The Transient Process Analysis On Subsection Layer Type Winding Model

When the transformer is in the operational process, it will be effected by varioustransient overvoltage, which will be great harmful on the transformer windinginsulation. Therefore, the study of variable pressure winding transient process will begreat significant on the transformer safely operation. In order to research the effectsof the transient overvoltage on the transformer winding insulation, this paperestablishes the reasonable equivalent circuit model of transformer winding, andanalyzes layers electromagnetic induction process, then it builds matrix differentialequations according to the equivalent circuit model. It calculates the potentialdistribution and gradient distribution of transformer winding based on the transientvoltage. And then it rationally designs of transformer winding insulation, which willguarantee the transformer safe and reliable operation. The finished work are shownbelow:1. It products section layer type winding model. This model is divided into foursections, each period of five layers, with each layer for a unit, and it consists of20units. According to the structure characteristics of the model, this paper buildsequivalent circuit. Through the equivalent circuit, it analyses the electromagneticinduction process of section layer type winding model.2. Through the matrix analysis of section layer type winding, it gets the matrixequations. Then it gets the matrix differential equations of section layer type windingequivalent network by the matrix equations.3. It solves the matrix differential equations by generalized eigenvalue andeigenvector method, and it works out the transient process of the model equivalentcircuit. It exerts lightning stroke simulation signal and VFTO simulation voltagesignal，which apparent wavefront time is10ns and amplitude is450V, respectively inwinding equivalent circuit first terminal, the unit5node and middle part. Then itcalculates each unit node voltage waveform, and fits potential distribution andgradient distribution along the winding according to each unit node voltagewaveform. 4. Some test equipments such as GMY-1type high voltage pulse source, aretested in the section layer type winding each unit node voltage waveform under thecondition of VFTO voltage signal. The voltage wavefront time is10ns and amplitudeis450V. It fits potential distribution and gradient distribution along the windingaccording to each unit node voltage waveform. Then it analysis the effect of windingmodel transient characteristics with iron core, and it compares experiment andsimulation results, which are in good agreement.