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为改进目前谐波电流检测方法,针对有源滤波器谐波检测,提出了一种新型变步长自适应算法,取得了比较好的效果。由于谐波检测属于适应噪声抵消技术低信噪比条件下的一种应用,因而在该算法中,没有以误差信号e(n)作为改变步长的自适应回馈量,而是将误差信号和上个工频周期的误差信号的差值△e(n)作为自适应回馈量,从而避免了误差信号e(n)一直较大,导致的自适应算法的稳态误差比较大的缺点;同时通过相干平均估计来避免测试计算过程中随机噪声的影响,调节算法的步长,其优越性在于:谐波检测过程能保证既具有较快的动态响应速度,又保证稳定后步长稳定很小,有较高的检测精度。理论分析和仿真试验证明了该算法的正确性和有效性。
In order to improve the current harmonic current detection method, a new variable step size adaptive algorithm is proposed for the active power filter harmonic detection, and the better effect is achieved. Since harmonic detection belongs to an application under low signal-to-noise ratio (SNR), the error signal e (n) is not used as the adaptive feedback for changing the step size. Instead, the error signal The difference △ e (n) of the error signal of the last power cycle is used as the adaptive feedback amount so as to avoid the disadvantage that the error signal e (n) is always large and the steady-state error of the adaptive algorithm is relatively large. At the same time The advantage of coherent average estimation to avoid the impact of random noise in the test calculation process and to adjust the step size of the algorithm is that the harmonic detection process can ensure both fast dynamic response and stable small step after stabilization , A higher detection accuracy. Theoretical analysis and simulation tests show that the algorithm is correct and effective.