基于动态虚拟电流前馈的预同步VSG功率二阶解耦策略

Second-order Power Decoupling Control in Pre-synchronized VSG Based on Dynamic Virtual Current Feedforward Control

随着分布式电源渗透率的逐步提高,虚拟同步发电机技术(virtual synchronous generator,VSG)得到了广泛的研究和应用,但传统VSG存在并网速度慢、有功/无功功率耦合影响调控效果的问题。首先在传统自同步VSG模型基础上,提出加入并网电压相角预同步单元以加快VSG并网速度。随后分析了中低压电网的功率耦合机理,结合虚拟阻抗技术,提出基于动态虚拟电流前馈的预同步VSG功率二阶解耦策略。最后,Matlab/Simulink 仿真结果表明:该新型预同步 VSG 不仅可以实现快速平滑的并网控制,而且调控过程中有功功率和无功功率得到较好的解耦,尤其在下垂控制中还可以提高功率稳态调控精度。

With the deep penetration of distributed renewable energy in the power grid,the virtual synchronous generator(VSG)has been widely studied and applied in recent years.However,the traditional VSG has problems like slow grid-connection speed and active/reactive power coupling,which may severely affect the regulation effect.Based on the operating mechanism of the traditional self-synchronized VSG,a novel pre-synchronization unit is proposed of the phase angle of grid-connection voltage to enhance the connection speed.Besides,the mechanism of the power coupling in medium-low voltage power networks is analyzed.Combined with virtual impedance control strategy,a second-order power decoupling control strategy based on dynamic virtual current feedforward control is proposed.Finally,Matlab/Simulink simulation results show that the new pre-synchronized VSG can not only achieve fast and smooth grid-connection,but also have good active/reactive power decoupling effects during the regulation.Specially in droop control,it can raise the steady-state power accuracy obviously.