Chapter 6, Problem 6.45P

A 200 bus power system has 160 PQ bus. For achieving a load flow solution by N-R in polar coordinates, the minimum number of simultaneous equation to be solved is

A synchronous generator is connected to an infinite bus by a transmission line as shown in the figure. The field current IF = 900A when the unloaded generator is synchronized to the infinite bus. a.) P_M is increased to 0.5pu while I_F is held constant at 900A. Find the complex power S_Inf supplied to the infinite bus in per unit. b.) Determine S_Inf in per unit if IF increases to 1600A and PM is held fixed at 0.5pu.

1. FIGURE 52 shows the one-line diagram of a simple three-bus power system with generation at bus I. The voltage at bus l is V1 = 1.0L0° per unit. The scheduled loads on buses 2 and 3 are marked on the diagram. Line impedances are marked in per unit on a 100 MVA base. For the purpose of hand calculations, line resistances and line charging susceptances are neglected a) Using Gauss-Seidel method and initial estimates of Va 0)-1.0+)0 and V o)- ( 1.0 +j0, determine V2 and V3. Perform two iterations (b) If after several iterations the bus voltages converge to V20.90-j0.10 pu 0.95-70.05 pu determine the line flows and line losses and the slack bus real and reactive power. 2 400 MW 320 Mvar Slack 0.0125 0.05 300 MW 270 Mvar FIGURE 52

The torque angle of synchronous machine operating from a constant voltage bus, is usually defined as the space angle between rotor mmf wave and resultant flux-density wave True False

(a) In the analysis and calculations of power systems, it is usual to use the Per- unit quantities instead of actual values. Give the advantages of using such a system. (b) What are the advantages for operating synchronous generators in parallel? (c) What are the conditions required for paralleling between the generators?

Explain the concept of load flow analysis in power systems. What are the main objectives and challenges associated with load flow analysis?

Discuss why power system load flow analysis is undertaken and why iterative methods are used.

Solve numerical : Following figure shows the one-line diagram of a two bus system. Take bus 1 as slack bus, bus 2 as load (PQ) bus. Neglect the shunt charging admittance. Obtain the bus admittance matrixYBUS and find V2 and δ2, power flows and line losses by using Fast decoupled power flow method.  All the values are given in per unit on 100MVA base. Use a tolerance of 0.001 for power mismatch.

Following figure shows the one-line diagram of a two bus system. Take bus 1 as slack bus, bus 2 as load (PQ) bus. Neglect the shunt charging admittance. Obtain the bus admittance matrixYBUs and find V₂ and 62, power flows and line losses using FDLF method. All the values are given in per unit on 100MVA base. Use a tolerance of 0.001 for power mismatch. 1 Z12= 0.12+10.16 Slack bus V₁ 1.0/0⁰ pu 2 PL2=1.0pu Q12=0.5pu