Novel hydraulic mechanism-based output power regulation for the wave energy converter

Abstract Due to the drastic input energy variation of realistic waves, the stability of the power take-off (PTO) is one of the paramount issues for wave energy converters (WECs). In this paper, a novel structure of the power regulation module in the hydraulic PTO is proposed. The proposed module comprises a pressure compensation valve and a throttle valve, which greatly enhances the stability of the hydraulic PTO under irregular wave circumstances. The complete state-space equations for the floater and hydraulic PTO emphasizing dynamic behaviors of the power regulation module are established and the modeling accuracy of hydraulic PTO in the system is validated with experimental data. The influences of key parameters of the power regulation module on the hydraulic PTO stability are also researched and the opening size of throttle valve is controlled to adjust the steady values of hydraulic PTO. The results demonstrate that the fluctuations of hydraulic motor speed and generator output power can be effectively suppressed by the proposed power regulation module and their steady values can be sensitively adjusted by controlling the opening size of throttle valve. This study provides a promising approach to increase the power quality of hydraulic PTO.