基于分段变目标控制的限流型双馈风电场连续故障穿越研究

Cascading trip-off of wind farms adjacent to HVDC caused by commutation failure has been one of the most severe problems with the development of wind farm cluster. Research on complex fault disturbance ride through is an important work to ensure the safety and stability of the wind power integrated power system. This project will research on the following scientific issues: 1.Mapping mechanism between key parameters of wind turbines and the multi-dimensional characteristics of recurring faults. 2. Synergy mechanism among decoupling and segmentation of the disturbance process and variable aim control strategy. Based on the aforementioned challenges, the project first presents a quantitative description of the recurring fault ride through failure mechanism based on the mapping relationship between the varying of key parameters of wind turbines and the fault characteristics. Then decoupling model of complex recurring fault process from the perspective of fault process segmentation will be established. Meanwhile the condition boundary of control system involving in the segmentation variable aim coordination mechanism is ascertained. Finally, an adaptive control scheme for recurring fault ride through of wind farms will be proposed, which considers the optimal reactive power support allocation and hardware & software coordination. Research results will provide theoretical basis and technical support for coordination control driven by recurring fault ride through capability enhancement while wind power cluster integration, and thus effectively promote the development of the wind power grid adaptability.

高压直流故障导致直流近区风电机组连锁脱网事故已成为集群风电发展过程中不容忽视的严重问题之一，研究适用于复杂故障扰动的穿越控制，是保障风电系统并网安全稳定的重要内容。本项目围绕“连续故障多维特征与风电机组关键参数映射关系刻画问题”和“扰动过程解耦与分段变目标控制协同作用机制问题”两个关键科学问题展开研究。研究风机关键参数变化与连续故障特征映射关系定量刻画方法；提出从连续故障扰动分段角度出发的复杂连续故障过程解耦和分段变目标协调机制的控制边界条件确定方法；进而提出连续故障穿越下考虑无功优化分配支撑的软、硬件协调风电场连续故障穿越控制方案。研究成果将为风电集群发展中连续故障穿越能力提升驱动的协调控制提供理论与技术支撑，有效推进风电机组并网适应性工作的发展。

针对集群式风电在高压直流故障引发的连续暂态电压扰动下存在的连锁脱网风险，本项目围绕“连续故障多维特征与风电机组关键参数映射关系刻画问题”和“扰动过程解耦与分段变目标控制协同作用机制问题”两个关键科学问题展开研究。. 本项目首先通过分段线性解耦等效的方法，分析了连续故障扰动下双馈风电场动态响应特性，指出由于电磁响应的叠加作用机制，连续电压扰动可能造成DFIG过压过流的多次增大，对风机的暂态冲击比单一事件型电压扰动更加严重，风电机组在扰动后期有更大的脱网风险。. 其次，对低高电压连续扰动下的DFIG定子磁链、转子感应电势以及撬棒电路触发后的转子电流表达式进行了推导和分析，根据Crowbar触发后的DFIG转子电流时域表达式，提出一种在电压连续扰动工况下防止直流母线过压的Crowbar阻值选择方法。. 基于前述理论分析成果，最后提出了多种低高电压连续扰动下的DFIG限流方案，包括基于转子串联阻抗的DFIG连续穿越方案、基于变流器重构的DFIG定子电压补偿方案、定子侧外接串联变压器的DFIG动态限流方案以及基于转子侧储能系统的连续故障穿越方案。搭建了实验平台并验证了部分理论研究。. 本项目共发表与录用标注SCI/EI论文13篇，授权中国发明专利5项。基于本项目研究内容进一步扩展，项目负责人郑子萱获国家自然科学基金面上项目资助。本项目研究成果对于认识风机在复杂连续暂态电压扰动下的响应特性，保障扰动下的风机安全稳定运行提供了理论依据与技术支撑，可有效推进风电机组并网适应性工作的发展，为加快高比例新能源的未来新型电力系统的推进提供指导。