【作者】 刘海波；

【导师】 毛承雄；

【作者基本信息】 华中科技大学 ， 电力系统及其自动化， 2009， 博士

【摘要】 一百多年来，作为电力系统应用最广泛的设备之一的电力变压器的工作原理、基本功能及其体积大和重量重等缺点一直没有发生变化。同时，在这一百多年的时间里，电力系统发生了深刻变化，大量非线性负荷的增长，迅速恶化了电力系统的供电品质；另一方面，用户对电能品质的要求却越来越高，从而使得电能质量问题成为了当前电力系统面临的亟待解决的重要问题。因此，如何克服常规电力变压器的缺点和从功能上对电力变压器进行革新，实现变压器技术的再一次飞跃，使其满足现代乃至未来电力系统的各种新要求，是一个很有价值的理论课题和实践课题。自20世纪以来，国内外学者都在积极探索研究新型电力变压器。电子电力变压器(Electronic Power Transformer,EPT)作为一种新型电力变压器，通过在常规电力变压器基础上，引入电力电子变换技术，使变压器的一次侧和二次侧电压或电流可以灵活控制，从而具备了解决现代电力系统面临的许多新问题的潜力。本文基于已有的研究基础，重点对配电系统电子电力变压器(EPT for distributionsystems,DEPT)的相关控制策略进行了研究。论文第一章对EPT的研究现状和发展状况进行了综述。第二章在分析EPT基本原理的基础上，对两大类EPT的实现原理进行了详细介绍。第三章提出了一种基于超级电容储能的EPT系统结构，给出了储能型EPT系统的控制策略，并构建了储能型EPT的试验研究系统；结果表明，所提系统能够补偿短时电压中断，提高供电可靠性。论文第四章对EPT并联及其控制进行了研究，归纳总结了EPT并联运行的六种方式，分析了EPT并联运行时需要解决的主要问题；对基于功率下垂控制理论的无互联线控制进行了仿真实现，结果表明，所提方案获得了比较好的有功功率、无功功率均分性能和良好的均流特性：构建了EPT与常规电力变压器并联的试验研究系统，提出将常规电力变压器二次侧电压作为EPT输出电压的参考基准电压以实现均流控制，结果表明，所提控制策略具有令人满意的均流效果，且能实现不同容量的EPT和常规电力变压器并联运行时的负荷合理分配。针对EPT在配电系统应用时所要实现的四个主要控制目标，为了提高系统的动态性能和抗扰动能力，论文第五章对DEPT线性最优控制策略进行了研究，建立了综合考虑其输入级、隔离级和输出级的DEPT简化数学模型，设计了基于最优控制理论的DEPT最优控制器。鉴于电子电力变压器实质上是带有开关器件的特殊非线性系统，论文第六章结合电子电力变压器非线性模型的特点，对DEPT非线性控制策略进行了研究，给出了多输入多输出非线性系统状态反馈精确线性化设计的基本原理和具体设计步骤，设计了基于微分几何理论和最优控制理论的DEPT非线性控制器。研究表明，设计的非线性控制器能在系统运行的大范围甚至全局实现系统的线性化，且很好的实现了DEPT的相关控制目标。更多还原

【Abstract】 Since the past 100 years, transformers have been widely used as an extremely important electrical component in electric power system, and its working principle, primary functions and disadvantages such as volume large, weight heavy, etc., have not been changed. Meanwhile, the electric power system has changed significantly and deeply: the increase of nonlinear load has deteriorated the power quality, and the customers required the high quality power energy simultaneously. So, the power quality problem becomes an increasingly important issue.It is a valuable issue to reform the functions of transformer and overcome its deficiencies, and make it meet different requirements of modern and future electric power system. Therefore, since twenty century, some domestic and foreign scholars have explored the new type power transformer actively.Electronic power transformer (EPT) is an entirely new class of transformer which retains the basic functions of conventional transformer and extends additional functions. A significant additional advantage of EPT is that the magnitude and phase angle of voltage in both the primary side and the secondary side of EPT are controllable in real-time. Due to such properties, EPT can meet many new requirements of future electric power system. This dissertation devotes itself mainly to the research on the relative control strategy of EPT for distribution system (DEPT).In Chapter 1 and Chapter 2, the basic theory of EPT and state of the art in this field are introduced firstly. An EPT with supercapacitors energy storage system is proposed in Chapter 3, and the control strategy of the proposed system is given. Also, an experimental research system is built. Simulation and experimental results have verified that the proposed system can compensate voltage momentary interruptions, thereby improve power system reliability effectively.In Chapter 4, parallel operation and its control scheme of EPTs are explored, and six parallel system configurations are given. And a wireless control based on the well-known droop method is realized by simulation, and the simulation results show excellent power sharing and voltage regulation characteristic, a proper dynamic response. Also, the parallel operation of EPT and conventional transformer based on the idea that the secondary voltage of conventional transformer is selected as the reference voltage of EPT’s output voltage is realized by simulation and experiment. Results show that the control strategy has good current-sharing regulation characteristic, and achieves reasonable load distribution in the proposed parallel system with different ratings.In view of the four objectives of DEPT, in order to enhance the dynamic performance and the disturbance rejecting capability of DEPT, a linear optimal control strategy of DEPT is presented in Chapter 5. And the mathematical model including the input stage, the isolation stage and the output stage of DEPT is built, and the optimal controller of DEPT based on the optimal control theory is designed.Considering that EPT is a special nonlinear system with some switch devices essentially, the nonlinear control of DEPT is studied in Chapter 6. And the basic principle and design method of multi-input multi-output nonlinear system state feedback exact linearization is proposed, and a nonlinear controller of DEPT based on the differential geometry and the optimal control theory is designed. Research results show that the proposed nonlinear controller can solve the nonlinearity problem of the model system completely in the whole operating range, and realize the relative control objectives of DEPT perfectly.更多还原