Power flow solution for multi-frequency AC power systems

Abstract

This work proposes the enhancement of existing power flow solutions for application in multi-frequency AC power systems. Such power flow solutions can be obtained using existing methods, provided that impedances of lines operating at different frequencies be reflected to their equivalent impedances at the fundamental power frequency. The study first presents a mathematical proof of equivalent parameters in terms of power flow of a transmission line operated at a low frequency and the fundamental frequency. It is then validated by analyzing the power flow solutions of a power system modeled in PSCAD/EMTDC when it is operated at multi-frequency and at conventional 60 Hz conditions. An application of a low frequency AC transmission line is illustrated to demonstrate its superiority in terms of power carrying capacity over a typical fundamental frequency AC transmission line. Finally, the power flow problem in a more general power system, which is a multi-frequency AC and multi-terminal HVDC system, is also completely solved by using two different approaches.