JNTU
JNTU B.Tech III POWER SYSTEMS ANALYSIS Previous Question Paper (February - 2023 - R16)
Note: i) Question paper consists of Part A, Part B.
ii) Part A is compulsory, which carries 25 marks. In Part A, Answer all questions.
iii) In Part B, Answer any one question from each unit. Each question carries 10 marks and may have a, b as sub questions.
PART – A
Define the following terms: (i) Co-tree (ii) loop.
Answer
(i) A Co-tree is the set of branches of a graph that are not included in a chosen tree. If a graph has b branches and n nodes, the co-tree consists of b - (n - 1) links. (ii) A loop is a closed path formed by a link and the unique path in the tree connecting the two nodes of that link.
What is a cut set and what are basic cut sets?
Answer
A cut set is a minimal set of branches whose removal disconnects the graph into two separate parts. A basic cut set is a cut set that contains exactly one tree branch and a set of links, such that the removal of these branches partitions the network into two specific subgraphs.
What are P-V buses?
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What are the assumptions in NR method to speed up the rate of convergence?
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What are different types of buses used in load flow studies?
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Define sensitivity and its importance in designing J matrix.
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What do you mean by symmetrical fault?
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What are effects of unsymmetrical faults on the power system?
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Define transfer reactance and inertia constant.
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Give the assumptions made in steady state stability analysis.
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PART – B
What do you understand by branch path incidence matrix P? What are the elements of matrix P and is the nature of this matrix? What is the relationship between the branch path incidence matrix P and the submatrix Ab of the bus incidence matrix A?
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Derive the expressions for bus admittance and impedance matrices by singular transformation.
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Derive the expressions for the Zloop using singular transformation in terms of primitive impedance matrix Z and basic loop incidence matrix I.
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The transpose of a bus incidence matrix of a transmission network is given. Draw the oriented graph of the network.
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What steps must be taken if the reactive power limits of a PV bus is violated?
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Draw the flow chart for load flow solution by GS Method using YBUS. What are PV buses? How are they handled in the GS Method?
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Describe the Newton-Raphson method for the solution of power flow equations in power systems.
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Get the algorithm for DC load flow method and give its limitations?
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Explain the necessary equations for the load flow solution using the Decoupled load flow method. What is the Jacobian matrix and the steps to get it?
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Explain with a flow chart, the computational procedure for load flow solution using fast decoupled method, deriving the necessary equations.
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Draw the positive, negative and zero sequence impedance diagrams for different 3-phase transformer winding connections.
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Derive the expressions for the fault current and the terminal voltages of a 3-phase alternators, when there is a double line to ground fault occurs at the terminals of Alternator. Assume generator neutral is solidly earthed.
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Write short note on series reactors used in power system.
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Derive an expression for fault current in case of line to line fault occurs in a 3-phase system.
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How do you determine the transient stability to single machine infinite system using equal area criterion?
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Derive the inertia constant for a multi machine system.
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What is swing equation? Derive its expression from fundamentals.
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Discuss any two methods to improve steady state stability.
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