Aggregated power profile of a large network of refrigeration compressors following FFR DSR events

Refrigeration systems and HVAC are estimated to consume approximately 14% of the UK’s electricity and could make a significant contribution towards the application of DSR. In this paper, active power profiles of single and multi-pack refrigeration systems responding DSR events are experimentally investigated. Further, a large population of300 packs (approx. 1.5 MW capacity) is simulated to investigate the potential of delivering DSR using a network of refrigeration compressors, in common with commercial retail refrigeration systems. Two scenarios of responding to DSR are adopted for the studies viz. with and without applying a suction pressure offset after an initial 30 seconds hut-down of the compressors. The experiments are conducted at the Refrigeration Research Centre at University of Lincoln. Simulations of the active power profile for the compressors following triggered DSR events are realized based on a previously reported model of the thermodynamic properties of the refrigeration system. A Simulink model of a three phase power supply system is used to determine the impact of compressor operation on the power system performance, and in particular, on the line voltage of the local power supply system. The authors demonstrate how the active power and the drawn current of the multi-pack refrigeration system are affected following a rapid shut down and subsequent return to operation. Specifically, it is shown that there is a significant increase in power consumption post DSR, approximately two times higher than during normal operation, particularly when many packs of compressors are synchronized post DSRevent, which can have a significant effect on the line voltage of the power supply.