基于加权差分电流的直流故障电弧检测方法

DC Arc Fault Detection Method Based on Weighted Differential Current

为了解决低压直流系统中传统电弧故障检测方法精确度不足及对不同系统通用性较差的问题,本文提出一种新的基于加权差分电流的直流电弧故障检测方法。首先搭建直流源实验平台,开展串联直流电弧高频特性实验,利用快速傅里叶变换提取电弧电流的特征频段为20~30 kHz、40~50 kHz和55~65 kHz。然后,研究电极材料和负载类型对电弧特征频率的影响,实验结果表明直流电弧的特征频段不随电极材料和负载类型改变。将3个特征频段内幅值的最大值I_(max)、幅值之和I_(sum)以及幅值的标准差I_(std)作为特征参量。基于对电弧电流特征频段和特征参量的双重加权差分,利用差分结果是否大于阈值0.5作为直流故障电弧检测判据。最后,在低压直流系统和光伏系统中验证所提出检测方法的有效性。检测方法能够准确区分开关动作与负载突变等系统正常操作。该方法克服了传统单一频段单一指标检测方法的不稳定性,能够有效检测直流电弧故障,提高检测的准确性,并在光伏系统中验证了检测方法的通用性。检测方法对保障低压直流系统的安全稳定运行具有重要的应用价值。

To solve the problems of low accuracy and poor universality of traditional arc fault detection methods in the LV DC system,a new DC arc fault detection method based on weighted differential current is proposed in this paper.Firstly,a DC experimental platform was set up for the high frequency characteristic tests of serial DC arc fault.And its characteristic frequency bands were extracted as 20-30 kHz,40-50 kHz and 55-65 kHz by fast Fourier transform.The influence of electrode materials and load types on arc characteristic frequency was studied,which show it does not change with electrode material and load type.Then the maximum amplitude,I_(max),sum of amplitude,I_(sum) and standard deviation of amplitude,I_(std) in the three characteristic frequency bands were taken as characteristic parameters.Based on the double weighted difference of characteristic frequency bands and characteristic parameters of the arc current,the criterion of DC arc fault detection is whether the difference result is greater than the threshold value 0.5 Finally,the validity of the proposed method was verified in the LV DC system and photovoltaic system.The results show that the proposed method can accurately distinguish the normal operation of the system,such as switch action and sudden load change,overcome the instability of traditional single frequency-band and single index detection methods,effectively detect DC arc faults,and improve the detection accuracy.Its universality is verified in photovoltaic systems.Moreover,it can play a crucial role in ensuring safe and stable operation of LV DC systems.