| The excellent and stable insulating ability is the key to ensure the runs safely and stably.With the optimization of electric power system, the insulation level of the transformer hasbeen raised gradually, and the insulation of the transformer has many problems to be solved.The practice shows that the mainly transformer fault is the insulation issues. Therefore,improving the insulation structure and insulating ability become the primary tasks in thetransformer design.The main insulation, external insulation and longitudinal insulation are three mainresearch aspects of transformer insulation. The main insulation calculation is under thepremise of meeting the insulation margin, and the economic also should be considered fully.The insulation margin has the characteristics of uneven in the design of transformer insulation,the electric field of some parts is high, these parts need to strengthen, some parts is low，theinsulation margin is too large, so the requirement of insulation of these parts can be reduced.Therefore, the main insulation, external insulation and longitudinal insulation of thetransformer are calculated and analyzed in this thesis.As the calculation of the main insulation electric field, it mainly examined in the end ofwinding and at the middle of winding, and find out the distribution of the potential and electricfield intensity. The insulation margin of each part is calculated to find out the maximumvuale of electric field strength and the minimum vuale of the insulation margin to provide thebasis for the design of transformer insulation.As the calculation of lead wire and high-voltage bushing, and according to the differentcharacteristics of the two parts,2D electric field and3D electric field are simulated andcaculated of the lead wire and high-voltage bushing to get the maximum vuale of electric fieldstrength, and the position where the maximum vuale is. Then, the minimum insulation marginis caculated using the Rigidity formulas.As the calculation of the longitudinal insulation of transformer, it mainly examined thelightning impulse voltage wave process. In this thesis, multi-conductor transmission linemodel is given, and the finite element method is used to calculate the parameters ofcapacitance, inductance, conductance and resistance. Anew method is given in this thesis thanit used the software of SIMULINK and MATLAB to simulate and calculate to get the initial potential, the biggest potential and the gradient of oil potential. As a basis to identify theweakest link in the insulation structure, and it has a certain significance for product design. |
