Study On Distribution Network Voltage Level Optimization

At present, load density has reached high level in some cities (especially the urban center), where220kV substation has penetrated the load center and began to assume the task of the urban distribution.It has been overlapping with110kV high voltage distribution voltage level function.It will cause a series of hurdles and distress of power grid construction.if the existing220kV/110kV/10kV/0.4kV four voltage power supply mode be continued to use in the center of the city of high load density. Such as, land acquisition willl be fairly difficult in the center of the city where name the "high cost of land", weather a large number of220kV and11OkV substation sites be fixed up; Because10kV line power supply capacity is obviously insufficient, a large number of cable runs fever and serious temperature rise in the limited space of the cable trench in centralization, not only reduces the cable insulation life, but also makes the cable current carrying capacity of a serious decline.The best way to solve resource and environmental dilemmas faced by the construction of power grids is improving the voltage level of medium voltage distribution network. The growth of electricity demand is matched with power supply capacity of city and speed of construction while supporting the reduction of transformer level, simplifying the voltage level, thus effectively reducing the substation number and medium voltage cable outlet.This paper builds a high load density area with the preferred mathematical model of the grid voltage level, according to network planning guidelines which based on the China Southern Power Grid Company. Considered Zhuhai Hengqin distribution network planning as the prototype, accomplished total power grid construction investment as minimum objective function, used the particle swarm algorithm to obtain the the Hengqin best voltage level building programs, It probe the feasibility of20kV as city distribution networ medium voltage level instead of10kV and cancel110kV transformer level, using220kV straight down the20kV. On this basis, the paper gives detailed planning and construction program of the Hengqin220/20/0.4kV voltage level, and completes the assessment of medium voltage distribution network planning programs.The work carried out in this paper provides a decision-making reference for considering to select the20kV medium voltage as power distribution voltage levels, simplifying the voltage level for power grid planning in high load density emerging regional.