Tidal Current Power Research Articles

Experimental Investigation of the Yaw Misalignment Effect on the Power Performance and System Loading of a Flapping‐Foil Hydrokinetic Turbine

ABSTRACTHydrokinetic turbines (HTs) extract power by utilizing hydrodynamic forces from flow energy. The surplus load not used for power generation acts as a system load and must be considered when designing the turbine. Additionally, due to the variability of the flow direction during tidal power generation, the effect of the yaw misalignment angle on the power generation performance and system loading is an important design consideration. This study investigates the characteristics of an experimental model of an HT that uses two flapping foils, at different yaw misalignment angles through circulating water tunnel experiments. Experimental results show that with a yaw angle change of 10°, the power performance decreases by approximately 10% and the load increases by about 30% compared to an aligned configuration. Notably, the load in the flow‐perpendicular direction was significant, with periodic changes due to repetitive up‐and‐down motions. Consequently, the hydrodynamic force characteristics of the HT differ from those of conventional rotary turbines, necessitating the development of a design method that fits these characteristics for the actual installation of flapping‐foil HTs at tidal current power generation sites.

A Proposed Hybrid Machine Learning Model Based on Feature Selection Technique for Tidal Power Forecasting and Its Integration

Renewable energy resources are playing a crucial role in minimizing fossil fuel emissions. Integrating machine learning techniques with tidal power forecasting could greatly enhance the accuracy and reliability of predictions, which is crucial for efficient energy production and management. A hybrid approach combining different methods often yields better results than relying on individual techniques. The accuracy of tidal current power is very important, especially for smart grid applications. This work proposes hybrid adaptive neuro-fuzzy inference system (ANFIS) with the Kalman filter (KF) and a neuro-wavelet (WNN) for tidal current speed, direction, and power forecasting. The turbine used in this study is driven by a direct drive permanent magnet synchronous generator (DDPMSG). The predictions of individual and hybrid models including the ANFIS, the Kalman filter, and the WNN for tidal current speed and the power it generates are compared with another dataset as a way of validation which is the tidal currents direction. Also, other published work results in the literature are compared to the proposed work. Different hybrid models are proposed for smart grid integration. The results of this work indicate that the hybrid model of the WNN and the ANFIS for tidal current power or speed forecasting has the highest performance compared to all other models.

Tidal current power in Capalulu strait, North Maluku: A feasibility study

The Indonesian government has set goals for increasing the use of renewable energy in the coming years. Currently, Indonesia relies heavily on non-renewable energy sources, which poses a threat to the environment due to the country's growing energy needs. This study aims to assess the potential for developing a tidal power plant in Capalulu Strait, North Maluku. Using hydrodynamic modelling, the study identified two potential locations at coordinates 1.877°S – 125.328°E (Capa-2) and 1.863°S – 125.323°E (Capa-4) which were selected for having median current speeds exceeding 1.8 m/s and maximum current speeds exceeding 3.5 m/s. The study tested a hypothetical implementation of KHPS Gen5 instrument(s) by Verdant Power, a 5 m diameter turbine with a rated nominal power of 37 kW and a maximum rated power of 56 kW. A power plant layout was designed to be placed at Capa-2 and Capa-4, each location accommodating 45 turbines. The development of this power plant is estimated to produce up to 22 GWh per year. Financial analysis resulted in a LCOE of IDR 5,930/kWh. However, this price is still high compared to the national electricity tariff of IDR 1,027.70/kWh. Variations in the number of turbines also may not result in a lower LCOE than the national tariff. Nevertheless, the estimated cost of generating electricity is still competitive compared to diesel, which is around IDR 5,804/kWh.

