Enhancing grid system performance by integrating compressed air energy storage

Abstract

Wind energy is a boundless renewable energy which can be tapped continuously. It is clean and free energy making it incomparable with conventional fossil fuels. However, high stochastic nature of the wind the electric power generated affects the power quality of grid system. Compressed Air Energy Storage (CAES) is a mature energy storage technology in handling wind fluctuation problems such that the generated energy would be supplied to the grid without affecting the grid performance. Its large scale capacity storage, long storage period, fast ramp rates and low capital cost has made it as the best choice to be tagged to wind turbine in dispatching wind power. But, operating system of existing CAES is more to economic benefit, in which it will only discharge during high electricity cost and charge during low electricity cost. This thesis proposes a parallel connection of CAES with wind turbine where it can promise continuous supply to grid system with low power consumption during charging process. The first connection is to connect the wind turbine, drive train, compressors, tank, turbine and generator. While the other one is bypassing the direct connection of drive train, (wind turbine to compressor on a shaft and compressed air turbine to generator on another shaft). Derivation of mass flow rates leaving the tank is based on single stage expansion process. Analysis was carried out using MATLAB simulink to prove the effectiveness of the storage to react to the changes of wind speed, in which the results were focussed on the grid’s voltage and active power. The results show that the proposed connection of wind CAES does not only able to smooth out wind power fluctuations but it also provides continuous power to supply the grid system compared to Battery Energy Storage. Moreover, its consumed lower power during charging process compared to existing CAES system.