Frequency control services by a building cooling system aggregate

• This paper proposes a control strategy for managing an aggregate of commercial buildings.
• Each building is equipped with Space Cooling Systems (SCSs).
• The objective is to make able the aggregate to provide frequency control services to the main grid.
• Two algorithms are developed for two classes of SCSs: inverter-driven SCSs and multi-state SCSs.
• Model Predictive Control and Mixed-Integer Predictive Control are used to design the algorithms.
• The effectiveness of the proposed control techniques is tested using a test network model.

This paper proposes a control strategy for managing an aggregate of commercial buildings equipped with Space Cooling Systems (SCSs), called to provide frequency control services to the main grid. The idea is to use the thermal energy stored into buildings to contribute to frequency regulation, during both normal and emergency operating conditions, always preserving the temperature comfort of end-users. Two specific algorithms are developed for two different classes of SCSs: inverter-driven SCSs, which allow the controller to define the current power demanded from the grid, and multi-state SCSs, which allow the controller to switch on-off one of the cooling units that compose the SCSs. In these two different cases, Model Predictive Control and Mixed-Integer Predictive Control, are respectively used to design a load aggregator algorithm able to coordinate the contribution to frequency regulation of each building, depending on their different thermal conditions. A test network model with a high penetration of renewable energy generation is implemented in a dedicated real-time simulation environment, in order to test the effectiveness of the proposed control techniques.