Frequency Response and Inertia Analysis in Power Systems with High Wind Energy Integration

In most of power systems, inertia has been usually estimated by considering only the rotating masses directly connected to the grid. However, the relevant integration of renewable energy sources into power systems, mainly wind and PV power plants decoupled from the grid by electronic converters, is decreasing the grid inertia and then affecting considerably both grid stability and reliability analysis. An alternative supply-side framework can be thus identified, where traditional generation is replaced by renewable energy sources. As an example of this integration process, renewables overtake coal and nuclear in EU for the first time during 2017. Under this new framework with a lack of rotating masses directly connected to the grid, terms such as `Hidden inertia', `Synthetic inertia' or `Virtual inertia' are currently under discussion. Moreover, alternative spinning reserves must be also considered and included in power sytems to maintain power system reliability and stability. A detailed analysis to estimate the effect of low inertia parameter for frequency control purposes is discussed in this paper. Different scenarios are simulated and analysed, taking into account high wind energy integration, demand variations and frequency oscillations.