A New Sliding-Mode Approach to Control the Active and Reactive Powers with Variable Switching Frequency for Grid-Connected Converter

ABSTRACT

This paper presents the development and implementation of a novel approach of Direct Power Control based on Sliding Mode control approach with Variable Switching Frequency (SM–DPC–VSF) to control the instantaneous active and reactive powers for three-phase grid-connected converters. The improved strategy combines the DPC principle, SM approach, and switching look-up table. The synthesis of the switching table (ST) is based on active and reactive power time derivative behaviours and the redundancy of the applied vector during two successive sectors. The ST is aimed to select the appropriate voltage vector and ensures the VSF operation mode, which simplifies the system design and improves the transient performance system. The SM–DPC–VSF uses an SM based on pre-defined sliding surfaces in powers error that improves the instantaneous power behaviour. The converter model developed in the stationary reference frame eliminates the need of the rotating coordinate transformation and angular information of grid voltage. An experimental test bench based on Dspace DS1104 is realized and a Power Quality Analyzer CA8334 is used to evaluate and measure the power quality. Several simulation and experimental results are presented in order to verify the performances and effectiveness of the SM–DPC–VSF algorithm under steady-state and transient operation. The capability of tracking is also inspected under a varying reference to forecast the possible future-tracking behaviour of the instantaneous powers. A smooth and decoupled control between powers with a very good total harmonic distortion (THD) of lines current (THD = 4.6%) is obtained.

KEYWORDS:

• Direct power control
• Grid-connected converters
• Instantaneous power regulation
• Sliding mode approach
• Switching table
• Variable switching frequency

Additional information

Notes on contributors

Bechir Bouaziz

Bechir Bouaziz was born in 1985 in Gabes, Tunisia. He received the diploma in electrical engineering in June 2008. He also received his master's degree and the PhD thesis degree in electrical engineering from the “École nationale supérieure d'ingénieurs de Tunis” in 2010 and 2015, respectively. He is currently an assistant professor at the Gabes University, Tunisia. Mr Bouaziz is a member and scientific researcher at the computer laboratory for industrial systems (LR11ES26). His research interests are focused on advanced control of power converters related to renewable power generation and micro-grids applications, also the digital control of power converters and power quality improvement.

E-mail: [email protected]

Faouzi Bacha

Faouzi Bacha was born in Ben Guerdanne, Tunisia in 1964. He received “Habilitation Universities” in electrical engineering in 2008 from the National Institute of electric engineering (ENIT), Tunisia. He is currently a professor at the “École nationale supérieure d'ingénieurs de Tunis (ENSIT)”, Tunisia. He has numerous publications on direct control of synchronous and induction machines. His research fields include modelling and simulation, power system, intelligent techniques, electrical machines, renewable energy, smart grids, and hydrogen energy. Prof. Bacha is a scientific researcher and vice president of the computer laboratory for industrial systems (LR11ES26).

E-mail: [email protected]

Moncef Gasmi

Moncef Gasmi was born in 1958, in Tunis, Tunisia. He received respectively, from the Tunis National School of Engineering (ENIT), the Principal Engineering Diploma in 1984, the Master's degree in 1985, the Doctorate in Automatic Control in 1989, and the State Doctorate in Electrical Engineering in 2001. Now, he is a professor and director of the computer laboratory for industrial systems (LR11ES26). His research interests include the modelling, analysis, and control of complex systems, advanced control strategies related to the renewable power generation system.

E-mail: [email protected]