The Optimization Of Insulation Structure And The Automatic Design Of Electromagnetic Scheme Of Power Transformer

Supported by the research fund for the doctoral program of higher education, and combining with the research project proposed by Baoding Tianwei Group Co. Ltd., the aim of this paper is to conclude the accomplishment realized by author recently. With the rapid development of computer technology and the perfect progress of numerical techniques of electromagnetic, it is possible to implement the optimization of transformer insulation structure and the automatic design of electromagnetic scheme. There are four parts in this paper. The first part consists of Cheaper 2. Based on the finite element method and the sensitivity analysis technique, the aim of this part is to create a new optimization technique that can solve the difficulties faced by the techniques now available. The research of optimization techniques now focuses on two main branches: the stochastic and the detective methods. The stochastic search procedure is to find the global optimal by millions and millions FEM calculation and proves unbearably time expensive; the detective search procedure is to find the optimal by the adjustment of search direction, but sometimes falls into the local optimal and can not escape by itself. To solve above problems, a new method has been created in this paper: to construct a Hermite polynomial approximation of the objective function by FE solution using the sensitivity idea. The main procedures are as following: to generate small increment of parameters automatically and to calculate the FE several times and obtain the sensitivity of objective function to the parameters, and then form a Hermite polynomial approximation, the calculation of FE solutions are substitute by the calculation of polynomial approximation, so time cost decreases dramatically. The second part consists of Cheaper 3. The reliability evaluation method of the whole insulation system are studied for the optimal arrangement of insulation parts, the whole region scan method are used to find the weakest path in the insulation system, the test results and the computation results of some models show it is an effective method and has acceptable precision. The third part consists of Cheaper 4 to 6. The application of Hermite polynomial approximation is represented by the optimization of shielding ring at the end region of tapped winding of transformer. The optimal arrangement of insulation barriers and angle ring.s and caps are also discussed to improve the insulation reliability of the whole system. With the mutli-segment regular curves combining technical, the best shapes of electrode in high voltage bushing are analyzed with evolution strategy. The three-dimensional electric fields of the high voltage winding of a shell type transformer arc calculated, and the insulation reliability is analyzed carefully. The fourth part consists of Cheaper 7. It points out the sensitivity idea can be also used to calculate the electromagnetic scheme automatically. To calculate the electromagnetic force and then obtain the sensitivity of inductance, and obtain the short circuit impedance and other performance parameters of transformer further. This method focuses on how to solve the difficulties faced in the design of shell-type transformer due to shortage the design experience in China. The Cheaper 8 is the conclusion of the whole paper. It gives the summary of main contributions and the work should be continued later.