| Power transformer is the most commonly used distribution equipment.Power transformer runs over load frequently will cause insulation damage and security risks,power transformer online monitoring system based on the composition and concentration analysis of dissolved gas in oil,can real-time monitor the working status of running transformer.It not only is helpful to substation automation,reduce patrol and maintenance,but also can prevent and reduce transformer failure through real-time monitoring.This paper has done the following work:(1)Describes the background and significance and domestic and international research status about the gas dissolved in power transformer oil online monitoring system,summed up the relationship between power transformer common fault type and the concentration of dissolved gas in power transformer oil.Combining the gas dissolved in power transformer oil online monitoring system with the fault type diagnosis,It has analyzed the relationship between the two subjects,and proposed an expert diagnosis algorithm.(2)Explained the concepts related to the gas chromatography.Explained the working principle,advantages and disadvantages of some common gas sensors.The design of the hardware circuit and gas circuit of the chromatographic instrument is completed.The selection of some hardware components is pointed out.Finally,all the modules are integrated on the same board.Finally,the chromatographic instrument software is designed.It has realized the program control of motor rotation and electromagnetic valve action,temperature control,and PC communication.It has realized chromatographic data acquisition and analysis,communication between chromatographic instrument program and PC program,data transmission between PC and chromatographic instrument.(3)The PC software of online monitoring system is designed,it can online monitor the gas composition and concentration of power transformer oil.The dynamic chromatogram can be displayed on the computer,and the historical data can be automatically saved for future reference.The PC software has the functions of chromatograms management,chromatograms collection and display,chromatograms processing,making sure quality and quantity,result output,automation,help and so on.The PC software also has the RS485 communication function.The hardware of the chromatographic instrument is mainly responsible for data acquisition,and the key to data acquisition is the number of bits of analog to digital conversion.The higher the number of bits,the higher the conversion accuracy.The sampling speed and accuracy of ADS 1246 is very high. |
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