【作者】 于雁南；

【导师】 吴斌； 徐殿国；

【作者基本信息】 哈尔滨工业大学 ， 电力电子与电力传动， 2017， 博士

【摘要】 采用动态无功补偿和有源滤波装置是改善和提高电能质量的主要手段,静止无功发生器(Static Var Generator,SVG)具有动态响应快、谐波含量少、储能元件体积小、成本低等特点。这些优点使级联H桥SVG具有广阔的应用前景,成为了近年来国际电力电子领域中的热点课题,并已在柔性交流输电领域获得了较好的工业化应用,对静止同步补偿器的理论研究起到了极大的推动作用。但是级联H桥SVG在电流环跟踪控制技术、数字延时问题、抗扰性和鲁棒性优化、动态性能优化等方面仍存在着一定的技术难题,这些问题严重制约了级联H桥SVG的进一步发展和应用。在此背景下,从级联H桥SVG的基本运行原理出发,对其数学模型进行了推导和分析。基于微分几何理论,判定了系统状态空间精确线性化的充要条件。根据SVG系统仿射非线性的特点,通过选取输出函数进行反馈线性化将非线性SVG系统降阶转换成2个线性系统,简化了控制算法,提高了系统动态性能。并从理论上分析了SVG系统的稳定性,对所提方案进行了仿真实验,并在实验样机上进行了实验验证。数字采样延时和输出脉冲等延时是导致系统动态响应速度慢的主要因素,为此提出了完整的无差拍改进控制算法。首先进行了延时环节导致系统性能恶化的机理研究,并探究和讨论了解决延时问题的三种方法。在此基础上,以SVG离散数学模型为基础,构造一种新的状态观测器,并采用重复预测控制对输出电压值进行预估,消除了延时带来的跟踪滞后问题,提高了电流环的跟踪精度。改进无差拍控制可以有效减小延时环节所带来的电流误差,但是其对系统的内外扰动和非线性交叉耦合所影响的动态性能及抗干扰控制效果不明显。为此,首先设计了自抗扰控制(Active Disturbance Rejection Control,ADRC)的基本构架,将最速控制综合函数设计为跟踪微分器,预设了跟踪变量及其微分轨迹,避免了系统高频震颤和滤波效果差。其次,采用扩张状态观测器实时提取系统所有的状态信息,抑制和消除了系统的内外扰动。最后,设计了线性和非线性自抗扰解耦控制器,所提控制方法在实验样机上进行了对比试验。在前述所提ADRC控制策略的基础上考虑时滞问题所带来的慢一拍问题,首先,建立了考虑延时环节的SVG系统数学模型,设计最速控制综合函数安排过渡过程并作为非线性状态误差反馈控制律,避免了SVG系统电流环输出积分饱和,设计了三阶非线性扩张状态观测器估计系统电流环的状态变量以及系统内扰和总和扰动。所提控制方案在实验样机上进行了各种稳态和动态实验,并与比例谐振(Proportional Resonant,PR)和无差拍控制算法进行样机对比实验和分析。基于以上所提出的运行控制方法,为了验证所提出的控制策略和总体方案的正确性及控制效果,搭建了10k V级联H桥SVG硬件系统平台,对级联H桥SVG开展了试验研究。给出了级联H桥SVG硬件系统的总体方案和主功率电路参数设计,并设计了功率单元模块、主控板的电路和参数,以及载波相移空间矢量调制算法。进行了各种工况的静态和动态试验,并验证了所提出的控制策略在级联H桥SVG上的动态、稳态、抗干扰等性能。更多还原

【Abstract】 Dynamic reactive power compensator and active power filter are two primary approaches of improving and enhancing the quality of grid power,among which,static var generator(SVG)is the most widely applied reactive compensator and has aroused extensive concern and discussion due to its main features of faster dynamic response,less harmonic components,smaller energy-storing elements and lower costs.Due to these characteristics,SVG has recently become the most attractive topology for industrial applicaiton and one of the hottest research topic in the fields of power electronics.It has revolutionized the flexible AC transmission technology and significantly pushed the development of theoretical research of static synchronous compensator.But the SVG has still beset by kinds of problems,such as technongy of current-loop tracking and controlling,digital delay consideration,interference rejection,robustness improving and dynamic performance optimizing,and all these problems have severely constrained the development and application of cascaded H-bridge SVG.Under this circumstance,the mathematical model has been deduced and analysed in this thesis,based on the fundamental principle of the cascaded H-bridge SVG.In addition,the necessary and sufficient condition for the precise linearization in the state space of the whole SVG system has been derivated based on the differential geometry theory.Furthermore,according to the affine non-linear features of the SVG system,by chosing a proper output function,the whole system can be linearized to 2 linear systems,the controlling algorithm can be simplified,and the dynamic performance can be improved as well.Moreover,the controlling strategy proposed by this thesis has been analysed and confirmed theoretically,and its stability has been tested and verified by MATLAB simulations and prototype experiments.The digital sampling delay,output pulse delay etc.are the main factors of deteriorating the dynamic response of the SVG system,a systematic dead-beat controlling algorithm has been put forward to cope with the problem.First of all,the principle of the delay elements that deteriorating the dynamic performance has been analysed,and three solutions have been explored and discussed.On this foundation,a new type of state-observer has been constructed via the discrete mathematical model of SVG.Finally,through repeatingly estimation of the output voltage,the lag of tracking caused by delay factors can be eliminated,and the tracking accuracy of the current-loop can be enhanced.The dead-beat controlling can minimize the current error caused by the delay factors effectively,but it has only limited effect on the dynamic performance and anti-interference result affected by internal and external disturbance and non-linear cross coupling.For this reason,sets up a controlling structure based on acticve disturbance rejection control(ADRC),adapts the time optimal function synthesizer as the tracking differentiator,and preinstalls the tracking variable and its differential trajectory,and all these actions can avoid the high-frequency viberation and poor filtering effect.And furthermore,restrains and eliminates the internal and external disturbance by adapting the extended state observer which can extract all the status of the whole system in real time.Finally,designs linear and non-linear ADRC controller respectively,and all the constrast experiments have been conducted on prototype machine.Based on the controlling strategy of ADRC listed above,the lag problem caused by time delay has been taken into consideration.Sets up the mathematical model of SVG included the delay elements primarily,designs the time optimal controlling synthetical function and arranges the transition process as the erro feedback controlling strategy of nonlinear state to prevent the output integral saturation of SVG current-loop.In addition,designs a three-order nonlinear extended state observer to estimate the variables of current-loop and the internal and external disturbance of the whole system.Kinds of static and dynamic experiments have been carried out on the prototype machine,and have also been compared to the traditional proportional resonant(PR)control and dead-beat control.Finally,in order to evaluate and verificate the validity and effectiveness of the controlling strategy and the overall design,a 10 k V cascaded H-bridge SVG has been built.In the fifth chapter of this thesis,designs the overall scheme and main power circuit of SVG,along with the specific design of power elements,main control board,carrier phase shift vector modulator and etc.Static and dynamic experiments have been taken on the SVG prototype machine under kinds of working conditions,with the control strategy and design put forward by this thesis.更多还原