Cities Voltage Level Selection And Substation Site Selection Study

In the planning of urban electric power network, several aspects have to be considered, such as power load forecasting, substation and network planning, distribution network power flow calculation, reactive power planning, reliability analysis in normal and emergency, distribution automation. As the connection between transmission network and consumers facilities, urban electric power network has been paid more and more attentions about its planning.According to the statues of electric power network in our country, some parts of research work about the electric power network planning are studied in this paper as following:The voltage patern (220/110/35/10/0.4kV) has been employed in most urban power grids, with 10kV as the intermediate. As load demand and load density are increasing greatly, 10kV level is no suitable to the national economy development.dense hierarchy causes overlapping and complexity of grid structure, resulting in higher investment and power loss, and inconvenience in operation and maintenance. Therefore, appropriate reduction of distribution networks hierarchy and selection of suitable distribution voltage levels are of significant.Based on the analysis of the essentiality for rational scheming of voltage levels in urban electric networks, the authors investigate the present situation about voltage level scheming in some cities in China as well as in developed country. Bymeans of technical economical comparison of rational scheming of voltage levels and the analysis on rational selection of voltage levels, a principal conclusion for rational voltage level scheming in China is obtained, i.e., simplifying voltage levels', boosting medium voltage level.Based on the principle of Analytic Hierarchy Process, a new way to locate a transformer substation in urban electric power network plan is introduced, factors. It makes full use of computer function, while takes electrical experts' experience and judgment to consideration. Some engineering applications indicate that the improved approach in this paper can better meet the practical planning requirements, and achieve a better result with high comprehensive fitness degree both in economy and geography. This new way is convenient, simple and practical by computing and analytic in the examples.