Energy limits in primary frequency control with short-term frequency-band allocation

Frequency stability of large power systems requires the use of very fast flexible resources to contain frequency excursions. Potential candidates able to provide such flexibility are demand response and storage. However, capacity and energy constraints usually restrict their use to exceptional and rare events. Recently, some interesting studies have looked at the integration of energy constraints in power system operations. One solution is discussed here: short-term frequency-band allocation (SFBA). Periodically, the system operator will change dead-band zones and saturation levels of the resources´ proportional controllers and thereby manage the energy constraints in a dynamic way. The paper presents a model for SFBA and highlights its interest: the integration of capacity and energy constraints as well as storage profile preferences. Finally, some limitations to the approach and ways to deal with them are discussed: the inability to recover previously delivered energy.