76. A power system network consists of three elements 0 - 1, 1 - 2 and 2 - 0 of per unit impedance 0.2, 0.4 respectively. Its bus impedance matrix is given by

1. 1. 		1		2
      1		7.5		-2.5
      2		-2.5		5.0

   
   
   

   2. 		1		2
      1		0.16		0.08
      2		0.08		0.24

   
   
   

   3. 		1		2
      1		0.16		-0.08
      2		-0.08		0.24

   
   
   

   4. 		1		2
      1		0.6		0.4
      2		0.4		0.8

   
   
   

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1. View Hint View Answer Discuss in Forum

   The Bus impedance matrix Z_BUS can be formed by using circuit theory knowledge
   

   Correct Option: B

   The Bus impedance matrix Z_BUS can be formed by using circuit theory knowledge
   

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77. Buses for load flow studies are classified as (i) the load bus (ii) the generator bus (iii) the slace bus The correct combination of the pair of quantities specified having their usual meaning for different buses is
    Load Bus Generator Slace bus

1. 1. P, |V| P, Q P, δ

   
   
   

   2. P, Q P, |V| |V| ,δ

   
   
   

   3. |V|, Q P, δ P, Q

   
   
   

   4. P, δ Q, |V Q, δ

   
   
   

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1. View Hint View Answer Discuss in Forum

   Load bus = P, Q
   Generator bus = P, |V|
   Slack bus = |V|, δ

   Correct Option: B

   Load bus = P, Q
   Generator bus = P, |V|
   Slack bus = |V|, δ

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78. The bus admittance matrix of the network shown in the given figure, for which the marked parameters are per unit impedance, is
    

1. 1. 	0.3		-0.2		-1
      	-0.2		0.2

   
   
   

   2. 	0.3		0.2
      	0.2		0.2

   
   
   

   3. 	0.3		-0.2
      	-0.2		0.2

   
   
   

   4. 	15		-5
      	-5		5

   
   
   

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1. View Hint View Answer Discuss in Forum

   y_jj = sum of all the admittance connected to node j
   y_jk = negative of the admittance between nodes, j and k.
   Figures are the admittance value
   ∴ y₁₁ = 10 + 5 = 15; y₂₂ = 5,
   y₁₂ = y₂₁ = – 5;
   

   ∴ yBMS =		15		-5
   		-5		5

   Correct Option: D

   y_jj = sum of all the admittance connected to node j
   y_jk = negative of the admittance between nodes, j and k.
   Figures are the admittance value
   ∴ y₁₁ = 10 + 5 = 15; y₂₂ = 5,
   y₁₂ = y₂₁ = – 5;
   

   ∴ yBMS =		15		-5
   		-5		5

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79. For a load flow solution, the quantities normally specified at a voltage controlled bus are

1. 1. P and Q

   
   
   

   2. P and |V|

   
   
   

   3. Q and |V|

   
   
   

   4. P and δ

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: D

   NA

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80. If the reference bus is changed in two load flow runs with same system data and power obtained for reference bur taken as specified P and Q in the latter run

1. 1. the system losses will be unchanged but complex bus voltage will change

   
   
   

   2. the system losses will be changed but complex bus voltages remain unchanged

   
   
   

   3. the system losses as well be as complex bus voltage will change

   
   
   

   4. the system losses as well be as complex bus voltage will unchanged

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: A

   NA

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