Adaptive PLL method using recursive least square algorithm

The implementation of conventional synchronous reference frame PLL(SRF-PLL) is simple and estimation performance of the phase angle is superior under balanced utility voltage. However, conventional SRF-PLL degrade its performance under unbalanced utility voltage. The proposed DIF-PLL to overcome this problem only compensate for amplitude variation of the phase voltage and estimation performance of the phase angle degrade under other unblanced utility voltage. This paper proposes SRF-PLL using recursive least square method(RLSM), which detect the phase angle by compensating in real time for the generated angle, amplitude and offset of the phase voltage by unbalanced utility voltage. The proposed method is verified through the simulation and experiments.