In a 100 bus power system, there are 10 generators. In a particular iteration of Newton Raphson load flow technique (in polar coordinates), two of the PV buses are converted to PQ type. In this iteration,

the number of unknown voltage angles increases by two and the number of unknown voltage magnitudes decreases by two.

the number of unknown voltage angles increases by two and the number of unknown voltage magnitudes increases by two.

the number of unknown voltage angles remains unchanged and the number of unknown voltage magnitudes increases by two.

the number of unknown voltage angles increases by two and the number of unknown voltage magnitudes decreases by two.

the number of unknown voltage angles remains unchanged and the number of unknown voltage magnitudes decreases by two.

Out of the following options, the most relevant information needed to specify the real power (P) at the PV buses in a load flow analysis is

rated power output of the generator

solution of economic load dispatch

rated power output of the generator

Both (A) and (R) are true and (R) is the correct reason for (A)

Both (A) and (R) are true but (R) is not the correct reason for (A)

1.	A 3-bus power system is shown in the figure below, where the diagonal elements of Y-bus matrix are: Y11 = -j12 pu, Y22 = -j15 pu and Y33 = -j7 pu.The per unit values of the line reactances p, q and r shown in the figure are
A.	p = -0.2, q = -0.1, r = -0.5
B.	p = 0.2, q = 0.1, r = 0.5
C.	p = -5, q = -10, r = -2
D.	p = 5, q = 10, r = 2
Answer» C. p = -5, q = -10, r = -2

2.	A 3 – bus power system network consists of 3 transmission lines. The bus admittance matrix of the uncompensated system is\(\left[ {\begin{array}{*{20}{c}}{ - j6}&{j3}&{j4}\\{j3}&{ - j7}&{j5}\\{j4}&{j5}&{ - j8}\end{array}} \right]Pu\)If the shunt capacitance of all transmission lines is 50% compensated, the imaginary part of the 3rd row 3rd column element (in pu) of the bus admittance matrix after compensation is
A.	-j7.0
B.	-j8.5
C.	-j7.5
D.	-j9.0
Answer» C. -j7.5

3.	In a 100 bus power system, there are 10 generators. In a particular iteration of Newton Raphson load flow technique (in polar coordinates), two of the PV buses are converted to PQ type. In this iteration,
A.	the number of unknown voltage angles increases by two and the number of unknown voltage magnitudes increases by two.
B.	the number of unknown voltage angles remains unchanged and the number of unknown voltage magnitudes increases by two.
C.	the number of unknown voltage angles increases by two and the number of unknown voltage magnitudes decreases by two.
D.	the number of unknown voltage angles remains unchanged and the number of unknown voltage magnitudes decreases by two.
Answer» C. the number of unknown voltage angles increases by two and the number of unknown voltage magnitudes decreases by two.

4.	A power system has 100 buses including 10 generator buses. For the load flow analysis using Newton-Raphson method in polar coordinates, the size of the Jacobian is
A.	\(189 \times 189\)
B.	\(100 \times 100\)
C.	\(90 \times 90\)
D.	\(180 \times 180\)
Answer» B. \(100 \times 100\)

5.	Out of the following options, the most relevant information needed to specify the real power (P) at the PV buses in a load flow analysis is
A.	solution of economic load dispatch
B.	rated power output of the generator
C.	rated voltage of the generator
D.	base power of the generator
Answer» B. rated power output of the generator

6.	Consider a power system consisting of N number of buses. Buses in this power system are categorized into slack bus, PV buses and PQ buses for load flow study. The number of PQ buses is NL. The balanced Newton-Raphson method is used to carry out load flow study in polar form. H, S, M, and R are sub-matrices of the Jacobian matrix J as shown below:\(\left[ {\begin{array}{{20}{c}} {\Delta P}\\ {\Delta Q} \end{array}} \right] = J\left[ {\begin{array}{{20}{c}} {\Delta \delta }\\ {\Delta V} \end{array}} \right]\) where \(J = \left[ {\begin{array}{*{20}{c}} H&S\\ M&R \end{array}} \right]\)The dimension of the sub-matrix M is
A.	(N - 1) × (N - 1 NL)
B.	NL × (N - 1 + NL)
C.	(N - 1) × (N - 1 + NL)
D.	NL × (N - 1)
Answer» E.

7.	Determine the correctness or otherwise of the following Assertion (A) and the Reason (R).Assertion (A) : Fast decoupled load flow method gives approximate load flow solution because it uses several assumptions.Reason (R) : Accuracy depends on the power mismatch vector tolerance
A.	Both (A) and (R) are true and (R) is the correct reason for (A)
B.	Both (A) and (R) are true but (R) is not the correct reason for (A)
C.	Both (A) and (R) are false
D.	(A) is false and (R) is true
Answer» E.