MODELING BATTERY-ULTRACAPACITOR HYBRID SYSTEMS FOR SOLAR AND WIND APPLICATIONS

Open Access
Author:
Tammineedi, Charith
Graduate Program:
Energy and Mineral Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
April 29, 2011
Committee Members:
  • Jeffrey Brownson, Thesis Advisor
Keywords:
  • Hybrid
  • Battery
  • Ultracapacitor
  • Battery-ultracapacitor
  • solar
  • wind
Abstract:
The purpose of this study was to quantify the improvement in the performance of a battery with the addition of an ultracapacitor as an auxillary energy storage device for solar and wind applica- tions. The improvement in performance was demonstrated through simulation and modeling. A ceraolo battery model and a third order ultracapacitor ladder model were implemented in Mat- lab/Simulink. Sample battery load cycles for solar and wind applications have been obtained from literature and the corresponding C-rates were quanti ed. The C-rate for the solar load cycle was found to be 0.3C and 0.2C for the wind load cycle. The performance of the battery- ultracapacitor system was checked for the sample solar and wind load cycles and compared with the performance of the battery system without an ultracapacitor. A reduction of 50.5% in bat- tery RMS currents was found for the solar load cycle and 60.9% for the wind load cycle. This reduction in battery RMS currents was found to be directly proportional to the ultracapacitor contribution. Given the low C-rates for the sample load cycles it was deduced that the addition of an ultracapacitor will not signi cantly improve the battery life to justify the high initial costs.