Research On Engineering Algorithm For Winding Hot Spot Temperature Rise For Power Transformer

Power transformer is one of the core equipment in power system,if winding hot spot temperature rise is too high,it will possibly produce local overheating and shorten the service life.Then it will affect the stable operation of the power grid.The temperature rise calculation is a hot topic in the field of domestic and foreign electrical technology.The main difficulties are the uncertainty of location and the complexity of the reasons for hot spot.The calculation method recommended by GB 2008 is widely used.The Hot-spot factor is a crucial thermal characterization parameter,but GB only gave several recommended values,and not made a detailed explanation and calculation method.Firstly,a reasonable 2D model of large power transformer is established by using the finite element software MF2 D,the distribution characteristics of leakage magnetic field and eddy current loss were analyzed.Using the uneven distribution characteristics of winding loss,the calculation method of Hot-spot factor was refined from two aspects of heat and cooling efficiency,and the engineering algorithm for winding hot spot temperature rise for oil-immersed self-cooled transformer was obtained.Second,the rationality and applicability of the engineering algorithm was tested by typical transformer products.On this basis,the causes of error and reasonable value range of the Hot-spot factor was analyzed and discussed.The calculation method of Hot-spot factor was established,and it provided a reference method of engineering calculation for winding hot spot temperature rise.Finally,the software was developed with high level programming language,which facilitated the real-time calculation of winding hot spot temperature rise for power transformer.Based on the comparison and analysis of the differences between GB 1994 and2008,the validity of the software was checked and the advantages of the new standard calculation model was summarized.