Design On The Electromagnetic Environment Of Power Frequency Monitoring System In Substation

With the rapid development of China’s economic construction and theimprovement of people’s living standards, the demand for electricity is also increasing,and the power enterprises speed up the construction and development of China’shigh-voltage transmission lines and substations. The voltage level of powertransmission project increased from the previous110kV,220kV to a high-voltage of500kV,750kV or even1000kV.These substations supplies the city with electricity,while the consequent electromagnetic pollution disturbs the neighboring inhabitants.Long-term excessive amounts of electromagnetic radiation, will lead to peoplenervous breakdown, increased risk of tumors and such problem. In this paper, a newelectromagnetic environment monitoring system of industrial frequency ofsubstations is designed by comparing the measurement principle and method of thepower frequency electric field and power frequency magnetic field. The mainresearch contents are as follows:(1) A research on power frequency electric field has been done, and the parallelplate-style electric field which based on electrical measurements has been deeplystudied. By calculating the parameters of the selected materials and deducing theories,the proportion of the output of parallel plate sensor and the frequency electric fieldintensity in environment is acquired, furthermore, the after effects of the externalmeasuring capacitance are reasoning. A research on the method ofMagneto-resistance measurement has been done, and then the proportion of theoutput of Magneto-resistive sensor and the power frequency magnetic field intensityis acquired by deducing the principle of anisotropic magneto-resistive sensor which isused for measuring the power frequency magnetic field intensity.(2) Based on the deep analysis of the measuring principle of the powerfrequency electric field, power frequency magnetic field and the audible noise, ascheme which involves selecting the system sensor, signal conditioning circuits,power circuits, communication circuits and other hardware circuits is designed indetail. In addition, the external circuit of temperature sensors，humidity sensors andpressure sensors are selected and designed.(3) Then program modularly for the temperature/humidity sensor, air pressure sensor, and design the corresponding AD program of Single chip microcomputer.Using c#programming language designed receives the display program.(4) After hardware debugging and software design, and the monitoring systemare overall debugging, including receiving display and communication test. Then usethe characteristics of structures of standard power frequency electromagnetic field tocreate the test environment and then use this standard calibration to verify thesensitivity and linearity of the monitoring system device. Finally, commissioned bythe Zhejiang province electric power company, on-the-spot investigation of asubstation is carried out, and the system application in the field.