交直流混合微电网中直流母线电压纹波抑制方法

Control Method of DC Bus Voltage Ripple Mitigation in Hybrid AC/DC Microgrids

在交直流混合微电网中,若汇入直流母线中的功率瞬时值中含有纹波分量(如三相不平衡交流负荷、交直流微电网互联功率存在不平衡有功功率分量等),均会导致直流母线电压出现纹波分量,严重时会影响系统供电电能质量和可靠性。为此,提出基于直流有源滤波器(DC active power filter,DC-APF)的直流母线电压纹波抑制方法,主要由直流电压纹波抑制、直流有源滤波器输入端电容电压控制以及电流闭环控制3部分构成。阻抗分析方法表明所采用的控制参数设计方法能保证拟抑制纹波频率处直流有源电力滤波器输出阻抗远小于直流微电网中其余单元的输出阻抗,从而能消除或减小直流纹波电压。此外,基于所提方法,还可实现多直流有源滤波器即插即用与并联运行。最后在Matlab/Simulink中搭建了含直流型分布式电源、交直流双向DC-AC变流器、直流负荷以及两台直流有源电力滤波器的交直流混合微电网仿真模型,建立了相应的实验平台,数字仿真和实验结果均验证了所提方法的有效性。

In hybrid AC/DC microgrids, when instantaneous active power flowing into DC bus contains harmonic components（due to unbalanced three-phase AC loads, unbalanced power components in interconnected power of hybrid AC/DC microgrids and so on）, pulsation component will appear in DC bus voltage, possibly affecting system power supply quality and reliability. For this reason, this paper proposes a DC bus voltage ripple suppression method based on DC active power filter（DC-APF） mainly consisting of DC bus voltage ripple suppression control, input side capacitance voltage control and closed-loop current control. Impedance analysis method shows that when DC-APF output impedance under harmonic frequency is far less than that of other units in the system, DC bus voltage ripple can be eliminated or reduced. Besides, plug-and-play function and parallel operation can be realized with the proposed method. Finally, simulation model containing a DC distributed generation, a bi-directional DC-AC converter, a DC load and two DC-APFs is established. Corresponding experimental platform is also setup. Simulation and experiment results indicate effectiveness of the proposed method.