Research On Detection Of Ultrasonic Characteristics Of Partial Discharge With Optical Fiber Sensing

Partial discharge is a prelude to the insulation failure of electrical equipment.Therefore,the real-time online detection of the partial discharge is performed,and the partial discharge is recognized as soon as possible and the position of the partial discharge can be quickly and accurately positioned.The safe operation of the power grid urgently needs to be solved.Compared with the traditional partial discharge detection methods,such as pulse current method,UHF detection method,dielectric loss analysis method,radio interference voltage method,etc.,the power cable partial discharge fiber-optic sensing method can achieve longdistance,distributed,Fast real-time detection,and the use of sensor fiber with intrinsic safety,anti-electromagnetic interference,laying a flexible and other advantages for the detection of power cable partial discharge provides a new idea.Partial discharge is common in the operation of power equipment such as transformer,power cable,switchgear,GIS and so on.The partial discharge of power equipment will be accompanied by various phenomena such as electricity,light and sound,which will generate ultrasonic signals.Therefore,in the background of partial discharge detection for electrical equipment,the optical fiber sensing detection method of ultrasonic characteristics of partial discharge was studied.To study the basic theory of partial discharge detection,analyze the generation of partial discharge and its ultrasonic characteristics,qualitatively and quantitatively analyze the relationship between partial discharge and ultrasonic wave,and analyze the characteristics of partial discharge signal and signal transmission through the analysis of power cable line model.The amplitude and frequency of changes in the process.Based on this,an interferometric Sagnac fiber-optic sensing system was set up,and the key components of the system,such as broadband lasers,fiber couplers,photodetectors,and acquisition cards,were analyzed for type selection and generated in the test chamber based on partial discharge.Ultrasonic characteristics,built a model to simulate partial discharge,and completed the design of the upper part of the fiber-optic sensing system based on the ultrasonic characteristics of partial discharge based on the LabVIEW platform.Through the use of standard ultrasonic transducing signals for analysis,the feasibility of fiber-optic partial discharge detection system for detecting ultrasonics was verified,and the spectrum range that can be detected by using fiber optic method was obtained.The directional analysis and sensing of the sensor probes were carried out separately.The analysis of the influence of the number of turns of the probe fiber and the inquiry test of the system sensitivity.Finally,combining with the practical application of the partial discharge optical fiber sensing detection in power cable,the localization method of the fiberoptic sensing detection of the ultrasonic characteristics of the power cable partial discharge is studied.The straight-line Sagnac interference type and dual-loop Sagnac interference partial discharge detection positioning is studied.The principle and algorithm,and analysis of the positioning test results.The test shows that the linear Sagnac interferometric partial discharge detection system based on the zero-frequency localization method has a lower cost and meets the positioning requirements.It can provide an effective basis for the partial discharge detection and power overhaul of long-distance power cables,eliminate fault points in time,and reduce Maintenance time.