Research On Optimal Planning For Urban Middle Voltage Distribution System Based On Power Supply Capability

As the key-ligament between the customer and the generation & transmission system, distribution system plays a very important role in ensuring the continuous power supply for customers in safety and in high reliability. Therefore, the scientific evaluation on the power supply capability of urban distribution network is of enormous social and economical significance.Firstly,to improve the insufficiency of traditional method based on the load supply capability referring from the transmission system,this paper proposes a simple method to evaluate the power supply capability of distribution network, which is based on the N-1 guideline and the interconnections between main transformers. The interconnection bottlenecks of the distribution system and the load transferring bottlenecks can be found easily by the method, which can provide effective references for urban distribution network planning. Meanwhile,a set of distribution system power supply capability evaluation index system was put forward based on the indexes such as maximum power supply capability, maximum load rate, proportionality, equipment load margin,system margin and so on, which provides a reasonable measurement on the matching degree between the power supply capability and the actual load.Secondly, based on the basic concepts and analytical methods above, the paper makes thorough study of parallel operation and split operation of the main transformer,power supply capability analysis on connection modes of urban middle voltage distribution network,power supply block scale and the optimal transfer capability of network. A series of practical recommendations on optimization and planning for present distribution network was obtained from the above research and they will provide a powerful basis for the urban distribution network construction.Finally, take a District network for example, the power supply capability was calculated and though the analysis on promoting space of the power supply capability and the improvement measures for the network, several suggestions were presented for the District, which has guiding significance for its network planning and network construction from 2006 to 2020.