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

A method for allocating var support cost 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 cost 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 cost resistance and equivalent injection current sources is established based on the algorithm of branch\´s complex power components. As a result, var support cost of each cost 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 cost 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.