Power flow solution for multi-frequency AC and multi-terminal HVDC power systems

摘要

This paper addresses to a power flow solution for AC-DC power systems. The AC system consists of transmission lines operated at 60 Hz and at low frequencies while the DC system has multi-terminal connections. The paper shows power flow in such power systems can be obtained by using the existing unified approach for AC-DC systems and reflecting impedances of lines operating at low frequencies in AC grids to their equivalent impedances at the fundamental power frequency. The equivalent transmission lines in terms of power flow of those lines operated at low frequencies are first mathematically established. The conventional unified approach to solve power flow in AC-DC systems is then discussed with a modification to reduce the size of the Jacobian matrix. The method is then verified by analyzing the power flow solution of a multi-frequency AC and multi-terminal HVDC power system modeled in PSCAD/EMTDC.