# FACTS Questions and Answers – Compensation Techniques – Set 3

This set of FACTS Multiple Choice Questions & Answers (MCQs) focuses on “Compensation Techniques – Set 3”.

1. Change in real power demand always causes voltage variation along the transmission line.
a) True
b) False

Explanation: Change in real power demand does not cause voltage variation along the transmission line. It is the change in real power demand which is the root cause of voltage variation along the transmission line. Hence, compensation aims at controlling the change in reactive line power in spite of changing real power demand across the transmission system.

2. Transmission line impedances are predominantly ________ in nature.
a) reactive
b) active
c) both active and reactive
d) neither reactive nor active

Explanation: Transmission line impedances are predominantly reactive in nature. On introducing an in-phase voltage component into the transmission system, a reactive current flows. This reactive current is substantially quadrature in nature.

3. Reactive power compensation must be done with appropriate polarity and magnitude control.
a) True
b) False

Explanation: Reactive power compensation must be done with appropriate polarity and magnitude control. The proper choice of polarity and control of magnitude of the reactive current flow due to associated compensation technique is the key to improve prevailing reactive power flow in the system. These are important parameters for designing a FACTS Controller.

4. The loads on transmission lines are predominantly motors.
a) True
b) False

Explanation: The loads on transmission lines are predominantly motors. An overloaded transmission system can lead to voltage collapse when the reactive demand is not properly compensated or supplied. These loads predominantly draw reactive current from the system decreasing the power factor and ultimately leading to voltage collapse.

5. ________ can be highly effective in controlling power flow in the transmission line.
a) Both shunt and series reactive compensation
b) Only series reactive compensation
c) Only shunt reactive compensation
d) Neither shunt nor series reactive compensation

Explanation: Both shunt reactive compensation and series reactive compensation can be highly effective in controlling power flow in the transmission line. Series reactive compensation can improve the dynamic behavior of the power system as well. Shunt reactive compensation can give voltage regulation as well.

6. Compensation aims at reactive power control.
a) True
b) False

Explanation: Compensation aims at reactive power control. FACTS controllers choose compensation techniques as per system requirement. Thus FACTS encompass a variety of devices each with its characteristic compensation principle.

7. Compensation aims at voltage control.
a) True
b) False

Explanation: Compensation aims at voltage control. FACTS controllers with proper compensation can support proper load balancing of transmission lines independently. However some FACTS controllers lack in supporting load balancing of transmission lines independently.

8. Compensation aims at damping oscillations.
a) True
b) False

Explanation: Compensation aims at damping oscillations. The ratio of reactive to resistive line impedance plays an important role in functioning of a FACTS controller exhibiting compensation. Some compensation techniques use on-load tap changers in their circuits.

9. Compensation aims at ________
a) both transient and dynamic stability
b) only dynamic stability
c) only transient stability
d) neither transient nor dynamic stability

Explanation: Compensation aims at both transient and dynamic stability. Series reactive compensation can effectively improve the dynamic behavior of the power system. Hence it ensures dynamic stability of the system connected.

10. On-load tap changers employed in the power system never leads to voltage collapse.
a) True
b) False

Explanation: On-load tap changers employed in the power system may lead to voltage collapse. This depends on the prevailing condition under certain circumstances. It may happen during an overloaded transmission system when the tap changers try to lessen the voltage drop and, thereby, increases its transformation ratio. This ultimately reduces the transmission voltage and in turn increases the current leading to voltage collapse.

11. The reactive power demand in the power system may lead to overall voltage collapse in the system.
a) True
b) False

Explanation: The reactive power demand in the power system may lead to overall voltage collapse in the system. It happens when the reactive power demand is not met with. It is common to be encountered in an overloaded transmission system, where the reduction in the transmission voltage and consequent increase in the current beyond the permissible limit lead to the voltage collapse.

12. Series reactive compensation can solve the problems related to transmission angle of the power system.
a) True
b) False

Explanation: Series reactive compensation cannot be helpful to sort out the problems related to transmission angle of the power system. It is generally highly effective for power flow control. With seasonal or daily change in loads in the system, the transmission angle may vary over a range too large to be possible for the power flow in some affected lines to be maintained within acceptable limits.

13. On-load tap changer with quadrature voltage injection is a possible configuration of compensation technique.
a) True
b) False

Explanation: On-load tap changer with quadrature voltage injection is a possible configuration of compensation technique. It solves active-power flow control problems. Thereby, it increases the utilization of transmission lines.

14. Transmitted reactive power through transmission power system is a function of the transmission line impedance.
a) True
b) False

Explanation: Transmitted reactive power through transmission power system is a function of the transmission line impedance. It also depends on the magnitudes of both sending-end and receiving- end voltages. Also the phase angle between these sending-end voltage and receiving-end voltage govern the transmitted reactive power through transmission power system.

15. With seasonal or daily change in loads in the system, the transmission angle never varies.
a) True
b) False

Explanation: With seasonal or daily change in loads in the system, the transmission angle varies. This is because with the change in loads, the reactive power-demand changes. Even it may happen that with seasonal or daily change in loads in the system, the transmission angle may vary over a range too large to be possible for the power flow in some affected lines to be maintained within acceptable limits.

Sanfoundry Global Education & Learning Series – Flexible AC Transmission System (FACTS).

To practice all areas of Flexible AC Transmission System (FACTS), here is complete set of 1000+ Multiple Choice Questions and Answers.

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