Discussion on the design of ring network power sup

Abstract: combined with the power supply design of Fenghuang District in Panzhihua City, some technical problems of ring power supply in residential district: the parameter selection of load switch and fuse in ring cabinet; The concept and selection of transfer current, transfer current and open-loop point; Overvoltage protection, metering, reactive power compensation of box type substation and special requirements of climate on box type substation; The selection of ring cable is discussed in depth. It also expounds the load calculation of the community and the topology of the ring power supply

key words: loop power supply box type substation load calculation Untitled Document complete facilities, beautiful environment, dense buildings are the construction characteristics of residential quarters. The traditional way of power supply in residential areas is overhead lines, transformers on platforms and poles, and various weak current lines, resulting in dense spiders in the air of the area, which are mixed with green trees. Accidents occur frequently, reducing the reliability of power supply and hindering the view. Today, people have higher and higher requirements for the quality of life and living environment. The use of box type substation (box transformer) and buried underground cables to form a ring power supply should be an ideal choice for the power supply scheme of today's residential quarters. According to the building environment with different method names corresponding to one experimental standard, the box transformer can choose different shapes and colors to stand in the building group in the form of a building sketch. Next, combined with the power supply design of Fenghuang community in Panzhihua City, the loop power supply mode of residential community is discussed. Panzhihua Fenghuang community has a total construction area of 248000 m2, including 11 18 storey residential buildings, 3 25 storey commercial and residential buildings, and the rest are mostly 7-storey commercial residential buildings, as well as several office buildings and comprehensive buildings. There are 2182 households, about 8637 people. It is a residential and living community dominated by commercial housing, which is compatible with an appropriate amount of public facilities. It is planned to build this community into a landmark demonstration community in the 21st century. 1 load calculation electric load is the basis for determining power supply grade, power supply mode and selecting equipment. Load calculation concerns the overall situation of power supply. China has a vast territory and great climate differences. At the turn of the century, it is unrealistic to calculate the load according to a unified standard at the time of economic transition. There is a multiple gap in the selection of household average load (kW/household) and simultaneous demand coefficient. The power supply of this community is based on 5kW/household, and the demand coefficient is averaged with reference to the standards of all parts of the country. For public buildings, according to the statistics of central air conditioning, the load density is: shopping malls 80W/m2;, The office building is 40W/m2, the equipment room is 20W/m2, and the warehouse (including garage) is 10W man-machine dialogue mode/m2. 2. The loop power supply of the power supply system can simplify the distribution line, facilitate management, and conveniently provide two power supplies for important loads. Moreover, it is easy to find the fault when it occurs, which is of great significance to realize the automatic management of electricity. Compared with radial power supply, its experimental machine in the plastic industry occupies an extremely important position, with less investment. Therefore. It is more and more widely used at home and abroad. A switching station is set in the center of Fenghuang community, which adopts ring power supply, and the East and west districts form a ring. The radius of low-voltage power supply is ≤ 250m, and the whole community is equipped with 17 box transformers and 7 substation points. The ring unit of Fenghuang community adopts a box type substation, with one input, one output and one transformer, single line and single ring, and the electric energy is measured at the low-voltage side. For users who are not suitable for box type substation in large public commercial buildings and underground garages, substation points can be set and ring cabinets can be configured as a unit of the ring power supply system of the whole community. In order to limit the short-circuit capacity and simplify the relay protection, the two ring power supply systems in the community adopt the open-loop operation mode. Some technical problems of box type substation