本项目提出将多VSC交互并联拓扑作为并网接口层的统一形式，围绕存在的内部环流、开关次纹波叠加、交互耦合失稳三方面共性基础问题展开研究，包括：①模块并联环流形成的机理，确定环流形成的影响因素，并制定相应的抑制策略；②从交互并联系统整机的角度，研究开关次纹波叠加问题，综合考虑系统谐振点的个数，分析并优化系统滤波方式，抑制并联系统开关次纹波，从而减小对电网的污染；③研究多VSC间、VSC与电网之间存在的交互耦合失稳问题，分析接入点电网阻抗的不确定性导致并联系统与电网存在潜在的稳定性问题，以及VSC并联模块数的变化引起并网阻抗波动使得并联系统与电网的交互作用问题，实现交互并联系统的稳定高效运行。本项目研究成果将突破VSC多模块并联存在的共性关键技术难题，推动可再生能源、储能以及有源谐波治理等并网电能变换应用领域的发展，具有重要的理论研究价值和应用前景。

The project proposes an unified concept of the grid-connected interface based on the interleaved-parallel VSCs .It is researched about three fundamental studies, including the inner current circulation of multi-parallel VSCs , switching wave superposition and the instability of the interleaved coupling. At first, the principle of loop currents between the paralleled modules will be investigated, and then, in order to suppress the loop currents and allocate the power between the different modules, the corresponding strategies will be proposed based on the specific factors. However, several existing problems decrease the performance of IPVSC, including loop currents between the different modules, the grid population caused by the power electronics facilities and the potential unitability of the VSCs. Therefore, the suppression strategies and the design for grid-connected filter are our focuses. Moreover, the research on impedance-based stability for our system is another focus. In addition, the interleaved stability, which exists in multiple parallel VSCs or between VSC system and the grid, could realize the stable and effictive operation of interleaved parallel systems.The research project will exceed fundamental techniques of interleaved-parallel VSCs, focusing on solving critical problems of high-capacity grid-connected equipment, and enhancing capacity of grid-connected equipment, capability, efficiency and reliability. Project-related achievements are versatile, and have important theoretical research value and application prospects.