Low-Voltage Ride-Through Remote Testing Method for Offshore Wind Turbines

Abstract

Grid-connected wind turbines (WTs) are required to have low-voltage ride-through (LVRT) capability. On-site LVRT test is a convincing certificating method. To tackle the limited accessibility and harsh conditions of on-site test for offshore WTs, this paper proposes a remote testing method, which places the testing device on shore to produce the specified fault voltages through a subsea cable to the WT. For further eliminating the effects of introduced cable on LVRT test, a stepwise voltage sag generation strategy is applied to suppress the overvoltage and maintain required voltage sags. First, the LVRT testing requirements and voltage sag specification need to be considered in a practical test are introduced. The stepwise generation strategy and its implementation procedure based on the designed testing device are presented. Second, the effects of submarine cable on the WT-side voltage are analyzed under different generation stages of voltage sags. Next, the testing device’s impedance configuration method, based on the derived residual voltage expression, is given to generate the required steady-state voltage sags. Finally, simulation results indicate that with the proposed method, the effects of cable can be eliminated and the required grid faults can be emulated for remote LVRT test.