A Robust Control Scheme for Grid-Connected Voltage-Source Inverters
A Robust Control Scheme for Grid-Connected Voltage-Source Inverters
复制标题
DOI：
10.1109/tie.2010.2045998
复制
发表时间：
2011
影响因子：
7.7
通讯作者：
Shuitao Yang;Qin Lei;F. Peng;Z. Qian
中科院分区：
文献类型：
--
作者：
Shuitao Yang;Qin Lei;F. Peng;Z. Qian
分析了带LC滤波器的并网电压型逆变器(VSI)的稳定性问题，指出采用常规比例积分(PI)控制器进行电网电流控制时，电网阻抗的变化对系统的稳定性有很大影响。随着电网感应阻抗的增大，PI控制器的低频增益和带宽必须减小以保持系统的稳定，从而降低了跟踪性能和抗扰能力。为了解决这一稳定性问题，提出了一种具有对电网阻抗变化的显式鲁棒性的H-∞控制器，以兼顾期望的跟踪性能和稳定裕度。通过适当选择加权函数，综合H-∞控制器在线频附近表现出类似于传统比例谐振控制器的高增益，同时具有足够的高频衰减以保持控制回路的稳定。还设计了高带宽的逆变器-输出-电流内环，以获得更好的干扰抑制能力。文中详细讨论了加权函数的选择、逆变器输出电流内环的设计以及系统的抗扰性能。给出了H-∞控制器和常规PI控制器的仿真和实验结果，并与传统的PI控制器进行了比较，验证了该控制方案的有效性。
This paper analyzes the stability problem of the grid-connected voltage-source inverter (VSI) with LC filters, which demonstrates that the possible grid-impedance variations have a significant influence on the system stability when conventional proportional-integrator (PI) controller is used for grid current control. As the grid inductive impedance increases, the low-frequency gain and bandwidth of the PI controller have to be decreased to keep the system stable, thus degrading the tracking performance and disturbance rejection capability. To deal with this stability problem, an H∞ controller with explicit robustness in terms of grid-impedance variations is proposed to incorporate the desired tracking performance and the stability margin. By properly selecting the weighting functions, the synthesized H∞ controller exhibits high gains at the vicinity of the line frequency, similar to the traditional proportional-resonant controller; meanwhile, it has enough high-frequency attenuation to keep the control loop stable. An inner inverter-output-current loop with high bandwidth is also designed to get better disturbance rejection capability. The selection of weighting functions, inner inverter-output-current loop design, and system disturbance rejection capability are discussed in detail in this paper. Both simulation and experimental results of the proposed H∞ controller as well as the conventional PI controller are given and compared, which validates the performance of the proposed control scheme.