αβ轴下的双环电流负反馈控制孤岛检测

Islanding detection based on double-loop current negative feedback control underαβaxis

针对被动孤岛检测法的检测盲区较大,主动孤岛检测法会对电能质量造成污染等问题,从控制策略入手,提出了电流双环负反馈控制的孤岛检测。由于孤岛前后的电流环传递函数发生改变,传统的控制策略难以检测出此变化;双环电流负反馈控制下的电流环反馈函数由于引入了谐振环节,改变了系统的闭环零极点,使得电流的动态调节时间变长,因此延长了系统从并网状态切换到孤岛状态的过渡时间。在过渡时间内,该方法的孤岛检测因数(Islanding Detection Factor,IDF)发生较大变化,通过比较IDF与阈值大小来判断是否孤岛发生。由于一些非孤岛行为也会造成IDF的变化,因此通过Matlab仿真环境模拟了三类非孤岛行为和五类孤岛行为,以验证该方案的有效性。仿真结果表明该方案可以快速地检测出孤岛现象,并且有效地识别出非孤岛行为,避免发生误检测。

In order to solve the problem that the large detection blind area of passive islanding detection method,and the active islanding detection method will pollute the power quality,the islanding detection based on current double-loop negative feedback control is put forward from the perspective of control strategy.Because of the change of the transfer function of the current loop before and after the isolated island,it is difficult for the traditional control strategy to detect this change,and the feedback function of the current loop of the double-loop current negative feedback control changes the closed-loop zero pole of the system because of the introduction of the resonance link,which makes the dynamic adjustment time of the current become longer,so it prolongs the transition time of the system from the grid-connected state to the islanding state.During the transition time,the islanding detection factor(IDF)of this method changes greatly,and whether the islanding occurs or not is judged by comparing IDF with the threshold size.Because some non-isolated island behavior will also cause the change of IDF,three kinds of non-isolated island behaviors and five kinds of isolated island behaviors are simulated by Matlab simulation environment,which verify the effectiveness of the scheme.The simulation results show that the proposed scheme can quickly detect the isolated island phenomenon,effectively identify the non-isolated island behavior,and avoid false detection.