Analytical Models and Evaluation for Novel Multi-Stage Flywheel Configurations for Grid-Connected Wind Power Applications

Flywheels are one of the commonly used devices for energy storage for grid-connected wind power systems. However, using large and heavy flywheels for high power storage applications could encounter some problems when installed in the areas with large variation of wind speed. This paper proposed a novel approach of multi-stage flywheel configurations where several sub-flywheels were used to extract the power from different levels of wind speed. There were 2 staging types proposed, an identical multi-stage flywheel and an incremental multi-stage flywheel. Their analytical models were first developed, following by the performance evaluation tests in the MATLAB-Simulink program compared to the conventional bulky flywheel. The case study of 6kWh energy storage was considered and thus allowed a stage of 6 identical l kWh sub-flywheels and a stage of 1 k Wh, 2kWh and 3kWh flywheels for identical and incremental multi-stage flywheels, respectively. The test results showed that the incremental multi-stage flywheel provided optimum benefits among high energy storage capacity, large wind speed variation operation and optimum system complexity.