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有源滤波器LCL滤波系统存在谐振,需要引入阻尼。通过对比分析,发现当有源滤波器采用电流定时比较控制时,滤波电容并联虚拟阻尼策略最为适宜。该策略检测滤波电容的谐波电压,通过比例环节等效于电容并联虚拟谐波电阻,增强系统的阻尼作用,整个策略实现简单且避免了微分运算。通过建立离散域的数学模型,根据朱利稳定性判据求得虚拟阻尼系数的稳定域条件:即采样频率需大于滤波器谐振频率的6倍,以保证系统的稳定性;进而,系统的稳定域随采样频率的提高而增大,随滤波器谐振频率或滤波器网侧总电感值的增大而减小。仿真和实验分析证明了所提出的虚拟阻尼策略及理论分析的正确性。
Active filter LCL filter system resonance, the need to introduce damping. Through the comparative analysis, it is found that when the active filter is controlled by the current and timing, the parallel virtual damping strategy of the filter capacitor is most suitable. The strategy detects the harmonic voltage of the filter capacitor. It is equivalent to the capacitance parallel parallel harmonic resistor through the proportional link to enhance the damping effect of the system. The whole strategy is simple and the differential operation is avoided. By establishing the mathematical model of discrete domain, the stability condition of the virtual damping coefficient is obtained according to the Juli stability criterion: the sampling frequency needs to be greater than 6 times of the resonant frequency of the filter to ensure the stability of the system; furthermore, the stability of the system The domain increases with the increase of the sampling frequency and decreases with the increase of the resonant frequency of the filter or the total inductance of the filter. Simulation and experimental analysis proves the correctness of the proposed virtual damping strategy and theoretical analysis.