| In order to achieve the carbon peaking and carbon neutrality goals,developing largescale wind power is the inevitable trend of power system development in the future.The characteristics of centralized access of wind power and far away from the load center in China make it difficult to absorb a large number of wind power locally.Coordinated dispatching through multi regional interconnected power grids is useful to promote wind power absorption,and the flexible dispatching ability of VSC is more suitable for the cross region transmission of large-scale wind power.Therefore,for the scheduling problem of multi regional AC / DC hybrid power grid with high proportion of wind power,how to give full play to the flexible regulation ability of VSC,how to coordinate the power generation resources of multi regional in the spatial dimension and how to conduct multi time scale coordinated dispatching are the key issues to promote wind power absorption.The main research contents of this thesis are as follows:(1)The day ahead decentralized coordinated dispatching model for cross region transmission of high proportion wind power is studied.The decentralized coordinated dispatching method is adopted to decouple the interconnected power grid into independent sub regions through VSC tie lines.Based on dynamic scene generation and random optimization method,a day ahead random group combination model of sub region is proposed.Based on the flexible regulation ability of VSC converter station,the flexible operation mode of VSC is established,and the VSC power is taken as the coupling variable for iterative solution by ADMM algorithm.On this basis,a day ahead random group combination model considering tie lines reserve is proposed,and the upper and lower reserve of tie lines is added as the coupling variable in ADMM algorithm.The 2-area-12 node grid is used for simulation.The results show that the decentralized coordination optimal dispatching model is feasible,and the flexible regulation ability of VSC converter station and considering tie line power reserve are helpful to promote wind power absorption.(2)A day-ahead hierarchical robust scheduling model for high-proportion wind power through VSC based multi terminal DC grid is studied.Based on robust optimization and analytical target cascading,a hierarchical robust optimal scheduling method is proposed for the AC/DC grid base on VSC.The upper model is a multi-period tie line power coordination optimization model for DC power grid,and the lower model is a two-stage robust safety constraint unit combination problem for each independent AC area.The power of the VSC is used as the quantity for coordinating the exchange between the AC area and the DC grid.Polyhedral uncertain set is adopted to reduces the conservativeness of robust optimization based on high-dimensional ellipsoid sets.The simulation of the 4-area-6-node grid proves the feasibility of the model.The results show that the flexible regulation capability and bidirectional controllability of the power flow of the VSC converter station can greatly improve the wind power absorption.(3)The intra day rolling optimization model of multi terminal flexible direct interconnected power grid is studied.Based on ATC algorithm,a hierarchical scheduling model of intra day ultra short-term AC / DC grid is established,and the system is divided into DC grid and independent AC power grid.The lower model is the intra day ultra short-term opportunity constrained scheduling model of AC power grid,and the upper model is the tie line power coordination optimization model of DC power grid.On this basis,the intra day rolling optimization strategy is proposed.According to the continuously updated ultra shortterm predicted power of wind power,the hierarchical scheduling model is rolling optimized to achieve the optimal intra day scheduling result.The simulation of the 4-area-6-node grid proves that the daily rolling optimization based on the day ahead scheduling greatly improves the level of wind power consumption. |
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