Harmonic detection and filtering of distributed photovoltaic grid-connected system under instantaneous reactive power theory

To solve the environmental pollution and resources shortage problems of traditional fossil fuels, distributed photovoltaic (PV) grid-connected system are used widely. The power quality problems caused by harmonics generated during the operation of the system have also received widespread attention. Fast and accurate detection and filtering of system harmonics is particularly important. In this paper, a brief description of the i(p)-i(q) harmonic detection method based on the instantaneous reactive power (IRP) theory is provided and used to detect the harmonics generated during the operation of the system. Then, a new LCL-type filter is designed innovatively to filter out the detected harmonics of the system. Finally, the above process is simulated and analyzed by MATLAB/Simulink software. The experimental results show that the designed LCL-type filter can reduce the harmonic content of voltage and current on the grid side and effectively improve the power quality of the grid.