Fault Distance Estimation for High-Voltage Cables Down the Mines Based on Voltage Continuity Considering Distributed Parameters

The harsh environment, complex working conditions and internal defects are main factors leading to faults in coal mine high-voltage cables which have a structure of multiple conductors with complicated electromagnetic couplings, posing challenges to establish equivalent circuit models for fault analysis to achieve fault distance estimation. This paper firstly constructs the distributed-parameter model for high-voltage cables. Then, the model is simplified to improve computational efficiency. Finally, a fault distance estimation algorithm is proposed based on the simplified model. There are three main contributions. First, the differential equations are decoupled by similarity diagonalization and inverse transformation to obtain voltage and current expressions of core, shielding and armor layers with respect to distance. Second, considering measurement ranges, the complex nonlinear formulas are transformed into the linear polynomial ones by using Taylor expansion. A fault distance estimation algorithm using voltage continuity principle is proposed for coal-mine cables. Third, the experiment model of high-voltage coal-mine cables is created by PSCAD/EMTDC. The experiment results show that the established model reduces voltage and current estimation errors to below 1.2 V and 0.15A, respectively. The method completes all calculations in only 0.01 s. The maximum error does not exceed 100 m and minimum one is only 1m under various conditions.