The dramatic reduction of inertia suffered by worldwide grids due to the transition towards renewable and power electronic based generation, rises the risk of disturbances and blackouts due to frequency related issues. Therefore, in this thesis, state of the art techniques aiming to minimise such challenges are reviewed and analysed. Also power and frequency control strategies are presented along with a deep analysis of the issues caused by large integration rates of renewable energy sources. Additionally, past and future relevant scenarios of the European grids are analysed. Subsequently, after presenting the topology of the Hybrid power plant (compound by a Wind Farm, a Photovoltaic Plant and a Battery Energy Storage System), a control strategy aiming to mimic the inertial response of synchronous generators is proposed and tested in a relevant simulation environment.

The obtained results show how, by mimicking inertial response, renewable plants are capable of responding to critical events, protecting the frequency stability of the grid without suffering undesired stresses, in a similar way as for the traditional synchronous generators.

In the last chapter, the findings and contributions of this work are summarised while also outlining directions for future research.