基于低频扰动的多分布式电源孤岛检测方法

Islanding detection method for multiple distributed power sources based on low-frequency disturbances

针对被动法检测盲区较大和主动法易产生稀释效应的问题,提出基于主、被动结合的多分布式电源(distributed generation,DG)孤岛检测方法。首先,该方法利用有源电力滤波器(active power filter,APF)实现无功功率扰动,即通过扰动APF的q轴参数来控制其输出频率为2 Hz的无功功率,以扰动孤岛频率周期性波动。然后,利用小波分解和小波重构算法提取频率信号中的低频分量。最后,利用快速傅里叶变换(fast fourier transform,FFT)算法计算2 Hz低频分量的幅值并判断是否越限,以实现多DG孤岛检测。Matlab/Simulink建模仿真结果表明:该方法能够有效地避免稀释效应,实现多DG孤岛检测。

There are problems of large blind spots in passive detection and dilution effects in active detection.Thus this paper proposes a multi-distributed generation(DG)islanding detection method based on active/passive combination.First,this method uses an active power filter(APF)to achieve reactive power disturbance.This controls the reactive power output frequency of 2 Hz by perturbing the q-axis parameters of the APF,in order to perturb the periodic fluctuations of islanding frequency.Then,wavelet decomposition and wavelet reconstruction algorithms are used to extract low-frequency components from frequency signals.Finally,the fast Fourier transform(FFT)algorithm is used to calculate the amplitude of the 2 Hz low-frequency component and determine whether it is out of limit,to achieve multi-DG island detection.The modeling and simulation results using Matlab/Simulink show that this method can effectively avoid dilution effects and achieve multi-DG island detection.