Research And Application Of Distribution Network Planning Technology For Class A Power Supply Area

Power systems include five links, i.e. power generation, power transmission, power substation,power distribution, and power consumption. As the closest stage to the users, urban distribution network is a key link in power systems. Due to the speeding up of modern urbanization and the rising demand for electricity, higher requirements of scientific and economic rationality of the planning of power distribution network are put forward. Besidesthe new requirements of safety, reliability, high quality, energy conservation and environmental protection have been imposed on power developments. Therefore, it is particularly important to construct power distribution networks coordinated with the overall planning of the city in order to satisfy the demands of economic and social developments.Based on the analysis and research on the future load growth and the present situation of urban distribution network, the optimal construction scheme is determined for power distribution networks, such as a new transformer substation, a new feeder, a new contact, replacement of wire, etc.,to make the distribution network construction and operation cost minimum under the premise of meeting the load growth and safelysupplying power. Class A power supply area, whose load density is large, requires higher reliability of the power supply. To design reasonable class A power supply area using science, new technology, it not only contributes to the quality of power supply, energy conservation, and the social and economic benefits, but also has guiding significance for other categories of distribution network plantings.In this paper, basic content and theory method of distribution network planning are firstly studied,including the traditional distribution network planning contents and requirements, the principle of power distribution network planningbased on the maximum power supply capacity (TSC), line loss calculation method and reliability-cost benefit analysis, and the main technology of power load forecasting and the selection and constrruction methods of connection mode.For the load forecasting method, we focus on the study of unit consumption method of output value, electricity consumption per capita, load density method, time trend extrapolation method,correlation analysis six kinds of traditional load forecasting method and grey prediction method,artificial neural network prediction method. The superiority and the applicable scope of various methods are summarized through the comparative analysis. Then we carry on the detailed research on the gray prediction model GM (1,1), find out its insufficiency, and improve it. A real example analysis of the power supply area lying in Zibo is performed. By the comparison with correlation analysis method and traditional GM (1,1) model prediction method, it is concluded that the prediction error of the improved model is smaller and accuracy is higher. Finally, the improved GM (1, 1) model is used to forecasting the load in the region.According to the comparative analysis of Medium voltage distribution network overhead lines and cabletypical connection model, we summe up the advantages and disadvantages of each connection mode and scope of application. Based on the actual circumstances of the load growth, three typical and flexible transition modes of network connection are established. In this paper,we develop a selection and construction method based on the reliability and economy of the choice of target distribution network, in which the average effective degrees ASAI are selected as indicators of reliability evaluation, and the unit load in costs is chosen as various wiring mode of economy evaluation index. At last, the practicability of the approach is verified bythe example analysis.