Modelling and grid integration of a 10 MW wave farm - Study of power quality with varying grid impedance angles and wave front incidence angles

Abstract: Grid connection of wave energy is one of the crucial remaining areas of development towards the commercialization of this renewable energy technology. One of the major challenges with the grid connection of the wave energy technology is power variability. The rapidly changing voltage and power production from very high peaks to lows, increases the complexity for the wave farm developers to reach an agreement with the grid owners to satisfy the grid compliance. Correspondingly, electrical network designs of the offshore wind sector also differ on some key features which includes the power variability, cable lengths, power ratings, connection layouts, sea depths and transmission distances. These differences present new challenges to engineers in adapting technology and knowhow from the wind industry wherever applicable; whereas in parts of the network where power ratings are <2 MW, new designs need to be derived. Hence, power system dynamic modelling of variable emerging wave energy puts a great field of research. CorPower Ocean AB is in the process of developing a 300-kW point absorber type Wave Energy Converter (WEC) that is a commercial fullscale prototype. In this regard, the thesis will discuss the topics of optimization of offshore wave energy electrical networks for farms primarily focused on a 10 MW rating. The modelling for RMS simulation, network efficiency, voltage profile and power quality analysis has been simulated on DIgSILENT PowerFactory. Grid connection compliance for voltage levels, voltage flicker and power factor has been evaluated against local site regulations and parameters for optimal efficiency and better power quality with respect to grid connection is discussed. The impact of grid impedance angle and the wave front incidence angle on the rating of wave farm being connected is also evaluated. The study leads to an optimized electrical layout of a wave farm which can tackle problems such as voltage flicker and varying power. The study also leads to the understanding of better layout for the point absorber with least transmission losses. This study can also be generalized for bigger wave farms in the future which will reduce the complexity and time for wave farms engineers while planning.