Improving wind turbines protection by shifting pickup current of overcurrent relay in distribution network

Wind turbines have some effects on short circuit current, which change the traditional protection schemes of distribution networks. One of these effects is reducing short circuit current of wind turbines in a short period of time after faults, as fault current magnitude comes below the pickup current of overcurrent protection. In this paper, the mentioned problem is investigated for different fault types. In addition, a new protection scheme, based on shifting the pickup current is proposed. The main idea of this new method is based upon decreasing the pickup current with respect to the voltage decline. To validate the proposed method a wind turbine connected to a distribution network is studied in MATLAB environment, and the obtained results show that the new method has a good ability for fault detection and clearance.