Research On The On-line Detection And Location Method Of Switchgear Cabinet Based On Linear UHF Sensor

Partial discharge(PD)is an important characterization of insulation deterioration of high voltage electrical equipment,and it is also an important reason for the final insulation breakdown of equipment.Therefore,the detection and location of partial discharge power supply is an effective means to avoid insulation breakdown failure,which can reduce the failure probability of distribution equipment.As a key component of power system,high voltage switchgear has been widely used in transmission and distribution network,which plays the role of switching,controlling and protecting electrical equipment.Its reliability directly affects the quality and safety of power supply in power system.On-line partial discharge detection and location of switchgear can detect faults and hidden dangers in time,which has guiding significance for further inspection and maintenance of inspectors.Ultra-high frequency(UHF)electromagnetic wave detection method for partial discharge has obvious advantages of high detection frequency and small external interference signal,which can realize the detection and location of partial discharge power supply in high voltage switchgear.In this paper,aiming at the problems of high sampling rate,large data storage,limited equipment acquisition channel and unknown propagation characteristics in the traditional switch cabinet partial discharge positioning,and combining with the characteristics of large number and wide distribution of switch cabinets,a new partial discharge online detection and positioning system based on UHF sensor array is proposed.The system uses the coaxial cable to connect the sensors in series to form a linear array,and uses the envelope detection circuit to reduce the frequency of UHF partial discharge signal.Finally,the cross-correlation time delay estimation analysis is carried out to realize the localization of the partial discharge signal source,so as to realize the partial discharge detection and localization of multi-sided switch cabinet two channels.In this paper,the propagation velocity and attenuation characteristics of coaxial cable are simulated and analyzed,and then the envelope detection circuit is designed according to the characteristics of partial discharge UHF signal.The performance of the designed circuit is tested and analyzed.Finally,the on-line detection and positioning system of array partial discharge is designed,and the partial discharge detection and positioning experiments are carried out in the laboratory.The results show that the system can simultaneously detect and locate the partial discharge of 8 switchgears,the maximum calculation error is 0.557 m,and it is scalable.It is finally proved that the system can meet the requirements of on-line detection and positioning of partial discharge signals in switchgear,and it lays a foundation for the field application of the system.