Research And Development Of Online Monitoring System Of Low-voltage Switch Cabinet

In 4.0 industrial era,our country is vigorously developing intelligent manufacturing technology,"Internet plus" technology and big data technology,these new technologies can’t be implemented and applied without the support of stable and reliable electric power support.The low-voltage switch cabinet is the key link of the power supply side and the electric power transmission,it is very important to monitor the changes of power parameters and the quality of power supply.This paper takes low-voltage switch equipment in smart grid environment as the research background,according to the IEC standards and national standards,innovatively proposes TMR magnetic sensor and Holzer type voltage sensor for real-time voltage and current measuring device,and on-line monitoring system of low voltage switch cabinet with embedded ARM as the core,basing on careful analysis of the research status of intelligent low-voltage switch equipment at home and abroad.This system makes the low-voltage switch cabinet more automatic and more intelligent,so that it can meet the various requirements of the future development of smart grid.The main contents of this paper include the following five aspects:(1)The topological structure and mathematical model of the measurement are designed according to the principle of measuring the current of the TMR magnetic sensor.According to the requirement of the dynamic real time system,the paper analyzes the basic principle,structure and AC signal acquisition method of high speed data acquisition system.(2)According to the actual situation of the system,the power quality algorithm is simplified,after reading through the relevant indexes of power quality and the range of accuracy.The influence of leakage and interference can be controlled by using the FFT algorithm when measuring harmonics and other parameters(3)The paper establishes hardware solutions by building the experimental hardware platform,then designs each module of the device selection and hardware circuit,including the signal acquisition and processing module,the main control module ARM board electrical design,finally,it carries out the PCB design of the hardware system.(4)The paper sets up experimental system software platform,and carries on the modular design to the functional program by using ARM to develop ADS1.2 system monitoring program,including data acquisition and processing module,abnormal alarm module,data display module,data communication module.It uses Studio C# Visual to develop human-computer interaction to achieve real-time display of power quality parameters.(5)Based on the analysis of interference sources,transmission and monitoring system of sensitive equipment,the paper simulates the magnetic field distribution of the switch cabinet bus bar by the ANSYS simulation,so it proposes the hardware and software anti-interference measures purposely.In the operation and debugging of the system,the relative error of the voltage measurement is not more than 0.58%,the current measurement error is not more than.8%,reaching the design standard of the 0.5 level accuracy.Compare measuring result of the measured power quality parameters of the monitoring system with that of high precision Fluke437 power quality analyzer,and it controls the error within the scope of the national standard,which is proved that the system can meet the high precision and real-time requirement of power quality monitoring.