Line-type Selection And Economic Analysis In Distribution Planning

As an important part of power systems, the performance of distribution system will directly influence the electricity quality or even destroy the users' requirements. Being an important step in distribution system plan, the choice of line type will affect the whole distribution system. So it is necessary to find an effective way to select line-type and reach the optimization in economy.Firstly, overhead lines and cable lines are compared after discussing the line connection mode in this paper. By analyzing their characters, the principle about line-type selection is summarized. Secondly, the economics of lines is introduced. Through analyzing the cable lines, the method of drawing load-cost curve is proposed. By studying the load-cost curves in different sections, the economy-load area is gained. This paper summarizes the relation between the distance and the voltage drop and puts forward the concept of economical load reach.Finally, based on above theory analysis, three methods are proposed for the line-type selection and economical analysis. The first method is called equal-economical-range method. The second is called operation-compare-method. In practical application the two methods show good results. The third method is called operation-plan-method. It can be proved that the operation-plan-method is the best in economic optimization.