基于残差生成器的Buck双向变换器改进模型预测控制

Improved model predictive control for Buck bi-directional converter based on residual generator

在以光伏储能装置为主体的直流微网中,外部扰动容易引起直流母线电压波动,导致系统输出电能质量下降。为提升系统动态响应性能,针对直流微网中常用的Buck型双向DC-DC变换器,提出一种基于残差生成器的改进电流补偿模型预测控制策略。首先,对模型预测控制(MPC)环节进行线性等效,证明采用校正前PI+MPC控制时,系统在0 rad/s时存在失稳风险。然后,由此设计负低-高通滤波器校正环节,并从调节系数变化和模型参数不确定性等角度进行分析,验证改进后系统的稳定性和动态性能得到明显改善。仿真与实验结果表明,基于残差生成器的电流补偿能有效平抑外界扰动引起的母线电压波动,负低-高通校正环节在改善系统性能的同时又进一步抑制电感电流噪声,进而平滑母线电压曲线。最终,证明提出的改进策略可显著提升直流微网的动态响应性能。

In DC microgrids dominated by photovoltaic energy storage devices,external perturbations are prone to cause DC bus voltage fluctuations, leading to degradation of system output power quality. In orderto improve the dynamic response performance of the system, an improved current compensation modelpredictive control strategy based on residual generator was proposed for the Buck bi-directional DC-DCconverter commonly used in DC microgrids. Firstly, a linear equivalent of the model predictive control(MPC) link was performed to demonstrate the risk of system instability at 0 rad/ s when using pre-correctionPI + MPC control. Secondly, the resulting negative low-high-pass filter correction link was designedand analyzed from the perspectives of regulation coefficient variation and model parameter uncertainty toverify that the stability and dynamic performance of the improved system were significantly improved.Through simulation and experiments, the results show that the current compensation based on residualgenerator can effectively stabilize the bus voltage fluctuation caused by external disturbances, and thenegative low-high-pass correction link can improve the system performance and further suppress the inductorcurrent noise, so as to smooth the bus voltage curve. Finally, it is proved that the improved strategycan significantly enhance the dynamic response performance of DC microgrid.