Comparing the Damping Capabilities of different Fast-Frequency Controlled Demand Technologies

Abstract

Modern power systems require an additional supply of fast-frequency reserves to cope with the reduction in overall system inertia and damping caused by the increasing share of inverter-interfaced generation. Batteries are commonly referred to as the most promising option to provide such reserves due to their fast activation capabilities. In this work, we show that inverter-interfaced thermal loads, i.e. heat pumps and refrigeration, tend to accommodate a slightly quicker response than batteries and can thus compete with their dynamic characteristics. To this end, we derive characteristic single-input single-output transfer functions that describe the linearized response of different technologies and include detailed load characteristics. The performed time-domain studies for a low-inertia scenario clearly show that thermal loads can improve frequency damping to the same extent as batteries.