Backstepping Controller Design to Track Maximum Power in Photovoltaic Systems

Abstract

Original scientific paperThis work presents a new control method to track the maximum power point of a grid-connected photovoltaic (PV) system. A backstepping controller is designed to be applied to a buck-boost DC-DC converter in order to achieve an optimal PV array output voltage. This nonlinear control is based on Lyapunov functions assuring the local stability of the system. Control reference voltages are initially estimated by a regression plane, avoiding local maximum and adjusted with a modified perturb and observe method (P&O). Thus, the maximum power extraction of the generating system is guaranteed. Finally, a DC-AC converter is controlled to supply AC current in the point of common coupling (PCC) of the electrical network. The performance of the developed system has been analyzed by means a simulation platform in Matlab/Simulink helped by SymPowerSystem Blockset. Results testify the validity of the designed control method.Key words: Backstepping, Buck-boost converter, Maximum power point (MPP), Photovoltaic system Sinteza backstepping regulatora za praćenje maksimalne proizvodnje energije u fotonaponskim sustavima. Ovaj rad predstavlja novu metodu upravljanja za slije enje točke maksimalne snage fotonaponskog (PV) sustava. Dana je sinteza backstepping regulatora za primjenu u silazno-uzlaznom DC-DC pretvaraču za postizanje optimalnog izlaznog napona PV-a. Ova je nelinearna metoda upravljanja zasnovana na Ljapunovim funkcijama osiguravajući tako lokalnu stabilnost sustava. Upravljačke reference napona prvo su estimirane korištenjem regresijske ravnine izbjegavajući lokalne maksimume, a zatim podešene tzv. modificiranom perturbiraj i uoči metodom (P&O). Prema tome, zagarantirano je maksimalno izvlačenje energije iz sustava proizvodnje. Naposlijetku, DC-AC pretvaračem upravlja se na način da osigurava željena izmjenična struja u točki zajedničkog spoja (PCC) elektroenergetske mreže. Ponašanje razvijenog sustava analizirano je kroz simulacije provedene u Matlab/Simulink okruženju uz korištenje SymPowerSystem biblioteke.Ključne riječi: Backstepping, silazno-uzlazni pretvarač, točka maksimalne proizvodnje energije (MPP), fotonaponski sustav

MPPT algorithms comparison in PV systems: P&O, PI, neuro-fuzzy and backstepping controls

“…The backstepping control proposed by A. D. Martin and J. R. Vazquez, [13][14], is a robust non-linear control. Besides, it guarantees the stability of the system through Lyapunov functions, reaching the control objective, to extract the maximum power even when there are changeable environmental conditions.…”

“…The equations that describe the behavior of the DC/DC converter are (2), (3) and (4), [13], being D the buck-boost duty cycle.…”

“…The two parameters that are controlled are the input voltage and the inductor current. The backstepping control follows a procedure, [13]. The error and its derivative are defined to enforce the PV module output voltage to reach the reference.…”

“…This control used a neuro-fuzzy system to find the voltage that supplies the MPP and a fuzzy control to achieve the reference voltage given by the neuro-fuzzy system. Finally, a backstepping control has been designed to implement the MPPT algorithm, [13][14][15]. In this case, the PV output reference voltage is provided by a regression plane and the reference voltage is reached by controlling the duty cycle of the buckboost converter through the switches using a robust non-linear control that guarantees the stability of the system by means of Lyapunov functions.…”

A Coefficient Diagram Method Controller with Backstepping Methodology for Robotic Manipulators

“…The control signal is written as follows A backstepping procedure [9][10][11][12][13][14][15][16][17][18][19][20] is proposed to determinate the gains matrix assuring the exponential stability result for the links positions tracking errors.…”