| The construction of Energy Internet is aiming at achieving the goal of "UHV Power Gridã€Smart Grid and Clean Energy". Large scale interconnection of power grid will inevitably become a new trend in the development of power systems. With the increasing size of power grid and interconnection of regional power grid, power system has evolved from the traditional tree structure of "power generation and consumption" to large-scale modern power grid structure, which combines power, communications, and automation control technologies, realizing the interaction of power flow and information flow. More and more complex structure of power grid increases the difficulty of traditional analysis and calculation of power system, and can not solve these large-scale, high dimensional and complex problems appropriately, therefore, the limitations of the method based on the theory of reductionism appear gradually. As a new developing interdiscipline, complex network science inherits research method of systematology, which combines reductionism and holism. As a result, complex network science provides a new perspective and method for the study of interconnected large-scale power grid, which is conducive to the operation, control and management of the regional power grid and improve the security and stability of power network.Specific research works of this paper are as follows:Firstly, this paper introduces the development status of power grid and its existing problems, and the application of power system based on complex network theory is presented, and the topology model of complex power system is built. Five kinds of static topology characteristics of complex network topology:Degree, clustering coefficient, shortest distance, betweenness centrality, and assortativity coefficient are introduced. These five parameters are analyzed and calculated with several examples of typical power grid data. The small world characteristics and the assortative mixing characteristics in large power system are quantitatively evaluated.Secondly, the topological division algorithm for complex networks is studied, and the difficulty of traditional graph partitioning is discussed. Therefore, the heuristic algorithm is used to optimize the topology division algorithm, taking two classical community detection algorithms:GN division algorithm and Newman fast aggregation algorithm for examples,the advantages and disadvantages of the two algorithms are compared and analyzed in terms of the time complexity, the algorithm resolution, and the community decoupling performance. The example analysis uses two kinds of topological structure of the IEEE39 bus system:unweighted topology network and weighted topology network,the modularity Q value is used as the index to evaluate the quality of division,and the electrical distance is use as the line weight for weighted network computing. The internal connection of the power grid community is close, and the connection between the community and community is sparse, which has obvious community structure characteristics, providing a theoretical basis for the actual power grid partition scheme.Finally, the traditional community detection algorithm has the problem of high time complexity and long operation time.The improved particle swarm optimization algorithm is used to improve the algorithm speed and the quality of the reactive power grid partition. The improved algorithm redefines a new particle coding mode, and optimizes the speed and position update mode, compared with the traditional PSO algorithm. And taking the IEEE 118 nodes system and the IEEE 2736 nodes system as examples, the algorithm obtains high quality results with high efficiency, the results show that the improved particle swarm optimization algorithm is effective and reasonable for large scale reactive power grid partition. The electric connection of the internal partition is close and the partition is highly decoupled, and the regional voltage is well controlled. |
