基于非特征频率突变量阻抗的多机集群孤岛检测方法

Islanding Detection Method for Multi-DGs Based on Noncharacteristic Frequency Variation Impedance

微电网中多类型电源并存的多机集群复杂工况对传统阻抗式孤岛检测法的应用提出挑战。提出了基于非特征频率突变量阻抗的孤岛检测方法。该方法采用外部集中扰动的方式注入扰动信号,并利用快速傅里叶变换计算公共耦合点处非特征频率突变量阻抗,同时将断路器流经的工频电流与相邻多机集群的非特征频率突变量阻抗作为辅助判据,以实现可靠有效的孤岛检测。通过理论分析与仿真验证可知,本文所提的孤岛检测算法不存在检测盲区,能够可靠应对负荷投切等系统暂态扰动,适应于多类型电源并存的多机集群微电网工况。

The complex operating conditions of multi-type distributed generators(DG)in the micro grid challenge the application of traditional impedance islanding detection method.Islanding detection method based on non-characteristic frequency variation impedance is proposed.The method injects the disturbance signal by adopting an external centralized disturbance mode and then uses the fast Fourier transform to calculate the non-characteristic frequency variation impedance at the point of common coupling.The power frequency current flowing through the circuit breaker and the non-characteristic frequency variation impedance of the adjacent multiDGs cluster are taken as an auxiliary criterion.Through the theoretical analysis and simulation verification,the islanding detection algorithm proposed in this paper does not have the none-detection zone,and can reliably deal with the system transient disturbance(such as load switching)and adapt to the micro grid operating operations of the multi-DGs.