Planning Of Urban Mid-Voltage Distribution Network Considering Cable Trench

Urban distribution network planning includes several steps such as Load Forecasting, Substation Locating and Capacity Calculating, Distribution Network Planning and Reactive Sources Optimal Planning. Among these steps, Urban Distribution Network Planning based on Load Forecasting and Substation Locating and Capacity Calculating is a complex but important step. Under the cabling of urban network and demanding of city landscape, the resources of cable trench have a direct impact on the routes of network. Therefore, the study on the urban distribution network planning considered cable trench will give some useful references to construction of distribution network and cable trenches.This paper reviews technical characteristics and economic comparation between different cable laying methods in urban distribution network, and analyzes installation costs of electrical pipe in detail. Combined with practical application, this paper proposes a general planning process for cable trench planning. What's more, several index are proposed to evaluate the status of trench network. In view of the trench construction in future, the demand forecasting and developing mode are analyzed.Considering the trench's influence on urban distribution network planning, this paper presents a new model of distribution planning. The economy index of this model includes investment and maintenance costs of high-voltage substation, cable lines, switching equipment, and electrical cable trench. This paper uses a simplified approach to deal with reliability which is considered as a constraint condition. In addition, the model also considered other constraint conditions, such as load capacity, voltage drop and geography information.In view of solutions of the planning model, this paper analyzes the specialties of distribution network spatial data structure, and then designs and improves GIS spatial database for distribution network planning. After that, Genetic algorithm is used to optimize the preliminary network, which is propitious to global optimal searching of complex system. During the realization of algorithm processing, the paper analyzes trench's restraint to lines'routes in detail and adopts an effective decoupled method to calculate their fitness.Finally, using GIS spatial database as platform, the model and solution algorithm presented above are applied to the radial network planning for a substation. The results shows that considering costs of cable trench in distribution network planning may get much more practical and economical projects, and it also have certain guidance for construction of cable trench.