Study On The Applicability Of Medium-Voltage Level In Distribution Network

At recent years, with the rapid development of national economy, urban load density has grown rapidly that causes the problem that existing lOkV distribution power grid capacity is obviously insufficient. To solve the situation, the main measures are tanken to construct or expand substation and strengthen grid construction. But. land acquisition willl be fairly difficult in the center of the city where name the "high cost of land". Many substations overloaded or overload operation in the long-term running. 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. Which endanger the safe operation of grid.The best way to solve resource and environmental dilemma 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.Firstly in the thesis, it compares the superiority among the10kV、20kV and35kV from the economic and technology. According to network planning guidelines which based on the China Southern Power Grid Company, building a regional power grid with the preferred mathematical model of the grid voltage level. Choosing a specific area, describing in detail the parameter and optimization process of the preferred mathematical model of the grid voltage level, and analyzing the optimization result. Selecting two different areas(100km2and50km2). By exploring the optimal building programs of various voltage levels in different levels of load density and different lines and equipment selection schemes. And exploring the scope of the application and choice principles about the medium voltage level in different load density in the urban. Providing the theoretical support for the selection of medium voltage level for new high load density area.