Study on the influence of ship waves on the dynamic response of floating tidal current power generation device

To study the influence of ship traveling waves on the hydrodynamic performance between the carrier platform and the turbine, the computational fluid dynamics method and the DFBI motion module of STAR CCM+ software were adopted. Under the condition of the coupling of the ship traveling wave and wave current generated at different speeds, the overall motion response of the power plant is simulated. What’s more, the influence of different wave conditions on the heave, pitch, and roll of the carrier platform and the energy efficiency of the turbine is analyzed. The results show that the ship speed has little effect on the carrier heave motion, but the maximum value of the carrier pitch motion increases with the increase in the ship speed. The value of turbine energy acquisition efficiency always decreases with decreasing lateral spacing and increases with decreasing speed. This paper has a certain reference value for the engineering application of floating tidal current power generation equipment.

Numerical Analysis of Resistance and Motions on Trimaran Floating Platform for Tidal Current Power Plant

Numerical Analysis of Resistance and Motions on Trimaran Floating Platform for Tidal Current Power Plant

Discussion on low-carbon energy supply and scour protection technology for cross-sea bridges combined with tidal current energy

In the context of achieving carbon peak and carbon neutrality, the construction and maintenance of transportation infrastructure should also comply with the requirements of green and low-carbon development. There are many long-span cross-sea bridges in Zhejiang Province, which consume large amounts of electricity for lighting, dehumidification, and anticorrosion, etc., and the energy required usually relies on external energy transfer, which is costly and intermediate losses are high. Tidal current energy, which is the kinetic energy generated during ebb and flood tides, is abundant along the coast of Zhejiang Province, mainly concentrated in Hangzhou Bay and Zhoushan Islands, which is also a dense area of sea-spanning bridges, and the foundation of sea-spanning bridges often suffers from severe scouring to the strong tidal current action. This paper discusses two forms of joint development of tidal current power generators and cross-sea bridges, analyses the advantages and disadvantages as well as the feasibility of each scheme, and gives suggestions for subsequent development.

A novel two-layer nested optimization method for a zero-carbon island integrated energy system, incorporating tidal current power generation

A novel two-layer nested optimization method for a zero-carbon island integrated energy system, incorporating tidal current power generation

Blade optimization for hydrodynamic performance improvement of a horizontal axis tidal current turbine

This paper proposes an innovative methodology applied to blade optimization for hydrodynamic performance improvement of a horizontal axial tidal current turbine (HATCT) considering the effect of Reynolds number. Axial induction factor, tangential induction factor and angle of attack are employed for identifying the accuracy and applicability of modified Blade Element Momentum (BEM) theory. Combined with the XFoil software, the hydrofoil shape function is represented by trigonometric functions through Theodorsen method. The hydrodynamic characteristics of the hydrofoil are employed as the optimization targets, and the particle swarm optimization algorithm is used to optimize the original hydrofoil. Based on the modified BEM theory and the optimized hydrofoil, the tidal current turbine power coefficient at different tip speed ratio (TSR) is optimized according to the MATLAB function. The optimized tidal current turbine shows better performance compared with the original tidal current turbine.

Assessment of Tidal Current Energy Resources in the Pearl River Estuary Using a Numerical Method

In this paper, a numerical method is employed to assess tidal current energy resources in the Pearl River Estuary, China. The numerical model for tidal current simulation in the estuary is developed based on the MIKE 21 model, which enables numerical simulations in estuaries, coastal areas, and oceans. The model has a grid resolution that varies from about 2500 m at the open boundary to 500–1000 m inside the estuary. Extensive model validation is performed by comparing the model predictions with field observations of tidal level and velocity at various stations in the Pearl River Estuary. The tidal characteristics are thoroughly analyzed. Energy fluxes and power densities are calculated along selected cross sections to evaluate the feasibility of tidal energy development in the Pearl River Estuary. The results indicate that the distribution of annual average tidal current power density in the Pearl River Estuary generally aligns with the spatial distribution of tidal currents. The annual average power density of tidal energy is typically below 0.10 kW/m2. The theoretical potential of tidal current energy resources in the Pearl River Estuary is assessed to be approximately 11,000 kW.

