微网系统Kuramoto建模与基于能量成型的无缝切换调频控制方法研究

To solve the pressing issue of distributed generators’ large-scale penetration, microgrid has become an effective carrier of the distributed generators. But due to its particularities of small inertia, multi-microsources’ intermittent and random outputs, and large transients between grid-connected mode and islanded mode, the stability of the microgrid under all the operation conditions, such as the grid-connected mode, the islanded mode and the switch process, can’t be fully guaranteed by conventional linear control strategies and small-signal stability theory. This project is based on a novel outlook, the view of dynamical network. It transforms the power balance problem among microsoures, energy storages and loads into the synchronization problem of multiple phase coupled oscillators. Therefore, a Kuramoto phase coupled oscillator model which can characterize the feature of microgrid will be built. And based on the oscillators dynamic and energy viewpoint, a new nonlinear frequency control strategy for the microgrid will be derived to realize steady operation and seamless transfer between the grid-connected and the islanded modes by energy-shaping control theory. Taking consideration of operation modes, oscillation suppression and seamless transfer, this method in which energy operates throughout the modeling and control, seizes the engineering background of the microgrid operation, emphasizes the nonlinear characteristics of the system, makes full use of the mircogrid’s structure and properties, and satisfies the system’s robust requirements with large signal stability. The implementation of this project will provide a stable theoretical foundation and a solid technical guarantee for applying advanced technology to microgrid operation and control in our country. And it will also be an important promotion of a large-scale distributed generation and future smart grids construction in China.

为解决分布式发电大规模并网问题，微网成为分布式发电的有效载体。微网具有系统惯性小、多微源间歇性随机出力、并网孤岛模式切换瞬变大的特殊性，使得传统线性控制策略和小信号稳定性理论难以确保其在各模式及模式切换下的稳定性。本项目以动力学网络的新视角，将微网中微源、储能、负荷的功率平衡问题转化为多耦合相位振子运动同步问题，建立表征微网特点的Kuramoto耦合相位振子模型，并将振子动态特性与能量观点结合，采用能量成型控制理论设计微网稳定运行且无缝切换的新型非线性调频控制策略。该方法综合考虑微网运行工况、振荡抑制、平滑切换等因素，以能量贯穿控制过程始末，紧扣微网运行工程背景、重视系统非线性特点、充分利用微网结构与特性，符合系统大信号稳定的鲁棒需求。项目成功实施将为我国微网运行与控制的先进技术应用提供坚实的理论基础和技术保障，也将对我国分布式发电规模化应用和未来智能电网的建设起到重要推动作用。

项目针对微网内部多分布式发电单元功率协同共享的应用场景，从动力学网络的新视角，将微网系统调频问题转化为多耦合相位振子运动同步问题。由此建立了表征微网特性的Kuramoto耦合相位振子模型，以非线性相位耦合关系取代线性的下垂特性，准确描述了DER单元输出功率与微网频率间的联系；并将振子动态特性与能量观点结合，遵循微网内部DER单元动态能量交互的物理规律，采用了基于能量观点的非线性控制理论，设计出基于平衡点配置的调频控制完成了DER单元非线性无差分布式控制，提升了微网系统调频能力，增强系统频率稳定性，实现了微网系统并网、孤岛模式运行稳定且无缝切换的能量成型非线性控制策略。最后，项目完成了对基于Kuramoto相位振子模型的电力网络暂态能量函数的构造方法的研究，分析了基于Kuramoto模型的微网系统稳定平衡点吸引域估计问题。研究了切增负荷、DER输出功率变化对基于能量观点的非线性控制策略下微网系统暂态运行特性，推导出微网系统全局渐进稳定的暂态稳定性判据。本项目上述研究结论为微网运行与控制的非线性技术发展提供坚实的理论基础，也对微网中高渗透率DER发电单元的分布式协同控制策略应用提供重要的技术支撑。