Frequency Synchronization And Economic Operation Of Microgrid With Community Structure

Distributed power generation(DG)is a small power generation system installed in the client to provide the user with self-use electricity.In China,distributed power generation is mostly used in a small range.In other words,DG of all users in a certain area is combined to form a small micro grid to supply power to local user groups.However,there are some defects in the synchronicity of the operation of small microgrid.In order to provide safe and reliable electric energy for local users,several microgrid systems in the nearby area need to be connected as a group,so that the largescale power generation system formed by interconnection will have more safe and reliable performance.Therefore,microgrid with community structure is an important direction for the development of microgrid in China.In this thesis,the island operation mode of microgrid with community structure is studied from the following aspects:Firstly,based on the complex network graph theory,the system model of microgrid is established based on the study of Kuramoto’s oscillator model synchronization problem.On this basis,the classical droop control theory is used to construct and simplify the dynamic equation of the system.Combining with the knowledge of matrix theory,two concepts representing the synchronization of the coupled network,namely frequency synchronization and phase synchronization,are deduced,and then the indexes to judge the synchronization of the micro-grid are given.Then,the influence of community structure on frequency synchronization of microgrid is studied.Mainly take the complex and changeable structure of the microgrid as the research object,by comparing the critical coupling strength,analyze the connection mode of the community,the number of internal and external connection edges of the community,the weight of the connection edge and other factors on the frequency synchronization of the microgrid and the random community in the microgrid.influences.Through MATLAB simulation experiments,the frequency synchronization of microgrids with different community attributes is compared.The results show that the frequency synchronization of the microgrid with the decentralized connection method between communities is better;and the appropriate increase in the number of connections inside and outside the community and the connection weight of the connection edges can improve the frequency synchronization ability of the microgrid.In addition,the economic operation method of microgrid is studied to maximize the economic benefits of microgrid stakeholders.In view of the conflict of interests between DG user groups and distribution companies,a non-cooperative game model is constructed based on game theory,which takes two communities of common DG user groups in microgrid and DG generation unit groups in distribution companies as two sides of the game.Using the duopoly competition model in Cournot model,the optimal power generation ratio of distribution company DG generation unit group and common DG user group is obtained by using iterative search method,taking the power generation of both parties as the strategy and aiming at maximizing the economic benefits of both parties.The optimal power generation ratio obtained will be used as the control target of the following control strategy.Finally,a secondary control strategy is proposed,which takes the DG unit in the microgrid to output power according to the ratio of the optimal power generation and maintains the frequency synchronization state of the microgrid as the two control objectives,to explore whether the microgrid at this time can meet the economic requirements at the same time.Run and synchronize.The simulation results prove that the proposed control strategy can enable the microgrid to achieve economic operation goals under different structures and scales.At the same time,the frequency of each DG in the microgrid has also reached a synchronized state,and the deviation between the synchronized frequency and the rated frequency is 0.Therefore,the significance of the proposed control strategy in terms of frequency synchronization and economy of microgrid operation is proved.