Fast power-flow solution by the method of reduction and restoration

Abstract

The paper gives a fast power-flow-solution technique retaining only voltage-controlled busbars in the iterative process. Voltages are represented in rectangular co-ordinates, and the change in voltages from the assumed values is estimated in the iterative process. Power mismatches are computed only at two stages instead of at every iteration. After obtaining convergence, the original network is restored and the voltages of the load busbars are calculated. The essential features of the method are (a) only voltage-controlled busbars are retained during the iterative process, (b) a smaller-order Jacobian is used which is computed and inverted only once, thereby reducing the time of computation, and (c) on convergence, the system is restored to the original size, giving the voltage of all the busbars. This method is faster than other methods and can be conveniently applied to analysis and planning studies of large power systems. List of symbolsn m V L Y E F J,H 1 l2 = number of busbars in the system = number of generator busbars in the system = m-dimensional vector of voltages of generator busbars = m-dimensional vector of currents of generator busbars = (n-m)-dimensional vector of voltages of load busbars = (n -m)-dimensional vector of currents of load busbars = admittance matrix of order n x n = submatrices of Y of appropriate order = real and imaginary parts of the admittance = conjugate of fcth busbar voltage v k = inphase and quadrature components of v k = real and imaginary parts of a,-= vector of inphase components of generator busbar voltages = vector of quadrature components of generator busbar voltages = matrices of order m x m and (m + 1) m x m , respectively

An enhanced RCGA for a rapid and reliable load flow solution of electrical power systems

“…A fast load flow method proposed in [2,14] is adopted in this study. In this method, the load busbars are eliminated, retaining only generator busbars for the iterative process.…”

Computer Aided Transient Stability Analysis

“…The classical model is used to study the transient stability of a power system for a period of time during which the dynamic behavior of the system is dependent largely on the stored energy in the rotating inertias. It's the simplest model and requires a minimum amount of data [6][7][8][9][10] .…”

Heuristic methods for postoutage voltage magnitude calculations

“…The second-order Newton-Raphson method, where the second-order derivatives were included in the computation process, was applied [5], and it was reported that this method gave tens of times faster results [6]. Another approach initially decreases the system size by focusing only on the voltage buses, and then applying the Newton-Raphson method [7]. The branch outage simulation results of this method were compared to the second-order Newton-Raphson method, and it was found that the former gave better results [5].…”