Investigating Impact of Conservation Voltage Reduction (CVR) on Efficiency of Air-Conditioning and Refrigeration Loads

It has been suggested in literature that by reducing the incoming voltage at distribution feeder head or at the input to commercial facilities, significant electricity savings can be achieved. Such programs are normally called Conservation Voltage Reduction (CVR) programs. The evidence for such assertions is primarily provided in terms of empirical energy consumption data before and after the introduction of the CVR programs. However, such data-based analysis does not provide the physical explanation for the reduction in energy consumption because of CVR. In this paper a MATLAB-SIMSCAPE model of the refrigeration/air-conditioning cycle is developed whose compression stage is replaced by an accurate model of the compressor, whose speed can be changed manually, or using the model of an electric motor in an electric thermal simulation. Simulations performed using this model show that efficiency of the cooling process (measured in terms of the coefficient of performance or COP) increases with reduction in applied voltage, which explains the reduction in energy usage of cooling equipment under CVR that has been reported in literature.