基于最小二乘参数辨识的电缆早期电弧故障测距

Cable Incipient Arc Fault Location Based on Least Square Parameter Identification

电缆本体和附件由于绝缘劣化而出现的绝缘缺陷与大地之间发展成间歇性的电弧接地故障,此类瞬时性电缆早期故障很难通过传统过流保护进行监测。针对此问题,提出一种基于电缆电流、电压测量的单相接地瞬时故障测距方法。建立不同早期故障形式下的等效零模电路,采用最小二乘拟合法求解电缆早期故障的微分方程组,计算故障电阻,其中参数辨识过程中以正弦逼近函数的精确求导来减小微分误差,通过移动合适的数据窗返回故障点距离。最后通过PSCAD软件仿真,验证了所提测距算法的有效性与准确性,为电力电缆早期自恢复故障测距提供了一种新的思路。

The insulation defect of the cable body and accessories due to insulation degradation develops into an intermittent arc grounding fault between the ground and the earth. In view of the problem that transient cable incipient faults are difficult to monitor through traditional overcurrent protection relays,the paper puts forward a single-phase grounding instantaneous fault location method based on cable current and voltage measurement. By establishing equivalent zero-mode circuits under different early fault forms, the least squares fitting method is used to solve the differential equation set during the early cable fault to calculate the fault resistance. In the process of parameter identification, the accurate derivation of the sine approximation function is used to reduce the differential error, and the distance to the fault point is returned by moving the appropriate data window. Finally, through PSCAD software simulation, the effectiveness and accuracy of the proposed ranging algorithm are verified, and a new idea is provided for early self-recovery fault location of power cables.