Analysis of the space-time distribution of frequency at the sending and receiving ends of active support type flexible DC based on PMM

Currently, active support type flexible DC transmission systems have been widely studied, and their frequency space-time distribution characteristics have become a key focus. This paper proposes an improved node frequency deviation measurement method based on power measurement to analyze the frequency space-time distribution characteristics of flexible DC transmission systems. Taking a four-port photovoltaic flexible DC transmission system as the research object, different types of disturbances are set at the sending and receiving ends respectively, and the node frequency deviations at the power supply sides of the sending and receiving ends under different operating conditions are compared. In terms of measurement methods, the node frequency deviation on the AC side is obtained by the Power measurement method (PMM), and the node frequency deviation on the DC side is obtained by converting the DC voltage. The combination of the PMM and the DC voltage drop conversion ultimately yields the frequency deviation between the ports of the flexible DC transmission system. Simulation results show that this method can more accurately reflect the impact of disturbances on frequency compared to traditional PLL and PMU measurement methods, and can effectively analyze the frequency space-time distribution characteristics of the sending and receiving ends of active support type flexible DC transmission systems, providing a new idea for the accurate measurement of node frequency deviations.