Power Self-Synchronization Control of Grid-Forming Voltage-Source Converters Against a Wide Range of Short-Circuit Ratio

Abstract

Power synchronization control (PSC) tends to destabilize the VSC connected to the stiff grid. For addressing this issue, this paper proposes a novel control scheme named as power self-synchronization control (PSSC), which enables VSC to operate under grid conditions with short circuit ratio (SCR) from 1 to infinity. Similar to PSC, the proposed method also includes power synchronization loop, voltage control loop, and current control loop. Yet, PSSC-based VSC(PSSC-VSC) can be self-synchronized to the grid without three-phase grid voltage detection. In PSSC, the output of the current control loop is fed back to calculate the instantaneous power, which is applied in the power synchronization loop. By the eigenvalue analysis, participating factor analysis, and impedance-based analysis, control parameters of PSSC are well-designed and the robustness of VSC under different grid conditions is obviously improved. Moreover, PSSC-VSC inherits the characteristics of the grid-forming converters, and the theoretical analysis for the proposed method is validated by experimental tests.