Power System Analysis


Three programs lfgauss, lfnewton, and decouple are developed for the solution of power flow problems by Gauss-Seidel, Newton-Raphson, and the fast decoupled power flow, respectively.
Optimal Dispatch of Generation
In an interconnected power system, the objective is to find the real and reactive power scheduling of each power plant in such a way as to minimize the operating cost. This means that the generator’s real and reactive power is allowed to vary within certain limits so as to meet a particular load demand with minimum fuel cost.  A program named bloss is developed for the evaluation of the transmission loss B coefficients which can be used following any one of the power flow programs lfgauss, lfnewton, or decouple discussed in Chapter 6. Also, a general program called dispatch is developed for the optimal scheduling of real power generation and can be used in conjunction with the bloss program.

Balanced and Unbalanced Fault Analysis
Fault studies are an essential tool for the power system engineer, and are required for system protection and the stability of the system operation. The fault analysis provides information regarding circuit breaker selection and relay settings. These studies involve the systematic computation of bus voltages and line currents during balanced and unbalanced faults.
Two functions are developed for the formation of the bus impedance matrix. These function are Zbus= zbuild(zdata) and Zbus = zbuildpi(linedata, gendata, yload). The latter one is compatible with power flow input/output files. A program named symfault is developed for systematic computation of three-phase balanced faults for a large interconnected power system. Two functions are developed for the symmetrical components transformations.
These are abc2sc, which provides transformation from phase quantities to symmetrical components, and sc2abc for the inverse transformation. Three functions named lgfault(zdata0, zbus0, zdata1, zbus1, zdata2, zbus2, V), llfault(zdata1, zbus1, zdata2, zbus2, V), and dlgfault(zdata0, zbus0, zdata1, zbus1, zdata2, zbus2, V) are developed for the line-to-ground, line-to-line, and the double line-to-ground fault studies.

Transient Stability
The stability problem is concerned with the behavior of the synchronous machine after a disturbance. MATAB and SIMULINK are used to obtain the dynamic behavior of a single-machine and multimachine systems due to small and large disturbances. The program trstab developed for transient stability work in synergy with the load flow program.

Power System Control deals with the control of active and reactive power in order to keep the system in the steady-state. The objective of the control strategy is to deliver power in an interconnected system as economically and reliably as possible while maintaining the voltage and frequency within permissible limits. Typical responses to real power demand are illustrated using the latest simulation technique available by the MATLAB/SIMULINK.

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