Research On Voltage Measurement Device Of ±1100kV UHVDC Voltage Transformer And Its On-line Monitoring System

DC voltage transformer,composed of primary DC voltage divider and secondary voltage measurement device,is the core equipment in measuring,monitoring,controlling and protecting of UHVDC transmission.In practical operation,the voltage signal of the DC voltage measurement device belongs to weak signal,and it is easily distorted in the case of harmonics and electromagnetic interference.As the interface part of photoelectric conversion,the distortion of electrical signal will directly cause the failure of photoelectric conversion and transmission and the protection misoperation.In addition,the working conditions of DC voltage transformer directly affect the operation performance of the entire DC transmission system,abnormal outage occurs due to the deterioration of DC measurement equipment's performance.In order to solve these problems,the following research is carried out in this paper.Firstly,based on the analysis and comparison of different implementation methods of DC voltage measurement,the basic principle of resistive-capacitive divider of DC voltage transformer is established.Combined with relevant standards and requirements,the overall research scheme of the DC voltage transformer is designed from three aspects: DC voltage divider,DC voltage measurement device and on-line monitoring system.Secondly,the DC voltage measurement device with multiple output,redundant configuration and strong anti-interference ability is designed and developed by the combination of simulation analysis and test,which realizes the standardization and digitization of DC voltage transformer's output signal.Then,based on the operation experience,simulation and measured data,±1100kV UHVDC voltage transformer on-line monitoring system,including multi-sensor and multi-feature information fusion module,fault waveforms storage and judgment module is proposed,which reflects the objective state of voltage transformer online and accurately.Finally,the performance test of the developed DC voltage measurement device and on-line monitoring system is carried out.The related tests include accuracy,temperature cycling accuracy and electromagnetic compatibility.The experimental results show that the accuracy of the DC voltage transformer is measured by the voltage comparison method,the accuracy of the analog and digital channel can meet the requirements of 0.2 class within measuring range and the linearity is 0.02% and 0.04%.At-20?~+40?,the error of DC voltage measurement device in temperature cycling accuracy test is within the allowable range;11 electromagnetic compatibility test results of DC voltage measurement device and on-line monitoring system have reached A level,that is,the function of device is normal.