This set of FACTS Multiple Choice Questions & Answers (MCQs) focuses on “Thyristor-Controlled Voltage and Phase Angle Regulators”.
1. The GTO-based voltage source utilizes transformer for injecting generated voltage.
a) True
b) False
View Answer
Explanation: The GTO-based voltage source utilizes transformer for injecting generated voltage. The GTO-based voltage source produces the requisite voltage for compensation. This generated voltage is injected to the line with the help of an insertion transformer, in series with the line.
2. TCVR and TCPAR are not thyristor controlled.
a) True
b) False
View Answer
Explanation: TCVR and TCPAR are obviously thyristor controlled. They exhibit static voltage and phase angle regulations. They are, therefore employed in FACTS.
3. Thyristor-controlled Regulators can be manifested using the concept of ‘tap-changing’.
a) True
b) False
View Answer
Explanation: Thyristor-controlled Regulators can be manifested using the concept of ‘tap-changing’. They can also be manifested using the concepts of ‘voltage injection’. Accordingly they play important roles in FACTS.
4. An on-load tap changer can save the lower voltage system from being affected with the large voltage variations of the high-voltage system.
a) True
b) False
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Explanation: An on-load tap changer can save the lower voltage system from being affected with the large voltage variations of the high-voltage system. It does so as it isolates the lower voltage system from the high voltage system by dint of its characteristic feature. Voltage regulators do employ on-load tap changers for voltage regulation.
5. Voltage regulators do employ on-load tap changers for ________ in the system.
a) only voltage regulation
b) neither voltage regulation nor control of reactive power flow
c) only control of reactive power flow
d) both voltage regulation and control of reactive power flow
View Answer
Explanation: Voltage regulators do employ on-load tap changers for both voltage regulation and control of reactive power flow in the system. Reactive power compensation is thus achieved to maintain the desired user-end voltage in the presence of changing transmission voltage and seasonal or daily load-changes. On-load tap changers carry out the transmission control function efficiently.
6. The tap changer based voltage regulator can implement reactive compensation by ________
a) either supplying or absorbing reactive power
b) neither supplying nor absorbing reactive power
c) only supplying reactive power
d) only absorbing reactive power
View Answer
Explanation: The tap changer based voltage regulator can implement reactive compensation by neither supplying nor absorbing reactive power. This is because the tap changer employed in such voltage regulator is unable to supply or absorb reactive power. It can only manage the transmission voltage on one side and transfers it to the power system which provides the necessary reactive power to maintain that voltage.
7. Reactive compensator and the tap changer based voltage regulator control the transmission line voltage directly.
a) True
b) False
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Explanation: Reactive compensator does not control the transmission line voltage directly. On the other hand the tap changer based voltage regulator does manage the transmission voltage directly on its one side and transfers it to its other side to the power system. Thus operation based difference exists between the reactive compensator and the tap changer based voltage regulator.
8. Reactive compensators can implement reactive compensation by________
a) either supplying or absorbing reactive power
b) neither supplying nor absorbing reactive power
c) only supplying reactive power
d) only absorbing reactive power
View Answer
Explanation: Reactive compensators can implement reactive compensation by either supplying or absorbing reactive power. This absorption or supply of reactive power to the connected power system, thus controls the reactive power flow in the system. Thus it indirectly controls the transmission line voltage of a system.
9. In case the power system fails to provide the reactive power demand, it can lead to overall voltage collapse in the system.
a) True
b) False
View Answer
Explanation: In case the power system fails to provide the reactive power demand, it can lead to overall voltage collapse in the system. In an overloaded transmission system, the transmission line is required to supply increasing load current at decreasing load power factor. This in turn reduces the transmission voltage further and also increases the current. Consequently the voltage collapses and the protection relays come into play to remove the load.
10. On-load tap changers employed in the power system may contribute to voltage collapse.
a) True
b) False
View Answer
Explanation: On-load tap changers employed in the power system may contribute to voltage collapse. This condition occurs during under certain conditions. It may happen when the tap changers goes on increasing the transformation ratio in order to lessen the voltage drop for an overloaded transmission system.
Sanfoundry Global Education & Learning Series – Flexible AC Transmission System (FACTS).
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