Retrofit Control: A New, Modular Gyrator Control Approach for Integrating Large-Scale Renewable Power

这个为期3年的NSF项目倡导一种具有超高风速和光伏渗透率的配电系统，其运行和管理由一种名为固态变压器(SST)的智能设备实现。SST是一种基于电力电子的可控变压器，可以轻松地将通信和智能集成在一起，以进行需求侧管理。SST的双向潮流能力可以将本地发电的电力以受控的方式反馈到电网，这使其成为大规模风能和太阳能发电一体化的定制选择。随着美国可再生能源装机容量的持续增长，还需要安装大量的SST。这将需要跨越数百到数千个SST的先进、复杂和交叉耦合的控制算法。我们在这个项目中的目标是研究这类支持SST的控制应用的不同变体，以实现平稳、稳定的可再生集成。我们将特别解决两个问题，即频率控制和电压控制，这两个问题是基于一个基本问题，即如何为配电网中的每个SST选择控制器设定值，以确保在风能和太阳能发电具有较高变化性的情况下稳定运行。目前，考虑到发电侧的物理约束，还没有一个定义良好的控制算法来解决这一问题。我们的控制器将实时响应发电和负荷的任何变化，并使用一种称为改装控制的新控制方法自动重新计算每个SST的设定值。该项目的智能优势将是开发下一代电网的控制设计，以新的电力电子变流技术为中心。将应用分叉分析、非线性控制、移动平衡系统和递阶控制等先进思想。更广泛的影响将是将控制系统、电力系统和电力电子这三个传统上截然不同的研究团体聚集在一起，联合起来，解决在可再生能源渗透率较高的情况下出现的稳定性和动态问题。研究成果将通过出版物、本科生和研究生教育以及会议教程进行传播。北卡罗来纳州立大学和东京工业大学之间的美日研究计划将促进国际合作。

This 3-year NSF project advocates a power distribution system with ultra-high wind and photovoltaic penetration, whose operation and management are enabled by a smart device called the Solid-State Transformer (SST). The SST is a power electronics-based controllable transformer wherein communications and intelligence can be easily integrated for demand-side management. The bi-directional power flow capability of the SST can feed locally generated power back to the grid in a controlled way, which makes it a tailor-made choice for integrating large-scale wind and solar generation. As renewable installations continue to grow in the United States, multitudes of SSTs will need to be installed as well. This will necessitate advanced, complex and cross-coupled control algorithms spanning hundreds to thousands of SSTs. Our goal in this project is to study different variants of such SST-enabled control applications that can enable renewable integration in a smooth and stable way. We will particularly address two problems, namely, frequency control and voltage control, based on the fundamental question on "how to choose controller set-points for every SST in a distribution grid to ensure stable operation despite high variability in wind and solar generation". Currently, there is no well-defined control algorithm that addresses this question considering the physical constraints from the generation side. Our controllers will respond in real-time to any change in generation and loads, and automatically recalculate the set-points for every SST using a new control approach called retrofit control. The intellectual merit of this project will be in developing control designs for next-generation power grids, centered on new power electronic converter technologies. Advanced ideas of bifurcation analyses, nonlinear control, moving equilibria systems, and hierarchical control will be applied. The broader impact will be in bringing together three traditionally distinct research communities - control systems, power systems, and power electronics - to join forces, and resolve emerging issues on stability and dynamics in face of high renewable penetration. Research results will be broadcast through publications, undergraduate and graduate education, and conference tutorials. International collaboration will be fostered through a US-Japan research initiative between NC State University and Tokyo Institute of Technology.