Active Distribution Network Operation Management Strategy Research Based On The Complex Network Theory

In recent years, with the steady growth of demands for electric power and the shortage of the traditional energy supply, the active power distribution network with its intelligent, flexible and sustainable development characters has gained widespread recognition and rapid development. Compared with the traditional distribution power network, the active distribution network can reinforce the comprehensive utilization of the distributed energy, which can improve the absorption capacity for green energy of power system, optimize the ratio structure of the primary energy and realize the sustainable development of current power system; but on the other hand, with the transition of the power supply mode from unidirectional tree structure to bidirectional ring structure, some limitations of the common power system analysis method on grid plan, operation and optimization etc have been revealed; in addition, the distributed power sources, e.g. photovoltaic and wind energy, are easily been influenced by the environment element, which inevitable cause volatility and changes of the power quality. Therefore, based on the operation and working characteristics of the active distribution network, exploring an effective planning and analysis method to compensate the existing shortage in the active distribution network study has become a significant research in power system area.As an effective method in analyzing and studying the characteristics of network system, in recent years, the complex network theory has been more and more concerned and applied on the Internet, the Internet of things, the biological molecular network and other fields. Though in power system modeling and stability analysis aspects, it is becoming a hot issue and being greatly studied, for now, its application in the active distribution network research remains to be further development. This paper tries to find the common features of complex networks and active distribution networks based on the fully research of the complex network related theory and the analysis of the working and operation characteristics of the active power distribution networks. And using the advantages and related basis theory of the complex network, the dynamic modeling, fault propagation characteristics, stability analysis of systems, synchronization and collaboration of the active distribution networks are researched.In this paper, the dynamic evolving phenomenon of active distribution networks covering its growth, reconnection and shrinking characteristics from the network topology perspective are exploited, and a novel dynamic network evolving model is produced through introducing the locating probability and shrinking mechanism. The statistical results reveal that the node degree distribution of the active distribution network follows the power-law distribution and the node removal probability of the network dynamic has a significant impact on the network evolvement and robustness. Such macroscopic topological findings can greatly benefit the active distribution network operators from many aspects, including network planning, vulnerability analysis, fault prediction and cost-effective reinforcement.By embodying the conception of neighbor edges, cascading failure studies are brought into directed networks. Furthermore, with the random attack strategy, the minimum in-degree attack strategy and the maximum out-degree attack strategy, their influences on the random network and scale-free network with directed flows and the standard IEEE 118-bus system are investigated. The results and comparisons demonstrate that the propagation of cascading failures has close relationships with not only the attack strategies and the directionality of network, but also its initial loads and the capacities of network lines, which may be great helpful to analyze the vulnerability of directed networks and provide evidences to avoid cascading disasters.After theoretically studying the synchronization of complex network and fully proving its feasibility of synchronization and coordination, this paper proposes an optimal energy scheduling strategy to realize the energy management among multiple autonomous microgirds, based on the operation characteristics of the active distribution network. With the aid of storage units, the problem between the distributed generations energy effectively used and critical loads energy demand satisfied is well solved. The strategy firstly constructs the network topology matrix by reasonable choosing connecting weights; secondly, adopting the improved minimum spanning tree algorithm to determine the optimal power supply-demand relationships; and finally, choosing the non-critical loads with the linear matrix inequality algorithm, and adding them to the new autonomous microgrid structures. Series numerical simulation results are used to demonstrate and verify the effectiveness of the proposed strategy in the aspects of improving overall system energy utilization and continually power supply for critical loads.During the process of experiment and simulation, this paper takes the IEEE standard test systems to ensure the accuracy and effectiveness of the experimental results, and provides the reliable basis for the related research achievements. According to the different characteristics of problems and properties of objects, in the analysis and research process for the active distribution networks, this paper makes full use of the complex network theories, research methods and the way of thinking, which promise the effectively solution and widely promotion and expansion to the problems.