基于调频连续波的长距离电缆高阻故障定位精度提升研究

As to high impedance fault detection for long-distance cable, several problems exist on the conventional frequency domain reflectometry, such as low detection efficiency, large shielding zone, and weak anti-interference capability. Therefore, a location method based on the frequency modulated continuous wave is proposed in this paper to improve the fault location accuracy. Firstly, the equivalent model of distributed parameters for faulty cable is established, and the fault location method based on the integral of frequency modulated continuous wave is illustrated. The wave is injected into the cable head, and the beat signal which carries the position and characteristic information of high impedance fault is obtained. By utilizing the generalized orthogonal integration algorithm, the fault diagnostic function is constructed. Then, the location results of single- and multi-point faults with various fault distances and transition resistances are analyzed via simulations. Finally, the feasibility of the method is verified by coaxial cable in the laboratory and 330 kV cable in the field. The simulated and experimental results show that the method, which is based on the integral of frequency modulated continuous wave, can be adopted to efficiently locate the high impedance fault for long-distance cable. The maximum transition resistance can be identified as 3 kΩ, and the fault location error is within 1%. Compared to the reflection coefficient spectrum method, the proposed method exhibits a high location accuracy, an enhanced anti-noise ability, and an extended detection range.