Efficient Method to Identify Islanding Condition for Wind Turbine as Distributed Generation

Abstract

Distributed generation is increasingly likely to play a major role in electricity supply systems. However, the integration of these units at distribution voltages is a major challenge for utilities. One of the problems of distributed generation working connected to the network is the unwanted islanding phenomenon causing physical or financial losses. Islanding is one important concern for grid connected distributed resources due to personnel and equipment safety. Several methods based on passive and active detection scheme have been proposed. While passive schemes have a large non detection zone (NDZ), concern has been raised on active method due to its degrading power quality effect. Reliably detecting this condition is regarded by many as an ongoing challenge as existing methods are not entirely satisfactory. The main emphasis of the proposed scheme is to reduce the NDZ to as close as possible and to keep the output power quality unchanged. In this paper, a developed algorithm is proposed based on passive methods to detect non-islanding protection for wind turbine which is connected to the network. The proposed algorithm is compared with the widely used rate of change of frequency relays (ROCOF) and total harmonic distortion (THD) and found working effectively in the situations where ROCOF and THD fails. The method is on the basis of the decisions of several parameters. These parameters are voltage changes, frequency changes, and active and reactive power changes. Different scenarios with various loads have been used at different wind conditions and many parameters have been studied in these experiments to propose the algorithm. Simulation results have been obtained using MATLAB/SIMULINK software and the effectiveness of the proposed algorithm is shown for the different performances.