Design And Research On Equipment Evaluation System Of FTU In Distribution Network

With the development of national economy and the improvement of people's living standard,the demand for power system quality is increasing.According to the State Electricity Regulatory Commission statistics,in China,more than 90% power system fault occurs in the distribution network.Therefore,in order to improve the stability of the distribution network,it is very important to test feeder terminal unit before leaving factory.This paper focuses on the research of the feeder terminal unit(FTU)of pole-mounted switch in 10 kV distribution network,and the equipment evaluation system of FTU in distribution network is designed,which can be used in the factory inspection and function detection of FTU.In this paper,based on the research of feeder automation technology in distribution network at home and aboard,according to the function of FTU and characteristics of virtual instrument,the testing process of evaluation system is analyzed,the detection scheme and test algorithm of FTU equipment evaluation is studied in depth.In this paper,LabVIEW is used as test platform development tools,the characteristic of the LabVIEW data flow programming is utilized in this design,logical order and specific algorithm of all FTU functions is studied,the sub-VI(Virtual Instrument)which can test all functions of FTU is programmed,the target of testing all FTU control and protection functions is achieved.The LabVIEW producer-consumer mode programming is studied,and the overall program framework of virtual instrument is designed.Using RS485 serial communication,the data exchange between FTU and host computer is realized.A combination of Microsoft SQL Server and LabVIEW is used in this design to create the data base,aiming to storage and call the test results.To improve the accuracy of program and reduce the measurement error,the digital signal processing algorithm is designed and optimized.On the side of hardware,to build signal acquisition and signal conditioning circuit,and collect the electric voltage and current signal of FTU,data acquisition card produced by the National Instruments is used in this design.To collect the opening and closing signal,optocoupler isolation circuit is designed.Experimental device is used to generate overvoltage and over current in the laboratory,simulating the real operating environment of FTU,monitoring the operation status of FTU,in order to test the protect and control functions of FTU such as over current protection,multiple reclosing,inrush current inhibition.A high degree of automation,convenient and practical FTU equipment evaluation system is designed in this paper.The experimental results show that the test of protection and control functions of FTU can be completed,improve the degree of automation.