链式STATCOM的控制策略研究

发布时间：2018-02-22 21:41

本文关键词： 链式STATCOM 直流侧电压不平衡无功补偿三相不平衡　出处：《济南大学》2014年硕士论文　论文类型：学位论文

【摘要】：链式的静止同步补偿器（Static Synchronous Compensator，STATCOM）在大功率高电压无功补偿方面具有良好的动态特性，具有模块化、多电平、可靠性高、易于扩展等优点，得到了人们的广泛关注。本文针对链式STATCOM相关技术进行研究，讨论了链式STATCOM的建模与控制，无功电流的检测以及直流侧电压的控制等问题，具体研究内容包括以下几个方面：介绍了STATCOM的基本工作原理。建立了链式STATCOM在三相静止坐标系下以开关函数描述的数学模型。为便于控制器的设计，建立了链式STATCOM的低频动态模型。利用坐标变换，得到了链式STATCOM在d q旋转坐标系下的频域等效模型，同时考虑了系统不平衡时的影响。对链式STATCOM在频域下的等效模型进行分析，，得到链式STATCOM是一个强耦合非线性系统。采用前馈解耦的内环电流控制策略实现了有功电流和无功电流的有效分离。对于功率外环，采用PI控制器得到链式STATCOM的电流参考值。基于此设计了链式STATCOM的控制器。此外，在设计过程中考虑了系统不平衡时链式STATCOM的控制问题。对两种基本检测方法：p q法和ip iq法检测谐波电流和无功电流的原理进行简单阐述。分析了传统三相锁相环在系统电压出现畸变和不平衡时不能实时准确的锁相，利用相序解耦谐振（Sequence-Decoupled Resonant，SDR）控制器对传统的锁相环进行改进，得到一种采用SDR锁相环的ip iq无功电流检测方法。分析了引起链式STATCOM的直流侧压不平衡的原因。从链式STATCOM装置的功率平衡入手，对系统进行正负序分析，得出正序电流影响系统的总体电压平衡，负序电流影响各相间的电压平衡。对传统的三级直流侧电压控制算法进行改进，得到一种新的三级直流侧电容电压平衡控制方法：第一级控制采用正序电流控制链式STATCOM的总体电压平衡；第二级采用负序电流控制实现链式STATCOM各相间的电压平衡；第三级针对相内各个单相逆变桥（H-Bridge Inverter，HBI）模块的电容电压平衡问题，通过在链节输出无功电流的基础上添加一个纯有功矢量，实现HBI模块的电压平衡。采用MATLAB/SIMULINK搭建了链节数为10级的仿真模型，仿真表明这种新型三级控制策略能有效实现链式STATCOM直流侧电压的平衡。
[Abstract]:The chain static Synchronous compensator has good dynamic characteristics in high-power and high-voltage reactive power compensation, and has the advantages of modularization, multilevel, high reliability and easy expansion. In this paper, the modeling and control of chain STATCOM, the detection of reactive current and the control of DC voltage are discussed. The specific research contents include the following aspects:. The basic working principle of STATCOM is introduced. The mathematical model of chain STATCOM described by switch function in three-phase static coordinate system is established. In order to facilitate the design of controller, the low frequency dynamic model of chain type STATCOM is established. The frequency domain equivalent model of chain STATCOM in d Q rotating coordinate system is obtained, and the influence of system unbalance is considered. By analyzing the equivalent model of chain STATCOM in frequency domain, it is concluded that chain STATCOM is a strongly coupled nonlinear system. The active current and reactive current are effectively separated by feedforward decoupling inner loop current control strategy. The current reference value of chain STATCOM is obtained by using Pi controller. Based on this, the controller of chain STATCOM is designed. In addition, the control problem of chain STATCOM when the system is unbalanced is considered in the design process. The principle of detecting harmonic current and reactive current by two basic detection methods:: PQ method and iq method are simply expounded. The traditional three-phase phase-locked loop can not be accurately locked in real time when the system voltage is distorted and unbalanced. The phase sequence decoupling resonant Sequence-Decouped Resonant (SDR) controller is used to improve the traditional PLL, and a SDR PLL is used to detect the reactive current of iq. This paper analyzes the causes of unbalance of DC side voltage of chain type STATCOM. Starting from the power balance of chain type STATCOM device, the positive and negative sequence analysis of the system is carried out, and the positive sequence current affects the overall voltage balance of the system. The negative sequence current affects the voltage balance between phases. The traditional three-stage DC side voltage control algorithm is improved. A new three-stage DC side capacitor voltage balance control method is presented. The first stage control adopts positive sequence current to control the total voltage balance of chain type STATCOM, the second stage adopts negative sequence current control to realize the voltage balance between each phase of chain type STATCOM, and the second stage adopts negative sequence current control to realize the voltage balance between each phase of the chain type STATCOM. In the third stage, aiming at the capacitor voltage balance problem of the H-Bridge Inverter HBI module, a pure active power vector is added on the basis of the reactive current output from the link. The voltage balance of HBI module is realized. A simulation model with 10 levels of chain nodes is built by using MATLAB/SIMULINK. The simulation results show that this new three-level control strategy can effectively balance the DC side voltage of chain STATCOM.
【学位授予单位】：济南大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM761.12

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