Application of Transmission Line in urban Transmission Line

In recent years, due to the rapid development of urban construction, the rapid increase in electricity load, power supply network can not meet the needs of the development of the electricity load, the city is bound to create a new high-voltage lines, the original city network lines for Rehabilitation. Traditional tower, large area, and the modern urban environment modeling and uncoordinated. Using expensive high-voltage cables, the use of reinforced concrete poles, its longitudinal, circumferential crack problem has been not well resolved. Using circular or polygonal cross-section tapering steel rod type, simple structure, the force is clear, easy manufacturing, construction convenient, safe and reliable operation, less maintenance. Cheng Jiang change - Rotary big to 110 kV Transmission Line in Guangdong Meixian new town planning and urban areas, a total length of 5.96 km, construction difficult, tight schedule requirements. Meizhou Power Supply Bureau in the construction design of the project in order to meet the urban planning, beautify the urban environment, according to the actual situation, this project uses vertically aligned single-loop steel pole, cross arm against the side of the driveway, along with urban planning to spend erection. 1 Transmission Line design ideas Tower design is overhead transmission line project an important part of the design, which directly affects the safe operation of power transmission lines and cost. According to statistics, 37% of the tower cost accounting Get Line Project Cost body. In Transmission Line Project, the share of the total number of straight tower towers generally share reached 80%, the cost of the main project has a great impact, and the longer the line, the effect is more obvious. Accordingly, under the "overhead transmission line steel pole design technology" provides, in ensuring quality, safety applicable premise, should as far as possible the design of technologically advanced, economical and reasonable. The impact of economic indicators tower main elements of meteorological conditions, conditions of use, and tower height of nominal maximum type. Select 2 meteorological conditions Design of meteorological conditions of the project in Guangdong Province typical weather conditions, ie, the maximum wind speed of 25 m / s, the design maximum ice cover is 15 mm, the lowest temperature of -10 ℃, the highest temperature of 40 ℃. 3 steel rod to determine the conditions of use 3.1 wire, grounding wire model and determine the maximum use of stress according to the preliminary design review approval documents, leads this project selected for LGJX-240/30 ACSR (GB1179-83 technical standards), design safety factor k = 5, maximum stress 52.06 N / mm2, lightning-line selection of a 5% aluminum-zinc rare earth alloy coating strand GJX-50, the safety factor k = 8, using the maximum stress 147 N / mm2, the other choice of OPGW fiber composite lightning line. 3.2 determine the span This project is taking into account the urban lines, flat terrain, so that different bits of the column level span, span vertical dispersion is not, and therefore the use of steel rod design span is determined as follows: the horizontal span of 180 m, the vertical span to 200 m, on behalf of span of 200 m. 4 Maximum HEIGHT OK The route along the city planning to set up with flowers, green trees case communication lines and low voltage lines with flowers, and in order to beautiful cities, the largest of nominal high set too small, no doubt will restrict the use of steel rod. However, the maximum HEIGHT set too high, the material will make the index a corresponding increase in the whole tower. After the spreadsheet, the premise does not lead to a single tower base index increased significantly, and the call is called high steel pole as: Strain corner HEIGHT 18 m, straight sections HEIGHT 19 ~ 20 m. In addition, the actual span considered in urban areas, in the case where there are cross-cutting and flat terrain, the maximum call 20 m, said the high use span can reach 200 m, so choose the 20 m as a steel rod maximum HEIGHT It is suitable. 5 Type Selection and Design Optimization 5.1 Electric determine the size Wire vertically arranged, this form of simple structure, small windward side, is a mature structure. Size determination including tower head between the conductor and lightning line lines from lightning line high bracket, wire line distance between wires on the tower's net distance. Determining principle tower head size is to meet clearance requirements to meet the wire, lightning line horizontal displacement, on the lower level of the wire, the vertical distance, lightning protection angle And other requirements, the combination of weather conditions, conditions of use, minimizing application-foot steel pole tower head Transmission Line in the city.