage

Answer

Negative voltage regulation occurs on lightly loaded or capacitive lines where the Ferranti effect raises receiving-end voltage above the sending-end value.

Question 3

Which reactive power device provides continuously variable voltage support without introducing harmonics?

Accepted Answer

Static VAR Compensator (SVC)

Answer

An SVC uses thyristor-controlled reactors and thyristor-switched capacitors to provide stepless, rapid reactive power control with minimal harmonic injection (filters included).

Question 4

Under which condition is the Ferranti effect most pronounced on a high-voltage transmission line?

Accepted Answer

Light load or open-circuit at the receiving end

Answer

The Ferranti effect is caused by line charging capacitance; with little or no load, there is no inductive current to offset the capacitive charging, so receiving-end voltage rises above sending-end voltage.

Question 5

A generator is operating at rated MW output. The operator increases excitation. What happens to the generator's reactive power output and terminal voltage?

Accepted Answer

Reactive power increases; terminal voltage tends to rise

Answer

Increasing field excitation raises internal EMF, which pushes more reactive power (MVAR) out of the generator and supports higher terminal voltage.

(SOPD) System Operator/Power Dispatching Practice Test

(SOPD) System Operator/Power Dispatching Practice Test

SOPD Voltage Regulation 2