一种光伏并网系统无功扰动孤岛检测方法

A Reactive Power Variation Islanding Detection Method for PV Grid-connected System

孤岛检测是并网光伏逆变器的必备功能。分析了光伏并网发电系统无功扰动孤岛检测的原理以及传统无功扰动孤岛检测的实现方法,并在此基础上提出一种单双向混合无功功率扰动(Mixed Unidirectional andBidirectional Reactive Power Variation,简称MUBRPV)的孤岛检测方法。该方法在光伏发电系统正常运行时逆变器向电网施以小幅度正负双向无功电流扰动,期间检测到网压频率偏差后,快速确定电流正馈扰动方向,并开始无功电流单向正馈扰动。实验验证表明该方法不仅能及时检测出孤岛状态,无盲区,而且能将孤岛检测对电网的不良影响降到最低。

Islanding detection is an essential function of photovohaic（PV） grid-connected inverter.Based on the reactive power variation islanding detection principle analysis of PV grid-connected system and traditional reactive power variation detection realization method, this paper presents a mixed unidirectional and bidirectional reactive power variation （MUBRPV） islanding detection method.PV inverter applies a small bidirectional amplitude reactive power variation for grid-connected system and detects the frequency drift instantaneously,ensures positive feedback variation direction quickly and applies unidirectional positive feedback variation.The method can detect islanding quickly and has non- detection zone, meanwhile influence the power quality least.