An innovative Fast-Converging speed MPPT approach without oscillation for temperature varying in photovoltaic systems applications

ABSTRACT

This paper offers an innovative maximum power point tracking (MPPT) approach for photovoltaic system under temperature varying. Basically, the innovative approach is introduced to improve tracking performance under difficult scenarios of temperature change. By far, it can be used to avoid the main shortcomings of the conventional MPPT strategies, e.g., ripple around the MPP at steady-state regime, sluggishness velocity converging, and loss of tracking direction under fast change of temperature. Also, it can be used to improve the tracking performance under low irradiance level and rapid load change. With respect to its direct control strategy based on the photovoltaic current control, it provides a quick tracking of the real MPP without steady-state fluctuations. To show the advantages and accuracy of the innovative MPPT approach, a comparison with other traditional strategies, e.g., P&O and INC techniques is investigated using simulation in MATLAB/Simulink® software under different scenarios of temperature, load, and insolation levels. In the light of the results collected, the innovative MPPT approach minimized the convergence time by five times, reduced the steady-state fluctuations to zero and improved the average tracking efficiency by 8.51% and 9.04% compared to the P&O and INC MPPT schemes, respectively.

KEYWORDS:

• Temperature varying
• sudden load change
• DC-DC boost converter
• steady-state fluctuations
• perturb & observe technique
• incremental conductance technique

Abbreviations

D Diode

DC Direct Current

DC-DC Direct Current-Direct Current

FF Fill factor

FL Fuzzy Logic

Ga Gate of switch

HC Hill Climbing

INC Increment of Conductance

MPP Maximum Power Point

MPPT Maximum Power Point Tracking

MPP CZ Maximum Power Point Current Zone

P&O Perturb and Observe

PV Photovoltaic

PWM Pulse Width Modulation

s Seconds

STC Standard Test Conditions

SW Switch

W Watts

List of symbols

$\mathrm{A}$ Diode ideality factor

$\mathrm{C}\left(\mathrm{d}\right)$ Voltage conversion ratio

${\mathrm{C}}_{\mathrm{i}\mathrm{n}},{\mathrm{C}}_{\mathrm{o}\mathrm{u}\mathrm{t}}$ Input and output capacitors of the step-up (boost) converter, respectively [F]

$d$ Step-up converter duty ratio

$\mathrm{\Delta }\mathrm{d}$ Increment value of duty ratio

${\mathrm{E}}_{\mathrm{g}}$ Semiconductor band-gap energy of the photovoltaic cell [eV]

f Switching frequency [Hz]

$G$ Solar irradiation level [W/m²]

$I_{ph}$ Photo generated current [A]

${\mathrm{I}}_{\mathrm{M}\mathrm{P}\mathrm{P}}$ Photovoltaic panel current at MPP [A]

${\mathrm{I}}_{\mathrm{M}\mathrm{P}\mathrm{P}\mathrm{\_}\mathrm{m}\mathrm{a}\mathrm{x}}$ Maximum MPP current [A]

${\mathrm{I}}_{\mathrm{M}\mathrm{P}\mathrm{P}\mathrm{\_}\mathrm{m}\mathrm{i}\mathrm{n}}$ Minimum MPP current [A]

${\mathrm{I}}_{\mathrm{o}}$ Photovoltaic cell reverse saturated current [A]

${\mathrm{I}}_{\mathrm{o}\mathrm{u}\mathrm{t}}$ Output current of the step-up converter [V]

${\mathrm{I}}_{\mathrm{p}\mathrm{v}}$ Output current of photovoltaic cell [A]

${\mathrm{I}}_{\mathrm{o}\mathrm{s}}$ Reverse saturation current at T_r [A]

$I_{sc}$ Short circuit current [A]

I-V Current versus voltage characteristics of photovoltaic panel

$\mathrm{\Delta }$ I_pv Variation of photovoltaic current

$K$ Boltzmann constant ($8.617\times {10}^{-5})\left[eV/K\right]$

${\mathrm{k}}_{\mathrm{i}}$ Temperature coefficient of the short-circuit current [%/° C]

L Inductance [H]

${\mathrm{N}}_{\mathrm{P}}$,${\mathrm{N}}_{\mathrm{S}}$ Parallel and series numbers of solar power cells, respectively.

${\mathrm{P}}_{\mathrm{M}\mathrm{P}\mathrm{P}}(\mathrm{t})$ Instantaneous extracted power [W]

${\mathrm{P}}_{\mathrm{M}\mathrm{P}\mathrm{P}\mathrm{a}}(\mathrm{t})$ Instantaneous average available power [W]

P-I Power versus current characteristics of photovoltaic panel

${\mathrm{P}}_{\mathrm{M}\mathrm{P}\mathrm{P}}$ Photovoltaic panel power at MPP [W]

${\mathrm{P}}_{\mathrm{p}\mathrm{v}}$ Output power of photovoltaic panel [W]

P-V Power versus voltage characteristics of photovoltaic panel

$\mathrm{\Delta }$ P_pv Variation of photovoltaic power

$\mathrm{q}$ Value of an electron charge ($1.6\times {10}^{-19})[$ C]

$\mathrm{R}$ Resistor [Ω]

${\mathrm{R}}_{\mathrm{i}\mathrm{n}}$,${\mathrm{R}}_{\mathrm{o}\mathrm{u}\mathrm{t}}$ Boost converter input and output side resistances, respectively [Ω]

${\mathrm{R}}_{\mathrm{l}\mathrm{o}\mathrm{a}\mathrm{d}}$ Load resistance [Ω]

${\mathrm{R}}_{\mathrm{P}}$ Parallel resistance in model of solar cell (Ω)

${\mathrm{R}}_{\mathrm{p}\mathrm{v}}$ Photovoltaic panel resistance [Ω]

${\mathrm{R}}_{\mathrm{S}}$ Series resistance in model of solar cell (Ω)

$T$ P-n junction diode temperature [$K$]

${\mathrm{T}}_{\mathrm{r}}$ Temperature of cell reference [° C]

${\mathrm{V}}_{\mathrm{M}\mathrm{P}\mathrm{P}}$ Photovoltaic panel voltage at MPP [V]

${\mathrm{V}}_{\mathrm{o}\mathrm{c}}$ Voltage of open circuit [V]

${\mathrm{V}}_{\mathrm{o}\mathrm{u}\mathrm{t}}$ Output voltage of the step-up converter [V]

${\mathrm{V}}_{\mathrm{p}\mathrm{v}}$ Output voltage of photovoltaic cell [V]

$\mathrm{\Delta }$ V_pv Variation of photovoltaic voltage

${\eta }_{\mathrm{M}\mathrm{P}\mathrm{P}\mathrm{T}}$ MPPT efficiency of tracking [%]

${\eta }_{\mathrm{M}\mathrm{P}\mathrm{P}\mathrm{T}(\mathrm{a}\mathrm{v}\mathrm{g})}$ Average efficiency of tracking [%]

Acknowledgments

The authors acknowledge “The MathWorks Inc.” for support in MATLAB/Simulink platform setup.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data Availability Statement

The authors confirm that all relevant data are included in the article and that no supplementary information files are available.