基于频差正反馈的孤岛效应检测方法  

An Islanding Detection Method Based on Frequency Deviation and Positive Feedback

作　　者：李秉键[1] 吴华波[1] 

机构地区：[1]广东嘉应学院,广东梅州514015

出　　处：《电力电子技术》2011年第5期1-3,共3页Power Electronics

摘　　要：研究了一种并网逆变系统的孤岛效应检测方法。首先分析了电网断电时,并网逆变器带不同性质负载的情况下,其输出电压频率漂移方向与负载性质的关系,在此基础上提出了一种基于频差正反馈的孤岛效应检测算法。电网断电时,通过检测输出电压频差来判定其频率的漂移方向,沿此方向施加频率扰动,实施频率正反馈加速频率漂移,使并网逆变器输出电压的频率超出正常工作的频率范围,从而实现了孤岛效应检测,进而将并网逆变器的输出端从电网断开,防止出现不受电力部门监管的供电孤岛,同时给出了确定频率扰动值的方法。在一台单相并网逆变器实验平台上进行验证,结果表明,在典型负载下,基于频差正反馈的孤岛效应检测方法能有效检测出电网断电状态并及时将并网逆变器从电网断开,防止孤岛效应的发生。An islanding detection method for the grid-connected inverting system is studied.Firstly,the relationship be-tween the frequency drifting direction of the output voltage and the load characteristic under different loads during power grid being powered off is analyzed.On this basis,an islanding detection method based on frequency differential positive feedback is proposed.When the grid is powered off,the system detects the frequency differential to decide the frequency drifting direction of the output voltage and asserts a frequency disturbance along the frequency drifting di-rection,so the frequency drifting is accelerated by the frequency positive feedback and the frequency of the output voltage of the grid-connected inverter exceeds normal range,and then the islanding will be detected,the output port of the grid-connected inverter will be cut off from the power grid and the powering island out of monitoring by the a-gency can be avoided.A method to establish the frequency disturbance is presented.To verify the algorithm,an experi-ment is done in a single phase grid-connected inverter platform.The experimental results show that with classical loads,the islanding detection method based on frequency differential positive feedback can effectively detect the pow-ering off of the grid and cut off the grid-connected inverter from the grid in time,and the islanding can be avoided.

关 键 词：孤岛效应 频率漂移 频率扰动 正反馈 

分 类 号：TM92[电气工程—电力电子与电力传动]