Causal Relationships Among Electrical Quantities in Grid-Connected Inverter Systems Following Short-Circuit Faults Based on Device and Network Excitation–Response Mechanisms

In recent years, large-scale power grid incidents triggered by faults in new-type power systems have occurred with increasing frequency. Due to the substantial differences in dynamic characteristics between new-type and conventional power systems, traditional fault analysis theories are no longer applicable, necessitating urgent research into fault analysis methods tailored to the characteristics of new-type power systems. This paper takes a three-phase-to-ground short-circuit fault occurring at the grid-connection point of a single wind turbine as a case study. This paper takes a three-phase-to-ground short-circuit fault occurring at the grid connection point of a single wind turbine as an example. Starting from the independent regulation of the internal voltage amplitude and frequency by PLL-based grid-connected devices through imbalanced active and reactive currents, as well as the current amplitude and frequency response characteristics regulated by the imbalance excitation of the active and reactive components of the voltage of the inductor in the network, this paper clarifies the causal mechanisms of the dynamic processes among electrical quantities after system faults.