采用VSG的柔性配电装备交流端口电压控制及稳定性分析

AC Port Voltage Control Strategy and Stability Analysis of Flexible Distribution Equipment Based on Virtual Synchronous Generator

向负载供电及接纳分布式电源是柔性配电装备的重要功能,因此柔性配电装备端口控制至关重要。文中针对柔性配电装备交流端口电压控制问题,在虚拟同步发电机控制基础上,对三相进行独立控制,通过级联准比例-谐振电压外环、电流内环提高其动态性能。进而以单相为例,详细分析柔性配电装备交流端口输出电流对电压的影响,并提出电流前馈控制策略,保证负载变化、分布式电源接入等变化过程中交流端口电压的稳定。利用阻抗建模方法分析交流端口的输出阻抗,并根据广义奈奎斯特判据验证柔性配电装备交流端口向负荷供电及接纳分布式电源时的稳定性。通过仿真和相关实验验证了所提控制策略的有效性和正确性。

Supplying power for loads and realizing the connection of distributed generators(DGs)are the essential functions of the flexible distribution equipment(FDE).Consequently,the control of AC port in FDE is intensely crucial.Aiming at the AC port voltage control of FDE,the three-phase voltage is controlled independently based on the virtual synchronous generator(VSG)control,and its dynamic performance is improved by cascaded quasi proportional-resonant(PR)voltage outer-loop and current inner-loop.Furthermore,the influence of AC port output current of FDE on the voltage is analyzed in detail by taking single-phase voltage as an example.And the current feedforward control strategy is proposed to ensure the AC port voltage stability while loads vary and DG access.The output impedance of AC port is obtained by the impedance modeling method,and the stability of FDE is analyzed by generalized Nyquist stability criterion when AC port supplies power for loads and realizes DG connection.Finally,the correctness and effectiveness of the proposed control strategy are verified by simulation and experiment.