Quantifying flexibility of load aggregations: Impact of communication constraints on reserve capacity

Abstract

Due to the increased use of variable renewable energy sources, more capacity for reserves is required. Nongenerating resources such as thermostatically controlled loads (TCLs) can arbitrage energy prices and provide reserves due totheir thermal energy storage capacity. The quantity of reserves depends not only on the aggregate power capacity, but also oninformation and communication technology, exogenous parameters, and system operator requirements. Specifically, thepractical limitations origin from (i) communication constraints, (ii) ambient temperature, and (iii) the dispatch time of theactivation signal. This study explores the impact of these parameters on the amount of reserves that an aggregator of TCLs canprovide to the system operator based on centralised control of a TCL population. A decision support tool is proposed that can beused by aggregators to decide on maximum dispatchable reserve bids. The method can accommodate the specific controlalgorithm and TCL population of an aggregator and is based on offline computation. It constitutes a powerful reserve bid libraryto be used when optimisation tools become computationally intractable due to the increased number of decentralised flexibleloads.