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    基于暂态阻尼增强的分数阶VSG并网控制策略

    Grid-Connected Control Strategy for Fractional-Order VSG Based on Transient Damping Enhancement

    • 摘要: 针对现有分数阶虚拟同步发电机(FOVSG)在并网有功与输出频率(简称“功频”)动态响应中存在的暂态超调抑制能力有限和控制参数调节自由度不足问题,提出一种基于暂态阻尼增强的分数阶虚拟同步发电机(TDE-FOVSG)并网控制策略。首先,分析FOVSG分数阶虚拟惯量对系统功频动态特性的影响;其次,在FOVSG有功环前向通道中引入基于角频率分数阶微分的前馈补偿环节,通过增加控制自由度和重塑零极点分布增强系统暂态阻尼,并结合Matignon稳定判据、零极点分布及Bode图完成控制参数整定;最后,通过有功指令阶跃和电网频率阶跃两种典型扰动工况开展仿真与硬件实验验证。结果表明,所提策略在保持并网有功稳态特性的同时,能够进一步减小FOVSG的并网有功暂态超调并提高功频动态响应速度,从而改善FOVSG并网系统的功频动态性能。

       

      Abstract: To address the limited capability of existing fractional-order virtual synchronous generators (FOVSGs) to suppress transient overshoot and their insufficient degrees of freedom for parameter tuning in the dynamic response of grid-connected active power and output frequency (hereinafter referred to as power-frequency response), a transient-damping-enhanced fractional-order virtual synchronous generator (TDE-FOVSG) grid-connected control strategy is proposed. First, the influence of fractional-order virtual inertia on the power-frequency dynamic characteristics of the FOVSG is analyzed. Then, a fractional-order differential feedforward compensation link based on angular frequency is introduced into the forward path of the FOVSG active-power loop. By increasing the control degrees of freedom and reshaping the pole-zero distribution, the proposed strategy enhances the transient damping of the system. The controller parameters are determined by combining the Matignon stability criterion, pole-zero distribution, and Bode analysis. Finally, simulations and hardware experiments are conducted under two typical disturbance conditions, namely an active-power reference step and a grid-frequency step. The results show that the proposed strategy can further reduce the transient overshoot of the grid-connected active power of the FOVSG and accelerate the power-frequency dynamic response while preserving the steady-state characteristics of the grid-connected active power, thereby improving the overall power-frequency dynamic performance of the grid-connected FOVSG system.

       

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