基于子空间的LQG控制及其在光伏并网逆变器的应用

摘要

Nowadays model based predictive control is widely used in grid-connected inverter current control, however, modeling accuracy is the key factor that affects its performance. In order to avoid the complex and time consuming modeling process, model free subspace based Linear Quadratic Gaussian (LQG) control strategy is proposed. Input and output measurements are utilized in the subspace predictor design, and then the predictor is used in model free predictive LQG control. This novel approach is applied to the grid-connected photovoltaic (PV) inverter control system. Simulation results show the inverter’s output current could comply with grid standards, which also verify good dynamical performance and strong robustness of the proposed method.%目前模型预测控制广泛地应用于并网逆变器的电流控制中，然而模型不准确是影响预测控制器性能的关键因素。为了避免复杂的建模过程，结合子空间方法和线性二次高斯(Linear Quadratic Gaussian，LQG)控制，提出了基于子空间的LQG控制。利用过去的输入输出数据和未来的输入数据，寻找出未来时刻的输出预测值，从而直接应用到LQG控制器的设计中，并将该方法成功地应用到三相光伏并网逆变器控制中。通过Matlab仿真结果显示逆变器输出电流符合并网标准，证明了该方法的可行性，并且具有良好的动态响应性能和鲁棒性。