基于无功电流-频率正反馈的孤岛检测方法

孤岛检测是光伏并网发电系统的必备功能,为了减小并网逆变器孤岛检测时的检测盲区,同时最大限度地减小孤岛检测对输出电能的影响,首先分析了逆变器输出的无功电流与频率之间的关系,然后在三相光伏并网逆变器锁相环的基础上,提出一种无功电流—频率正反馈的孤岛检测方法,推导了正反馈成立的参数条件,并对各个参数的获取方式进行了分析。仿真和实验证明,在电网正常时,该方法对系统几乎没有影响,但是一旦电网出现孤岛情况,无功电流与频率之间的正反馈会让频率迅速朝一个方向变化,直到触发孤岛保护。

A Novel Islanding Detection Method Based on Positive Feedback Between Reactive Current and Frequency

Islanding detection is one of the most important functions in the photovoltaic power generation system.In order to eliminate the non-detection zone and minimize the effect on the power quality,a novel islanding detection method using the positive feedback between reactive current and frequency is proposed based on the phase-locked loop of three-phase photovoltaic grid-connected inverter.The parameters are selected to guarantee the positive feedback and the flowchart of this method is given out.Simulation and experiments show that the method almost has no disturbance on the system under normal operations.But when an islanding occurs,the positive feedback between the reactive current and frequency will change the frequency quickly in one direction until triggering the islanding protection.