Optimal Design of a Submerged Tidal Device for Low Current Environment

The tidal current power is one of the reliable renewable ocean energy resources that can be deployed at the region having ocean current. The feasible current speed for the application of tidal device is known to be more than 2m/s. As there are many islands in Asia where the current speed is below than the feasible speed, the submerged device that can produce the power at lower current speed with easy deployment and retrieve is introduce. To simplify the installation and O&M operations, the 4-point taut mooring system is applied that can also secure the designated position. In this study, a HAT (horizontal axis turbine) of 5-kW submerged tidal device is designed and analyzed for a low current region that consist of two buoyancy tanks, a yaw control strut, and a diffuser-type brimmed duct. To analyze the most stable condition, 9 different cases of width and height of the device and 8 different mooring arrangements (total 72 different cases) are investigated both by frequency and time domains. The results show that the dynamic behavior that mainly affects the turbine performance decreases with lower strut height. However, it was observed that the device width has little effect on the dynamic response of the device. The device dynamic motion decreases with decreasing azimuth angle and increasing hang-off angle of the mooring configuration. The optimal design configuration that can produce the maximum power is found that of 4.42 m width, 2 m height, 30° azimuth angle and 60° hang-off angle. According to API RP 2K code, the mooring system is also designed in both intact and damaged conditions. The proposed tidal device could be applied for the low current speed areas with easy implementation and maintenance.

Design and performance analysis of a passive rotatable deflector diversion tail for tidal current power generation hydrokinetic turbines

In the present study, a deflector that can passively rotate is designed for use on a hydrokinetic turbine that generates power from tidal currents. This deflector is capable of self-adjusting its position with changes in the water flow, so that the hydrokinetic turbine can generate maximum power at both high and low tides. The purpose of this study is to maximize the output power of a hydrokinetic turbine by improving the geometry of the deflector and the diversion tail. The rotation of both the turbine and the deflector are simulated with finite element analysis software. In addition, the accuracy of the simulation results is verified through experimental tests. The improved design of the deflector and the diversion tail is considered in terms of the parameters, including the deflector reduction angle, the gap between the deflector and the turbine, and the height of the diversion tail. The geometrical design of the deflector and the diversion tail is compared to a turbine without the deflector and to another turbine with the original deflector over the entire operating range using CFD simulations. Without the deflector, the maximum power coefficient of the turbine was 0.0979 at a tip-speed ratio of 0.4, whereas the maximum power coefficient of the turbine was 0.306 at a tip speed ratio of 0.57 when using the improved deflector. The results indicate that, after adding the improved deflector, the power coefficient of the turbine was 3.13 times greater compared with the turbine without the deflector and 18% greater compared with the turbine equipped with the original deflector.

A comparison of the power potential for surface- and seabed-deployed tidal turbines in the San Juan Archipelago, Salish Sea, WA

The San Juan archipelago lies along the axis of tidal movement between Straits of Juan de Fuca and Strait of Georgia in the Salish Sea. The amplitude of the tidal exchange produces significant tidal currents between the islands, as well as in Rosario Strait to the east and Haro Strait to the west. These currents are of interest as a future source of electrical power generation, given the archipelago’s dependence on electricity supply by a subsea cable from the United States mainland. Here, we evaluate the tidal current energy potential in this region through a re-analysis of measurements collected by the National Ocean Service (NOS) and a high-resolution numerical model. Given the considerable variations in water depth and vertical velocity profiles across candidate tidal energy sites, we consider the trade-offs between tidal turbines deployed from a floating platform and those anchored to the seabed. Measurement re-analysis indicates several locations that could support tidal current power generation by MW-scale turbines with an acceptable balance between turbine size, rated power, and capacity factor. Even for relatively large (30 m) turbine diameters, surface-deployed turbines would be expected to produce up to 30 % more electricity than the same turbine deployed near the seabed due to vertical shear, with this difference increasing for smaller diameter turbines. As anticipated for sparse measurements, the regional simulation identifies several locations with power generation potential more than twice as high as locations in the measurement re-analysis. These sites were either not surveyed or excluded due to data quality issues. A benchmark comparison at the measurement locations with the highest power generation potential shows relatively good model fidelity, though time-average power density disagreements of ± 50 % persist throughout the water column. In addition to the case study, we also treat three general considerations for measurement data: (1) the accuracy of energy generation estimates from hub height speed relative to rotor-averaged power density, (2) the feasibility of extrapolating profiles towards the surface and seabed, and (3) trends in energy generation with rotor size and position in the water column. Overall, these results demonstrate that models and measurements can be used in a complementary manner for tidal energy site assessment and that tidal currents could be an important source of electricity generation in the San Juan archipelago.

