| The stable operation of the power system is the guarantee for people’s normal life.It is very important to prevent and repair electrical equipment.However,due to the shortcomings of traditional preventive maintenance,such as long time period,high cost,and large-scale power outage,normal operation cannot be guaranteed.With the improvement of automation technology,the maintenance methods of high-voltage equipment in power systems are also constantly improving.State maintenance is an inevitable trend in the future development of electrical equipment maintenance technology.The real-time data of online monitoring of electrical equipment is the main basis for state maintenance.The metal zinc oxide arrester is used as a protection device for eliminating overvoltage in the power system,and online monitoring is an inevitable requirement for ensuring the normal operation of the power system.According to the simplified circuit of the metal zinc oxide arrester,the relationship between the fault of the arrester and its current is analyzed.Several methods of online monitoring of the arrester are introduced,and the advantages and disadvantages of each method are analyzed.Considering the aging or tidal resistance of the arrester,the characteristics of the resistive fundamental current and the resistive third harmonic current are increasing differently.The voltage and current of the metal zinc oxide arrester are separated by harmonic analysis method,and the required resistive fundamental current and resistive third harmonic current,are obtained,monitoring their changes.With the single chip STM32 as the core of the control unit,the online monitoring hardware circuit of metal zinc oxide arrester is designed,including precision current transformer and voltage transformer,small current amplification,I/U conversion and protection circuit,and several kinds of filtering are compared through simulation circuit,the Butterworth filter circuit is selected to filter the voltage and current signals.Secondly,the level lifting of the voltage and current signals is designed to meet the input requirements of the subsequent units.The voltage and current signals processed by the conditioning circuit are passed through the STM32.After the A/D conversion,the signal is transmitted to the host computer(PC)using RS232.Based on the LabVIEW platform,the software system for online monitoring of metal zinc oxide arrester is designed.The system realizes the functions of data processing analysis,data storage,history waveform query,fault record and network transmission,and the metal zinc oxide arrester judge,moisture or aging.The signal generator is used to verify the feasibility of the hardware circuit and joint test of the software and hardware system.Then the lightning arrester model is built by Matlab/Simulink,the model is called in LabVIEW,and the simulation operation is performed to verify the performance of the software system for data processing. |
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