Selective Harmonic Detection and Compensation Based on Observer Theory

近年来电网谐波污染日益严重，谐波的研究和治理受到了国内外的高度重视。为了实现谐波的选次、精确补偿，本文分别对谐波检测和有源电力滤波器（APF）的控制策略两部分内容进行了研究。首先，观测器理论运用在谐波检测领域的研究，国内外学者才刚开始涉及。本文提出了一种基于观测器理论的新型谐波电流检测方法，实现了指定次谐波的快速、精确检测，为谐波检测提供了一种新的思路；其次，工业过程中环境干扰给系统的结构参数带来很大的不确定性，按照理想模型设计的最优控制器在此情况下难以保持最优。本文设计了一种自适应的模型预测控制方法，能够计算出电路参数变化给系统模型带来的偏差，在等效的实际电路模型上实现逆变器的精确电流跟踪；...In recent years, the power network’s harmonic pollution becomes more and more serious. The study and governance of harmonic absorb high attention in the world. In order to realize selective and accurate harmonic compensation, harmonic detection and control strategy of APF are studied in this paper. Firstly, it’s just the beginning for the foreign scholars to involve the research of observer theory...学位：工学硕士院系专业：航空航天学院_电气检测技术及仪器学号：1992013115291

A Current Harmonics Detection Method Based on Input Observer Theory

基于输入观测器理论,对电流谐波在线检测问题进行了研究,得到了一种能够快速准确地提取电流信号中各频率分量的方法。首先,将被测电流信号和其各频率的分量作为状态量,构建线性时变的状态空间模型。然后,设计基于状态空间模型的观测器对未知状态变量进行在线观测,从而实现各频率分量的信息提取。所设计的观测器是时变的,其稳定性和收敛性由Lyapunov定理及Lasalle不变集原理所证明。最后,搭建仿真和实验平台对该方法进行验证,结果表明其具备检测速度快、精度高、动态跟踪性能和抗干扰性好等优点。Based on the input observer theory,the online current harmonics detection method is proposed,which can detect all the frequency components within the current signal accurately and rapidly. Firstly,by setting the state variables as the value and each frequency component of the measured current,a linear time-varying state space model is established. Then,based on the proposed model,a time-varying observer is constructed to estimate the unknown states in order to achieve the extraction of each frequency component. The stability and convergence of the observer are proved by the Lyapunov theorem and the Lasalle invariant set principle. Finally,the simulation and experimental results show that the proposed method has advantages in detection speed,accuracy,dynamic tracking performance,and robustness.中央高校基本科研业务费资助项目(20720150088

Study on Expansion of Micro-EDM Discharge Channel

为了模拟微细电火花放电通道扩展的过程,对放电等离子体通道进行了深入研究,建立了一个适用于微细电火花放电加工的等离子体扩展模型。基于介质击穿机理和磁流体力学的相关知识,模型综合考虑了等离子体扩展过程中的粘性力、表面张力及磁场箍缩力等各个作用力,使扩展过程更接近于真实。最后,通过比较微细电火花rC单脉冲放电的模型计算直径与实际加工直径,验证了等离子体扩展模型的正确性。To simulate the process of micro-EDM discharge channel expansion,discharge plasma channel has been studied.A suitable plasma expansion model of micro-EDM has been established.Based on the dielectric breakdown mechanism and relevant knowledge of MHD,the various forces such as viscous force,surface tension and magnetic pinch force,in the process of plasma expansion has been considered,which makes the expansion process closer to the real.Finally,comparing the calculation diameter of micro-EDM RC single pulse discharge model with the actual machining diameter,the correctness of plasma expansion model is verified