电压正反馈式孤岛检测方法的边界条件及改进算法

孤岛检测是光伏并网逆变器必须具备的功能。好的孤岛检测算法不仅能及时检测出孤岛状态,而且能将孤岛检测对电网的不良影响降到最小。电压正反馈式孤岛检测方法具有实现容易、效果好的特点,但如果算法参数选择不当也会导致检测失败或对电网扰动过大。本文通过建立控制算法的大周期模型探讨了电压正反馈式孤岛检测成功的充分条件,阐明了孤岛检测成功与负载间的关系,并给出了数学解析表达式,为工程应用及实现符合国标要求的并网光伏系统提供了理论依据。

Boundary Conditions of Voltage Shift Techniques for Islanding Detection

Anti-islanding is a mandatory feature for grid-connected inverters.A desired method not only can detect islanding within acceptable duration,but also have less adverse impact on power quality.Voltage shift technique is a good solution because it has high effective and costless in implementation,while the effect depending on parameters and anti-islanding failure may occur if the algorithm are not adjusted properly.The paper proposes a long-cycle model to analyze the issue.The boundary condition of effective anti-islanding is deduced and relationship between anti-islanding effect and inverter output power is proposed,which gives guideline to commercial applications.