Grid frequency regulation by recycling electrical energy in flywheels

Grid frequency regulation function addresses the balance between the network´s load and power generated. The system operator generates a signal, area control error (ACE) signal at PJM, based on the difference between these two parameters. The expected goal is to keep the system near nominal 60 or 50 Hz. Traditionally, frequency regulation is managed by varying the output of fossil fuel or hydro generators connected to the electric grid. The authors present a new method in which electric energy is recycled. First, absorbing energy when it is in abundance, then discharging the same for the desired frequency regulation effect. The proposed system is based on kinetic energy storage technology in high-speed flywheels. Performance modeling results, based on actual ACE signals, indicate that a modular flywheel system matrix is effective in providing frequency regulation. The cost of this system is attractive compared with today´s generator-based approach. The controlled injection or absorption of reactive power, inherent to the system, extents its capability to provide voltage support. Further, fast acting control electronics allow for the damping of grid oscillations. All the above functions, once deployed in moderate numbers, could help prevent frequency and voltage shifts that have been linked to significant blackouts in recent history