基于虚拟同步机控制的双馈风电机组预同步并网策略

Pre-synchronous Grid-connection Strategy of DFIG-based Wind Turbine with Virtual Synchronous Generator Control

采用虚拟同步机控制的双馈风电机组能提高电网惯量和频率支撑能力,成为实现可再生能源友好并网的有效途径之一。基于虚拟同步机控制的双馈风电机组直接参与电网并网时,由于缺少预同步锁相控制,双馈风电机组定子与电网的电压幅值和初始相位可能存在偏差。针对上述存在的并网问题,提出了一种虚拟同步机控制的双馈风电机组无锁相环预同步控制策略。通过在虚拟同步机外环控制中加入频率相位控制器和幅值预同步控制器,可以控制双馈风电机组并网前定子频率、相位和电压幅值与电网相同,并提出在无功功率-电压环中引入虚拟阻抗,实现了双馈风电机组快速地平滑并网。最后,通过理论分析和仿真结果验证了无锁相环预同步控制方案对虚拟同步机控制的双馈风电机组并网的有效性。

The doubly-fed induction generator(DFIG)-based wind turbine with virtual synchronous generator(VSG) control can improve the inertia and frequency support capability of the power grid,which becomes one of the effective ways to achieve the friendly grid connection of renewable energy.When DFIG-based wind turbine with VSG control is directly involved in grid connection,there may be some errors of voltage amplitude and initial phase for DFIG-based wind turbine stator and the grid due to the lack of pre-synchronous phase-locked control.In order to the above grid-connection problems,a pre-synchronization control strategy with VSG control for DFIG-based wind turbine without phase-locked loop is proposed.By connecting frequency-phase controller and amplitude pre-synchronization controller to the VSG outer loop control,the stator frequency,phase and voltage amplitude of DFIG-based wind turbine can be controlled to be the same as those of the power grid,and the virtual impedance is introduced into the reactive power-voltage loop,the fast and smooth grid-connection of DFIG-based wind turbine is realized.Finally,theoretical analysis and simulation results verify the effectiveness of the pre-synchronization control scheme without phaselocked loop for DFIG-based wind turbine with VSG control.