| Summary: | 碩士 === 中原大學 === 電機工程研究所 === 91 === For electricity insulation and security in the power systems, insulators are widely used to isolate power lines from the grounds. Insufficient insulation of an insulator may lead to flashover, causing unreliable or even interrupted power supply. The degree of insulation of an insulator is related to distribution of tangential fields on its surface. On the other hand, the distribution of tangential fields is determined by the contours of insulator. A superior contour design of the insulator may improve the isolation effectiveness of the insulators.
Aiming at achieving superior contour design of the insulator, the thesis employs the charge simulation method (CSM) to analyze the electric field distribution of the energized insulator. To obtain uniform and minimal tangential fields along the insulator surface, different genetic algorithms (GA) are used to optimize the contours of the support and the suspension insulators, respectively. Regarding the contour design of the support insulators, three different shapes of exponential, elliptic and linear functions are used to describe the contours of the support insulator. Besides, in the contour design of the support insulator, to prevent GA from spending most of its efforts in repeatedly calculating the fitness functions of the same solutions searched before through the time-consuming CSM, a Hashing technique is used in the GA to store and access the calculated fitness values of the solutions searched before. Via the usage of the Hashing table in the GA, the calculation efficiency of the GA is greatly upgraded without the expense of the solution quality. In the contour design of suspension insulator, contour points and cubic spline functions are used to describe the shape of the insulator. Based on the describing functions, the optimal contour design of the suspension insulator is achieved by using the dynamically adjustable GA, where the search ranges are adjusted successively according to the best solution found so far.
To verify the proposed approaches for optimal contour design of the insulators, the methods have been implemented in Matlab programming package. Comparing the proposed optimal designs with the initial ones in terms of the distribution of tangential fields, it is shown that more uniform distributions along the insulator surfaces have been obtained from the proposed approaches for both the support and the suspension insulator. Utilization of the Hashing technique in the support insulator contour design also results in the execution time reduction of the GA up to 92.2% around.
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