基于自适应陷波滤波器的有源阻尼控制方法

Adaptive notch filter based active damping control method

LCL滤波器因具有良好的高频衰减特性而被广泛用作并网逆变器与电网的接口。弱电网情况下,并网模型中电网感抗值不可忽略,电网感抗的存在会影响LCL谐振频率的大小,对传统有源阻尼控制方法提出挑战。在分析基于带阻滤波器的有源阻尼控制方案基础上,引入自适应陷波滤波器,提出了一种能够跟随系统参数变化自适应调整陷波滤波器负谐振点位置的有源阻尼控制方法。以光伏逆变系统为载体对该算法进行仿真分析,结果验证了该方法在弱电网情况下的有效性和自适应性:系统谐振频率发生偏移时该方法能够实现对其的准确跟踪,并且显著降低谐振频率点及附近频率段的谐波含量;电网电压发生±5%以内电压突变时,该方法的动态响应特性仍能满足系统的稳定运行要求。

The LCL filter is widely applied as interface between grid-connected inverter and grid due to a preferable high frequency attenuation characteristic. In the condition of weak grid, impedance value of grid model cannot be ignored, and the existence of grid impedance results in different LCL resonant fre-quencies, which challenges traditional active damping control. Based on the analysis of band pass filter based active damping control strategy, an adaptive active damping control was proposed by introducing the application of active notch filter, which can adjust the position of negative resonance point adaptively so as to manage sudden grid changes. Theoretical analysis and simulation results presented on the plat-form of grid-connected PV inverter system indicate the effectiveness and adaptability of this active damp-ing strategy：deviation of system resonance point is correctly traced, besides, harmonic contents of the resonance point and nearby frequency bands is significantly reduced. In addition, system stability can be ensured by the rapid dynamic response characteristic when there is a voltage leap within ± 5%.