电力电子系统大信号频域近似解析方法研究

With fast development and applications of renewable energy technologies, the control requirements of power electronics systems have been directed towards acquiring the maximum power from satisfying dynamic properties of loads, and meanwhile the primary side power source and types of the loads show features of diversification and complication where the control systems being always in the large-signal operation states are the typical manifestations. To assure the high quality and reliable operations of the systems under such complicated conditions, it has been the fundamental issue that crucial to be solved that engineering-oriented large-signal design of the power electronics systems. This project will focus on frequency-domain based approximately analysis and design of large-signal behaviors of the power electronics systems in averaging sense. According to the nonlinear physical characteristics of the power electronics systems in large-signals, it is proposed that frequency-domain based approximately analysis of large-signal behaviors of the power electronics systems will be achieved on the abstraction of key information of the nonlinerites via simplifications of the nonlinearities in the control loops. Furthermore, the main characteristic parameters that affecting the large-signal behaviors of the systems are to be determined, based on which, the structure optimization and parameters design of compensators will also be discussed for the large-signal operated power electronics systems in the aim of amending or optimizing control design of the classic frequency-domain method.. As a result, the research will provide theoretical basis for the engineering-oriented large-signal design of the power electronics systems and also serve as supplement and reference to the existing frequency-domain analysis and synthesis method.

随着可再生能源技术的飞速发展和应用，电力电子系统的控制要求正从以满足负载动态特性为主转向以获取最大功率为目标，同时一次侧能源供给和负载类型呈现出多样化和复杂性等特征，其典型表现为控制系统长期处于大信号工作状态。为确保系统在复杂工况下的高品质可靠运行，研究电力电子系统的大信号工程设计理论成为亟待解决的基础问题，本项目将着重探讨平均意义下如何从频域角度近似解析与设计电力电子系统的大信号行为。针对电力电子系统在大信号作用下的非线性物理特性，提出对控制环路中非线性进行简化处理提取其关键信息，以此达到频域近似解析系统大信号行为的研究思路；在此基础之上确定主要特征参数对系统大信号行为的约束关系，并由此探讨大信号工作电力电子系统补偿器的结构优化及参数设计准则，以修正或优化经典频域法的控制设计。本项目研究将为电力电子系统大信号工程设计奠定理论基础，并为完善现有频域分析与综合方法提供补充和借鉴。

电力电子系统的大信号分析与综合是电力电子学领域亟待解决且极具挑战性的重要基础理论问题，同时快速发展的分布式发电系统在源-荷两侧表现的强随机性和间歇性也为电力电子接口的大信号工程设计提出了越来越迫切的实际需求。.本青年科学基金项目以直流微电网为应用背景，开展了光伏接口变换器的动态特性建模与稳定性分析、DC-DC变换器的大信号频域近似分析与通用控制策略构建、DC-DC变换器的瞬态响应提升方法以及直流微电网的非线性下垂控制等四个方面的研究工作，所取得的主要成果有：(1) 分析了不同负载条件下光伏接口MPPT控制DC-DC变换器的动态特性，揭示了负载类型对于改变系统阶数的影响，对闭环阻抗的分析结果发现：电流型负载会大幅提高输入阻抗的低频幅值，导致光伏接口电压硬度变软，抗扰能力下降。分析结果可为光伏电源接口和直流母线接口稳定性的设计提供理论依据。(2) 针对DC-DC开关变换器控制环路普遍存在占空比饱和非线性问题，探讨了频域大信号近似分析方法，拓展了小信号线性频域稳定设计结果；针对DC-DC开关变换器主电路平均模型的非线性，研究基于凸分解的大信号近似建模方法，进而提出通用大信号控制策略的构建思路。(3)从电流模式控制的基本原理出发，研究了一种DC-DC变换器的瞬态响应提升方法；将电容电荷平衡控制的思想引入超级电容接口双向DC-DC变换器，实现了母线电压对高频负载扰动的快恢复。(4) 针对直流微网母线电压控制单元均流精度与电压跌落之间的矛盾问题，提出了分段式非线性下垂控制策略，可在一次控制层面从不同程度改善均流与母线电压调整的折中设计。.通过本项目资助，目前发表论文7篇，其中SCI收录1篇，EI收录2篇，CSCD收录1篇，1篇获得中国电源学会第二十二届学术年会优秀论文奖，另有3篇期刊论文和1篇会议论文在审，2篇论文准备投稿；申请中国发明专利2项并进入实质审查阶段；参加ECCE、ECCE-Asia、中国电源学会年会及中国高校电力电子年会等国内外重要学术会议共4次；依托本项目培养毕业硕士研究生1名，正在培养硕士研究生2名。