本项目通过电力系统、优化理论、可靠性理论和气象学等多学科的交叉，从探寻海上风电场的VSC-HVDC并网系统风险评估理论入手，根据VSC-HVDC的运行控制特性、风电出力的间歇性、海上恶劣天气因素等，建立海上风电场VSC-HVDC并网系统的可靠性评估指标体系（如等值有功功率、无功调节度、风电场和并网系统的协调度等）和三层递阶可靠性评估模型。根据计入因素不同，该模型可分别用于：VSC-HVDC系统本身、基于VSC-HVDC的陆上风电场并网系统、基于VSC-HVDC的海上风电场并网系统可靠性评估，开拓了VSC-HVDC系统可靠性分析的新途径。结合VSC-HVDC对大电网的可靠性贡献，计及设备的投资、安装、运行维护等费用建立海上风电场VSC-HVDC并网系统设备选型和并网拓扑的统一优化模型，提高电网可靠性、减少停电损失，为VSC-HVDC并网系统的规划、运行和改造提供新的分析方法和量化决策依据。

By subject crossing of electrical power system, optimization theory, reliability fundamentals and meteorology etc., this project started its work with studying the risk assessment theory about VSC-HVDC transmission systems for grid connection in offshore wind farms. Given the operation control features for VSC-HVDC system, intermittent wind power output, as well as the bad sea weather and so on, this project has built a reliability evaluation index framework (such as equivalent active power, reactive adjust degree, coordination degree of wind farms and VSC-HVDC, etc.) and a three-level hierarchical reliability evaluation model for VSC-HVDC transmission systems for grid connection in offshore wind farms. According to different factors involved, this model can be applied respectively to do reliability evaluation over VSC-HVDC system itself, VSC-HVDC systems for grid connection in onshore wind farms, VSC-HVDC systems for grid connection in offshore wind farms, and this means it has created a new way to do the reliability analysis on VSC-HVDC system. Combined with the contribution VSC-HVDC has done for the reliability of the large power grid, along with the cost of equipment investment, installation, operation and maintenance and so on, a unified optimization model for equipment selection and grid connection topology is built to serve VSC-HVDC systems for grid connection in offshore wind farms. This model is designed to improve the reliability of power grid, reduce the loss caused by outage, and to provide a new analysis method and quantitative decision-making foundation for VSC-HVDC system planning, operation, and improvement.