一种新的频率偏移技术在光伏并网发电系统孤岛检测中的应用

目前通过频率偏移技术进行孤岛检测的方法有很多,但是这些方法一般都是在假设并网失败后,逆变器电压的频率一直朝某个方向变化(变大或变小)直到超出额定频率范围为止的前提下才成立的。而实际中,当负载的品质因数比较高时,逆变器频率将围绕某个值震荡而不会超出额定频率范围。本文提出一种新的频率偏移技术———自适应逻辑频率偏移技术。他以一般频率偏移技术为基本扰动工具,必要时再叠加一新的偏移量,从而可以快速检测到弧岛效应,并且正常并网时频率扰动量也较小。

Application of a New Phase-shift Technique on Islanding Detection of Grid-connection PV System

Recently,many phase shift techniques of anti-islanding have been proposed.However,these techniques are all based on the assumption that at a grid failure,the voltage frequency of the inverter can be in a desired direction,up or down,until it exceeds the rated frequency.However,when the quality factor is high,the frequency of the inverter could oscillate around a certain frequency point after islanding occurs.A new phase shift technique is proposed in this paper,which uses the traditional phase shift technique as a basic phase shift tool,and has a additional phase shift at the necessary situation.In order to detect anti-islanding.