The Optimization Research On The Capacity And Location Of MV Distribution Transformer

With the fast development of computer technique and optimization theory, many power system experts begin to be devoted to using the computer to solve the planning problem of electric network, thus improved the speed and quality of planning greatly, has injected new vigor into traditional electric network planning. With the setting-up of the location theory, the research about the location problem of the equipment is deepened day by day, include the constant appearance of the model and solution of different various kinds of goal function of location problems, its application field has got further expansion too.The fund has time value, its value increases gradually as time goes while fund input economic activity.The appreciation of the fund is named time value of fund. In equivalence of the fund the basic calculating method has laws of simple interest and compound interest law. This paper utilizes the law that capital is paid once and retrieved equivalently among compound interest, convert present investment to annual expenses of transformer substation, consider network loss and investment and operation expenses of circuit of secondary side line, have set up static optimized models with the law of annual minimum expenses.The question of selecting location and capacity among the questions of planning of urban power network is an especial location question including the question of plane location and combinatorial optimization. Considering the number of distribution transformer being enormous we adopt the strategy that calculates according to piece after detaching into pieces on the question of selecting location of MV distribution transformer. Because according to the current load level a city has generally thousands of distribution transformer and box transformer. If we take the enormous project as a whole calculating, it is difficult to guarantee its convergence and calculating time. We can detach into pieces according to the power supply range of superiortransformer, also according to geographical area of city (namely the plot dispatched by street, river, railway). The paper adopts the solution that dispatch according to geographical area, it can avoid power supply across district, it has feasibility.A deterministic planning model to optimal the locations, sizes and service areas of MV/LV distribution transformers is presented firstly, and then an algorithm-triangular successive partition algorithm (TSPA) which can automatically search the optimal solution over a wide range is proposed. The model and the algorithm can efficiently consider the impact of cost of the investment and power loss of feeders on planning scheme, so an economic and reasonable scheme can be obtained. Some practical examples show that the model and algorithm are very efficient.