A Single-Phase Multilevel PV Generation System with an Improved Ripple Correlation Control MPPT Algorithm

Abstract

Abstract:The implementation of maximum power point tracking (MPPT) schemes by the ripple correlation control (RCC) algorithm is presented in this paper. A reference is made to single-phase single-stage multilevel photovoltaic (PV) generation systems, when the inverter input variables (PV voltage and PV current) have multiple low-frequency (ripple) harmonics. The harmonic analysis is carried out with reference to a multilevel configuration consisting of an H-bridge inverter and level doubling network (LDN) cell, leading to the multilevel inverter having double the output voltage levels as compared to the basic H-bridge inverter topology (i.e., five levels vs. three levels). The LDN cell is basically a half-bridge fed by a floating capacitor, with self-balancing voltage capability. The multilevel configuration introduces additional PV voltage and current low-frequency harmonics, perturbing the basic implementation of the RCC scheme (based on the second harmonic component), leading to malfunctioning. The proposed RCC algorithm employs the PV current and voltage harmonics at a specific frequency for the estimation of the voltage derivative of power dP/dV (or dI/dV), driving the PV operating point toward the maximum power point (MPP) in a faster and more precise manner. The steady-state and transient performances of the proposed RCC-MPPT schemes have been preliminarily tested and compared using MATLAB/Simulink. Results have been verified by experimental tests considering the whole multilevel PV generation system, including real PV modules, multilevel insulated-gate bipolar transistor (IGBT) inverters, and utility grids.

Performance Comparison of Mismatch Power Loss Minimization Techniques in Series-Parallel PV Array Configurations

“…Therefore, according to KVL, the string voltage equals the summation of modules voltage in the string, and according to KCL, the array current equals the summation of string current in the array [31]. However, in a practical PV array, a central maximum power point tracker (MPPT) [45][46][47][48] is used to get its global maximum power (GMPP) [49][50][51][52]. Therefore, all modules are led to work at their maximum potential, which is not exactly same for all modules even from same power rating due to the manufacturing tolerances, which causes MML in the PV array.…”

Three-Phase Three-Level Flying Capacitor PV Generation System with an Embedded Ripple Correlation Control MPPT Algorithm

“…On the contrary, ripple correlation control (RCC) algorithms exploit the inherent PV voltage and current oscillations to track the MPP. In particular, for single-phase PV systems the 2 nd harmonics are exploited [4,[7][8][9][10][11][12][13]. The RCC algorithm has good dynamic performance comparing with the P&O algorithms and it does not require additional perturbations in tracking the MPP.…”

“…The basic RCC-MPPT method has been investigated in references [9,12,14] where two low-pass filters and two high-pass filters are used for ripple extraction and implementation. In reference [10], a modified RCC method has been proposed by using the moving average concept instead of high/low-pass filtering to improve the dynamic response, without the need to tune the time constant of the low/high pass filters. Moreover, the scheme has been simplified by using only the sign of the product of power and voltage ripple to drive the PV operating point toward the MPP.…”

“…In general, adopting a multilevel inverter introduces different low-order voltage and current harmonics on the dc-link side compared to the case of a single-phase H-bridge inverter where only the 2 nd order harmonics are present. The application of the RCC algorithm in case of a single-phase inverter with level doubling network (LDN) has been introduced and examined in reference [10]. Due to the multiple harmonics, the basic implementation of the RCC-MPPT scheme becomes deficient, leading to a misestimating of the voltage derivative of the power (dP pv /dV pv ).…”

Design and Experimental Implementation of a Hysteresis Algorithm to Optimize the Maximum Power Point Extracted from a Photovoltaic System

“…In consequence, the load seen by the panel is manipulated to achieve the MPPT objective [23,24]. Previously, numerous MPPT techniques have been proposed, developed and efficiently implemented [1,6,22,23,[25][26][27][28][29][30][31][32][33][34]. Some of them are based on the PV model; for instance, those methods that fit in this branch are the Fractional Open-Circuit Voltage and Short-Circuit Current [24].…”