直流微电网DAB变换器和直流固态变压器的非线性控制策略

Nonlinear Control Strategy of Dual Active Bridge Converter and DC Solid State Transformer in DC Microgrid

直流微电网中,当双有源全桥(DAB)变换器及直流固态变压器(DCSST)带恒功率负载运行时,恒功率负载负阻抗特性会对系统的稳定性造成不良影响。文中提出了一种基于非线性扰动观测器及反步控制的新型复合带恒功率负载直流变换器控制策略,推导得出DAB变换器和DCSST数学模型的布鲁诺夫斯基标准型,采用基于非线性扰动观测器的大信号非线性扰动估计方法作为前馈补偿提高输出电压调节的准确性,结合反步控制方法保证DAB变换器和DCSST在大信号扰动下的稳定性。实验结果表明,所提出的控制方法既能在大信号扰动下保证DAB变换器和DCSST的稳定性,又能在不同工况下保证快速动态响应和准确的电压跟踪。

In DC microgrid, when the dual active bridge(DAB) converter and the DC solid state transformer(DCSST) operate with the constant power load, the stability of the system is adversely affected due to the negative impedance characteristic of the constant power load. This paper proposes a new compound control strategy for the DC converter with constant power load based on the nonlinear disturbance observer and the backstepping control. The Brunovsky′s standard types of mathematic models of DAB converter and DCSST are derived. The large-signal nonlinear disturbance estimation method based on the nonlinear disturbance observer is adopted as the feedforward compensation to improve the accuracy of output voltage regulation, and the stability of DAB converter and DCSST under large-signal disturbance is ensured by combining the backstepping control method. The experimental results show that the proposed control method can not only guarantee the stability of DAB converter and DCSST under the largesignal disturbance, but also ensure the fast dynamic response and accurate voltage tracking under different operation conditions.