风电并网存在功率及公共耦合点（point of common coupling，PCC）电压波动问题，常规方法为采用储能装置与无功补偿装置分别进行调节，但会导致系统结构复杂。文中研究了一种基于模块化多电平变换器拓扑的电池储能系统（modular multilevel converter based battery energy storage system，MMC-BESS），可对风电场功率及电压进行综合调节。由于风速的随机性导致风电场输出功率波动，提出将风电场有功功率输入到一阶低通滤波器中，滤波器输出与输入的差作为MMC-BESS有功参考信号，以平滑风电场并网功率。由于风电场负荷突变导致PCC电压波动，提出将PCC电压的d轴分量与额定值作差，通过PI调节生成无功参考电流，实现PCC电压调节。最后在模拟风电场场景下进行实验，实验结果验证了风电场中MMC-BESS四象限功率补偿能力。
英文摘要:
Wind farm has power and point of common coupling (PCC) voltage fluctuation problems. The conventional method is to use energy storage and reactive power compensation device to adjust separately, but it will lead to complex system structure. In this paper, a battery energy storage system (MMC-BESS) based on MMC is studied, which can comprehensively regulate the power and voltage of wind farms. Aiming at the fluctuations of power due to the random wind speed, it was input into a first-order low-pass filter, and the difference between the filter output and the input was used as the MMC-BESS reference signal to smooth the wind farm grid-connected power. In order to suppress PCC voltage fluctuations due to sudden changes of load, the difference between the d-axis component of PCC voltage and the rated value was made. And then the reactive power current reference was generated by proportional integral(PI) controller to adjust the PCC voltage. Finally, experiments were carried out in a simulated wind farm scene, and the results verified the MMC-BESS four-quadrant power compensation capability in the wind farm.