Reactive power optimization with time-varying fuzzy load demand for distribution systems

In this paper, an algorithm for reactive power optimization with time-varying fuzzy load model (RPOTF) for medium-high voltage distribution networks is presented. This algorithm simplifies the mathematical model of unknown control variables, determines the assumed switching time of control devices and then converts the time-varying optimization model into the same one as static optimization. This methodology considers the uncertainties in load demands, therefore, control devices are believed to need few operations after the optimization. Numerical tests are carried out and results show that the proposed algorithm is practical and efficient for energy loss minimization in distribution systems. At last, this paper discusses the requirements for the application of RPOTF, and presents a solution to put it into practice.

I. Introduction

VOLTAGE/VAR control is an essential measure to reduce the power losses in distribution systems. Many algorithms have been used to solve this problem. However, the applicability of these algorithms to a practical system is limited because of the constant load model they adopt. In fact, the load demands in power systems vary from time to time. The optimal control scheme should also change due to the time-varying load demands [8]. Thus, the optimal dispatch scheme considering constant load data cannot be put into practice in real time applications. Only the optimization with time-varying load demand could get the feasible dispatch scheme in a duration.