In this paper, a model-based current control strategy with virtual time constant is proposed for three-phase grid-connected LCL-filtered voltage source inverters. The proposed control strategy is based on controlling the inverter currents in the rotating dq frame by using current-oriented proportional-integral (PI) controllers rather than voltage-oriented PI. The PI controllers determine the inverter current references in the d- and q-axes by regulating the grid current. It is shown that the proposed strategy decouples the inverter current from other variables provided that the inverter-side inductance and its resistance values used in the control variable match the actual values in the system. In addition, the virtual time constant is introduced in the control variables to offer flexibility for adjusting the inverter current dynamics as desired. Moreover, the integral gain of PI controller has the ability to keep the LCL-resonance peak below 0 dB. Unlike the existing methods, the proposed strategy does not require a dedicated active damping. Computer simulations and experimental studies show that the proposed control strategy exhibits a good performance in achieving fast dynamic response and sinusoidal grid current with low THD under balanced, unbalanced, and distorted grid conditions.

中文翻译：

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用于改进三相并网 VSI 动态响应的虚拟时间常数的基于模型的电流控制策略

在本文中，针对三相并网 LCL 滤波电压源逆变器，提出了一种基于模型的具有虚拟时间常数的电流控制策略。所提出的控制策略是基于通过使用面向电流的比例积分 (PI) 控制器而不是面向电压的 PI 控制器来控制旋转 dq 坐标系中的逆变器电流。PI 控制器通过调节电网电流来确定 d 轴和 q 轴上的逆变器电流参考。结果表明，如果逆变器侧电感及其在控制变量中使用的电阻值与系统中的实际值相匹配，则所提出的策略将逆变器电流与其他变量解耦。此外，在控制变量中引入了虚拟时间常数，以便根据需要灵活地调整逆变器电流动态。此外，PI 控制器的积分增益能够将 LCL 谐振峰值保持在 0 dB 以下。与现有方法不同，所提出的策略不需要专用的主动阻尼。计算机模拟和实验研究表明，所提出的控制策略在平衡、不平衡和失真的电网条件下，在实现快速动态响应和低总谐波失真的正弦电网电流方面表现出良好的性能。