Revisiting the Need for Conventional Safety Measurements in Modern Power Grids

The growing adoption of Inverter-Based Resources (IBRs) in power grids has enabled the integration of renewable energy sources as viable alternatives to fossil-fuel-based thermal generators. Historically, conventional power grids have relied on synchronous generators, with safety indicators such as the Rate of Change of Frequency (RoCoF) being essential for handling reactions to disturbances and faults. However, due to the fundamental differences in the operation of inverters, the utilisation of such safety indicators can yield unintended and adverse outcomes, potentially compromising the reliability of the network. This paper investigates the impact of integrating inverter-based resources in the grid and examines the applicability of RoCoF as a safety indicator in modern power networks dominated by inverter-based generation. Through detailed simulations, we explore the behaviour of the grid during fault conditions and the subsequent frequency response of inverters. Our results demonstrate that, despite experiencing very high RoCoF values at the onset and clearance of faults, inverters can successfully maintain frequency synchronisation, even when inverter-based generation forms the majority of the grid’s supply. These findings suggest that traditional safety measures, such as the automatic disconnection of inverters based on high RoCoF values, may no longer be appropriate.