Modeling and simulation of power quality detection for tidal current power generation based on HHT

On the basis of summarizing the characteristics of tidal current power generation and power quality analysis methods at home and abroad, this paper comprehensively analyzes the power quality problems existing in tidal current power generation, and Hilbert–Huang transform (HHT) is finally applied to detect and analyze the issues. Using MATLAB to establish the simulation model, and the analysis algorithm of power quality in frequency domain and time domain is focused. The simulation results of single disturbances and some mixed disturbances show that this method has good adaptability to the non-stationary and multi-disturbance characteristics of tidal power generation.

Analysis and Research of China’s Marine Renewable Energy Standards

China has already had relatively mature marine renewable energy utilization, among which tidal current energy power generation has achieved grid connection, and wave energy power generation has been commercialized. However, in spite of progress in the marine renewable energy utilization, China’s marine renewable energy standard system still needs improvement as there is still no marine energy standards for some subsystems, which can’t provide effective support for the innovation of marine renewable energy and the development of the industry. This paper explains the status quo of marine renewable energy standards both at home and abroad, analyzes China’s current problems in the development of marine energy standards, and offers recommendations for future development.

Simulation and study of maximum power point tracking for rim-driven tidal current energy power generation systems

This paper presents a maximum power point tracking (MPPT) control algorithm based on an intelligent reinforcement learning. The proposed model-free Q-learning algorithm realizes the online learning of the control algorithm of the tidal power generation system by updating the action values stored in the Q-table. By learning the optimal rotor speed-output power curve, the algorithm fits the optimal generator curve and applies the optimal Pe−ωr curve to the optimal control method of the tidal power generation systems.

Performance Evaluation Of Permanent Magnet Synchronous Generator (PMSG) On Tidal Power Generation Optimization

In a tidal current energy generation system, optimization of power generation can be done through turbine design, system design, and control of mechanical transmission from the turbine to the generator, as well as from the aspect of electronic generator output control. This research aims to analyze the performance of the PMSG generator from a prototype of the tidal current energy power plant. Turbine rotation is simulated using an ac motor equipped with an ac drive that supports separate speed and torque control. The hydraulic transmission system consists of a pump and a hydraulic motor that transfers the rotation of the turbine to the generator, where the power output is observed with variations in turbine speed and torque. The results indicate that the transmission system has worked well in transmitting the turbine’s mechanical power and increasing the rotational speed. The decrease in speed with increasing load and low average efficiency (less than 20%) occurs, mainly due to the characteristics of the generator being tested. The generator has a large rated torque requirement of 32 Nm, which is much higher than the main drive capacity of the turbine simulator. The design of a tidal energy conversion system, in which the tidal current speed fluctuates, requires careful selection of the generator, not only from the aspect of power capacity and rated rotational speed, but also from the initial torque value and required rated torque.

