Traditional fossil fuel power plants release substantial amounts of greenhouse gases, primarily contributing to anthropogenic climate change. Integrating renewable energy sources into the energy supply systems is crucial to mitigate these environmental challenges. One untapped renewable energy source is wave energy, which can contribute to the transition towards a 100% renewable future. Initially, this thesis presents a case for the potential value of adding wave energy to the electric grid by analysing the complementarity of the wave resource with other renewable energy modalities (wind, tidal and solar) and load requirements in the Island of Ireland. The analysis shows that wave energy has a role to play in the future Irish supply mix. Wave energy, like other renewable energy resources, presents a considerable challenge for integrating it into the power grid due to its intermittent, and relatively unpredictable nature. Wave energy grid integration entails several issues, including managing power output variability, effective control of the wave energy device and power converters, and optimal storage requirements. Additionally, an added complexity in wave energy grid integration lies in implementing reactive wave energy converter (WEC) control, which requires bi-directional power flow between the device and grid sides. In general, many grid integration studies involving wave energy have deficiencies, such as simplified hydrodynamic and power converter models, simplified passive damping hydrodynamic control and relatively rudimentary PI power converter control. It is imperative to address the issues mentioned above to enhance the integration of wave energy into power grids, maximising power capture and the economic benefit of wave energy. To this end, this thesis presents a wave-to-grid (W2G) control framework for a direct-drive wave energy conversion system, including control-oriented models for each component in the powertrain and high-performance controllers for both device and grid sides, to achieve a range of control objectives. A short-term ultra-capacitor-based storage system supports both device-side (hydrodynamic control support) and grid-side (grid support during faults and power quality improvement) functionalities. Additionally, the negative (reactive) power peaks are analysed by recognising the importance of reactive power requirements of reactive hydrodynamic WEC control and its implications for the powertrain equipment. As a result, this thesis provides analytical and simulation results regarding the excessive reactive power peaks requirements of hydrodynamic WEC control and offers recommendations on how to deal with them.