Study On Monitoring And Analyzing Of Multichannel Power-Frequency Electric Field Based On FPGA

With the fast development of civil economy,power loads in cities become greater by and by,as high-voltage transmission and transfer devices provide power for cities,electromagnetic field they produce also brings lots of electromagnetic pollutions,which not only affect normal working of electrical devices around them,but also endanger people's health and security.So the influence and restrain of electromagnetic pollutions must be taken into account during the laying of high-voltage aerial transmission lines and the design of transformer substations.For the purpose of ensuring people's health and security,maintenancing safe operations of power networks,providing a measurement about real-time monitoring to electric field environments around high-voltage aerial transmission lines and transformer substations,here we design a suit of multichannel monitoring and measuring instruments of power-frequency electric field environments after studying the monitoring and analyzing methods to electric field environments around high-voltage aerial transmission lines and transformer substations , which can measure multi-spots power-frequency electric field's characteristics around high-voltage aerial transmission lines and transformer substations,and circumjacent environments such as temperature and humidity,process and store those data,send them to host PC for analyzing and studying,give some advices for the laying of high-voltage aerial transmission lines and design of transformer substations.Here we expatiate the monitoring and analyzing method about mulitichannel integrative power-frequency electric field environments,a series of designes of interface and display circuits and UART based on VHDL and Quartus II,the design of man-machine interface to host PC SCI based on VC++/MSComm and the method of calibration and usage of power-frequency electric field measurement instruments.An instrument of spherical dipole antenna is adopted during the measurement of power-frequency electric field strength,which converts electric field signal into voltage signal,then by V—f transform and measuring the frequency,we can get the real value of electric field by looking up the frequency—electric field relational table which we got it by calibrating.We get the temperature & humidity through a digital temperature & humidity sensor,which adoptes a protocol similar to I2C.Taking advantages of Quartus II and VHDL,we designed frequency measurement circuit,frequency—electric field relational table and display circuit,temperature & humidity sensor interface,large dense serial flash interface,and accomplished UART with the host PC.ALL those are realized in the Cyclone FPGA chip—EP1C3T144C8 of ALTERA corperation and work successfully and efficiently.We can access those measured data stored in the flash,calibrate the value of temperature & humidity,and store them in a given format by using VC++,MSComm and RS232 UART,then we can analyze and study them,and get some advices.The calibration to the spherical dipole antenna is key to ensure the measurement precision of power-frequency electric field.By calibrating in high-voltage lab , we can get the frequency—electric field relational table.After testing the whole instruments unitedly , we can measure power-frequency electric field strength according to the national standard.