Load Scheduling of a Refrigerated Warehouse with Homogeneous Compressors Under Dynamic Pricing

Abstract

We consider the electrical load scheduling problem for a multi-chambered refrigerated warehouse with each chamber consisting of a screw compressor operating under load-unload control. Considering loading and unloading time duration of the compressors to be fixed, we propose a simple load scheduling scheme where the loading of the compressors starts with a uniform time delay. We provide analytical models to calculate the cumulative load of the warehouse compressors at any given time and the electricity cost under dynamic pricing considering the proposed load scheduling scheme. We then validate the analytical models via simulations. As a benchmark, we consider a warehouse system where the loading time of the compressors starts randomly. We investigate that the total load under the proposed scheduling scheme do not vary significantly with time. However, the traditional system has significant variation in total load with time. We compare the electricity cost of warehouses for the proposed and the traditional systems under a dynamic pricing model. We find that the proposed load scheduling scheme significantly reduces the electricity cost compared to the traditional system. However, the cost reduction decreases with increasing the loading-unloading duty cycle, i.e., with increasing the ratio of loading time duration to the total loading-unloading time duration.