Research On Stability Characteristics Of AC/DC Hybrid Transmission Grid Based On Multi-energy Complementarity

With the development of new energy sources and the construction of UHVDC project,the regional transmission grid will become new network source structure of AC/DC hybrid power grids with multi-energy complementation.The substantial increase in the penetration rate of new energy in the transmission grid will affect the safety and stability characteristics of the AC/DC hybrid transmission grid.This paper focuses on the three issues of large-scale new energy grid-connected schemes,power organization schemes,and new energy limit capacity from the perspective of transient stability for the multi-energy complementary AC/DC hybrid transmission grid.The characteristics of large-scale new energy transmission-side power grids with different topologies and grid-tied point are analyzed.Two large-scale new energy grid-connected topologies are proposed.The theoretical and simulation aspects of the power flow characteristics about the two grid-connected topologies and the degree of influence of different grid-connected topologies on grid stability under large disturbances are compared.Two schemes that near-DC and near-AC substation grid-tied point are proposed,and the two schemes are compared based on the transient stability of the power grid under different types of fault sets.This paper proposes a conventional unit combination optimization method under the change of new energy permeability.By quantifying the electrical distance and dynamic reactive voltage characteristics to quantify the contribution of different conventional units to the stability of each new energy grid-connected point,a unit combination model based on the optimal stability was established,and the uni t combination optimization method was simulated and verified.Obtain the transient stability of the operation mode under the expected fault set.A calculation method based on the relative strength of the AC/DC grid for the new energy limit dissipation capacity is presented,which provides a basis for new energy installation planning.Analyze the adaptability of differe nt AC and DC relative strength indicators,study the mathematical description of the impact of different influencing factors on the new energy consumption capacity,and compare the limits of new energy consumption capacity under different conditions from t heoretical calculations and simulations.The results show that the proposed calculation method can reflect the influence of grid relative strength change on the new energy limit capacity.