Collaborative Research: Innovative Approaches for Robust and Reliable Operation of Voltage Source Converters in Critical Conditions of Emerging Grids

合作研究：新兴电网临界条件下电压源变流器稳健可靠运行的创新方法并网电压源变流器越来越多地应用于能源领域，例如用于分布式能源与电网的互连。转换器功能不佳的瞬间可能会导致本地和系统级问题。例如，在南加州的1，200 MW故障引起的太阳能光伏资源中断的原因被识别为逆变器控制系统中采用的锁相环的错误功能。现场数据还显示，电网电压谐波和常规公用事业拥有的电容器切换事件造成的部分或全部发电损失造成的光伏逆变器的不稳定操作。在具有挑战性的条件下，准确可靠的频率估计、电压同步和电流生成等功能对于保持分布式资源高度渗透的电网的可靠性至关重要。本研究确定了1）电网薄弱，2）电网电压失真，3）电网电压和频率干扰，广泛描述了主要的关键电网条件。因此，它建议1）调查这些条件对逆变器功能的影响，2）综合创新和有效的解决方案。拟议的研究投资于开发模块化，实用和高效的解决方案，完全集成转换器组件，并尽量减少要求苛刻的组件，损害这个多目标系统的完整性。该项目的结果将提高未来电网临界条件下逆变器响应的质量和强度，并将导致1）提高电力系统的可靠性，2）改善其电能质量，3）增加其逆变器托管容量。这将加强公共电力输送服务，增强相关能源行业的能力，并在各种教育和研究社区之间建立新的联系。该项目将刺激和维持对多样化学生的跨学科培训，特别是在密西西比州立大学和格鲁吉亚南方大学参加STEM课程的代表性不足的少数民族，并改善广泛的STEM课程。这项研究将建立理论，以有效地制定并网转换器的组件之间的相互作用，如它的锁相环和控制器之间的转换器和它的托管电网。将开发有效的建模、分析和控制过程，用于将转换器鲁棒地集成到弱的、污染的和受干扰的电网条件。锁相环、最佳和鲁棒控制、信号和发电机仿真理论用于将转换器组件牢固地连接在一起，并以最佳方式进行设计。该项目的方法是完全集成和优化转换器组件，而不添加冗余和不相交的组件，这些组件可能会损害这个多方面和高度耦合的工程系统的其他方面。特别地，将部署和结合锁相环的最新先进模型和最新的最优控制设计方法，以将锁相环完全集成到转换器的整个控制系统中，并以最优和鲁棒的方式设计整个控制系统。高保真电源硬件在环测试将被用来检查所提出的方法的实用性和有效性。通过全组件集成，减少振荡和不稳定性，拟议项目将增加给定电网的逆变器托管容量，以及其可靠性和电力质量。该项目还将加强这些多个领域的基础知识（即锁相环，最佳和鲁棒控制，和信号），适用于将可再生资源整合到我们20世纪的电力和能源系统的关键问题，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进行评估，被认为值得支持的搜索.

Collaborative Research: Innovative Approaches for Robust and Reliable Operation of Voltage Source Converters in Critical Conditions of Emerging GridsGrid-connected voltage source converters are increasingly deployed in the energy sector, e.g. for the interconnection of distributed energy resources to the power grid. An instant of the converter's poor functionality can cause local and system level problems. For example, the cause of the 1,200 MW fault-induced solar photovoltaic resource interruption in Southern California is identified in erroneous functioning of the phase-locked loop employed in the inverter control system. The field data also show an unstable operation of photovoltaic inverters caused by grid voltage harmonics and partial or full generation loss caused by routine utility-owned capacitor switching incidents. Functions such as accurate and robust frequency estimation, voltage synchronization, and current generation during challenging conditions are crucial to maintaining the reliability of a power grid with high penetration of distributed resources. This research has identified 1) grid weakness, 2) grid voltage distortions, and 3) grid voltage and frequency disturbances, as broadly describing the major critical grid conditions. Thus, it proposes to 1) investigate the impacts of these conditions on the inverter functions, and 2) to synthesize Innovative and Effective Solutions. The proposed research invests in developing Modular, Practical and Efficient solutions that fully integrate the converter components and minimize demanding components that compromise the integrity of this multi-objective system. The project results will advance the quality and strength of inverter responses during critical conditions of future grids and will lead to the 1) improvement in the power system reliability, 2) improvement in its power quality, and 3) increase in its inverter hosting capacity. This will enhance the public power delivery services, empower the related energy industry, and develop new ties among various education and research communities. The project will stimulate and sustain the cross-disciplinary training of diversified students, particularly the underrepresented minorities enrolled in STEM programs at Mississippi State University and Georgia Southern University, and improve the broad STEM curricula. This research will establish theories to effectively formulate interactions among components of a grid-connected converter such as its phase-locked loop and its controller and between the converter and its hosting power network. Effective modeling, analysis and control processes will be developed for robust integration of the converter to the weak, polluted, and disturbed grid conditions. The phase-locked loop, optimal and robust controls, signals, and generator emulation theories are used to solidly tie the converter components together and design them in an optimal way. The project's approach is to fully integrate and optimize the converter components without adding redundant and disjoint components which may compromise other aspects of this multi-faceted and highly coupled engineering system. Particularly, recent advanced models of the phase-locked loops and recent optimal control design approaches will be deployed and joined to fully integrate the phase-locked loop into the entire control system of the converter and to design the entire control system in an optimal and robust way. High-fidelity power-hardware-in-the-loop testing will be used to examine the practicality and effectiveness of the proposed methods. Through full components integration leading to reduced oscillations and instabilities, the proposed project will increase the inverter hosting capacity of a given power grid, as well as its reliability and power quality. The project will also enhance the fundamental knowledge in those multiple fields (i.e. the phase-locked loops, optimal and robust controls, and signals) as applied to the crucial problems of integrating renewable resources to the power and energy system of our twenty-first century.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.