【作者】 刘冰；

【导师】 高晗璎；

【作者基本信息】 哈尔滨理工大学 ， 电力电子与电力传动， 2013， 硕士

【摘要】 近些年，低压供电系统中非线性负载和电力电子装置得到普遍应用，因而负载不平衡和谐波等问题在三相四线制电网中逐渐显现，而零序电流对电网的危害尤为突出。本文针对三相四线制电网中的负载不平衡，零序、负序和谐波的消除，以及无功补偿等问题，研究并设计了三相四桥臂SVG的无功补偿控制系统。本文首先介绍了电力系统中无功补偿的背景、研究意义、危害以及发展现状；然后阐述了SVG的工作原理，并且介绍了三相四线制SVG三种常见的主电路拓扑结构，通过对比各结构的优缺点，选用了更为简单、实用的三相四桥臂拓扑结构；接着对比分析了三相四桥臂系统中几种常用的无功电流检测方法，并采取了对ip-iq电流检测方法进行改进的基于瞬时无功功率理论的零序电流分离法，这种方法能够很好地检测三相四桥臂SVG系统中的无功电流；再然后又仔细研究了三相四桥臂SVG主电路的控制策略，并且对补偿电流的控制算法选取了3D-SVPWM方式，简要介绍了在α-β-γ坐标系下的空间矢量调制，着重阐述了在a-b-c空间坐标系下的三维空间矢量的调制原理，及此方法的开关矢量选择、占空比计算和排列方式。推导出的占空比计算公式表明，与在α-β-γ坐标系下的空间矢量调制方法相比，在a-b-c坐标系下的三维空间矢量调制法计算起来更简单、更易于实现数字化。同时，主电路的控制策略采用了PI调节的控制方式稳定了直流侧的电压。利用MATLAB仿真软件对本文所采用的无功电流检测方法及主电路的控制策略进行仿真实验分析，仿真结果理想。最后，以TI公司的数字信号处理器TMS320F2812作为核心控制器，设计了三相四桥臂SVG控制系统的硬件电路和软件程序，并搭建了三相四桥臂SVG系统的实验平台，试验结果表明本文所选用的设计方法对系统中的无功电流有很好的补偿作用，同时也能补偿系统的三相不平衡电流，进而消除零序电流对系统产生的影响。更多还原

【Abstract】 In recent years,nonlinear load and power electronics devices were widely usedin the low-voltage power supply system,so load balancing and harmonic problemsappear gradually in three-phase four-wire system,and zero sequence current to theharm of power grid is particularly prominent.According to these problems such asload imbalance,zero sequence,negative sequence,harmonic elimination,reactivepower compensation and other issues in the three-phase four-wire grid,we haveresearched and designed reactive power compensation control system of three-phasefour-leg SVG.Firstly,this paper introduced the background of reactive power compensation inthe power system,the research significance,the harm and the developmentstatus;Then expounded the working principle of SVG,and introduced three commonmain circuit topology of three-phase four-wire SVG.By comparing the advantagesand disadvantages of each structure,we chose the three-phase four-leg topologicalstructure which is more simple and practical;Then compared and analysed severalcommonly used reactive current detection methods in the three-phase four-wiresystem,and took zero sequence current separation based on the theory ofinstantaneous reactive power which is improved from ip-iq current detection.Thismethod can well detect the reactive current in three-phase four-leg SVG system.Thenthe control strategy of three-phase four-leg SVG main circuit was studied,and chosethe method of3D-SVPWM to compensate current,and briefly introduced the spacevector modulation in the α-β-γ coordinate system.This paper focused on the principleof three-dimensional space vector modulation in a-b-c space coordinates,and switchvector selection,duty ratio calculation,as well as arrangement of this method.Thecalculation formula of duty ratio which is deduced indicated that compared with thespace vector modulation method in the α-β-γ coordinate system,the algorithm in a-b-c space coordinates is simpler and easier to digitize.At the same time,the controlstrategy of main circuit adopted PI regulator to stabilize the DC voltage.Using MATLAB to simulate and analyze the reactive current detection method and control strategy of the main circuit which was adopted by this paper,and thesimulation results were satisfactory.Finally, with TMS320F2812as the corecontroller,we designed hardware circuits and software programs of the three phasefour-leg SVG control system,and built the experimental platform.The test resultsshowed that the design method chosen in reactive current had a good compensationeffect,as well as three-phase unbalanced current,thus eliminating impacts of zero-sequence current.更多还原