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

Modeling and control of the hydraulic actuator in a ladle furnace

“…In the review of the works of [ 35 , 36 , 37 , 38 ] and through the observation and analysis of the case study itself, the static nonlinearities in the process were determined: dead zone and saturation. The dead zone of the process is determined by checking the cylinder begins to move when voltage values greater than 0.87 V in the upward movement and less than -0.76 V in the downward trend are present at its input.…”

Speed-and-pressure combined control for the CPHPTO of an inverse pendulum wave energy converter

“…where P M J  is the total inertia moment of the NIPWEC around the rotational centre, 55 J  the additional mass at the wave frequency of + ,  the swing angle, ( ) K t the impulse response function of ( ) K  , B F the buoyancy force, P G the gravity force of the inversed pendulum, M G the gravity force end M t the end-stop moment avoiding the swing angle exceeding the upper limit. Moreover, the detailed CPHPTO model references Literatures [10,18].…”

“…OCs suggest that CPHPTO should work at the designed oil pressure and hydraulic-motor speed under the different oil flowrates induced by variable WEC motion laws in irregular waves, in order to maintain the CPHPTO high-efficiency and stability. Concurrently, several methods, such as electric-load control [8], motordisplacement control [9], and throttle-valve-opening-size control [10], were put forward in succession, attempting to realize the stability control for the oil pressure or hydraulic-motor speed. However, the above methods are based on the single actuator and difficult to stabilize both oil pressure and hydraulic-motor speed at the same time in regular waves.…”

Research on Thermodynamic Characteristics of Hydraulic Power Take-Off System in Wave Energy Converter

“…The main functions of the accumulator are to store energy, stabilize pressure, eliminate periodic fluctuations of the system pressure and flow generated when the cylinder is reversing, and enhance the consistency of the system. The overflow valve can avoid the high pressure in the pipeline, and the function of the flow control valve is to control the flow rate and participate in the control of the power; the oil tank is used to compensate for the leakage and short-term negative pressure that may occur in the system and to supplement the oil pressure in time [9,22,23,26].…”

“…Yue proposed integrated characteristic curves in constant voltage conditions, which are used to optimize system design and improve the operating efficiency of the PTO system [22]. Geng proposed a novel hydraulic PTO power module consisting of a pressure compensator and throttle valve by adjusting the parameters to improve the consistency of hydraulic motor speed and output power [23]. The focus of the research on the consistency and efficiency of the hydraulic PTO system is focused on how to select pivotal components and optimize parameters and control strategies, which ignored the influence of the characteristics of the working medium on the consistency of the output power and efficiency when the wave energy converters are running.…”