Microgrid Interconnections Control via Voltage Angle Droop Methods

该项目提出了一种新的未来配电网的系统结构，其中多个微电网通过配电网线路耦合，并以独立的可控实体的形式呈现。基于传感器(微型同步相器)和执行器(电力电子接口)的创新，我们设想未来的配电网将由许多微电网集群组成，每个集群通过公共耦合点连接，惯性很小或没有惯性。预计该项目的成果将帮助许多社区(如农村和发展中地区)跨越已有百年历史的配电网，以一种设想的清洁方法，以更高的可靠性整合更深层次的可再生资源。该项目将提供一个新的视角，激励学生设计一种本质上不同的电力输送系统，该系统是为传感和控制技术的范式转变量身定做的。该团队位于美国最大的大学电力/能源项目之一，将引入关于未来配电网主题的新课程模块，该模块紧密结合了200多名目前在德克萨斯农工大学攻读电力课程的本科生和研究生的电力电子和电力系统背景知识。该团队将继续吸引本科生进行研究的良好记录，特别是在代表性不足的群体中。样机和模拟可视化将在每年吸引300多名高中生和家长参加的年度“探索欧洲教育”活动上展示。该项目的科学目标是研究新型电力电子接口以及微电网集群的控制，以确保配电网级别的动态安全。该项目将解决以下问题：a)全直流或交流微电网应该如何通过适当设计的电力电子接口与配电系统交互；以及b)什么样的控制架构将利用电力电子和传感器的先进技术，并实现可证明的动态性能。该项目提出了一个真正的跨学科研究议程，以利用电力电子和控制来推动配电网科学的发展。电力系统和电力电子的交叉融合将为未来的配电网提供新的视角。这个项目的智力价值有四个方面。首先，研究小组将调查通过分布式下垂管理来保证配电系统级暂态稳定的可能性。这一难题将利用闭环微电网模块动力学的结构，进而将配电网暂态模型作为具有时不变扇区有界无记忆非线性的Lur‘e系统。其次，当微电网与配电系统有多个连接时，该项目将引入微电网的多点公共耦合(PCC)控制。这将允许将一个兆瓦级逆变器分解为多个较低额定功率的逆变器，成本更低，可靠性更高。第三，针对具有兆瓦级容量的直流微网，提出了一种有限LC输出滤波阻抗的电压型逆变器输出电压和相角调整的闭环迭代过程，并对其进行了验证。第四，针对交流微电网的情况，将开发一种具有容错功能的最优电力电子变压器拓扑结构，以实现现代微型同步相器所实现的微电网角度下垂动态控制方法所要求的快速响应的大范围电压幅值和角度调整。用于电压/角度调整的现有技术方法响应慢且范围有限，使得它们不适合所提出的控制体系结构。

This project proposes a novel system configuration for a future distribution grid in which multiple microgrids are coupled through distribution lines and present themselves as individual controllable entities. Built upon the innovations on sensors (micro-synchrophasors) and actuators (power electronic interfaces), we envision a future distribution grid to be comprised of many microgrid clusters, each interfacing through points of common coupling with little or no inertia. It is anticipated that the results of this project will help many communities (such as rural and developing regions) to leapfrog the century-old distribution grid through an envisioned clean slate approach to integrating a much deeper level of renewable resources at a much higher level of reliability. The project will provide a fresh perspective on inspiring students to engineer a qualitatively different electricity delivery system that is tailored for the paradigm shift in both sensing and control technologies. Housed at one of the largest university power/energy programs in the U.S., this team will introduce new course modules on the topic of the future distribution grid, which closely integrates power electronics and power systems background knowledge for more than 200 undergraduate and graduate students currently enrolled in power courses at Texas A&M. This team will continue a strong track record of engaging undergraduate students for research, in particular underrepresented groups. The prototype and simulation visualization will be presented at the annual "Discover ECE" event, which attracts more than 300 high school students and parents annually. The scientific objective of this project is to investigate novel power electronic interfaces, as well as the control of microgrid clusters for ensuring dynamic security at the distribution grid level. The project will address the following questions: a) how should an all-DC or AC microgrid interact with distribution systems through an appropriately designed power electronics interface; and b) what would be a control architecture that leverages advances from power electronics and sensors, and achieves provable dynamical performance. This project puts forward a truly interdisciplinary research agenda to leverage power electronics and control for advancing the distribution grid sciences. The cross-fertilization of power systems and power electronics will provide fresh perspectives for the future distribution grid. The intellectual merit of this project is four fold. First, the research team will investigate the possibility of guaranteeing distribution system-level transient stability via distributed droop management. This difficult problem will draw upon the structure of the closed-loop microgrid module dynamics, which, in turn, lends the distribution grid transient model as a Lur'e system with time invariant sector bounded memoryless nonlinearities. Second, the project will introduce a multiple points of common coupling (PCC) control of a microgrid when it has multiple connections with distribution systems. This will allow for decomposing an MW-level inverter into multiple lower rating inverters with much lower cost and increase in reliability. Third, for the case of DC microgrids with MWs of capacity, a closed loop iterative process of adjusting the output voltage and phase angle for voltage source inverters with finite LC output filter impedance will be will introduced and tested. Fourth, for the case of AC microgrids, an optimal power electronic transformer topology (with fault tolerant features) will be developed to achieve the wide range of voltage magnitude and angle adjustments at fast response as required by the microgrid angle droop dynamic control approach enabled by modern micro-synchrophasors. Prior art methods for voltage/angle adjustment are both slow in response and limited in range, rendering them unsuitable for the proposed control architecture.