Development Of Insulation Diagnosis Device Based On Return Voltage Meaurement

Power transformer is a very important equipment in power system,which mainly takes on the task of converting voltage,transmitting electric energy and distributing electric energy.Only if it runs normally,can the power system be safe,reliable and high quality.By detecting and evaluating the insulation condition of transformer,the operation plan and maintenance plan can be worked out.It is of great significance to improve power transformer utilization ratio,power system reliability and power quality.Return Voltage Meaurement(RVM)is a newly proposed online monitoring method.The diagnostic method is based on the dielectric response principle.It does not need to sample the equipment in the testing process,and it will not damage the equipment.At the same time,it is easy to operate and has strong ability of anti-interference.This makes up for the shortcomings of traditional detection methods.In this paper,the significance of safe operation of power system is expounded,the common methods of transformer fault diagnosis at home and abroad are summarized,and the more mature insulation diagnosis equipment based on dielectric response characteristic is introduced.The research status of RVM in China is further analyzed and introduced.Secondly,based on Debye model,the formula of recovery voltage is deduced,and the influence of charging voltage,charging time and charge-discharge time ratio on the parameters of recovery voltage is analyzed by using Simulink.Thirdly,we design the charging device of the test system,including the design of HVDC power supply unit and switch unit.According to the characteristics of high impedance weak signal and the principle of measurement,the selection of device and the design of test circuit are completed.At the same time,the amplifier circuit and filter circuit are designed.We also propose solutions for shielding,grounding and EMC.Finally,the paper introduces the data acquisition part of the hardware test system of the return voltage meaurement,including AD module,fast storage module DMA and communication module.