摘要
基于电压源逆变器(VSI)的静止无功发生器(SVG)直接应用PWM控制技术,具有动态无功功率补偿、稳定节点电压、阻尼系统振荡等多项先进功能,同时结构紧凑、易于控制、谐波含量小且功率密度大。先定义二值逻辑开关函数,再建立SVG在abc三相坐标系下的四阶动态数学模型,然后利用坐标变换得到了αβ与dq坐标系下SVG的三阶动态数学模型。该模型可以详细描述SVG的动态工作过程。SVG在αβ坐标系下的模型中两电流分量不存在耦合,便于控制系统设计。α轴分量与β轴分量(或d轴分量与q轴分量)正好是有功电流分量与无功电流分量,从而有利于对SVG的瞬时有功功率与瞬时无功功率分别进行控制。应用MATLAB对采用滞环电流跟踪控制的±150 kVA SVG在感性负载与容性负载两种情况下进行了仿真研究,仿真结果验证了所建数学模型的准确性与正确性,同时证明了基于VSI的SVG具有良好的动态性能与静态补偿效果。
VSI-based SVG （or called Static Synchronous Compensator-STATCOM）, which uses the PWM technology, can compensate reactive power, stabilize nodal voltage and improve the power factor and damp system oscillation. It has some advantages such as compact structure, simple control, low harmonics and high power density compared with SVC, so it has been researched recently and used in power system widely, particularly in power distribution system. In this paper, the research situation of SVG dynamic model recently is summarized at first, the importance and necessity of D-STATCOM using PWM in power distribution system is pointed out. Logic switch function which has tow values is defined, dynamic mathematic model of VSI-based SVG is established with fourth-order, and then it is transformed to third-order model under the αβ and dq coordinate using coordinate transform. All of the models under three coordinates are transformed to transfer function model through Laplace transform, and the transform matrix between different coordinate are given. The model under αβ coordinate is decoupled between Iα and Iβ, that is easy to control. Although there is couple between Iα and Iβ, it can be decoupled in control system design. The model established in this paper can describe the dynamic process of VSI-based SVG precisely. In the same time, the using of coordinate transform degrades the order of its system model. At last, the 150 kVA SVG using current hysteresis comparator control method is simulated with MATLAB in different situations, whatever with capacitive load and inductive load system, reactive power can be compensated timely, the transitional process from inductive load to capacitive load is completed in no more than two seconds. The simulation results verifies the exactness of the model, and the excellent dynamic and static performance of VSI-based SVG is obvious according to the simulation wave forms given in this paper.
出处
《高电压技术》
EI
CAS
CSCD
北大核心
2006年第6期84-87,124,共5页
High Voltage Engineering
基金
江苏省高新技术项目(BG2004024)
