Evaluating load flow capability with thermostically controllable building loads

Through demand side management programs, buildings are increasingly being used to provide respite where generation inadequacies exist. Buildings are commonly dispatched as thermostatically controllable loads by adjusting internal temperature setpoints. Thermal load variations can be attributed to the HVAC equipment and are highly dependent on internal-external temperature gradients as well as equipment capacities. Since buildings are also connected to the electric grid, thermal load variations in a given building can have significant impacts on all interconnected buildings and the electrical grid. The primary focus of this paper is the analysis of load flow capability of the electric grid with thermostatically controlled building loads. The load flow capability will be evaluated through temperature distances to bus voltage, branch current and building specific temperature-load limits.