POWER SYSTEM MCQS SET 13

POWER SYSTEM MCQS SET 13

1․ Specified quantities of load bus are
a. P and Q      b. V and δ            c. P and δ              d. Q and V
Explain:
Load bus is also known as PQ bus. Load bus is related to consumer requirements in which P and Q are known or specified quantities, for supplying these quantities δ and V are to be calculated. Load bus: Known quantities - P and Q Unknown quantities - V and δ Generator bus: Known quantities - P and V Unknown quantities - Q and δ Slack or reference bus: Known quantities - V and δ Unknown quantities - P and Q Where P = Active power, Q = Reactive power, V = voltage and δ = load angle.

2․ Specified quantities of slack bus are
a. P and Q       b. V and δ            c. P and δ     d. P and V
Explain:
Every power system network containing one slack bus. This slack bus is used to supply active and reactive power requirements of the transmission line, for this purpose one of the generator bus which is most efficient is used as slack bus. Slack or reference bus: Known quantities - V and δ Unknown quantities - P and Q Where P = Active power, Q = Reactive power, V = voltage and δ = load angle.

3․ Which of the following quantities are to be calculated for generator bus?
a. P and V            b. P and Q     c. Q and δ               d. δ and V
Explain:
In generator bus P and V are known quantities and range of Q is also specified for safe operation of equipments and Q and δ are top be calculated. Load bus: Known quantities - P and Q Unknown quantities - V and δ Generator bus: Known quantities - P and V Unknown quantities - Q and δ Slack or reference bus: Known quantities - V and δ Unknown quantities - P and Q

4․ In a 4*4 Y bus matrix the number of non zero elements are 12. Find the sparsity of the system?
a. 0.25        b.  0.5         c.   0.75       d.  1
ANSWER: a

5․ In a 4 bus,4×4 Y bus matrix the number of non zero elements are 12. Find the number of transmission lines?
a. 8         b. 4            c. 2               d. 5
ANSWER: b
 

6․ Range of accelerating factor is
a. 50 to 100     b. 1 to 10        c. 1.6 to 1.8           d. 10.8 to 11.2
Explain:
Accelerating factor is used for reducing number of iterations using gauss-siedel method. The range of accelerating factor is 1.6 to 1.8.

7․ A network containing 100 buses in which 10 are the voltage control buses, 5 are fixed shunt capacitor buses, 20 are the reactive power support buses, 6 are the generator buses. Find the size of the Jacobian matrix?
a. 163 × 163           b. 164 × 164           c. 165 × 165           d. 162 × 162
Explain:
Size of the Jacobian matrix = (2n-m-2)×(2n-m-2) Where, n = Total number of buses m = Total number of PV buses m = Voltage control buses + Reactive power support buses + generator buses except slack bus Fixed shunt capacitors are supplying constant amount of reactive power, so that fixed shunt capacitors are considered as load buses or PQ buses. Therefore, n = 100 and m =35 Size of the Jacobian matrix = (2×100 - 35 -2)×(2×100 - 35 - 2) = 163×163

8․ Which of the following buses is/are not PV buses?
a. voltage control buses             b. fixed shunt capacitor buses
c. reactive power support buses           d. both 1 and 2
Explain:
Size of the Jacobian matrix = (2n-m-2)×(2n-m-2) Where, n = Total number of buses m = Total number of PV buses m = Voltage control buses + Reactive power support buses + generator buses except slack bus Fixed shunt capacitors are supplying constant amount of reactive power, so that fixed shunt capacitors are considered as load buses or PQ buses.

9․ Which of the following is/are advantages of N-R method?
a. Number of iterations are less
b. Applicable for large power system network
c. Time taken for each iteration is less
d. both 1 and 2
Explain:
Advantages of N-R method: 1. Number of iterations are less, so that it has fast convergence.
2. Convergence is not effected by the choice of slack bus.
3. No need of accelerating factor.
4. Applicable for large power system network.
Disadvantages of N-R method: 1. Time taken for each iteration is larger if size of the Jacobian matrix is larger.
2. Computer memory required is larger.
3. Computer programming is difficult.

10․ Advantages of gauss siedel method is/are
a. calculation time for each iteration is less
b. number of iterations are less
c. applicable for large power system network
d. all of the above
Explain:
Advantages of gauss siedel method: 1. It is a simple algebraical equation, so that calculation time for each iteration is less.
1. More suitable for small size networks.
Disadvantages of gauss siedel method: 1. More number of iterations are required, so that it has slow convergence.
2. Initial approximate guessing value is required for convergence.
3. It required accelerating factor for convergence.
4. The choice of slack bus affects the convergence.
5. It is not applicable for the large power system networks.