Discussion on the construction and transformation

Discussion on the construction and transformation of county (city) urban electricity

Abstract: through the analysis and Research on the existing problems of county (city) urban electricity in this region, the technical problems in the construction and transformation of county electricity are analyzed and discussed according to the guidelines for urban electricity planning and design issued by the Ministry of raw water and power and the Ministry of construction and the technical guidelines for county electricity construction and transformation of national power company system issued by the state household appliance company in 2003

key words: County Power Construction and transformation 1 preface county power is the general name of all levels of voltage levels that supply power to the county within the county. It includes high-voltage power transmission, high-voltage power distribution, medium voltage distribution. Dr. Feng Xiaohai said that polyglutamic acid and polylysine belong to poly amino acid power and low-voltage power distribution. County power has the characteristics of high load density, centralized power consumption and high reliability requirements of power supply. It is an important part of the power system and one of the important infrastructure of modern urban construction. In recent years, with the acceleration of the construction and urbanization of the county, the area of the county has expanded rapidly. However, due to the lack of funds for power construction, the management system is not smooth, and other reasons, the development of power in the county is relatively slow, obviously lagging behind the urban construction and the development of local economy. According to the overall deployment of the State Grid Corporation of China, the power construction and transformation of the county will be strengthened in the next few years, and the power supply capacity of the county will be expanded to meet the needs of urban construction and local economic development. 2. The main problems that need to be solved urgently in the county power supply. With the improvement of the living standards of urban residents and the acceleration of urbanization, the urban power consumption of all counties (cities) has increased rapidly. According to the requirements of the technical guidelines for the construction and transformation of county power in the national power company system recently issued by the state power company and the several opinions on accelerating the construction and transformation of urban power (Guo Dian An Yun [1998] No. 418), At present, the county electricity urgently needs to solve the following problems: (1) the local economy is developing at a high speed, the urbanization process is accelerating, and the power supply capacity of the county electricity is seriously insufficient. With the rapid growth of local economy and the acceleration of urbanization, the requirements for power supply in the county are becoming higher and higher. Due to the shortage of power construction funds, the management system is not smooth, and other reasons, the development of power in the county is relatively slow. According to statistics, in 2002, the capacity load ratio of 110kV system in the overall county was about 1.65, and the ratio of 10kV distribution transformer capacity to 110kV main transformer capacity was about 2.05, which was significantly lower than the requirements of urban planning and design guidelines. During the "Tenth Five Year Plan" period, China will enter the stage of building a well-off society in an all-round way, and the living standards of urban and rural residents will be greatly improved. The county electricity will become the main power growth point in China in the next 5 to 10 years. It is estimated that the average annual growth rate of county electricity in the three years after the "Tenth Five Year Plan" of our bureau will reach 19%, and the contradiction between supply and demand of county electricity will be very prominent. (2) The high and medium voltage power distribution network structure in the county is weak, mostly radiating, and the power supply reliability is low. At present, the 110kV high-voltage distribution network of county power is still relatively weak, with more single main transformer and single circuit power supply, poor power transfer capacity between substations, complex protection configuration, and low safety level. For example, in 2002, there were 14 110kV substations supplying power for single main transformer or single power supply, accounting for 30% of the global substations. At present, the medium voltage distribution network is mostly radiation, the ring power supply mode is very few, the load transfer capacity is poor, and the scope of accident and maintenance power outage is large. According to statistics, the power supply reliability rate of all counties (cities) of our bureau in 2002 was 99.55% - 99.96%, but the actual situation was slightly lower than the statistical value. (3) The power quality of the county is low, the line loss rate remains high, and the power supply efficiency of enterprises is poor. Due to the rapid growth of power load in the county, the qualification rate of electric voltage in the county is generally low due to the thin wires, few loops, insufficient distribution and transformation points, lack of reactive power compensation capacity and other reasons. For example, in 2002, the qualification rate of 10kV distribution voltage in all counties (cities) was 95.73% - 99.31%, while the qualification rate of low-voltage electric voltage was lower. At the same time, due to the imperfection of 10kV frame, the loss rate of medium voltage distribution lines in the county remains high. In 2002, the overall loss rate of 10kV distribution lines was 4.64%. And respond to its proliferation changes (4) the county electricity technology is backward, the equipment is obsolete, and the automation level is low. At present, the electric technology and equipment in the county are generally backward. Although some new technologies and equipment have been introduced and used in recent years, there is a big gap compared with advanced cities at home and abroad, the equipment grade is generally low, and the automation level is not high. For example, in 2002, the overall county 10kV distribution cable rate was only 13.5%, and the insulation rate was 50.4% (including cables). County distribution automation is still in the planning stage. 3 discussion on the construction and transformation of county electricity 3.1 the construction and transformation objectives according to the requirements of the "guidelines for urban electricity planning and design" issued by the Ministry of raw water and electricity and the Ministry of construction and the "technical guidelines for the construction and transformation of county electricity in the national electricity company system" recently issued by the national household appliance company, and in combination with the actual situation of the local district and county electricity, the construction and transformation objectives are: (1) strengthen the county electricity construction, improve the overall power supply capacity of electricity, and eradicate the phenomenon of "bottleneck" in power supply. (2) Optimize the network structure, improve the safe operation level of power in the county, and enhance the ability to resist natural disasters and accidents. The reliability of power supply in the county is more than 99.7%. (3) Improve power quality and reduce power loss. The qualified rate of electric voltage in the county is more than 95%, the 10kV comprehensive line loss rate is less than 6%, and the low-voltage line loss rate is less than 9%. (4) To improve the automation level of power distribution in the county, the selection of power equipment in the county should pay attention to miniaturization, oil-free, automation, maintenance free and less maintenance. 3.2 discussion on construction and transformation according to the current situation and power consumption level of cities and towns in the region, the county power should correctly deal with the following technical problems in the process of construction and Transformation: (1) simplify 110kV power, reduce voltage level, and optimize high-voltage distribution network structure. With the development and improvement of 220kV system network, taking automobile wheels as an example, its power supply reliability has been greatly improved. Especially in recent years, new technologies and products have been widely used in the power system (such as SF6 circuit breaker, fully enclosed switchgear and microcomputer protection), as well as the increasingly reasonable network structure and layout, which have enhanced the power supply between regions