乌兰煤矿是宁夏煤业集团公司主要的焦煤生产矿井，矿区井田面积约15平方公里，目前矿井的年生产能力为90万吨。 按照宁夏煤业集团公司“北部挖潜，南部发展”战略的总体部署，正在进行矿井技术改造设计，预计2006年后矿井年生产能力可达到240万吨以上，续采服务年限可达30年之久，将成为宁夏大型的现代化焦煤矿井。 本文介绍了乌兰煤矿供电系统的现状，提出了乌兰煤矿供电系统技术改造的方案，对新建工业广场35kV变电所进行了重新设计，并首次在变电所采用微机继电保护，旨在提高供电系统的可靠性和安全性。本文重点对新建工业广场35kV变电所的设备选择、继电保护作了较详细的计算和说明，并对变电所改造设计加以技术经济分析。 通过供电系统的改造设计能解决好乌兰煤矿电能损耗高、供电可靠性低、电能质量差的问题，为企业的高产和大发展提供能源保证。

Wulan Coal Mine is a main coke mine of Ning Xia Coal Industry Group Co.,Ltd . The area of the mine is 15 square kilometers. The designing capacity of annual production was 900,000 tons at present. Following the general planning of “ making thorough inquiry in the north and working hard in the south ”, the coal mine technique reforming is being actively designed, and it is estimated that the yearly producing capacity will be reached over 2.4 million tons in 2006,and the mining year can be continued over 30 years. The mine will be a new large-scale modern coke mine in Ning Xia. The current situation of Power System in Wulan Coal Mine was introduced in this article, the technical reform and design of Power System was put forward, and the general design of the new industry plaza 35kV Power Station is started again, and the Power Station introduces the computer relay protection devices firstly, improving the reliability and safety of the Power Supply Systems. The electric appliances choosing of the new industry plaza 35kV Power Station and the relay protection setting are calculated and demonstrated in detail in this article .The technical and economic analysis was given. According to the technical reform and design, the questions such as high loss, low reliability, poor quality are solved, and providing the energy source to ensure the high production and great development of the mine.