Abstract:
This paper presents the implementation of a maximum power point tracking (MPPT)
algorithm in a multilevel three-phase photovoltaic (PV) system using the ripple correlation control
(RCC) method. Basically, RCC adopts the inherent oscillations of PV current and voltage as
perturbation, and it has been predominantly used for single-phase configurations, where the
oscillations correspond to the 2nd order harmonics. The implementation of an RCC-MPPT algorithm
in a three-phase system has not been presented yet in the literature. In this paper, the considered
three-phase three-level converter is a three-level flying capacitor (FC) inverter. The proffered RCC
method uses the 3rd harmonic components of PV current and voltage for the estimation of the voltage
derivative of the power dPpv/dVpv (or current, dIpv/dVpv), compelling the PV array to operate at or
very close to the maximum power point. The analysis and calculation of the low-frequency PV current
and voltage ripple harmonic components in the three-phase flying capacitor inverter is presented first,
with reference to centered carrier-based three-level PWM. The whole grid-connected PV generation
scheme has been implemented by MATLAB/Simulink, and detailed numerical simulations verified
the effectiveness of the control method in both steady-state and dynamic conditions, emulating
different sun irradiance transients.