直流微电网并网换流器的滑模变结构控制策略研究

Research on Sliding-mode Variable Structure Control Strategy of DC Microgrid Gridconnected Converter

直流微电网通过并网变换器与交流电网相连,实现功率的双向流动及直流母线电压的稳定。文中针对双向DC/AC变换器的非线性特性及工作点大范围突变的问题,提出了一种基于滑模变结构的两级式并网变换器的非线性控制策略。首先建立了两级式高频并网变换器的非线性数学模型,并以直流侧电压恒定和交流侧单位功率因数为控制目标,选取直流侧电压和网测无功电流为状态变量,设计了DC/AC和DC/DC的滑模面函数和变结构控制率,最后在MATLAB/Simulink环境下,搭建了直流微电网控制系统仿真模型,分析了不同工况下系统的动、稳态性能,验证文中提出的控制策略的有效性。结果表明,滑模变结构控制策略具有良好的动、静态性能,对系统参数变化和状态的突变具有很好的鲁棒性。

The DC microgrid is through connecting the grid converter and the AC power grid,thus the bidirectionalflow of power and the stability of the DC bus voltage are achieved. The paper focuses on the nonlinear and the widerange mutation of working point of the bidirectional DC/AC converter. A nonlinear control strategy of two stage bidi-rectional converter based on sliding-mode variable structure is proposed. First,the nonlinear mathematical mode ofthe high frequency two stage bidirectional converter is established,with control target constant DC voltage and unitpower factor of AC grid and the state variables the voltage of DC side and the reactive current of AC grid. Second,thepaper design the sliding-mode plane function and the variable structure control of the DC/AC and DC/DC. Finally,the paper set the simulation model of control system of the DC microgrid and analysis the system performance of thedynamic and steady state under the different working conditions to demonstrate the effectiveness of the proposed con-trol strategy. The results show that sliding-mode variable structure control strategy has good performance of the dy-namic and static and robustness for parameter change and state mutation of the system.