Comparing Disturbance-based Methods for Inertia Estimation in the island of São Vicente, Cape Verde

Abstract

The energy transition by means of the decarbonisation of the power system poses several technological challenges. For instance, system strength is directly affected by the decommissioning of traditional synchronous generator units in favour of renewable energy units. While synchronous units provide inertia to the system, renewable units are effectively decoupled from the grid via power electronics. This transition unequivocally leads to a decrease in system stability. Particularly, isolated systems are more exposed to these problems as they tend to be smaller and have faster dynamics. Therefore, it is important to know the system inertia constant after a sudden disturbance as it may help to predict the possible nadir frequency. Obtaining the inertia constant is a hard task due to the many parameters that have to be monitored. Hence, inertia estimation methods based on disturbance measurements have been used for a while. In this study, a comparison between different approaches is analysed. In the meantime, this paper aims to give a more practical approach to the selected method. This will highlight the technical difficulties when estimation methods based on disturbances are used. Here we show how the size of the power disturbance together with the system rate of change of frequency is crucial for accurate results.