School of Electrical and Electronic Engineering, North China Electric Power University, Beijing102206, China

Scientific and accurate calculation of variable transmission costs is of great significance for the fair competition of electricity market. Through power flow tracing, it is found that the transmitting power process from the power sources to electricity admittance components also generates active power losses, which in turn affects the final variable transmission cost. Therefore, when calculating the variable transmission cost, it is necessary to consider the physical and economic characteristics of the electricity admittance components. First, a model is established to satisfy the power balance characteristics of active loads and reactive loads such as electricity admittance. Then, by using the principle of cost conservation, a cost calculation model that conforms to economic characteristics is obtained. The variable transmission cost calculated by using the proposed model can provide rich and accurate economic information. Finally, the rationality and the accuracy of the proposed calculation model and results are verified through case study.