Dynamic frequency control support: A virtual inertia provided by distributed energy storage to isolated power systems

In electrical islands, frequency excursions are sizeable and automatic load shedding is often required in response to disturbances. By injecting active power in the timeframe of hundreds of milliseconds up to a few seconds after the loss of a generating unit, fast-acting storage can support the conventional production assets during the activation of their primary reserve. Using dynamic and hardware-in-the-loop (realtime) simulations, the provision of such a dynamic frequency control support by distributed energy storage systems has been studied in the case of the French island of Guadeloupe. Dedicated control algorithms have been developed and tested on a small-scale ultracapacitor storage unit. By acting as a virtual inertia, it has been shown that fast storage systems can improve substantially the dynamic performances of electrical islands.