scholarly journals Advanced Maximum Power Control Algorithm Based on a Hydraulic System for Floating Wave Energy Converters

Processes ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1712
Author(s):  
Chan Roh ◽  
Yoon-Jin Ha ◽  
Seungh-Ho Shin ◽  
Kyong-Hwan Kim ◽  
Ji-Yong Park
Keyword(s):  
Power Generation ◽  
Wave Energy ◽  
Control Algorithm ◽  
Maximum Power ◽  
Torque Control ◽  
Damping Coefficient ◽  
Wave Excitation ◽  
Wave Energy Converters ◽  
Power Generation Performance ◽  
Energy Converters

An integrated analysis is required to evaluate the performance of control algorithms used in power take-off (PTO) systems for floating wave energy converters (FWECs). However, research on PTO systems based on the existing hydraulic device has mainly focused on the input power generation performance rather than on obtaining maximum power through hydraulic device-based electrical load control. The power generation performance is analyzed based on the control variables of the existing torque control algorithm (TCA); however, the amount of power generation for each control variable changes significantly based on the cycle of wave excitation moments. This paper proposes a control algorithm to obtain the maximum power by modeling a hydraulic-device-based integrated FWEC. It also proposes a TCA that can obtain the maximum power regardless of the period of wave excitation moment. The proposed TCA continuously monitors the power generation output and changes the PTO damping coefficient in the direction in which the power generation output can be increased. The proposed TCA increased the output power generation by up to 18% compared to each PTO damping coefficient of the conventional TCA. Thus, the proposed method results in higher power generation regardless of the wave excitation moment cycle and performs better than the existing torque control algorithm.

scholarly journals Revisiting Theoretical Limits for One-Degree-of-Freedom Wave Energy Converters

2020 ◽  
pp. 1-11
Author(s):  
Nathan Tom
Keyword(s):  
Power Generation ◽  
Wave Energy ◽  
Degree Of Freedom ◽  
Upper And Lower Bounds ◽  
Complex Conjugate ◽  
Hydrodynamic Coefficients ◽  
Damping Coefficients ◽  
Wave Energy Converters ◽  
Heave Motion ◽  
Energy Converters

Abstract This work revisits the theoretical limits of one-degree-of-freedom wave energy converters (WECs). This paper considers the floating sphere used in the OES Task 10 WEC modeling and verification effort for analysis. Analytical equations are derived to determine bounds on displacement amplitude, time-averaged power (TAP), and power-take-off (PTO) force. A unique result found shows that the TAP absorbed by a WEC can be defined solely by the inertial properties and radiation hydrodynamic coefficients. In addition, a unique expression for the PTO force was derived that provides upper and lower bounds when resistive control is used to maximize power generation. For complex conjugate control, this same expression only provides a lower bound, as there is theoretically no upper bound. These bounds assist in comparing the performance of the floating sphere if it were to extract energy using surge or heave motion. The analysis shows because of differences in hydrodynamic coefficients for each oscillating mode, there are different frequency ranges that provide better power capture efficiency. The influence of a motion constraint on TAP while utilizing a nonideal power take-off is examined and found to reduce the losses associated with bidirectional energy flow. The expression to calculate TAP with a nonideal PTO is modified by the mechanical-to-electrical efficiency and the ratio of the PTO spring and damping coefficients. The PTO spring and damping coefficients were separated in the expression, allowing for limits to be set on the PTO coefficients to ensure net power generation.

A Hybrid Power Generation Platform Combining Floating Wind Turbine and Oscillating Water Column Wave Energy Converters

2019 ◽  
Author(s):  
Zheng Chen ◽  
Weijian Zeng ◽  
Ming Tan ◽  
Dahai Zhang ◽  
Yulin Si
Keyword(s):  
Power Generation ◽  
Wind Turbine ◽  
Water Column ◽  
Wave Energy ◽  
Wind Farms ◽  
Offshore Wind ◽  
Oscillating Water Column ◽  
Offshore Wind Farms ◽  
Wave Energy Converters ◽  
Energy Converters

Abstract Recent years have seen rapid development in offshore wind technology. Particularly, floating offshore wind turbines possess great potential in deep water coastal places around the world, though they are now still in the demonstration phase. At the same time, the unused wave energy is also abundant at the sites of offshore wind farms, especially those in deep sea regions. Collecting wave energy in offshore wind farms might benefit both total energy production and reduce maintenance cost. Therefore, integrating offshore wind turbine with wave energy conversion devices could be a good idea to achieve higher efficiency and lower cost. In this paper, we report a combined wind and wave energy power generation concept called WindOWC, which constits of a 5MW wind turbine and three oscillating-water-column (OWC) wave energy converters (WECs). The wind turbine is mounted on a semi-submersible floating platform, which is similar to OC4-semibsubmersible, and the OWCs are located in its three offset columns. In this design, the wind turbine and WECs share the same supporting platform and the power transmission system, thus is expected to reduce the cost of energy. Also, it is possible the OWCs may improve the platform dynamic performance by providing positive damping through controlling the air turbine rotational speed. In this work, we describe the geometry properties of the proposed WindOWC concept and conduct preliminary hydrodynamic analysis using potential flow theory. The ANSYS AQWA is used to obtain the system dynamic responses in frequency and time domain, respectively. The OWC dynamics and expected positive damping from them will be investigated in the future.

scholarly journals Electrical Power Generation from the Oceanic Wave for Sustainable Advancement in Renewable Energy Technologies

2020 ◽  
Vol 12 (6) ◽  
pp. 2178 ◽  
Author(s):  
Omar Farrok ◽  
Koushik Ahmed ◽  
Abdirazak Dahir Tahlil ◽  
Mohamud Mohamed Farah ◽  
Mahbubur Rahman Kiran ◽  
...  
Keyword(s):  
Power Generation ◽  
Renewable Energy ◽  
Electrical Power Generation ◽  
Wave Energy ◽  
Electrical Power ◽  
Extensive Literature ◽  
Energy Devices ◽  
Wave Energy Converters ◽  
Oceanic Wave ◽  
Energy Converters

Recently, electrical power generation from oceanic waves is becoming very popular, as it is prospective, predictable, and highly available compared to other conventional renewable energy resources. In this paper, various types of nearshore, onshore, and offshore wave energy devices, including their construction and working principle, are explained explicitly. They include point absorber, overtopping devices, oscillating water column, attenuators, oscillating wave surge converters, submerged pressure differential, rotating mass, and bulge wave converter devices. The encounters and obstacles of electrical power generation from the oceanic wave are discussed in detail. The electrical power generation methods of the generators involved in wave energy devices are depicted. In addition, the vital control technologies in wave energy converters and devices are described for different cases. At present, piezoelectric materials are also being implemented in the design of wave energy converters as they convert mechanical motion directly into electrical power. For this reason, various models of piezoelectric material-based wave energy devices are illustrated. The statistical reports and extensive literature survey presented in this review show that there is huge potential for oceanic wave energy. Therefore, it is a highly prospective branch of renewable energy, which would play a significant role in the near future.

Sign in / Sign up

Export Citation Format

Share Document