Active Anti-Islanding technique with reduced Non-Detection Zone for Centralized Inverters

This paper presents an active anti-islanding scheme for grid-tied centralized inverters for large Photovoltaic (PV) power plants. The proposed technique involves appropriate reactive power injection into the grid which results in the positive/negative rate of change of frequency. The proposed algorithm is simple and can be easily integrated into DQ based current control technique. It has a smaller Non-Detection Zone (NDZ) and faster response as compared to other active anti-islanding schemes. As the proposed method is based on alarm generation and confirmation, it does not inject any periodical disturbance into the grid unlike other anti-islanding techniques and thus does not cause any power quality issues. The proposed active anti-islanding algorithm is simulated in MATLAB/SIMULINK under different loading conditions as per IEEE/IEC standards. The algorithm is also experimentally verified on a 25 kW centralized inverter prototype using TMS320F2812 DSP controller. The experimental and simulation results are presented to validate the effectiveness of the algorithm.