Multi-Objective Planning Of Urban Electric Network Structure With Different Voltage Grades

Urban electric network usually includes several networks with different voltage grades. In this paper, according to their individual characteristics and different requirements in planning, the multiobjective planning methods for the structure of transmission network, High-Voltage (HV) distribution network, and Medium-Voltage (MV) distribution network are proposed. Among these, MV distribution network is the key of improving power supply reliability of the final customers, also is the emphasis of urban electric network planning research presently; therefore, the effects of new ideas that improving power supply reliability on MV distribution network structure planning are explored further. The following researches have been developped:(1) A united planning method for the network structure and partition mode of urban transmission network is proposed. The bilevel multiobjective united planning model is formulated, which is solved by a sepecial designed Multiobjective Genetic Algorithm (MOGA). Precondition of the solution is assumed, based on which the solution of the bilevel multiobjective model could be transferred to the solution of a corresponding single level multiobjective one. Key steps of the MOGA are designed, and the efficient solution set of the bilevel multiobjective problem could be formed with the solution of the corresponding single level problem.(2) A planning method for"hand in hand"urban HV distribution network structure is proposed. Power load forecasting values are presented as the equilateral triangular fuzzy numbers, and the multistage multiobjective fuzzy planning model is formulated. The characteristics of"hand in hand"network structure in multistage planning are explored, and then the optimization objectives in multistages planning are obtained, serving as the evaluation indices of the planning schemes. The arithmetic, comparison, and order criterions of triangle fuzzy numbers are explored, which make the MOGA applicable for solving the fuzzy planning model.(3) A method based on ComGIS network analysis and MOGA is proposed for the open-loop MV distribution network structure planning. The multiobjective planning model of open-loop MV distribution network structure is constructed. And a special MOGA is designed based on the network dataset built by ComGIS platform. The network analysis function of the ComGIS is embedded in the MOGA to find the single-loop optimal paths, which improves the efficiency of evolutionary coding and operators obviously. Finally, the Pareto Optimal Set (POS) of the multiobjective planning problem is obtained, including several candidate planning schemes.(4) The effects of Performance Based Regulation (PBR) reliability government modes on the multiobjective planning of urban MV distribution network structure are researched, and two modes are compared to find their individual applicable environment. The uniform reliability power price-compensation mechanism and reliability indices reference values are designed, and then the standards of the two PBR modes are established. The financial risk of the electric utility is obtained according to the probabilistic characteristic of power supply reliability indices. Then the MV distribution network structure multiobjective planning model under PBR reliability government is constructed.(5) The effects of Distributed Power System (DPS) on the multiobjective planning of urban MV distribution network structure are researched. Being treated as the measure of improving power supply reliability of the important customers, DPS are included in the uniform planning of MV distribution network structure: two operation modes are proposed for DPS connected in the MV distribution network, and the processing mode for DPS in the modeling of distribution network planning is presented; the outage cost calculation method for distribution network including DPS is proposed, based on which the multiobjective planning model is constructed. And the uncertain problems in DPS constructing and their effects on the planning model are analysed.Practical networks are selected to test the effectiveness of the structures planning methods for the different voltage grades networks. And the effects of PBR reliability government modes and DPS on MV distribution network structure planning are analysed through the planning results of the practical distribution network.