A robust quasi-direct continuous power-flow analysis using two-bus equivalents for voltage stability analysis of radial distribution systems

摘要

This paper presents a new and fast method to trace the P-V curves in voltage stability of radial distribution power systems. The proposed method is suitable for ill-condition problems since it is formulated based on the direct solution of a two-bus equivalent. This two-bus equivalent is formulated by expressing the downstream laterals of a certain bus by an equivalent power injection. Each bus, starting from the substation with its downstream bus, forms a two-bus equivalent with known voltage and demand. An iterative scheme for the solution of many two-bus equivalents in a study system leads to a global convergence of the power-flow problem. This novel approach has been implemented to correct the voltage at each point to track the P-V curve during voltage stability simulation. The overall performance of the developed continuation method is enhanced by applying the first order secant predictor. The proposed method is tested out using different sizes of radial distribution power systems. The performance is compared with well-established algorithms including the Newton-Raphson and the forward/backward sweep methods. Extensive simulation results yield same results as the Newton-Raphson method, despite its ease of implementation, fast execution time, and exhibition of less number of iterations.