Reliability And Economy Analysis On Distribution System

The distribution network is connected directly to customers in power system, its main function is to supply customers with electricity. Modern society demands that electrical energy should be as economical as possible with a reasonable degree of continuity and quality. The continuity of energy supply can be increased by improved system structure, increased investment during either the planning phase, operating phase or both. Over-investment can lead to excessive operating cost, which must be reflected in the tariff structure .Consequently, the economic constrain will be violated although the probability of the system being inadequate may become very small. On the other hand, under-investment leads to the opposite situation. How to plan distribution networks and get the balance between economy and reliability is a very important problem. Reliability cost/worth assessment provides the opportunity to incorporate cost analysis and quantitative reliability assessment into a common structured framework.In distribution systems, the reliability cost is conflict to the reliability benefit. The objective function of the optimization investment strategy of the distribution systems is presented by combining the reliability cost with the reliability benefit in this dissertation. According to these two criterions which whether the fuse should be mounted and whether the stand by transformer should be prepared in the load branch, the simple objective function of the optimization investment strategy is obtained by predigesting. The optimal configuration of sectioned switches in distribution network is a non-linear combined optimization problem, in which both economy and reliability should be considered at the same time. To solve this problem, a bi-level optimization planning method to determine the optimal number of sectional switches and their installation positions is proposed. In this method, the annual investment cost of switches, annual operating maintenance cost of sectioned switches as well as customer outage cost are comprehensively considered in objective function; according to different number of sectional switches the outer layer optimization progressively approximates to optimal number of sectional switches by use of dichotomy; under given number of sectional switches the insufficient power supply is used as the evaluation index of inner layer optimization by which the installation positions of sectional switches are optimized.The results are used to illustrate the optimization procedure of dengzhou I . This paper analyzed whether the stand by transformer should be prepared in the load branch. The arithmetic flow chart is provided. The number of switches and the locations for dengzhou I are optimized. The results are compared with the original switch location. It can be concluded that the switch mix will be very different if demand side concerns are considered in the evaluation. Compared with direct search, the bisection search can reduce the account and guarantee to find the global optimal number of switches and locations. The bisection technique is very efficient.