A power take-off (PTO) system for an oscillating water column (OWC) wave energy converter comprises a turbine-generator-power converter. In this study, only the topologies of the power converter that affect the load control algorithm are compared. A power converter for renewable energy is composed of a diode-dc/dc converter and a pulse-width modulation (PWM) converter operating at small and large capacities, respectively. However, selecting a power converter according to the capacity based on the characteristics of the wave energy converter, in which the input energy is highly fluctuating, can significantly reduce the power performance. Thus, to verify load control characteristics according to the topology of the power converter, the turbine-generator-power converter was incorporated in the modeling, and the power performance based on the power converter topology under various wave conditions was analyzed. Further, torque control to obtain the maximum power among load control algorithms was applied under irregular wave conditions, and the power performance and PTO system characteristics according to the torque coefficient were analyzed. The results of this study suggested an increase in the torque coefficient of the maximum power control for the operational stability of the OWC-WEC, and it was confirmed that the RPM characteristics of the PTO system were reduced.

In this study, a method for effectively estimating the airflow rate of the turbine of an oscillating water column (OWC) pilot plant was developed. The validity of the proposed method was verified through computational fluid dynamics simulations. The method was applied to estimate the airflow rate in irregular wave states based on the operation data obtained for the Yongsoo OWC pilot plant installed in the western seas of Jeju Island, South Korea. As an alternative to estimating the airflow rate of the OWC pilot plant, the impulse turbine performance chart-based interpolation method is introduced, and it is shown that the airflow rate time series calculated using the two methods were in good agreement.