A Comparative Analysis of Different Virtual Inertia Controllers in Power Grids with Renewable Energy Sources

The inertia of a power grid measures the system's ability to counteract frequency changes, remaining synchronized and stable when triggered by external disturbances. Renewable energy sources (RES) are interfaced with the grid through power converters without the intrinsic (mechanical) inertia of synchronous machines; therefore, a strong presence of RES reduces the global inertia of the system, compromising its stability and reliability. Thus, it is fundamental to develop power converter controllers that provide synthetic inertia by mimicking the electro-mechanical behavior of a synchronous machine. This paper investigates the performances of three different power converter control techniques that generate virtual inertia. As a case study, we consider a 4-bus power network to analyze the grid reaction to a rapid load increase.