Analysis of an improved harmonic currents detection method based on LST

According to the method based on linear sinusoid tracer of adaptive theory for active power filter, there was contradiction between detecting accuracy and dynamic response. And the error in the algorithm was affected by the high order-harmonics, so this system couldn´t detect harmonic current accurately. Based on the analysis above, a method based on improved sinusoid tracer of adaptive theory was presented, h the introduction of the low-pass filter to solve the problem. Fist we discussed the stability of improved system. Then theoretical analysis and simulation test show that the algorithm was provided with characteristic of narrow-band. Therefore the improved system can get rid of the contradiction between detecting accuracy and dynamic response.