Monitoring Of Traction Transformer's Electrical Life And Its' Implement In PSMIS

Traction transformer is one of the most important electrical equipments in traction substation. The status of traction transformers directly influences traction power supply system's stability and reliability. So the on-line monitoring of transformer's electrical life is great significant for its condition based maintenance.The transformer's structure, losses and the factors that influence the electrical life of transformer are discussed. The three methods, directly measuring method, thermal model method and indirectly calculating method, to acquire transformer's winding hot-spot temperature are compared, and the indirectly calculating method is seemed to be more fitter. The paper demonstrates two calculating method, one is the method recommended by IEC354, and the other is the method recommended by IEEE Std.C57.91. There are two shortages in IEC354 and IEEE Std.C57.91. First, they do not consider the affection of transformer's oil and winding losses change caused by temperature. Second, they do not consider temperature delay caused by the transformer's internal structure, which appears when the load changed. The method proposed by Linden W. Pierce is adopted in the simulation, because it conquers the forward two shortages.The method given by Linden W. Pierce is used as the simulation model in the paper. The affection of transformer's oil and winding losses change caused by temperature is analyzed. The paper compares the Linden W. Pierce's method and IEC354's method in two conditions-load increase and decrease. The difference of the values of steady and transient hot-spot temperatures calculated by the two methods and its reason is analyzed too.The implement of monitoring of transformer's electrical life in PSMIS is described in detail. The implement is complemented using three-tied framework of Delphi Midas 3.0.