Compressed air energy storage (CAES) could play an important role in balancing electricity supply and demand when linked with fluctuating wind power. This study aims to investigate design and operation of a CAES system for wind power at design and off-design conditions through process simulation. Improved steady-state models for compressors, turbines and the CAES system for wind power were developed in Aspen Plus (R) and validated. A pseudo-dynamic model for cavern was developed in Excel. Compressor and turbine characteristic curves were used in model development for process analysis. In the off-design analysis, it was found that the CAES system for wind power at variable shaft speed mode utilise more excess wind energy (49.25 MWh), store more compressed air (51.55 x 10(3) kg), generate more electricity (76.00 MWh) and provide longer discharging time than that at constant shaft speed mode. Economic evaluation based on levelized cost of electricity (LCOE) was performed using Aspen Process Economic Analyser (R), it was found that LCOE for the CAES system for wind power at variable shaft speed mode is lower than that at constant shaft speed mode. Research presented in this paper hopes to shed light on design and operation of the CAES system for wind power and cost reduction. (C) 2019 Elsevier Ltd. All rights reserved.