| Electric power industry is an important pillar and the leading industry of the national economy. The structure and layout of the electricity network, determination and combination of voltage grade, especially the reasonable selection and timely improvement of medium voltage distribution voltage level which plays a role as a bridge between the power system and the users is very important. The determination of voltage level standards and grid voltage is important for a country’s economic construction and development, and increasing the degree of modernization, both far-reaching strategic significance, more practical significance. They will not only affect the network structure and layout, design and manufacture of electrical equipment, operation management of power system, but also determines the power system construction investment and annual operating costs. In the mid-1950s, China began to boost transformation, until the late1970s, the medium-voltage distribution voltage unified to lOkV, this initiative which improved the voltage quality, greatly reduced the supply and distribution system line losses, unified equipment standard, simplified the system, is of great significance. However, with the rapid development of the national economy and the improving of people’s living standard, the electricity consumption and load density grew just as fast, lOkV distribution network can’t meet the requirements of the development trend has become exposed. Urban areas with high load density, too many10kV substation distributions and the line loops, take up a lot of site resources and corridors resources. The tension of increasingly prominent between the increasing number of substation equipments and land resources make the distribution network development restricted. In rural areas, the density is low but the supply distance is long,10kV line loss rate is too high, the voltage quality is difficult to guarantee. Thus, both in urban and in rural areas, the operating characteristics of the10kV distribution network is not ideal, so the increasing of pressure voltage level is very necessary. In this case,20kV network came into being.20kV distribution network contribute to loss reduction and energy saving, conservation of land resources, pressure to improving the power supply capacity of the power grid. The application of foreign decades has provided valuable experience for the country to promote applications, the application of Domestic Suzhou Industrial Park and Benxi Nanfen can learn basic data for the application of20kV. This paper analyzes the problems of10kV as medium voltage, pointed out the necessity of20kV distribution network; verified in the theoretical aspects of the feasibility and economics of the20kV distribution network; discuss the technical aspects of20kV with neutral Point grounding of equipment selection. Focus to the Dalian Changxing Island region20kV distribution network design, for example, design completed from load forecasting, power system planning, equipment selection, technical implementation, reactive power compensation, boost transformation strategy,medium voltage power wiring to the switching stations and distribution stations. According to20kV in the Changxing Island area with grid applications engineering examples to verify the feasibility and economics of the by10kV boost transformation of20kV, and summarizes the operating experience of the20kV distribution network. |
