Proactive Demand Management for Electric-powered Transport Refrigeration Units 2011-01-2300

As commercial fleets adopt more electrically-powered hardware, including vehicles and transportation equipment, new demands are being placed on the existing electrical infrastructure. Demand management is critical as facilities reach their electrical capacity through growing electric energy demands or come under electricity use restrictions through banding and time-of-day use agreements (which incentivize reduced demand on electrical resources). Most current demand management systems focus on reactive actions such as denying availability (e.g. rolling brown out) during peaking events. In many situations, this denial of service may be highly undesirable, as is the case with electric-powered transport refrigeration units (eTRUs), which must maintain a narrow temperature band to protect perishable products. While most eTRUs have the capability to automatically switch to diesel power if electrical power is not available, operating on diesel fuel significantly reduces the economic benefit to the warehouse or refrigerated facility. In addition, eTRUs operating on diesel power produce emissions that may cause them to be noncompliant with local or state regulations. In these cases, proactive demand management may be a better solution. By forecasting demand in advance of the occurrence, a proactive demand management system can meet all thermal requirements by preemptively altering the eTRU demand schedule while adhering to desired electrical system loads. A proactive demand management system for eTRUs was developed for the New York State Department of Correctional Services Food Processing Center in Rome, NY. This paper summarizes the results of that project, including the design approach used and lessons learned.