Research On Cable Partial Discharge Detection And Location System

With the rapid development of new technology,power cable lines have been widely used in people's life and production.However,in the process of cable production or operation,partial discharge often occurs because of some insulation defects,it will lead to more serious insulation defects under long-term high voltage operation,eventually leading to insulation breakdown,affecting the normal operation of cables,bringing huge economic losses.Therefore,it is of great significance for the stable operation of the power grid to timely detect insulation hazards,accurately locate fault locations and timely replace fault segments through online partial discharge monitoring and positioning of cables in normal operation.Based on the advantages and disadvantages of various on-line detection methods of cable faults,this thesis uses HFCT sensor(high frequency current sensor)and ultrasonic sensor to build detection system,and studies on on-line detection and location of Cable Partial discharge.Firstly,based on the partial discharge theory of cables,this thesis introduces the forming principle of partial discharge and typical insulation defects,and expounds the forming reasons and characteristics of corona discharge,surface discharge,suspended discharge and internal discharge,which provides a theoretical basis for experiments.Secondly,the cable circuit model is built on the MATLAB simulation platform to simulate the propagation process of partial discharge signal in the cable.The simulation results are analyzed by changing the length and distribution parameters of the cable model,and the propagation characteristics of partial discharge signal in the cable are explored.The simulation experiment of partial discharge location for cable model is carried out by using time delay estimation method,which verifies the feasibility of the location method.The simulation is of great significance to the practical detection experiment of partial discharge in theory.Finally,under the laboratory conditions,the model of Cable Partial Discharge defects is designed and the experimental measurement system is built.According to the actual discharge defect of the cable,four discharge modes,namely corona discharge,surface discharge,suspension discharge and internal discharge,were simulated.The discharge characteristics of different discharges were detected and analyzed by using HFCT sensor and ultrasonic sensor respectively.Then,the method of combining the amplitude method and the delay estimation method is used to locate the partial discharge signal of the actual cable accurately.The results show that the cable partial discharge detection device can effectively identify different discharge models and accurately locate them in the laboratory environment,so the device basically meets the design requirements.