Load Clustering Based Mesh Planning Method And Routing Algorithm For Medium Voltage Distribution Networks

The network routing planning is an important part of the medium voltage(MV) distribution network planning, and is an important prerequisite to ensure the stable, safe and reliable operation of a power grid. In recent years, more and more power supply companies carry out the pilot work about the power supply meshes based distribution network planning, which can effectively solve the problems of overlapping or unclearpower supply rangesof power supply lines, complicatedtie connection relationship of lines, indirect line routing and the long power supply radius.On the basis of the home and abroad excellent theory and practice of distribution network planning, load clustering based the meshing planning method are proposed for medium voltage distribution networks. The main contents of the idea and approach include three aspects: conceptual routing network, network constructing mode and standardized mesh design. Based on the topography, load distribution and main channel construction of a planning area, the conceptual routing network is to depict the macro routingof lines. Based on the conceptual routing network and the result of power supplyblock dividing, the network constructingmode is to obtain a relatively independent and "self-healing" power supply mesh which is made of several power supply blocks, which can satisfy the requirements of transformer loading rates and transformer “N-1” safety and substation “N-1” safety. Combined the guideline's requirement of reliability and safety, with a power supply mesh being regarded as a unit, the standardized mesh design is to set the standardized and normative guidance on the construction and transformation for different power supply areas, which involves the contents of line connection modes, load control, user connection, equipment type selecting and distribution automation constructing, etc.Considering the actual situation that it is difficult to determine the connecting positions of load points(distribution transformers and ring main units) for the target year, a new thinking idea is presented for the routing optimization of urban medium voltage distribution networks. The main lines of medium voltage distribution networks are determined beforehand, and then the load points are connected to the main lines through some measures such as a lateral line once their connecting positions are known. Also, a practical approach is proposed for the routing of main linesbased on power supply meshes. Firstly, based on the results of spatial load fore-casting and substation planning, the power supply area of each substation is divided into several power supply blocks; Then, in order to determine the blocks' tie directions, the minimum weight matching algorithm in graph theory is employed to find three types of block matching types(i.e., matching of the blocks between different substations, matching of the blocks in the same substation and matching of no blocks), and the matching of a number of blocks is regarded as a power supply mesh with a certain "self-healing" function; Finally, under the constraints of the streets' routing and the blocks' load centers, the shortest path algorithm is respectively used to find the path of a main power supply line for each block and the path of a main tie line between the blocks of a power supply mesh.In this paper, three examples are given. One is the application of the meshing planning method and approach to the planning of a real distribution network; another is the line macro routing and network mode constructing of two relatively large zones; the third is the application of new routing approachto main 10 kV line planning in a city, based on the spatial load forecasting and substation planning. Through the analyses of thethree example, it is shown that the proposed method is practical and is of important guide significance to planners.