Collaborative Research: Large-Signal Stability Analysis and Enhancement of Converter-Dominated DC Microgrid

职务名称：合作研究：大信号稳定性分析和增强转换器主导的DC微电网摘要：虽然DC微电网具有许多众所周知的优点（例如，更简单、更有效和紧凑的功率转换系统以及电缆中更少的铜消耗），独特的DC电特性，例如直接P-V耦合（即，即使很小的负载/发电变化也会导致电压闪烁和设备故障）和低系统惯性（即，非常小的过载能力），对电网稳定性提出了巨大的挑战。小干扰稳定性只能保证系统在平衡点处的稳定性，但不能确定稳定域的真实边界，因此当系统存在大干扰时，保证系统稳定性存在很大的局限性。文献中现有的大信号分析工具要么适用范围有限，要么理论基础不严格。因此，有迫切需要开发一个基本的知识库的大信号稳定性分析在变流器为主的直流微电网和直流电网稳定性的综合设计准则。该项目的研究成果直接有助于我国在越来越多的微电网和分布式能源的情况下保持高可靠性和弹性电力的总体目标。拟议的教育和推广研究计划将（i）将理论框架，策划的数据集和测试平台从这个项目纳入现有的课程在两个里根迪尔伯恩大学和得克萨斯大学奥斯汀分校;（ii）促进K-12学生的STEM的兴趣; ㈢通过公共网站、顶级会议和期刊出版物以及各种媒体在公共领域传播所有项目材料、进程、设计和成果;和（iv）通过创建对微电网有社会意义的项目，为代表性不足的本科生提供丰富的研究机会。该项目的目标是（a）朝着推导具有多个分布式能源和恒定功率负载的DC微电网的大信号全局稳定性的充分标准迈出严格的一步，这仍然是一个未解决的难题，因为传统的小信号稳定性分析不适用于当发生大扰动时的变流器主导的电力系统，例如故障、脉冲功率负载或负载切换;以及（B）研究一种系统的方法，以理论上合理但易于实现的方式改善变流器主导的DC微电网的全局渐近稳定性，最终弥合三个传统脱节领域（控制理论、电力系统和电力电子）之间的技术差距。拟议的项目旨在通过利用主要研究者的专业知识（例如，电力系统、电力电子、优化、控制理论和机器学习）。该研究将在以下领域具有智力优势：（1）基本知识库，以了解具有100%恒定功率负载和基于变流器的分布式能源的无惯性直流微电网的大信号稳定性标准;（2）稳定性感知转换器，以理论上合理但易于实现的方式共同提高转换器主导的DC微电网的全局渐近稳定性。实施方式;（3）用于估计一般动态系统的吸引区域的严格数学方法和安全学习算法（即，该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Title: Collaborative Research: Large-Signal Stability Analysis and Enhancement of Converter-Dominated DC MicrogridAbstract: While DC microgrids have many well-understood advantages (e.g., simpler, more efficient and compact power conversion system as well as less copper consumption in the cables), the unique DC electric characteristics, such as direct P-V coupling (i.e., even a small load/generation change can lead to voltage flickers and equipment malfunctions) and low system inertia (i.e., very little overload capacity), pose great challenges to grid stability. Small-signal stability can only ensure the stability of the system at the equilibrium point, but the true boundary of the stability domain cannot be determined; hence there are major limitations in securing stability when the system has large disturbances. Existing large-signal analysis tools in the literature have either limited applicable ranges or non-rigorous theoretical foundations. Therefore, there is an urgent need to develop a fundamental knowledge base of large-signal stability analysis in converter-dominated DC microgrids and a comprehensive design guideline for DC grid stability. The research findings of this project directly contribute to the overall goal in our country to maintain high reliability and resilience electricity with more and more microgrids and distributed energy sources. The proposed education and outreach research plan will (i) incorporate theoretical frameworks, curated data sets, and testbed from this project into the existing curriculum at both the University of Michigan-Dearborn and the University of Texas at Austin; (ii) promote K-12 students’ interest in STEM; (iii) disseminate all project materials, processes, designs and results in the public domain via public-access websites, top-ranking conference and journal publications and in diverse media; and (iv) provide rich research opportunities to under-represented undergraduates by creating societally meaningful projects on microgrids.The goal of this project is to (a) take a rigorous step toward deriving the sufficient criteria for large-signal global stability in DC microgrids with multiple distributed energy sources and constant power loads, which is still an unsolved puzzle because traditional small-signal stability analysis does not apply to converter-dominated power systems when a large disturbance occurs, such as a fault, a pulse power load, or load switching; and (b) investigate a systematic methodology to improve the global asymptotic stability of a converter-dominated DC microgrid in a theoretically sound yet easy-to-implement manner, ultimately bridging the technology gap between three traditionally disjointed areas: control theory, power systems, and power electronics. The proposed project aims to fulfill this goal by leveraging the range and depth of the PIs’ expertise (e.g., power systems, power electronics, optimization, control theory, and machine learning). The proposed research will have intellectual merits in the following areas: (1) a fundamental knowledge base to understand the large-signal stability criteria of inertia-less DC microgrids with 100% penetration of constant power loads and converter-based distributed energy sources; (2) a stability-aware converter to collectively improve the global asymptotic stability of converter-dominated DC microgrids in a theoretically sound yet easy-to-implement manner; (3) rigorous mathematical methods and safe learning algorithms for estimating the region of attraction of a general dynamic system (i.e., a DC microgrid) with multiple equilibria; and (4) a power-hardware-in-the-loop testbed allowing for dynamic interactions of the proof-of-concept prototypes of innovative stability-aware converters.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.