Design Of An On-line Monitoring System Of Circulating Current Of High Voltage Power Cable And Its Electromagnetic Coupling Properyt Simulation

As the power cable has been increasingly applied in the power system and theinsulating condition of power cable directly affects the security and reliability ofpower system, power supply utility and power user pay more and more attention to thereliability of power cable. In recent decades, the researches about online monitoringof the insulation status of power cable progress rapidly at home and abroad.However,most of the studies have concerntrated on the main insulation status, and there are fewresearches for the outer sheath or metal sheath.From the perspective of on-line monitoring of metal sheath circulating current ofpower cable, by analyzing the changes of metal sheath circulating current of power todiscover latent defects and faults in power cables, latent defects and faults areprevented and handled timely to ensure the safe and stable operation of the cable.Based on the description of the composition of single-core power cable and cablemetal sheath grounding protection, this paper analyzes the features and limitations ofthe application of on-line monitoring methods of current power cable insulation, andpresents a solution by monitoring the insulation of metal sheath circulating current ofpower cable online.This paper analyzes the generating mechanism of metal sheath circulating currentof power cable and makes an analysis and derivation on the metal sheath inducedvoltage; with the circuit analysis, the analytic formulas of the metal sheath inducedvoltage during normal operation and the case of short circuit were derived, meanwhile,the calculation of metal sheath circulating current was finished. The characteristics ofthree-phase single-core power cable of the electromagnetic coupling characteristicswere studied by applying the finite element software Ansoft Maxwell, it providescriteria and theoretical reference for the design metal sheath circulating current ofpower cable on-line monitoring system based on GPRS.Finally, the paper elaborates a design of monitoring system based on GPRS tosupervise the metal sheath circulating current of power cable on-line. The system’shardware debugging and software design has been completed.The spot running resultsin this paper show that the moniroring system designed for metal sheath circulatingcurrent of single core power cable is stable and reliable. And also the system has someother merits such as the accuracy of measurement and real-time data transmission. It can meet the operating-demand of on-line monitoring system for metal sheathcirculating current of power cable in the power cable network.