Adaptive LVRT Control Strategy for VSC Based on Hybrid Synchronization Control

In recent years, the problem of large-scale renewables tripping caused by power grid faults has occurred from time to time. By analyzing the power angle and fault current characteristics of the hybrid synchronization control (HSC)-based voltage source converter (VSC), this paper presents an adaptive low-voltage ride-through (LVRT) control strategy for HSC-based VSC. The proposed strategy includes three adaptive control measures: adaptive power angle control, adaptive internal potential control and adaptive virtual impedance control. The adaptive power angle control can keep the power angle equal to its pre-fault value, which greatly improves the transient stability of the system and effectively suppress the fault current. The adaptive internal potential control quantitatively suppresses fault current by adjust voltage reference in the voltage control. The adaptive virtual impedance control is used to suppress pulse currents at the instant of grid voltage dip/recovery. Finally, both theoretical and simulation analyses are conducted to validate the effectiveness of the proposed adaptive LVRT control strategy.