A Double-voltage Distribution Mode In Middle-low Voltage Power Network And The Comprehensive Decision-making Method

As an important section of electric power system,distribution network,which links superior power source to user terminals,has direct effects on users' power safety,reliability and supply quality.Distribution mode has decisive influence on the benefit of power distribution network.It determines the structure and operation mode of the power grid.So it's very important to study the optimization method of distribution mode to guide its scientific plan and optimal operation.Power grid construction in China has attached too much importance to the power generation,but paid less attention to the distribution network,thus making the structure of the medium-low voltage distribution network so weak.According to the statistics,more than 60% power loss comes from medium-low voltage distribution network;over 80% power system faults are caused by unreliability.Improving the economy and reliability of distribution network depends on the reasonable selection and optimization of distribution mode.This article first analyzed the effects on distribution network by different distribution mode,then studied the previous comprehensive decision-making methods in middle-low distribution network,finally proposed a new distribution mode to provide a reference method for precise distribution under different load conditions.The main contents of this paper include:(1)Analyzed the impact of load distribution,size and asymmetry to the energy loss.Researched the relationship between load,supply radius and voltage loss.Analyzed the impact of different load distribution on network reliability,combined with typical connection mode.The analysis and research laid foundation for the establishment of distribution mode decision-making method in middle-low voltage power network behind.(2)Aimed at the problem that existing distribution mode can not meet the requirments of nebulous and satellitic load,this paper proposed a double-voltage distribution mode to solve the optimization problem of the distribution voltage in different distribution shaped load.This distribution mode can meet the energy saving and efficient power supply requirments of both close and distant load.(3)Built up a comprehensive distribution mode decision-making method.The method took life cycle cost and power loss cost as the objective function,limited by reliability and safety indexes,which can make the best choice among various distribution modes.Finally validated and analyzed the double-voltage distribution mode and the comprehensive distribution mode decision-making method through an example and verified the effectiveness of the proposed mode and method.