Analysis of Current Limiting Algorithm with Anti-Windup Control for Transient Stability of Grid-Forming Converters

In modern power grids, renewable energy sources (RESs) are integrated to the grid through voltage source converters (VSCs) with grid-forming capabilities. Grid forming VSCs’ weak overcurrent capability revealed the need for current limiting techniques under large disturbances like short-circuit faults. However, current saturation algorithms induce transient instabilities due to the AC voltage controller windup issue when the current is saturated. Therefore, analyzing the transient stability of the grid-forming units in case of fault conditions is crucial for ensuring the reliable and secure operation of the grid. This paper investigates the effects of the current limiting algorithm with anti-windup control to handle transient instabilities during fault conditions. An elaborated theoretical analysis of the presented system is performed by considering different case studies. The simulations are conducted by using Matlab/Simulink software to test the validity of the presented system. The obtained results highlight the advantages of an anti-windup controller during current saturation mode.