Robust Droop and DC-Bus Voltage Control for Effective Stabilization and Power Sharing in VSC Multiterminal DC Grids
Robust Droop and DC-Bus Voltage Control for Effective Stabilization and Power Sharing in VSC Multiterminal DC Grids
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DOI：
10.1109/tpel.2017.2715039
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发表时间：
2018-05
影响因子：
6.7
通讯作者：
M. Davari;Y. Mohamed
中科院分区：
文献类型：
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作者：
M. Davari;Y. Mohamed
基于电压源换流器（VSC）的多端直流电网作为将可再生能源、能量存储单元和现代直流型负载集成到现有交流电网中的使能技术而得到广泛接受。下垂控制是一种常见的功率共享策略，以促进直流电网中不同终端之间的自主功率共享。然而，动态和稳定性的电网连接的VSC与直流功率共享下垂控制可以受到几个重要因素，没有在当前的文献中提到。其中重要的是：1）在设计DC链路电压控制器时忽略外下垂回路对DC链路电压动态特性的影响，这引起了不稳定动态特性，特别是在变换器中断和意外情况下的最佳经济运行、能量管理和成功网络运行所需的可变下垂增益下; 2）DC电网参数的不确定性（例如，无源负载电阻和从直流侧观察的等效电容（VSC）;以及3）直流电网中的干扰（即，从DC电网吸收或注入到DC电网的功率），其通过充当依赖于状态的扰动而改变工作点和变换器动态特性。为了克服这些困难，本文提出了一种鲁棒的功率共享和直流母线电压调节控制器的并网电压源转换器在多端直流电网的应用。建立了一个详细的动态模型，该模型考虑了下垂控制器的动态特性以及有效直流侧负载参数和施加在VSC上的干扰的影响。然后，设计了一种保持系统稳定性和鲁棒性能的鲁棒控制器。理论分析，包括MIMO动态分析的多端直流电网与所提出的控制器，以及仿真和实验结果，以显示所提出的控制器的有效性。
Voltage-source converter (VSC)-based multiterminal dc grids are receiving widespread acceptance as an enabling technology to integrate renewable energy sources, energy storage units, and modern dc-type loads into existing ac grids. Droop control is a common power-sharing strategy to facilitate autonomous power sharing among different terminals in dc grids. However, the dynamics and stability of a gird-connected VSC with dc power sharing droop control can be affected by several important factors that are not addressed in the current literature. Important among these are: 1) ignoring the effect of the outer droop loop on the dc-link voltage dynamics when the dc-link voltage controller is designed, which induces destabilizing dynamics particularly under variable droop gain needed for optimum economic operation, energy management, and successful network operation under converter outages and contingencies; 2) uncertainties in the dc grid parameters (e.g., passive load resistance and equivalent capacitance as viewed from the dc side the VSC); and 3) disturbances in the dc grid (i.e., power absorbed or injected from/to the dc grid), which change the operating point and the converter dynamics by acting as a state-dependent disturbance. To overcome these difficulties, this paper presents a robust power sharing and dc-link voltage regulation controller for grid-connected VSCs in multiterminal dc grids applications. A detailed dynamic model that considers the droop controller dynamics and the impact of the effective dc-side load parameters and disturbances imposed on the VSC is developed. Then, a robust controller that preserves system stability and robust performance is developed. Theoretical analyses, including the MIMO dynamic analysis of a multiterminal dc grid with the proposed controller, as well as simulation and experimental results are provided to show the effectiveness of the proposed controller.