Design Of Intelligent Control System For Power Transformer Cooler

As the core equipment of the whole power system,power transformer plays a key role in the connection,transmission and distribution of electric energy.The operation life of transformer is closely related to its internal temperature,so the performance of transformer cooling control system is very important to its normal operation.Based on the analysis of the existing transformer cooler control system,there are some problems such as single control strategy,high energy consumption and failure rate of the cooler,and the cooling capacity transition is not smooth,which are difficult to meet the requirements of the existing intelligent substation operation and maintenance system.In response to these problems,the 500 k V transformer cooling system in a northern province was investigated and analyzed,and the Oil Natural Air Forced(ONAF)transformer,which was the most used transformer,was selected as the object of this study.First,the control strategy of transformer cooler was designed.The hardware and software of the control system based on dual CPU PLC are designed.Firstly,the calculation model of heat dissipation and temperature rise of oilimmersed air-cooled transformer is established.For oil immersed natural air cooled transformer,different internal heat dissipation modes are studied.Heat conduction,convection and radiation are analyzed and calculated respectively,and the calculation model of transformer loss and heat loss is established.Further,the windings,the average and the top layer temperature rise of the transformer are calculated,and the relevant factors affecting the transformer temperature rise are explored.The transformer temperature rise model is obtained,which provides a basis for the improvement and optimization of the control strategy of the cooler.Then,the control strategy of transformer cooler is studied.Based on transformer operation and maintenance experience and related operation and maintenance rules,aiming at the problem of high energy consumption of the existing cooler control system,a strategy was designed to select different control modes according to the top oil temperature interval.Aiming at the problem of unbalanced input of coolers in the existing coolers control system,the intelligent rotation switching mode of cooling fans was proposed.Aiming at the problem that the existing three-position control system has poor control effect on the transformer temperature control system,combining the fuzzy control,PID control and neural network control methods,the cooler controller with adaptive function is designed,and the function of controlling the input quantity of cooling fan by the top oil temperature is realized.Finally,the software and hardware design of transformer cooler control system is completed.Based on the above control strategy,the hardware equipment selection and design are carried out.The design of hardware redundancy configuration and related components of PLC is emphasized,and the site installation layout is designed.Further,the software design of the control system is completed,which mainly includes the design of the main program of the control system,the fuzzy control program of the cooling fan and the intelligent switching subroutine of the fan,and the design of the humancomputer interaction interface with monitoring function,so as to realize the fuzzy control and intelligent switching of the cooling fan.In this paper,the intelligent control system of main transformer cooler is designed based on the multi-type problems encountered in transformer field operation and maintenance.The system has the advantages of high intelligence,flexible and convenient control,smooth temperature change and so on.It can provide reference for the design of new equipment and the transformation of old equipment.