On-line Monitoring System Of The Dry-type Transformer Winding Based On Inverse Problem Model

With the development of the technology,the dry-type transformer can satisfy the actual demands in capacity?environmental protection?fire proportion?space and more other aspects. So that the proportion of the dry-type transformer in transmission and distribution network is increasing year by year.Therefore it is very important to ensure the stable and reliable operation of the dry-type transformer to maintain the stable operation of the transmission and distribution network.Overloads ? local insulation damage and other reasons can lead to thermal anomaly of the winding,if not treated in time,when the temperature reaches a certain limit,it will lead to insulation damage or breakdown and even other serious consequences such as transformer explosion,thus causing local or a wide range of power outages.Therefore it is of great importance to monitor the temperature distribution and the hot spot temperature of the transformer.The heat transfer and heat dissipation process of the dry-type transformer are described in the paper firstly. Simplify the process properly and combine the inverse heat transfer theory,the mathematical model of three-dimensional heat transfer inverse problems identification is established.The processes of the model are as follows:estimate the heat flux density of the inner high voltage winding through monitoring the temperature of the outer high voltage winding,which can accurately identify the temperature and space position of the hot spot of the low voltage winding.And then,based on the model,the research on PSCD/500 dry-type transformer winding temperature distribution and hot-spot temperature when the transformer is under different loads has been done.Compared with the calculation results bythe“dry-type transformer load guide”,the error is not more than 2%.The accuracy of the model is proved to be high, which provides a new method for obtaining the hot spot temperature of dry transformer.Finally,a set of on-line monitoring system for winding temperature is built.In order to ensure the accuracy of on-line monitoring system,on the hardware front,comprehensive consideration of various factors,S101 infrared temperature sensor is selected;on the software front,as the distance influential factors of the infrared temperature sensor is not negligible,so compensation is necessary.The distance correction formula is obtained by using the proportional error factor,and the error is compensated in software.In the end, the accuracy of the on-line system is verified at different distances,after verification the system is applied to the research on the temperature measurement of the dry-type transformer.