基于正交小波分解的直流微电网高阻故障检测方法

High Resistance Fault Detection Method for DC Microgrid Based on Orthogonal Wavelet Decomposition

直流微电网中,高阻故障信息特征较弱,难以检测。高阻故障发生以后,有可能会导致直流微电网长期带电运行,引发安全事故,因此需要对高阻故障进行有效检测并切除。首先,针对电压源型换流器所构成的直流微网故障,提出了应对直流微电网高阻故障的利用时域电流平均值法和时频域正交小波分解法的检测方法,兼顾了故障检测的正确性和灵敏性。然后,利用小波层级分解的系数进行奇异值分解,根据奇异值变化特征对高阻故障的微弱特征进行检测。最后,基于电磁暂态仿真软件PSCAD/EMTDC建立了直流微电网仿真模型,并利用Matlab进行了算法验证,结果表明所提方法可以对高阻故障进行检测以及识别。

In DC microgrid,the characteristics of high resistance fault information is weak and difficult to detect.After the occurrence of high resistance fault,it may lead to long-term live operation of DC microgrid and cause safety accidents,so it is necessary to effectively detect and remove the high resistance fault.Firstly,aiming at the DC microgrid composed of voltage source converter,this paper proposes a high resistance fault detection method for DC microgrid.The proposed method uses current average value method in time domain and orthogonal wavelet decomposition method in time and frequency domain,giving consideration to the correctness and sensitivity of fault detection.Then,the coefficient of wavelet hierarchical decomposition is used for singular value decomposition,and the weak feature of high resistance fault is detected according to the singular variation characteristics.Finally,based on the electromagnetic transient simulation software PSCAD/EMTDC,the DC microgrid simulation model is established,and the algorithm is verified by Matlab.The results show that the proposed method can detect and identify high resistance faults.