The inertia of power systems is a key aspect of frequency dynamics and stability. The increasing penetration of non‐synchronous generation reduces the available inertia and makes it fluctuating during the day depending on the online units. This causes problems for grid operators, particularly in relatively small power systems. The present work examines the impact of decreasing inertia using an aggregate model based on the swing equation, considering future lower inertia scenarios and the implementation of the current protection schemes. The frequency stability of the system is assessed by considering the reference incident, i.e. the loss of the largest operating unit in under‐ and over‐frequency cases. New solutions to balance the grid are addressed and compared, considering the technical impacts of synchronous compensators and battery energy storage systems (BESSs) operated with a new equivalent saturation logic. The model is tested and validated using the real data of a small insular power system (Sardinia Island, Italy), outlining the importance of the high‐voltage direct current and of the BESS control strategies to guarantee the frequency stability of the power system.

The worldwide spread of the COVID-19 pandemic in 2020 forced most countries to intervene with policies and actions—including lockdowns, social-distancing and smart working measures—aimed at mitigating the health system and socio-economic disruption risks. The electricity sector was impacted as well, with performance largely reflecting the changes in the industrial and commercial sectors operations and in the social behavior patterns. The most immediate consequences concerned the power demand profiles, the generation mix composition and the electricity price trends. As a matter of fact, the electricity sectors experienced a foretaste of the future, with higher renewable energy penetration and concerns for security of supply. This paper presents a systemic approach toward assessing the impacts of the COVID-19 pandemic on the power sector. This is aimed at supporting decision making—particularly for policy makers, regulators, and system operators—by quantifying shorter term effects and identifying longer term impacts of the pandemic waves on the power system. Various metrics are defined in different areas—system operation, security, and electricity markets—to quantify those impacts. The methodology is finally applied to the European power system to produce a comparative assessment of the effects of the lockdown in the European context.