H infinity controller design for primary frequency control of energy storage in islanding MicroGrid

For the frequency stability of microgrids assumed with storage devices, droop frequency control is generally applied for primary frequency control. However, the transient response of frequency is not quite good without any control of its performances (overtaking, time response). Moreover, many storage devices can be installed to guarantee microgrid stability, and a more centralized control may be interesting to coordinate the participation of each device. A Hinfinity controller is then proposed to improve the transient response and the robustness against any small disturbance of the frequency. A model is first proposed in accordance with the global formulation of H infinity control. Then, control specifications are defined in the frequency domain by definition of weighting functions. Finally, simulations of the system with H infinity controller allow verifying that the transient frequency response respects dynamic specifications.