Relation between overheating of distribution transformers and switching frequency of electric loads used for demand response

Utilities and researchers are looking for ways to coordinate the operation of thermostatically controlled loads (TCLs) to help integrate higher penetrations of renewable energy generation. However, using TCLs for demand response can result in an increase in TCL switching frequencies, which could affect distribution transformer (DT) temperatures. This paper explores the relation between DT overheating and TCL switching. We simulated a fleet of TCLs and found that higher switching frequencies result in lower maximum DT temperatures. We develop a DT-TCL model that estimates maximum DT temperatures as a function of the frequency of the power consumption of a small aggregation of TCLs, and we validate it through simulation. Additionally, we perform a case study to show that how TCL control impacts maximum DT temperatures. In general, control increases switching frequencies, reducing maximum DT temperatures; however, in some cases, it increases power amplitudes which can increase maximum DT temperatures.