| During switching operations in electric power system very fast transient overvoltage occured.With the increasing number of operating voltage,especially the development of UHV technology,the insulation margin of power equipment become reduced.The problem of insulation caused by various kinds of switching transients in power system is increasing,which has become an important issue in the field of international high voltage.Then,the problem of VFTO with high voltage,extremely steep wave front time and lots frequency components can be discussed from three perspectives:a great threat to the security and stability of the power grid,a severe challenge for the development of the power grid and a higher requirement for the present measurement of high voltages.In this paper describes a method for measurement of VFTO based on electric field measurement,design and development high frequency electric field probe.Selected high-frequency digital instrument which named DigitizerNETBOX of German company Spectrum as a data acquisition and transmission development and operation platform.Used NI LabVIEW to program the host computer control system and data processing module development part.Designed a complete solution to achieve the measurement system of VFTO.And tested the system in Yunnan Province,ultra-high pressure experimental base to measure the VFTO of GIS.Contents of this paper are as follows:(1)Detailed description of the recognition of the research background of VFTO measurement,describes the face recognition technology research and system construction,characteristics and development process problems,etc.Compared and analyzed the circuit structure and measurement principle of several VFTO measurement methods.Researched current situation of VFTO measurement technology,compared the advantages and disadvantages of different measurement systems(2)This paper makes theoretical modeling of VFTO,include DC circuits,single-phase AC circuits,substations and transmission lines.(3)Then,make numerical simulation calculation.Proposed a VFTO measurement method based on high frequency electric field probes with greater.This system can be used for VFTO measurements in any scene,the placement for the sensor become more flexible and facilitates,it could be used for different voltage level.(4)This paper designed and developed high frequency electric field probe,explained the principle of the sensor in detail.Selected high-frequency digital instrument which named DigitizerNETBOX.The paper briefly describes the parameters,performance,sampling frequency and data transmission situation of DigitizerNETBOX.The host computer part consist Lab VIEW,spcm lib,TDMS.(5)In order to verify the high frequency electric field probe sensor and VFTO measurement system.This paper designs a comparative experiment of using high-frequency electric field probe and conical sensor of Xi’an Jiaotong University in GIS pipeline at the same time.The experimental results show that the high frequency electric field probe can successfully measxure the VFTO.The sampling frequency is 5GS/s.A complete waveform could be obtained stably.This system can be used for VFTO measurements in any scene,the placement for the sensor become more flexible and facilitates.The collected data can be monitored on-site by wireless transmission and be monitored for long-distance by network transmission.Using a large number of sensors to form a monitoring network to formate large data of the VFTO monitoring application system. |
