Research On Capacity Optimal Configuration Of Grid-Connected Island Microgrid

As an important fulcrum for the development of marine undertakings,islands have extremely important strategic significance.However,the submarine cables connected to the onshore power grid are seriously aging and often fail.The problem of low reliability of the island’s power supply needs to be solved urgently.There are abundant renewable resources around the island,and at the same time using the residual value of the submarine cable,the construction of the island microgrid is an effective measure to solve the problem of power supply reliability,and it has certain economic benefits.How to plan and configure the number of distributed power sources in the island microgrid to meet the reliability of the island’ s power supply while minimizing the cost of the island’s microgrid system during the operating cycle is a key issue in the construction of the microgrid.At present,at the component level,an accurate reliability model for submarine cables has not been established.An accurate reliability model can effectively reduce the cost of grid-connected island microgrids and make the island’s power supply strategy clearer;at the system level,there has not been established a grid connection that considers submarine cable failure optimal configuration model of island microgrid capacity.In response to the above problems,the specific work of this article is as follows:(1)The typical structure of the grid-connected island microgrid is described and the distributed power generation is mathematically modeled.The control strategy of "on-site power supply and the remaining online" is proposed,and the island power supply strategy when the submarine cable fails and when the submarine cable is not faulted is briefly described.(2)The submarine cable failure risk factors are summarized and analyzed,and the failure factor indicators of the submarine cable reliability model are established.The subjective and objective weights are determined by the analytic hierarchy process and the entropy weight method,and the combined weights are obtained through comprehensive solutions,and solve with cloud model,and finally the operating state of the submarine cable is simulated using the Monte Carlo method,and the accuracy of the cloud model is verified.(3)The cost minimization in the operating cycle is taken as the optimization goal of the island microgrid capacity configuration.The constraints include submarine cable power supply constraints,power supply reliability constraints,energy storage battery constraints,and diesel generator capacity constraints.The proposed model is solved by genetic algorithm.A case study is carried out on an island and its submarine cable in Dalian area.The results show that the submarine cable model established by the cloud model is more accurate and universal;the island microgrid model based on this can reflect the actual situation.The operation situation has extensive guiding significance for islands with low power supply reliability and a certain failure rate of submarine cables.