Research And Design Of Transformer Dc Bias Monitoring System

The stability of transformer is seriously affected by dc magnetic bias.Dc magnetic bias will lead to the increase of transformer vibration,temperature rise and more serious power harmonics.Urban rail transit will generate a dc component.The DC component takes the earth as the conductor,passes through the neutral point of the transformer and finally returns to the transformer,affecting the transformer.This subject mainly completes the transformer dc magnetic bias monitoring system design.The modularized integrated sensor is used to measure the neutral current of transformer.The power quality monitoring module is used to measure the power harmonics of the three-phase electricity measured by the transformer.Zig Bee wireless sensor is adopted to measure transformer vibration and temperature parameters.Adopt 4G wireless communication mode for long-distance data transmission,Using embedded integrated touch screen to realize man-machine interface interaction.This design adopts modular design scheme.It reduces the structure and complexity of the system,improves the function of the monitoring system,reduces the cost and improves the availability of the system.Firstly,the thesis introduces the background and significance of the topic.It analyzes the cause and harm of dc bias of transformer.It actually measured the transformer central point current of the urban rail transit in dalian area.It analyzes the current dc magnetic bias problems in the region and gives some Suggestions.On this basis,it puts forward the design of transformer dc magnetic bias monitoring system and determines the design requirements.By comparing and analyzing the shortcomings of the traditional dc magnetic bias monitoring system for transformer,and combining with the specific application requirements in this design,the overall design scheme of the system is put forward.On the basis of the overall design scheme,the design of each functional unit of the system is improved.The device selection and circuit design of each unit are analyzed in detail.The circuit of each unit based on STM32F103VET6 processor is drawn.Finally,the paper completes the design of the software unit and the function test of the system.The software system is divided into upper level monitoring system unit and field embedded software unit.The upper monitoring system software is divided into presentation layer,data analysis layer and data storage layer according to MVC pattern.According to the different functions of the field detection unit,the embedded system software is divided into different subroutines.The function test of each hardware unit of monitoring system is discussed.Based on the completion of the test,it analyzes the neutral point current test and the overall running test of the system.Through the test,it can be known that the overall function of the system is realized,and the high performance can meet the use requirements of the system.At last,the influence of urban rail transit on dc magnetic bias of transformer is analyzed.