An Online Insulation Monitoring System Based On Partial Discharge For Mine High Voltage Cable

As the main power transmission medium,power cables play an extremely important role in the power supply system of coal mines.The existing power supply system of China’s coal mines generally uses a voltage level of 6kV or 10 kV.The high-voltage cables used in mining bear the task of power transmission and continuously transmit electrical energy sources to various electrical equipment.Therefore,the safe and reliable operation of cables determines the entire coal mine.Safe operation.Carry out real-time online monitoring of the insulation performance of cables,prevent cable hazards in advance,reduce the occurrence of equipment failures,and reduce user losses caused by power outage maintenance,which is of great significance for ensuring the safety of coal mine power supply.This paper compares the existing online monitoring methods at home and abroad,analyzes the characteristics and shortcomings of the existing technology,and based on the operating environment of the mining high-voltage power cable,establishes an online monitoring of the mining high-voltage cable insulation based on the partial discharge method.technology.Starting from the structure of mining high-voltage power cables,the process of gradual insulation degradation was analyzed,the principle of partial discharge pulses was analyzed,and the signal characteristics and propagation characteristics of partial discharge pulses were studied by establishing partial discharge models and mathematical models.Aiming at the characteristics of partial discharge monitoring signal with small amplitude and susceptibility to interference,a partial discharge signal denoising method based on variational modal decomposition and adaptive threshold is proposed,and the steps of the method are given.Compare and analyze with the existing wavelet transform,and quantify the results through the signal-to-noise ratio,mean square error,and waveform similarity coefficient,verifying that the noise signal can be effectively removed under different noise conditions,and the original signal waveform can be more completely retained.Improved the accuracy of the acquired signal.Completed the hardware and software design of the on-line monitoring system for mining high-voltage cable insulation based on partial discharge,including: highfrequency current sensor,signal processing module,data communication module and host computer.A high-frequency current sensor based on Rogowski coils is designed to achieve non-destructive testing with existing coal mine power supply systems.Using optical fiber transmission technology,the collected data is transmitted to the remote monitoring room in time.Completed a background online expert analysis system to enable real-time monitoring of the cable’s real-time insulation status.Finally,this paper carried out a variety of test analysis on the entire monitoring system.First,a needle-plate electrode discharge model was set up in a laboratory environment to simulate the experimental study of sharp angles,burrs,and protrusion defects of the cable,and then a live electrification test was performed in the field.According to the comprehensive evaluation of the discharge volume and the PRPD spectrum,a partial discharge of a 6kV cable was determined,and an insulation defect was determined.The experimental results show the effectiveness and reliability of the insulation monitoring system for mining high-voltage cables based on partial discharge from different aspects.