新型单相储能型Quasi-Z源光伏系统双模式运行机理及优化控制研究

随着光伏和其他分布式电源渗透率的不断增长，光伏系统与电网的交互且在并网和离网模式均可靠运行至关重要。本项目针对单相Quasi-Z源光伏系统双模式运行的理论和关键问题开展研究：1)提出一种新型单相储能型Quasi-Z源逆变器，克服传统多端口和储能型Quasi-Z源逆变器的本质困难，以单级式紧凑结构实现双模式运行且全天持续供电，通过探究其内特性与两倍频脉动特性，提出系统参数优化和能量管理策略；2)结合变换器建模理论与阻抗稳定判据，建立完善的系统阻抗模型，深入探讨模式过渡过程的阻抗匹配、内在交互和稳定性，研究运行模式无缝切换的机理；3)研究系统级的模型预测优化控制策略，克服传统控制的结构和设计复杂的难题，仅一个控制回路、无需控制策略转换的情况下，实现双模式安全稳定运行。为进一步研究Quasi-Z源逆变器在光伏发电中的应用，以及分布式电源的双模式运行提供理论基础和支持，有重要的理论意义和应用价值。

With the ever-increasing penetration of Photovoltaic (PV) and other distributed power generations, the PV systems interacting with the grid and operating reliably in both grid-connected and off-grid modes are of vital importance. This project investigates the theory and key technology of dual-mode operation for the single-phase quasi-Z-source PV system: 1) A novel single-phase energy-stored quasi-Z-source inverter is proposed, overcoming the essential difficulty of traditional multi-port and energy-stored quasi-Z-source inverters. It achieves dual-mode operation in a single-stage compact structure and can provide power continuously for the whole day. Through investigating the internal characteristics and double-line-frequency characteristics, system parameters optimization and power management strategy in dual modes are proposed. 2) According to modeling theory of converters and impedance-based stability criterion, a complete system impedance model is established, the impedance matching, internal interaction, and stability of modes transient process are thoroughly analyzed, and the mechanism of seamless transition between operating modes is investigated. 3) Furthermore, system-level model predictive optimization control strategy is developed, overcoming the challenge of complicated structure and design of traditional control methods, while achieving the dual-mode operation safely and steadily as well as seamless transition in only a single control loop and without the need of control strategy transform. Thus, provide theoretical basis and support for further investigations on applications of the quasi-Z-source inverter in PV power generations and dual-mode operation of distributed generation, which has important theoretical significance and application value.