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基于前馈修正的电压非平衡电网状况下构网变流器并网控制策略

Grid-connected Control Strategy for Grid-forming Converters Under Voltage Unbalanced Grid Conditions Based on Feedforward Correction

  • 摘要: 构网型变流器技术是从电源侧应对电力系统“双高”(高比例可再生能源、高比例电力电子设备)趋势带来的安全稳定问题的一种解决方案。而电网电压出现不平衡情况会导致传统的构网型控制方法无法正常并网,为此提出一种基于虚拟同步发电机的前馈修正并网方法。在分析VSG控制算法的基础上,根据VSG在dq0坐标系下的电压前馈,结合三相电流在α-β轴上的有效值平衡分析,使VSG在非平衡电网的情况下实现三相电流的平衡控制。该方法不需要知道具体传输线参数,且在各种工况下均可实现三相电流的平衡。仿真结果验证了该控制策略的有效性。

     

    Abstract: Grid-forming control is a solution to address the safety and stability issues brought about by the trend of "dual highs" (high proportion of renewable energy and high proportion of power electronics equipment) in power systems from the power source side. However, when the grid voltage is imbalanced, traditional grid-forming control methods fail to achieve normal grid connection. Therefore, a voltage feedforward correction grid-forming method based on the virtual synchronous generator is proposed. Based on the analysis of the VSG control algorithm, the voltage feedforward of the VSG in the dq0 coordinate system combined with the effective value balance analysis of the three-phase current on the α-β axis enables the VSG to achieve balanced control of the three-phase current in the voltage imbalanced grid. This method does not require specific transmission line parameters and can achieve balanced three-phase current under various operating conditions. Simulation results verify the effectiveness of this control strategy.

     

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