On-Line Equivalent Method for Main Grid Suitable for Coordinated Support of Transmission and Distribution Voltages

With the rapid development of society and the increasing depletion of global fossil energy, traditional power generation and distribution methods have gradually revealed their drawbacks. Clean energy generation represented by distributed photovoltaic power generation and new distribution methods represented by DC power distribution are becoming important directions for the future development of the power industry. Aiming at the problems of the modern power grid, such as massive and constantly changing data, complex and cumbersome short-circuit capacity calculation, and difficulty in ensuring timeliness and accuracy, this paper proposes a dynamic equivalent impedance method based on the Thevenin equivalent circuit. To address the stability issue of power systems with multi-station photovoltaic integration, the system stability is determined based on the short-circuit capacity. The measurement principle is derived using circuit theory, focusing on the problem of quantifying voltage support strength under non-fault disturbance conditions. The correctness and accuracy of the measurement method are verified through simulation examples in the IEEE 33-bus distribution network.