一种穿越频率自适应的四阶广义积分锁频环

Fourth-order Generalized Integrator Frequency-locked Loop With Crossover Frequency Adaptation

滤波器级联型锁频环可以抑制电网电压中非基频分量对频率估计的影响,适用于直流偏置严重和谐波复杂多变的场景,但是难以同时兼顾动态和稳态性能。分析对比了级联二阶广义积分锁频环(cascaded second-order generalized integrator frequency-locked loop,CSOGI-FLL)和四阶广义积分锁频环(fourth-order generalized integrator frequency-locked loop,FOGI-FLL)两种典型的滤波器级联型锁频环,推导并建立了两者传递函数和线性模型,采用振荡指标法整定两者的控制参数,证明了FOGI-FLL的参数设计灵活性优于CSOGI-FLL。针对FOGI-FLL分析了中频宽和幅值穿越频率影响其动态和滤波性能的规律,提出了根据电网电压估计误差自适应调整FOGI-FLL幅值穿越频率的方法,从而实现FOGI-FLL动态和滤波性能的自适应调节,称其为穿越频率自适应的四阶广义积分锁频环(FOGI-FLL with crossover frequency adaptation,CFAFOGI-FLL)。最后,实验对比了CFAFOGI-FLL、SOGI-FLL、CSOGI-FLL和FOGI-FLL的各项性能。实验结果表明,CFAFOGI-FLL相较于其他比照技术可以兼顾动态和稳态性能,能够同时满足收敛速度快、估计精度高、滤波能力强的应用要求。

The filter-cascaded-type frequency-locked loop can reject the influence of the non-fundamental frequency component in the grid voltage on the frequency estimation,so it is suitable for scenarios with severe DC offset and complex harmonics,however,it is difficult to achieve fine dynamic and steady-state performance at the same time.For this reason,the two typical filter-cascaded-types of the frequency-locked loops are analyzed and compared,which are the cascaded second-order generalized integrator frequency-locked loop(CSOGI-FLL)and the fourth-order generalized integrator frequency-locked loop(FOGI-FLL).Based on the derivation of their transfer function and the establishment of their linear model,their control parameters are tuned in the oscillation index method,which proves that the parameter design of FOGI-FLL is more flexible than that of CSOGI-FLL.The rules of the bandwidth and the crossover frequency influencing on the dynamic and filtering performance of FOGI-FLL are analyzed.Base on the analysis,a method for adjusting adaptively the crossover frequency of FOGI-FLL according to the grid voltage estimation error is proposed,realizing the adaptation of the dynamic and filtering performance of FOGI-FLL,which is called the FOGI-FLL with crossover frequency adaptation(CFAFOGI-FLL).Finally,the experiments are carried out to compare the performances of CFAFOGI-FLL with SOGI-FLL,CSOGI-FLL,and FOGI-FLL.It has been shown by the experimental results that the CFAFOGI-FLL can achieve concurrently better dynamic and steady-state performances than the other compared techniques,and the CFAFOGI-FLL can simultaneously meet the application requirements of fast convergence,high estimation accuracy,and strong filtering capability.