Performance Improvement using A-PO Algorithm of MPPT for PV System

This paper proposes adaptive-perturbation & observation(A-PO) method for efficiency improvement of PO MPPT method in photovoltaic. The conventional perturbation & observation(PO) and incremental conductance(IC) MPPT control algorithm generally uses fixed step size. A small step size reduces a tracking error in the steady state but slows a tracking speed in the transient state. Also, a large step size is fast a tracking speed but increases a tracking error. Therefore, this paper proposes A-PO MPPT algorithm that adjust automatically step size according to operating conditions. To improve a tracking speed and accuracy, when operating point is far from the maximum power point(MPP), the step size uses maximum value and when a operating point is near from the MPP, the step size uses variable step size that adjust according to slope of curve. The validity of MPPT algorithm proposed in this paper proves through compare with conventional PO and IC MPPT algorithm.