Research On Portable Detection Device Of Transformer Winding Fault Based On Impulse Frequency Response Method

Power transformer is one of the core equipment in the power plant/substation.The health of the transformer will directly determine whether the power system can steable and reliable supply.Transformer winding deformation fault is one of the common faults of the transformer.At present,the running state evaluation of the winding can only be carried out under the offline conditions.It cannot meet the development requirements of the electrical equipment live detection and intelligent diagnosis.Therefore,if we can detect the transformer winding deformation mastering its running state real-time,the transformer condition maintenance could be carried out purposely.It have a great significance for ensuring safe and reliable operation of the transformer and facilitate the construction of smart grid.The impulse frequency response method has the advantages of high SNR,low cost and less impact on the normal operation of the system having a good application prospect.However,the method of real engineering applications still need to solve a series of scientific and technical problems,such as impulse signal lossless injection,accurate measurement of response signals,stable and reliable impulse generator development and real-time evaluation software development.To this,this article developed portable detection device can be applied to the transformer winding fault detection.The basic principle of the impulse frequency response method is described.The signal injection and collection devices were designed and their performance were tested.A transformer winding deformation portable live detector was developed illustrating the design scheme and testing its performance.The transformer winding deformation faults were designed verifying the validity of the designed device.The main conclusions of this thesis are as follows:(1)Designed a set of signal injection and acquisition devices to achieve the signal lossless injection and measurement.The capacitive coupling sensor was designed based on the principle of capacity coupling.The simulation model of the sensor and bushing were built in COMSOL infinite element software analyzing the effect to electric field distribution of bushing when the sensor was installed.The withstand voltage test was doing verifying that installation of the sensor will not affect the safe running of the bushing.Signal injection/ protection device was designed and implemented signal excitation without prejudice.At the same time,to protect detection device the power frequency high voltage was filter out.The capacitive coupling voltage divider was designed and the response signal was acquired in live diction.The frequency band was obtained by experiment.(2)A stable and reliable,intelligent control of the portable detector was developed.The solid-state nanosecond impulse generator was designed based on the FPGA realizing amplitude,width and repetition of excitation impulse signal controllable.The signal acquisition circuit was designed having dual channel acquisition function at the same time.The intelligent control of signal acquisition was realized based on FPGA.According to the design requirements,the corresponding man-machine interface was designed,realizing the intelligent control to portable detector.The working performance meet the design requirements verified by the performance testing.(3)The transformer winding deformation faults were carried out in laboratory.Designing the typical transformer winding deformation faults,the experiment verifies the available of detection device and portable detector.At the same time,the influence of different winding deformation faults on frequency response characteristics were preliminary analyzed.