Optimization Study Of Medium Voltage Distribution Networks Connection Modes In The City Of Guangzhou

The connection modes of medium voltage distribution netwoks is an important factor determining the reliability of power supply.In a long historical period,the investment in research and construction of distribution netwoks in our country has been insufficient,which results in irrational structure,regular power accidents and low power supply reliability rate of distribution networks.At present,there are no uniform standards of connection modes in distribution netwoks,resulting that domestic distribution netwoks are complicated and distribution netwoks planning largely depands on designers’ s experiences.Distribution netwoks connection modes must be selected to accommodate local economic level,pwer supply reliability requirements,and meet the needs of long-term development.The optimization of distribution networks connection modes is based on the status quo of Guangzhou,power supply reliability and economy of each typical connection modes.This paper investigated the distribution,characteristics and applications of different typical connection modes.The average interruption hours of customers and power supply reliability rate are considered as important evaluation standards of power supply reliability in Guangzhou.First a set of adaptive basic parameters is collected based on statistics of distribution networks in Guangdong province,and calculate the average interruption hours of customer and power supply reliability rate based on the load rate,connection modes and reliability parameters,then analyze the influence of load rate on power supply reliability in distribution networks.The results show that power supply reliability will be improved,while the load rate becomes lower.However,when the load rate is low enough,its impact will be reduced.Based on the economic development,load densities,and power supply reliability rate of different connection modes in Guangzhou,calculate the loss value of unit power outage of different areas.According to comprehensive construction investments of distribution networks,calculate unit load annual operation expenses of different connection modes,comparing their economies.The analysis reveales that the unit load annual operation expenses would decline,as load densities increase.Guangzhou is divided into five regions,based on economic conditions and load densities of each region.Depending on power supply reliability and operating costs of different connection modes,searching for the most appropriate connection modes of distribution netwoks in each region.Most power load in Guangzhou is still in the stage of development,the power shortage problem is still serious in some areas.Based on the status quo of Guangzhou,the typical connection modes should be selected to transform distribution netwoks,which is easy to realized,and choose the typical connection modes with higher reliability rate and more contacts between stations for new distribution netwoks construction,in order to increase the ratio of typical connection modes of distribution netwoks in Guangzhou.