Power Smoothing in Smart Buildings using Flywheel Energy Storage

Emergence of concepts such as smart grids and smart cities has led to a more closely monitored and managed power systems. As such, the power production is shifting towards more distributed generation consisting of renewable energy sources whose fluctuating nature complicates the balancing of supply and demand. Demand response methods have been employed to smooth the power needs by shifting loads to when there is a surplus of production. In this paper, power smoothing of fluctuating loads using a flywheel storage system is investigated for a small grid connected microgrid. A model of a low speed flywheel system is developed with a current control of the grid-side converter and field-oriented control of the motor-side converter. A moving average filter is used for power smoothing in a small microgrid. The performance of power smoothing could be adjusted by varying the length of the time window of moving average filter. An 81.9 % reduction in RMSE of grid power fluctuations was accomplished showing that flywheel storage can be successfully used to smoothen microgrid power.