This paper describes a diode-clamped three-level inverter-based battery/supercapacitor direct integration scheme for renewable energy systems. The study is carried out for three different cases. In the first case, one of the two dc-link capacitors of the inverter is replaced by a battery bank and the other by a supercapacitor bank. In the second case, dc-link capacitors are replaced by two battery banks. In the third case, ordinary dc-link capacitors are replaced by two supercapacitor banks. The first system is supposed to mitigate both long-term and short-term power fluctuations while the last two systems are intended for smoothening long-term and short-term power fluctuations, respectively. These topologies eliminate the need for interfacing dc–dc converters and thus considerably improve the overall system efficiency. Themajor issue in aforementioned systems is the unavoidable imbalance in dc-link voltages. An analysis on the effects of unbalance and a space vector modulation method, which can produce undistorted current even in the presence of such unbalances, are presented in this paper. Furthermore, small vector selection-based power sharing and state of charge balancing techniques are proposed. Experimental results, obtained froma laboratory prototype, are presented to verify the efficacy of the proposed modulation and control techniques.

Item Type:	Refereed Article
Keywords:	Diode-clamped three-level inverter, direct integration of battery energy storage systems, space vector modulation, unbalanced operation of diode-clamped three-level inverter
Research Division:	Engineering
Research Group:	Electrical engineering
Research Field:	Electrical engineering not elsewhere classified
Objective Division:	Energy
Objective Group:	Renewable energy
Objective Field:	Wind energy
UTAS Author:	Jayasinghe, SDG (Dr Shantha Jayasinghe Arachchillage)
ID Code:	101186
Year Published:	2011
Web of Science® Times Cited:	74
Deposited By:	Seafaring and Maritime Operations
Deposited On:	2015-06-11
Last Modified:	2017-11-03
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