Nonlinear Adaptive Backstepping Controller Design for Three-Phase Grid-Connected Solar Photovoltaic Systems

Abstract

A cascaded control structure is proposed in this paper for injecting active and reactive power in a three-phase grid-connected solar photovoltaic (PV) system by considering external disturbances. In the proposed cascaded control structure, there are two control loops—the outer loop voltage controller is used to ensure a continuous balance in power flow between the PV arrays and electrical power grid whereas the inner loop current controller controls the output current of the inverter. Moreover, the DC-DC boost converter is controlled to achieve a constant voltage at the input of the inverter. In order to obtain the power balance and extract maximum power, an incremental conductance (IC) based maximum power point tracking (MPPT) method is used in this paper. The current controller is designed using a nonlinear adaptive backstepping technique to regulate the active and reactive components of the grid current. The regulation of these currents towards desired values which in turn control the active and reactive power delivered into the grid. The overall stability analysis of the system is performed based on the formulation of control Lyapunov functions (CLFs). Finally, the performance of the designed controller is tested on three-phase grid-connected PV systems with single as well as multiple PV units under different environmental conditions and compared with an existing sliding mode controller. Simulation results confirm the effectiveness of the proposed adaptive backstepping control scheme and demonstrate the superior performance over the sliding mode controller.

Keywords::

• adaptive backstepping controller
• maximum power point tracking
• solar photovoltaic systems
• external disturbances
• active power
• reactive power

Additional information

Notes on contributors

Tushar Kanti Roy

Tushar Kanti Roy received the B. Sc. degree from Rajshahi University of Engineering and Technology, Rajshahi, Bangladesh, in 2008 in Electrical & Electronic Engineering and Master of Engineering by Research from the University of New South Wales, Canberra, Australia, in 2012 in Electrical Engineering. He is currently working toward the Ph.D. degree in the School of Engineering, Deakin University, Australia. His research interests include nonlinear control theory and applications, excitation control, microgrid, renewable energy, and power electronics.

Md Apel Mahmud

Md Apel Mahmud received his Ph.D. in Electrical Engineering with the best thesis award from the University of New South Wales, Australia in December 2012 and a Bachelor Degree in Electrical Engineering from Rajshahi University of Engineering and Technology (RUET) in 2008 with the University Gold Medal. Currently he is working as a senior lecturer in Electrical & Renewable Energy Engineering at Deakin University, Australia where he also worked as a lecturer. He also worked as a lecturer in Electrical & Electronic Engineering at Swinburne University of Technology, a research fellow at the University of Melbourne, and a research publication fellow at the University of New South Wales. Over the last seven years, he has published more than 150 research articles including three high impact journal papers and he has attracted more than 1 million dollars internal and external grants. According to Google Scholar, his research articles have received more than 1200 citations with an H-index of 19. He was also listed as program committee members of several IEEE conferences. His research interests include various topics of electric power engineering.

Amanullah Maung Than Oo

Amanullah Maung Than Oo received his Masters and Ph.D. qualifications in electrical engineering from the University of Melbourne and Victoria University, Australia, respectively. He is currently Deputy Head of School of the School of Engineering at Deakin University and Course Director of the Electrical & Electronics Engineering Discipline. He has made significant research contributions in the area of electrical power engineering and renewable energy, engineering education and published more than 250 scholarly articles in the peer reviewed high impact journals, books, and conference proceedings. He has supervised more than 10 Ph.D. students to completion and is currently supervising several Ph.D. students in the area of electrical power engineering and renewable energy engineering. He has been actively working with several international and national professional communities and industries. He is sought worldwide to deliver keynote addresses and presentations at workshops and conferences. Aman has research interests and expertise in renewable energy & energy storage system integration, smart grid communication, power system stability and control, energy management and efficiency, protection and security of smart grids, sustainable operation and control of microgrids as well as in engineering education.

Ramesh Bansal

Ramesh Bansal has more than 25 years of teaching, research & industrial experience. Currently he is Professor and Group head (Power) in the Department of Electrical, Electronic and Computer Engineering at University of Pretoria, South Africa. In previous postings he was with the University of Queensland, Australia; the University of the South Pacific, Fiji; Birla Institute of Technology and Science, Pilani, India; and Civil Construction Wing, All India Radio. He has published over 250 papers in journals and conferences. Prof. Bansal is an Editor of several reputed journals including IET-Renewable Power Generation and Electric Power Components and Systems. He is a Fellow, and CPEng. IET-UK, Fellow Engineers Australia, Fellow Institution of Engineers (India), and Senior Member-IEEE. He has diversified research interests in the areas of renewable energy and conventional power systems which includes wind, PV, hybrid power systems, distributed generation, grid integration of renewable energy, power systems analysis (reactive power/voltage control, stability, faults and protection), smart grid, FACTS, and power quality.

Md Enamul Haque

Md Enamul Haque graduated in Electrical and Electronic Engineering from Rajshahi University of Engineering Technology (RUET), Bangladesh, in 1995. He received the M.Eng. degree in electrical engineering from University Technology Malaysia, Malaysia in 1998, and the Ph.D. degree in electrical engineering from University of New South Wales (UNSW), Sydney, Australia, in 2002. He has worked for King Saud University, Saudi Arabia, United Arab Emirates University, and University of Tasmania, Australia. He is currently working as a senior Lecturer in Renewable and Smart Energy Systems in the School of Engineering, Deakin University, Australia. His research interests include control of variable speed wind turbines, grid integration impact of renewable energy sources, performance enhancement of power system using STATCOM and energy storage, power management of microgrid with wind, photovoltaic, plug-in hybrid vehicle, fuel cell and energy storage, and power electronics applications in renewable energy and power systems.