earticle

영어

Islanding detection is one of the essential features for photovoltaic grid-connected systems; detection performance is directly related to safe operation of the equipment. Summarize existing islanding detection, then an active method based on frequency – reactive power feedback islanding detection is proposed. Once an islanding condition occurs, the method introducing a load frequency - reactive power characteristics associated component as input of reactive power perturbation, breaks the existing islands of stability point in the case of the power balance. Then it detects the system frequency deviation by real time, and draws into the function of reactive perturbation to form a positive feedback loop. So the frequency drifting is accelerated and the frequency of the output voltage of the photovoltaic grid-connected inverter exceeds a preset threshold value, and then the islanding will be detected. Simulation shows that the proposed method has no detection dead zone and it is fast and has little influence on power quality.