Study And Application Of Evaluation Method On Urban Medium Voltage Distribution Network

Distribution network planning is the support of network development, and its planning level directly affects the security, reliability and economy of power supply. Present network evaluation and planning network evaluation are important components of network planning. The authenticity assurance of evaluation result is to construct a scientific, rational and effective evaluation hierarchy.The complex structure and numerous equipments within urban medium voltage networks result in its complicated analysis. Traditional distribution network evaluation focuses on reliability and economy, lacking comprehensive and synthetic analysis, and cannot meet the demands of distribution network's rapid development.In view of the characteristics and the evaluation purpose of present and planning distribution networks, evaluation theory is deeply discussed, comprehensive evaluation hierarchy is constructed, and evaluation method is proposed, for present and planning distribution networks respectively.Firstly a comprehensive evaluation system suitable to urban present distribution system is established by means of analytic hierarchy process (AHP) to assess distribution network in such aspects as technical reasonableness, system security, etc. Next, by use of several quantitative analysis methods combined with the individual case and the whole, the problems existing in power system can be overall reflected, and the substations and feeders where most problems exist are given. To solve discovered problems a short-term power network planning is proposed, and short-term renovation projects of power network construction and their priority ordering are put forward. A software package of the presented method is developed and successfully applied in power supply companies belonging to Beijing Electric Power Company.Firstly a comprehensive evaluation system suitable to urban planning distribution system is established to assess distribution network in such aspects as system security, reliability, economy, adaptability, coordination, etc. Next, base on the comprehensive marking, the problems existing in power system can be overall reflected by thorough study. To supply supplementary analysis for distribution network planning decision-making, the evaluation results of different planning programs are compared with each other. The case study verifies that the distribution network planning evaluation hierarchy is able to seize the key elements influencing the characteristics of network planning, is able to integrally and quantitatively describe the planning program good or bad, and possesses significant engineering practicability.