Real-time Measurement Method of Grid Impedance with Resonant Characteristics for Control of Distributed Power Generation Systems

The introduction of distributed power generation systems is expanded worldwide, many grid-connected inverters are connected to the grid. Since the grid impedance affects the stability and control performance of the grid-connected inverter, it is important to accurately estimate the grid impedance. The grid impedance has resonant characteristics because the capacitor component is connected to the grid in addition to the wiring LR component for power factor improvement. In this paper, the impedance measurement method with variable sampling frequency for grid impedance with resonant characteristics is proposed, and the measurement accuracy of the grid impedance with resonant characteristics is verified.