Detection Method And Realization Of Corrosion State For Grounding Grids

Grounding grid of the substation plays an important role in the safe and stable operation of the electrical power system.However,the corrosion of the grounding grid is inevitable due to the fact that the grounding grid is buried in the soil all the year round.Thus,it is very urgent and important to detect the corrosion state of the grounding grid and know the corrosion state of the grounding grid in time.At present,many technologies can be used in the comprehensive detection of the grounding grids,but most of them are not effective enough.Therefore,it will be the main development trend and direction in the future to develop a device that can realize the intelligent detection of the corrosion state of the grounding grid and provide advanced and practical solutions for the operation and maintenance of the grounding grid.By analyzing the characteristics and weaknesses of existing detection approaches in grounding grids,a new method which combines the galvanostatic transient detection and adaptive wavelet filtering algorithm is proposed to measure the corrosion state of grounding grid.First of all,the three-electrode sensors are used to simulate the corrosion of grounding grid.Then the method adopts galvanostatic transient measurement technology to obtain the corrosion rate and annual average corrosion depth,so as to characterize the corrosion condition of the grounding grid.Meanwhile,considering complex interference factors in the grounding grids,an adaptive wavelet filtering algorithm based on wavelet transform is proposed.The maximum signal-to-noise ratio is used as a metric to adaptively determine optimal number of decomposition layers in wavelet decompositin,and an adaptive threshold selection method which introduce layered adaptive factors into global thresholds is used to dynamically adjust threshold of each decomposition layer,and thus to achieve more reasonable signal decomposition and denoising.The algorithm filters out interference signals effectively and improve the accuracy of the test results.Furthermore,based on the above methods,an intelligent detection system composed of upper and lower computer system is designed.The lower computer system uses the STC8A8K64S4A12 microcontroller as the hardware core,and the peripheral hardware is composed of six module,namely,resistance measurement,transient measurement,signal amplification,hardware filter,communication,and power.The upper computer system uses the Android platform as hardware carrier and is developed from Android Studio software platform.The system uses Java languageas the development language,and includes five subsystems,namely,command control,data collection,data processing,human-computer interface and communication.Meanwhile,serial communication is realized between the upper computer and the lower computer according to the self-written communication protocol.Finally,the laboratory simulation test and field test are carried out for the developed intelligent detection system of grounding grids.The accuracy of the detection results and the feasibility of the detection method of the intelligent detection system are verified through detailed data,which provides a comprehensive,fast,accurate and advanced measurement tool for the realization of the regular detection and safety maintenance of the grounding grid.