LCL型并网逆变器电容电压微分反馈有源阻尼实现技术研究*

Research on Realization Technology of Active Damping Method with Differential Feedback of Filter Capacitance Voltage for LCL Filter Based Grid-connected Inverters

  • 摘要: 基于LCL滤波器状态变量反馈实现有源阻尼的方法具有控制灵活、鲁棒性强的优点。在已有方案中,滤波电容电流比例反馈因实现简单得到广泛应用,但滤波电容电流脉动较大,精确检测需要配备高精度电流传感器。理论推导可知对滤波电容电压微分反馈能够实现相同阻尼效果且无需配备高精度传感器,但微分环节易引入高频噪声,影响进网电流质量;另外,现有常规微分实现方法未考虑电容漏电流对LCL滤波器高频段特性的影响。为此,基于滤波电容电流与漏电流矢量关系,提出一种改进型滤波电容电压微分反馈有源阻尼方法,与常规微分相比具有高频噪声抑制能力且不影响LCL滤波器性能。最后,通过试验结果证明了上述优点。

     

    Abstract: Active damping(AD) methods based on LCL filter state variables feedback have the advantages of flexible control and strong robustness. Among these methods, the filter capacitor current proportional feedback algorithm is widely used because it is easy to implement, but the filter capacitor current has a large pulsation, only high-precision current sensors can accurately measure. The theoretical derivation shows that the differential feedback of the filter capacitor voltage can achieve the same damping effect and does not need to be equipped with a high-precision sensor, but the differential link easily brings high-frequency noise into the control system, which affects the quality of the grid current. Moreover, conventional differential implementation methods do not consider the influence of leakage current of the filter capacitor, which affects the high frequency characteristics of the LCL filter. Therefore, based on the vector relationship between the filter capacitor current and its leakage current, a new differential realization method is proposed, which has high frequency noise suppression capability and does not affect the performance of the LCL filter compared with the conventional differential realization method. Simulation and experimental results prove that the proposed control strategy can achieve satisfactory results in all aspects compared with traditional methods.

     

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