Improved active and reactive transmission power loss coefficients using nonlinear least squares data fitting

Abstract

In traditional power system economic dispatch (ED), only active power production and active power loss are usually considered. Active power loss is commonly approximated by the B -coefficients that are pre-determined according to certain base-case loading conditions of a system. The obstacle of these coefficients is that they guarantee a satisfactory precision for minor deviations from the base-case conditions, consequently, they do not guarantee accuracy for significant deflections from these conditions. They also ignore impact of reactive power generations on real power losses. In ED and similar optimization problems that rely on the B -coefficients, the optimal generator power productions usually deviate considerably from the base-case values, which implies that the optimal values of ED would be based on misleading power loss values. Conversely, reactive power loss is different from the active power, because it lacks direct or estimated explicit formulas for ED or similar operational problems involving reactive loss concerns. Utilizing the nonlinear least squares data fitting, this paper defines and uses formulas for both reactive and active losses to address the shortcomings of the conventional B -coefficient loss formula and improve the customary ED formulations and solutions that employ less precise active loss formulas and disregard reactive power losses and loads. The results and comparisons demonstrate the proposed reactive and real power loss coefficients and formulas yield much more practical results with greater accuracies across various system sizes and operating conditions. Results also show that accounting for reactive power can noticeably affect the results of the standard ED.