Simulation And Software Analysis Of Wave Process In Winding Of SFSZ11-180000/220 Power Transformer And Software Verification And Analysis

Transformer is one of the vital electrical equipments in power system.In last few years,transformers with on load tap changer(OLTC)have been widely applied in power system.Along with the wide application of transformer with OLTC,insulation problems of the windings get people's higher attention gradually.The research on the insulation structure design of transformer with OLTC is an important and complex work in transformer design.The safe operation of the transformer is one of the key factors of a safe,reliable,stable and economical operation power system.Calculation and analysis of the process of winding wave play a major guiding role in power transformer insulation structure design.In this thesis,we take an example of 220kV three-phase transformer with OLTC,established a equivalent circuit of transformer winding,base on the model and the theoretical formula,calculate the inductance,capacitance and resistance in the equivalent circuit.Take an example of K1 part of HV winding and calculate its longitudinal capacitance by VB software,and analysis the process of winding wave by this way.We calculated the initial distribution of potential and potential gradient of high voltage winding of the transformer in two different winding forms of inner-continuous type and continuous type by program.Then did simulation calculation of wave process of different type of HV winding by Simulink software,and contrast and analyze it.In this thesis,in the case of three different taps,we used Simulink simulation software do simulation calculation of initial distribution and oscillation process for transformer HV winding and Tapping winding respectively and got initial potential distribution and potential gradient of HV winding and Tapping winding accordingly.Both initial distribution potential and potential gradient potential of tapping winding are smaller,the initial distribution and the potential gradient of HV winding at 3 different tapping are almost same as the simulation result that we calculate HV winding separately.Through Simulink simulation,we find that the maximum gradient potential of continuous type is higher than that of inner-continuous type.The corresponding insulation margin of inner-continuous winding is higher,after comparing with testing data,you can see,high voltage winding of inner-continuous is more safe and reliable.And we can get the oscillation process diagram of HV winding and Tapping winding,when the tapping winding at rated tap,initial potential distribution is degressive,the oscillation of maximum and minimum tap is similar,appeared small peak instead of degressive.And the oscillation maximum potential of high-voltage winding at maximum tap is close to wave-in voltage,oscillations maximum potential of maximum and minimum tap is slightly lower than wave-in voltage.This thesis calculated the main-insulation and end-insulation margin by oscillating maximum potential of high-voltage winding,the results show that,all the main-insulation of high voltage winding and tapping winding,and the end-insulation of HV winding meet requirement of insulation margin.Finally,we designed a lightning impulse test scheme for SFSZ11-180000/220 power transformer,then tested the transformer,and got the lightning impulse wave under 50%and 100%voltage.This transformer passed the lightning impulse test,the test result is in accordance with the simulation results,and this verified the validity of the simulation.