An Improved Low Voltage Ride Through Control Strategy for Offshore Wind Power Based on PLL Dynamic Compensation

The low voltage ride through (LVRT) capability of offshore wind power has significant engineering value in ensuring the secure and stable operation of power grids. Long-distance submarine cable integration results in an extended electrical distance and weak grid strength, making stable fault ride-through difficult for conventional control strategies. To address this issue, an improved LVRT control strategy based on phase-locked loop (PLL) dynamic compensation is proposed. A mathematical model of the PLL is established to analyze the coupling between generator terminal voltage, phase angle, and angular velocity. Circuit theorems are applied to determine fault point voltage parameters, which are then substituted into the PLL model to derive the motion equations of the generator. The equal-area criterion is employed to define optimal transient stability conditions. A dynamic compensation mechanism is designed within the PLL to enhance the control strategy. A simulation model of an offshore direct-drive permanent magnet synchronous generator (DD-PMSG) is developed on the PSCAD platform, and comparative studies are conducted under different control strategies. Simulation results indicate that voltage oscillations are effectively suppressed under weak grid conditions. System stability is enhanced, and dynamic response characteristics are superior to those of conventional methods.