Application of particle swarm optimization for optimal setting of Phase Shifting Transformers to minimize unscheduled active power flows

Abstract

Today’s interconnected power systems require increased flexibility in control to ensure the capability for maintaining power flows at acceptable limits. Recently, this issue has become increasingly important, mainly due to the significant unscheduled flows that can violate system security. In response to this challenge, the transmission system operators introduced various measures to control unscheduled flows. The most effective are Phase Shifting Transformers (PSTs). A higher number of PSTs operating in the transmission grid increases the total control capabilities. Since the achieved control effects can be both strengthened and weakened because of various actions of individual PSTs, coordinating the settings of the PSTs will achieve the best results. This paper addresses a new, intelligent approach by using a combination of two methods: the discrete particle swarm optimization method for the optimal setting of the individual PSTs and the power flow method for calculating the value of the optimization objective. The case studies consider the IEEE 118-bus test system as well as a model of the real network of Central Eastern Europe. In both cases, the minimization of unscheduled flows was adopted as the objective. As a result of PSTs settings optimization, a significant reduction of unscheduled flows was obtained.