All-electric Wave Energy Converter array with energy storage and reactive power compensation for improved power quality

Power electronics and advanced motion control has allowed for creating Wave Energy Converters (WECs) with the generator directly coupled to the sinusoidal motions of the prime mover. However, this results in large fluctuations in output power, and the resulting peak to average power ratio exceeds most other energy producers. Moreover, the typical average power production from a WEC is lower than that of other power plants, and array connection of several WECs is necessary to help mitigate these shortcomings. Earlier studies performed on arrays by Fred. Olsen (FO) has shown a favorable outcome, and has demonstrated a reduction factor of four in the peak to average ratio for a small array. These results were obtained without further power conditioning and resulted in poor utilization of installed capacity. In an endeavor to fully optimize the WEC system for grid connection, this study investigates three possibilities for power quality improvements: Introduction of energy storage, implementation of controlled power capping and implementation of reactive power compensation. By simulation of annual production for a specific production site, the resulting power quality improvements are estimated, and demonstrates that the WEC system can obtain a power quality level close to wind power. Reactive power compensation demonstrate the ability to increase the power quality and to improve the local power balance by optimizing the grid utilization during no production periods.