New active islanding detection scheme for constant power and constant current controlled inverter-based distributed generation

This study presents an active islanding detection scheme based on voltage positive feedback control strategy in synchronous d-q frame with a variable voltage gain. The proposed method employs the injection of a variable voltage gain at the DG end in order to monitor the responses of the proposed islanding detection technique. In this study, a complex frequency-dependent ZIP-exponential load model is included to assess the impact of load´s active power frequency dependence on the performance of the proposed islanding detection scheme. The upper and lower limits of the voltage gain are designed for constant power and constant current controlled inverter with frequency-dependent ZIP-exponential load. The complete scheme is developed and tested in MATLAB/simulink environment and the results obtained after extensive testing indicate that the proposed scheme can be reliably detect islanding events in distributed generation.