Research On Obtainment Of Load Density Index And Selection Of Medium Voltage Level In Distribution Network Planning

Urban distribution network is an important part of the power system, and primary load center of the power system, and it burdens a large number of power consumption, has high load density, and requires high standard of reliability and power quality. With the improvement of urban load density, the 10kV voltage level distribution network highlights a number of drawbacks, and 20kV voltage level has been the urgent needs in some distribution network for cities and development zones. However, there has been certain subjective blindness in the process of selecting the MV voltage level. Urban power load density forecast is the basis for urban distribution network planning and has its direct impact on the quality of distribution network planning, choosing appropriate methods to improve prediction accuracy of load density indicators of distribution network planning is always in a research direction. In this paper, research on the two key issues, which are identifying load density index and selecting the MV voltage levels, has their important practical significance.Load forecast is the first step of distribution network planning, load density index is the foundation of spatial load forecasting of distribution system. The paper gives the systematic analysis of the main affecting factors of load density index, establishes a hierarchy of load density index and proposes a method to obtain load density index based on matter-element analysis. This approach has effectively improved the objectivity and veracity of load density index compared with traditional empirical methods.The paper puts forward a more comprehensive and systematic comprehensive evaluation method of MV voltage level, based on comprehensive consideration of the main affecting factors of MV voltage level and the introduction of AHP theory. The method takes economic, technical, social, and environmental protection, status and many other factors into consideration, avoiding the traditional method only considers a single indicator or expert's opinion, which makes the decision-making more scientific.Finally, a city Jinghu New District and Didang New Town have been taken for example, and the results demonstrate scientificity and practicality of the above theory. Moreover, through the analysis of 20kV distribution network home and abroad, the paper summarizes principles and measures of stepping up and reforming in 10kV distribution network.