Search

This article presents an efficient algorithm for the loss minimization by automatic sectionalizing switch operation in large-scale distribution systems. Simulated annealing is particularly well suited for large combinational optimization problems, but the use of this algorithm also requires excessive computation time. Tabu search attempts to determine a better solution in the manner of a greatest-descent algorithm, but it cannot give any guarantee for the convergence property. The hybrid algorithm of these two methods with some adaptations is applied to improve the computation time and convergence property. Numerical examples demonstrate the validity and effectiveness of the proposed methodology using a Korea Electric Power Corporation''s distribution system. [Copyright &y& Elsevier]

In this paper we explore a new method for evaluating the impact of voltage sags in the power distribution systems. The proposed method incorporates the generalization of the evaluation method as well as the effects of voltage sags on customers. To generalize the evaluation method, historical reliability data will be used. We take into account the impact of voltage sags on customers using a representative power acceptability curve and a fuzzy model. The final result of the evaluation model yields on a yearly basis the magnitude of customers’ risk caused by voltage sags. The evaluation methodology is divided into the analytic and probabilistic method. The time sequential Monte Carlo simulation is used as probabilistic method. The proposed method is tested using the modified Roy Billinton Test System (RBTS) form and the reliability data of Korea Electric Power Corporation (KEPCO) system. Through the case study, we verify that the proposed method evaluate the actual impact of voltage sags and can be effectively applied to the real system using the historical reliability data as the conventional reliability indices in power distribution systems. [Copyright &y& Elsevier]

This paper summarizes the results of the research for load management of pole-transformers done in 1997–1999 in Korea. The purpose of the research is to enhance the peak load estimation of pole-transformers. For this purpose, we concentrate on two parts. One is to modify the load regression equation for load management of pole-transformers. The other is to estimate the cooling load possessions of customers and reduce estimation errors of the peak load for pole-transformers in the summer season. To do this, we propose indices of cooling load estimation using the increment of electric energy from spring to summer. Case studies for sample pole-transformers show that the proposed peak load estimation method could reduce estimating error of the peak load in the summer season, compared with the conventional method in Korea. [Copyright &y& Elsevier]