Integrating Large Shares of Thermal Loads in Frequency Reserves

Extended research in recent years has unveiled a plethora of uses of loads as demand response resources. This thesis focuses on the use of thermal loads as frequency reserves, under the current frequency control setup of power systems. In the proposed methods loads can be utilized in parallel to conventional spinning reserves. Most of the literature usually neglects practical load constraints or large assumptions are made to simplify the analysis and modeling. In this thesis various constraints are addressed, such as anti short-cycling compressor timers, ramping constraints, start-up dynamics etc. Their impact on the loads’ response is thoroughly analyzed and control methods are proposed to improve performance. The resulting algorithms can be applied under realistic loads, with simulations showing very promising results. The good performance of the models was validated by dynamics simulations in a two-area power system. From the investigation it can be concluded that spinning reserves can be reliably replaced by thermal loads, significantly improving the system’s stability under large disturbances.