This set of FACTS Multiple Choice Questions & Answers (MCQs) focuses on “Power Semiconductor Devices – Voltage Sourced Converter – Set 2”.
1. Voltage Sourced Converter is the building block of STATCOM.
a) True
b) False
View Answer
Explanation: Voltage Sourced Converter is the building block of STATCOM. Without the reverse voltage capability requirement the VSC will have lower forward conduction. This will lead to lower switching losses.
2. Voltage Sourced Converter is the building block of SSSC.
a) True
b) False
View Answer
Explanation: Voltage Sourced Converter is the building block of SSSC. Without the reverse voltage ability, Voltage Sourced Converter can be thinner. Also with no reverse voltage ability, VSCs have lower forward conduction.
3. Voltage Sourced Converter is the building block of UPFC.
a) True
b) False
View Answer
Explanation: Voltage Sourced Converter is the building block of UPFC. With no reverse voltage ability, Voltage Sourced Converters have lower switching losses. Also in the later case they exhibit higher forward withstand voltage.
4. Voltage Sourced Converter is the building block of IPFC.
a) True
b) False
View Answer
Explanation: Voltage Sourced Converter is the building block of IPFC. The harmonic content of VSC can be minimized with several technological methods. The controlling scheme defining a VSC is not at all complicated.
5. Voltage Sourced Converters with no reverse blocking capability do not exist.
a) True
b) False
View Answer
Explanation: Voltage Sourced Converters with no reverse blocking capability do exist. Voltage Sourced Converters with no reverse blocking capability are known as asymmetric turn-off devices. Often they are designated as just turn-off devices.
6. In the G-parameter modeling of a voltage amplifier, the input terminal has an infinite admittance.
a) True
b) False
View Answer
Explanation: In the G-parameter modeling of a voltage amplifier, the input terminal does not have an infinite admittance. The input port has actually a voltage input. The voltage input terminal exhibits a finite admittance.
7. The G-parameter model of two-port network of a voltage amplifier characterizes only voltage controlled voltage source.
a) True
b) False
View Answer
Explanation: The G-parameter model of two-port network of a voltage amplifier does not characterize only voltage controlled voltage source. Of course, the output port is voltage controlled voltage source. But the input port is current controlled current source.
8. In the G-parameter model of two-port representation of a voltage amplifier, the input and output ________ changing the power gain of the amplifier.
a) can be interchanged without
b) can be interchanged but with
c) cannot be interchanged
d) are always interchanged without
View Answer
Explanation: In the G-parameter model of two-port representation of a voltage amplifier, the input and output can be interchanged but with changing the power gain of the amplifier. The input to input port and output to output port exhibits more than unity power gain in the forward signal path. But the output to input port and input to output port exhibits less than unity power gain.
9. For FACTS application, VSC is preferred over CSC.
a) True
b) False
View Answer
Explanation: For FACTS application, VSC is preferred over CSC. With the appropriate vector control strategy VSC can perform independent control of active and reactive power at both ends. Thus it satisfies the basic requirement of FACTS controller.
10. The output voltage of VSC changes with load.
a) True
b) False
View Answer
Explanation: The output voltage of VSC does not change with load. The output voltage of VSC rather remains constant under any loading condition. This makes it suitable for FACTS application all the more.
11. The efficiency of voltage source converter is ________ that of current source converter
a) higher than
b) lower than
c) equal to
d) either higher or lower than
View Answer
Explanation: The efficiency of voltage source converter is higher than that of current source converter. This is because VSC does not incorporate any series reactor. This results in relatively less losses in the VCS.
12. In voltage source converter based transmission system the DC voltage polarity for power reversal________
a) changes
b) may or may not change
c) remains the same
d) cannot be ascertained
View Answer
Explanation: In voltage source converter based transmission system the DC voltage polarity for power reversal remains the same. Actually power transfer depends only on the direction of the DC current. So change of current polarity manifests the power reversal.
13. The VSC cannot work in all four quadrants.
a) True
b) False
View Answer
Explanation: The VSC can work in all four quadrants as it able to work both as a rectifier and an inverter. The converter able to convert dc into ac is known as an inverter. On the other hand the converter used to convert ac into dc is called a rectifier.
14. A VSC is unable to control the magnitude of the output voltage.
a) True
b) False
View Answer
Explanation: A VSC is able to control the magnitude of the output voltage. Also the VSC can be employed to control the phase angle of the output voltage. Additionally the frequency of the output voltage can also be controlled by the VSC.
15. A VCS is unidirectional.
a) True
b) False
View Answer
Explanation: A VSC is bidirectional. This is because the VCS allow the both way direction of current flow. It has the capability to transfer power in either direction.
Sanfoundry Global Education & Learning Series – Flexible AC Transmission System (FACTS).
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