Optimal Coordination of Spinning and Standing Reserve with energy Payback of Thermostatically Controlled Loads

Thermostatic loads are expected to support the transition to low-carbon systems by providing an array of ancillary services. The delivery of energy-intensive services requires the thermostatic appliances to payback the deployed thermal energy via extra power consumption at a later time. This is made available by conventional generators providing contingency reserve. Previous works acknowledged the interplay between secondary response and contingency reserve. However, the structure of the payback period was fixed and did not fully consider the capabilities of generators providing contingency reserve, e.g., modelling only spinning generators while neglecting standing units. This paper introduces a novel methodology that allows to optimally coordinate the energy recovery of thermostatic loads and the allocation of contingency reserve among spinning and standing units. To do so, the commitment times and structures of secondary response and contingency reserve can be optimally chosen depending on system needs and current availabilities at each time step. The model is applied to the Great Britain network, which is connected to the power system in Continental Europe via a high-voltage direct-current link. Results illustrate the techno-economic advantages stemming from the proposed methodology.