Fuzzy Control System Design Of Transformer Cooler

Both core and winding can generate energy losses which will change into heat when the transformer is at run-time. The heat will make the temperature of the transformer higher, consequently quicken the transformer's ageing and reduce the transformer's service life. Therefore the transformer must be equipped with cooling devices. The oil-immersed transformer is the most widly used whose cooling mode includes natural draft(air) cooling, forced-air cooling, forced-oil–air cooling. The relay system which is used in the traditional transformer's cooling control, usually has complicated wiring, multifarious components and many fault points, what is more, it can only work at the commercial frequency which will cause unnecessary electrical waste when temperature rise is not high.This dissertation discusses the orced-oil–air cooler at length, and designs a new cooling controller. Firstly, the paper reviews the traditional PID temperature control system, which employed the top oil-temperature as input and the PID controller to make the cooler on-off. This control mode was better in the function of automation and communication, but on the other hand, it can not resolve the noise problem when the cooler was at startup and can not change frequency smoothly. In consideration of the nature of the temperature control system, Mamdani fuzzy system is proposed, which uses both top oil-temperature and current load as inputs, Siemens S7-300 PLC as processor to change the output of the frequency converter to control the cooler. The frequency converter may help lower the noise and reduce the losses of the electrical energy and make the cooler soft start.To meet to the demand of the transformer's intelligent control, the cooling controller supports remote/local function, automatilc/manual function, and the paper also designs a cooler minitoring system, which makes use of Siemens Wincc 6.0 as development software of the host computer, Siemens S7-300 PLC as the lower computer, PROFIBUS as the communication standard. This system is comprised of printing reports, on-line monitoring, data archives, alarm, historical data inquiry and so on, which will improve the reliability of the cooler, decrease maintenance and consequently a more effecient factory management will be achieved.