Use of air chamber in gas-turbine units for frequency control and energy storage in a system with high wind penetration

The scope of this paper is to investigate the dynamic performance of a compressed-air chamber introduced to a gasturbine unit for enhancing frequency control capability, as well as for energy storage. The considered unit is part of an autonomous power system with high wind penetration. Two different configurations are studied: (a) a small-scale air chamber injecting compressed air into the combustion chamber in case of system disturbances, and (b) a conventional gasturbine unit combined with a large-scale air chamber for energy storage using a separate compressor driven by an electric motor. In the latter case, power is generated when required by expanding the stored air through a separate turbine, while the gas-turbine unit operates independently. In both cases, the autonomous system is simulated for the loss of a generating unit. It is found that the small air chamber significantly improves primary frequency control by providing increased spinning reserve, while configuration (b) exhibits improved post-disturbance response both in generation and in storage mode, while reducing fuel consumption and CO₂ emissions.