Electric power system inertia: requirements, challenges and solutions

The displacement of conventional generation by converter connected resources reduces the available rotational inertia in the power system, which leads to faster frequency dynamics and consequently a less stable frequency behaviour. This study aims at presenting the current requirements and challenges that transmission system operators are facing due to the high integration of inertia-less resources. The manuscript presents a review of the various solutions and technologies that could potentially compensate for reduction in system inertia. The solutions are categorized into two groups, namely synchronous inertia and emulated inertia employing fast acting reserve (FAR). Meanwhile, FAR is divided into three groups based on the applied control approach, namely virtual synchronous machines, synthetic inertia control and fast frequency control. The analytical interdependency between the applied control approaches and the frequency gradient is also presented. It highlights the key parameters that can influence the units' response and limit their ability in participating in such services. The manuscript presents also a trade-off analysis among the most prominent control approaches and technologies guiding the reader through benefits and drawbacks of each solution.