A Novel Pre-synchronization Control Strategy for Virtual Synchronous Generator Based on NLADRC-PLL

Due to the mismatched voltage amplitude, phase and frequency between virtual synchronous generator (VSG) and utility grid, there may exist significant impulse current when VSG connects to the gird through the point of common coupling (PCC). This paper designs a NLADRC-PLL and proposes a novel pre-synchronization control strategy to decrease the impulse current. Firstly, a phase lock loop based on nonlinear active disturbance reject control (NLADRC-PLL) is designed to obtain the voltage information of the PCC quickly and flexibly. Then, PCC voltage information obtained by NLADRC-PLL is embedded into both active and reactive control loops of VSG through certain logic control. Finally, the impulse current caused by the VSG-grid connection in the presence of PCC voltage magnitude, frequency and phase suddenly changing is effectively suppressed. Simulation results of 5 cases are given to demonstrate the effectiveness and feasibility of the proposed presynchronization control strategy.