| With the intensification of global energy shortage and environmental pollution,taking more effective measures to develop and use renewable energy has become an inevitable choice in today’s world.The large-scale integration of renewable energy sources with strong volatility and uncertainty into the distribution network not only challenges the flexibility of the distribution network,but also causes the distribution network to face problems such as local voltage exceeding and power back.As an efficient and flexible regulation resource,the energy storage system has the advantages of two-way conversion and rapid response,and has the ability to improve the power distribution and voltage quality of the distribution network and solve the time mismatch of source and load.Therefore,this thesis conducts in-depth research on the ability of energy storage to deal with wind and solar uncertainty and improve system flexibility,focusing on the optimal configuration of energy storage devices in the distribution network.The following are the results of the work and thesis research completed in this thesis(1)A fuzzy C-mean clustering algorithm and robust optimization theory are used to integrate the distributed wind power and PV output curves in the distribution network,and obtain the typical scenarios of scenery output and the set of uncertainty operation scenarios in the distribution network,respectively.On this basis,the optimal number of cluster numbers and the worst operation scenarios are selected through the XB clustering effectiveness index function and the endpoint scenario method,respectively,and the wind and solar output data at this time are brought into the distribution network system,which lays a foundation for the establishment of the subsequent optimal configuration model and simplified calculation.(2)The flexibility analysis process,definition and characteristics of flexibility of power system are expounded,which creates theoretical conditions for improving the flexibility of distribution network.In addition,the basic flexible supply and demand relationship in the distribution network is expounded,and the flexible needs to maintain the smooth operation of the distribution network and the various flexibility resources that provide flexibility are introduced,which lays a foundation for formulating the optimal configuration scheme of energy storage considering flexibility.(3)A distribution network cluster division method considering flexibility is proposed,a distribution network cluster division model with flexibility demand as the main objective function is established,and the traditional distribution network structure is transformed into a three-layer grid structure of distribution network-cluster-node.Based on cluster division,a two-layer multi-objective energy storage optimal allocation model considering flexible supply and demand balance is established,and the volatility and uncertainty of renewable energy are solved through overall analysis and local optimization.Finally,the proposed energy storage optimal configuration scheme is verified by example,which can not only improve the system flexibility and reduce the cost of energy storage configuration,but also improve the stable operation capacity of the distribution network.(4)A cluster division method that integrates load-storage flexibility resources and considers robust optimization of wind and solar output is proposed,and an optimal allocation model of energy storage in distribution network considering the risk cost of insufficient flexibility is established.Through the verification of examples,it is shown that considering the optimal allocation scheme of system flexibility resource interaction energy storage,it not only reduces the investment cost of optimal allocation of energy storage devices,but also greatly reduces the risk loss of insufficient flexibility caused by the imbalance between flexible supply and demand,and finally further improves the flexibility and economy of the distribution network. |
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