Var Support Cost Allocation Based on Branch's Complex Power Components

Abstract

A method for allocating var support based on branch's complex power components is presented. First it is pointed out that source's active power and load's complex power should be responsible for var support based on analysis. Then each of source's active power and load's complex power is modeled by its equivalent nodal injection current sources based on reactive optimal power flow (OPF) solution. Each of source's reactive power used for var support is modeled by a shunt reactance called cost reactance. Finally, the nonlinear relationship between resistance and equivalent injection current sources is established based on the algorithm of branch's complex power components. As a result, var support of each reactance is accurately allocated between source's active power and load's complex power. The proposed method is of the following properties by comparison with the existing methods: The var support of a power system is always recovered; It is applicable for any transmission systems of looped configurations and loop flows; It needs no any assumption and simplification, and takes into account the interaction between active and reactive power; The proposed method gives a completely novel and analytical way of allocating var support cost. Simulation results of different power networks show that the proposed method is effective.