基于正反馈无功扰动的逆变器孤岛检测方法研究

基于传统主动检测方法在负载相位与逆变器输出进行匹配的过程中存在很大的检测盲区,并且会向电网注入一定的谐波,提出了一种基于正反馈无功扰动的孤岛检测方法。通过对系统无功功率添加正反馈扰动,打破功率平衡时的孤岛稳定运行点,在较短的时间内逆变器输出电压频率迅速超过额定阈值,从而准确地检测出孤岛。仿真结果表明,检测方法不仅响应速度快、不存在检测盲区,而且对电能质量的影响也较小。

Research on Inverter Islanding Detection Method Based on Positive Feedback Reactive Power Disturbance

Traditional active island detection methods,such as frequency and phase shift,can inject harmonic into the grid and have non-detection zone when the phase between the output of inverter and load matches. Based on this,a positive feedback reactive power disturbance islanding detection scheme was proposed. Once an islanding condition occurs,this new method breaks the stable operating point in power equilibrium condition by introducing a reactive power disturbance and makes the frequency of the photovoltaic grid-connected inverter＇s output voltage exceeds a preset threshold value in a short time. As a result of this,the islanding will be detected. The simulation result shows that the proposed method has high response speed,no detection dead zone,and little influence on power quality.