Synthetic Inertia and Primary Frequency Regulation Services by Domestic Thermal Loads

This paper proposes a control framework for allowing domestic thermostatically controlled loads, such as refrigerators and electric water heaters, to provide synthetic inertia and primary frequency regulation services. The basic idea is to modify the standard thermostat logic as a function of local measurements of the grid frequency, using a set of thresholds, generated with a proper probability distribution. In this way, the aggregate load response to frequency variations can be proportional to the frequency rate of change (RoCoF), providing synthetic inertia or/and primary frequency regulation. A combined solution is also proposed. The three control schemes are tested using a scenario of the Sardinian electric power system.