Grounding Grid Detector Prototype Development Based On Broadband Electromagnetic Method

The substations need to be protected by the grounding grid during its operation.Grounding grid can protect the substation staff and a variety of substation power transmission equipment.Both power grid department and electric company give sufficient research and attention to the grounding performance of the substation and equipment.The grounding grid is susceptible to corrosion problems during operation.Especially the steel material of the grounding grid,if it is corroded to a certain extent,grounding resistance will increase.In the event of lightning or overvoltage,it will be easy to damage the staff and equipment on the station.In the case of normal substation operation without affecting,accurate detection to grid structures is of great importance for subsequent fault diagnosis and periodic maintenance of the grounding grid.The common ground grid detection methods at present include electrical grid analysis method,electrochemical detection method,and electromagnetic field detection method and so on.Broadband electromagnetic method is based on electromagnetic induction principle,and its detection mode is safe,efficient and fast.So the development of broadband grounding grid detection equipment has practical significance.Based on the advanced instruments of foreign countries,this paper designed a broadband grounding grid detector on DSP platform,and realized the production of transmitting and receiving prototype.The transmitter uses the DSP data processing platform to generate the high precision PWM signal.The signal went through the level isolation and the driving circuit to control the MOSFET in the inverter circuit,leading to generate the fixed frequency sine wave in the transmitting coil.The receiver using of high-precision AD sampling chip,receive the secondary field signal through the pre-amplifier circuit and the signal filter circuit.The signal was stored in the SD card and transmitted to the host computer for processing.The design and implementation of the system software part was mainly based on DSP,MCU and PC software programming,including the pulse signal programming,DSP and analog conversion chip data transfer DMA design,the initial extraction and calculation of the signal,interactive interface of the launch part and single-chip SD card storage design.MATLAB software was also used in the design to compile a program in the host computer.Finally,the transmitter and the receiver were tested to verify the correctness of the design.In the laboratory,the detection test of the metal body and the grounding grid were carried out.The validity of the design was verified by analyzing the test data.