Evaluating energy loss with the entropy production theory: A case study of a micro horizontal axis river ducted turbine

Hydrokineticpoweras acleanrenewableenergy has been aroused awidespread concern. Horizontal axis turbines are widely used in the field of tidal and river current energy power generation, but their internal flow loss characteristics have not been fully revealed. In this paper, a micro horizontal axis river ducted turbine is taken as the research object, and the flow loss characteristics of the turbine under different yaw angles and tip clearances are analyzed by numerical simulation method combined with entropy production theory. A detailed entropy production analysis shows that most of the energy losses take place near the blade tip, at the outlet of the duct, and in the downstream wake region. The turbulent dissipation is the main cause of entropy generation in the ducted turbine. Results demonstrated that with the increase of the yaw angle, the power coefficient Cp increases first, and then reduces. The Cp is up to maximum at θ = 10°. When θ = 25°, the maximum value of Cp decreased by 24.8%, compared with θ = 10°. It is also suggested that there is no obvious negative effect to shaft work and power coefficient for ducted turbine under certain yaw environment (θ ≤ 10°) and the optimal tip clearance should be between 0.02D and 0.04D.

A decision framework for tidal current power plant site selection based on GIS-MCDM: A case study in China

To reach carbon neutrality, renewable energy development will gradually accelerate. Tidal current energy, with high energy density, long-term predictability and potentially large reserves, is an important research direction. As the prerequisite for tidal current energy development, Tidal Current Power Plant Site Selection (TCPPSS) affects its future benefits. Although some studies have been conducted on TCPPSS, further work is still needed on criteria system, research scales and methods. In this paper, a three-stage decision framework is proposed based on Geographic Information System (GIS) and Multi-Criteria Decision Making (MCDM) to determine potential marine areas, extract and evaluate site alternatives. In this framework, a scientific criteria system with exclusion and evaluation criteria is established. To reduce subjective deviations in Analytic Hierarchy Process (AHP), a combinative weighting method based on Fuzzy Group decision making AHP (FGAHP) and CRiteria Importance Through Intercriteria Correlation (CRITIC) is developed to calculate the criteria weights. Considering the maximum group utility and minimum individual regret, VlseKriterijumska Optimizacija I Kompromisno Resenje (VIKOR), a compromise method, is used to rank the alternatives. The proposed framework is applied to a case of Shandong Province, Eastern China. The results are verified through sensitivity analysis and can provide a direct reference for decision-makers.

Tidal current prediction based on a hybrid machine learning method

Accurate and reliable tidal current forecasting plays a key role in application of grid-connected tidal current power generation systems. Hence, a novel tidal current prediction method based on a hybrid machine learning method is proposed in this paper. Compared with previous tidal current prediction method, the proposed tidal current prediction method considers the influence of turbulence on multi-layer tidal velocity difference. A hybrid machine learning method based on hierarchical extreme learning machine(H-ELM) and long short-term memory (LSTM) is adopted to reduce effect of the turbulent flow, which enables to increase the accuracy of the prediction result. The tidal data that collected by using acoustic doppler current profiler (ADCP) in Zhejiang province China is used to validate the effectiveness of the proposed method. The results of the case study show that the proposed method has higher accuracy than results from standard harmonic analysis using UTide (a freely available academic research product).

Double Armature HTS Bulk Synchronous Machine for Contra-Rotating Turbine Generator

Many high-temperature superconducting (HTS) rotors of the radial flux type mainly use the magnetic field from single sided surface of the field pole. However, field poles using HTS bulk have the advantage of capturing high magnetic fields on both sides of the field poles, which can be effectively used to generate electricity. Therefore, we have developed a double armature structure in which a field stator is sandwiched between both the inner and outer armature rotors of the HTS synchronous generator. Due to the high magnetic field captured by the HTS bulk, it is also possible to directly join a counter-rotating turbine. In this paper, we designed the developed model and performed electromagnetic field analysis. The analytical speed was calculated at a low speed depending on the design of the 500kW reverse rotation turbine. Using the HTS bulk as the boundary pole, the torque consistency with the input mechanical torque of the turbine was confirmed, and it was obtained from the compatibility analysis with the 500kW class tidal current power generation. We also analyzed the model with the smallest torque ripple from multiple models with different HTS bulk placements and found the model with the best placement.