Improved Transient Stability Analysis of Multi-Loop Droop-Controlled Grid Forming Inverters with Current Limiter

Grid-forming control is regarded as a promising technology for achieving high levels of renewable energy integration in future power grids. To fulfill this role, grid-forming devices are expected to possess a fault ride through capability. This paper focuses on the transient stability of a droop control-based grid-forming inverter that utilizes current reference saturation as a current limiting strategy. The objective of this work is to investigate the fault recovery process of the grid-forming inverter and analyze the criterion for transitioning the inverter out of the current limiting mode. The theoretical analysis in this study is validated through time-domain simulations, which compare the results obtained using the d-axis priority-based current limiting method. Various operational conditions are considered to comprehensively evaluate the performance of the grid-forming inverter during a three-phase short circuit scenario. The simulation results confirm the effectiveness of the proposed theoretical approach.