Emeel Kerikous, Doddamani Hithaish, Abdus Samad, S. Hoerner, Dominique Thévenin
The oscillating water column (OWC) is an extensively studied wave energy converter that produces pneumatic power from the motion of the sea waves, which can be harvested using a pair of turbines without additional devices. However, its efficiency is hampered by poor flow blockage. Researchers have proposed a fluidic diode (FD) to improve flow blockage. Its performance is given by diodicity, which is the ratio of pressure drop in reverse to forward flow. A higher resistance in the reverse path signifies enhanced flow blockage, while a lower resistance in the forward flow minimises power loss at the turbine entry. In the present study, the numerical investigation was performed by solving three-dimensional unsteady Reynolds-Averaged Navier Stokes equations using ANSYS-Fluent 16.1 to simulate the flow behaviour inside the FD. Five geometrical parameters for FD were varied to obtain its optimal shape leading to a lower pressure drop in the forward direction and higher in reverse. The optimal shape was obtained through the genetic algorithm, showing a 12% improvement in performance compared to the base model. Detailed fluid flow and performance analysis of both base and optimum models are presented in this article.
振荡水柱(OWC)是一种被广泛研究的波浪能转换器，它从海浪的运动中产生气动动力，可以使用一对涡轮机收集，而不需要额外的设备。然而，其效率受到流动阻塞不良的影响。研究人员提出了一种流体二极管(FD)来改善流动阻塞。它的性能是用逆压降与正流压降之比来表示的。较高的阻力在反向路径表示增强流动阻塞，而较低的阻力在正向流动最小化功率损失在涡轮入口。本文采用ANSYS-Fluent 16.1软件对三维非定常reynolds - average Navier - Stokes方程进行数值模拟，模拟FD内部的流动特性。通过改变FD的5个几何参数，得到FD的最佳形状，使其正向压降较低，反向压降较高。通过遗传算法获得最优形状，与基本模型相比，性能提高了12%。本文对基本模型和优化模型进行了详细的流体流动和性能分析。
{"title":"Performance Enhancement of Fluidic Diode for a Wave Energy System through Genetic Algorithm","authors":"Emeel Kerikous, Doddamani Hithaish, Abdus Samad, S. Hoerner, Dominique Thévenin","doi":"10.36688/ewtec-2023-182","DOIUrl":"https://doi.org/10.36688/ewtec-2023-182","url":null,"abstract":"The oscillating water column (OWC) is an extensively studied wave energy converter that produces pneumatic power from the motion of the sea waves, which can be harvested using a pair of turbines without additional devices. However, its efficiency is hampered by poor flow blockage. Researchers have proposed a fluidic diode (FD) to improve flow blockage. Its performance is given by diodicity, which is the ratio of pressure drop in reverse to forward flow. A higher resistance in the reverse path signifies enhanced flow blockage, while a lower resistance in the forward flow minimises power loss at the turbine entry. In the present study, the numerical investigation was performed by solving three-dimensional unsteady Reynolds-Averaged Navier Stokes equations using ANSYS-Fluent 16.1 to simulate the flow behaviour inside the FD. Five geometrical parameters for FD were varied to obtain its optimal shape leading to a lower pressure drop in the forward direction and higher in reverse. The optimal shape was obtained through the genetic algorithm, showing a 12% improvement in performance compared to the base model. Detailed fluid flow and performance analysis of both base and optimum models are presented in this article.","PeriodicalId":201789,"journal":{"name":"Proceedings of the European Wave and Tidal Energy Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115855833","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Today, humanity is facing the great pressure of fossil fuels exhaustion and environmental pollution. This obliges governments and industries to make accelerated efforts on producing green energy. The focus is spotted on marine environment which is a vast source of renewable energy. Among several classes of designs proposed for wave energy conversion, spherical Wave EnergyConverters (WECs) have received considerable attention. The problems of water wave diffraction and radiation by a sphere has been examined by a substantial amount of literature, i.e., [1]–[4], whereas in [5]–[8] linear hydrodynamic effects on a spherical WEC have been examined. All these research works are based on potential flow methodologies. Nevertheless, overthe last decade there has been a significant interest on Computational Fluid Dynamics CFD modelling due to its detailed results, focusing also to spherical WECs [9]–[10].In the present work a semi-analytical model is applied to solve the wave radiation problem around a spherical WEC (Figure 1), in the context of linear potential theory. The outcomes of the theoretical analysis are supplemented and compared with high fidelity CFD simulations (Figure 2 for a semi-submerged sphere). Furthermore, the two methodologies are compared with a theoretical approach for the hydrodynamic analysis of floating bodies with vertical axis as being presented in [11]. The method is based on the discretization of the flow field around the body using coaxial ring elements, which are generated from the approximation of the sphere’s meridian line by a stepped curve.Numerical results are given from the comparison of the three formulations, and some interesting phenomena are discussed concerning the viscous effects on the floater. [1] Havelock, T. H. 1955. Wave due to a floating sphere making periodic heaving oscillations. R. Soc. London,A231, 1-7.[2] Hulme, A. 1982. The wave forces acting on a floating hemisphere undergoing force periodic oscillation. J. FluidMech., 121, 443-463.[3] Wang, S. 1986. Motions of a spherical submarine in waves. Ocean Engng., 13, 249-271.[4] Wu, G.X. 1995. The interaction of water waves with a group of submerged spheres. Appl. Ocean. Res., 17, 165-184.[5] Srokosz, M.A. 1979. The submerged sphere as an absorber of wave power. J. Fluid Mech., 95, 717-741.[6] Thomas, G.P., Evans, D.V. 1981. Arrays of three-dimensional wave energy absorbers. J. Fluid Mech., 108, 67-88.[7] Linton, C.M. 1991. Radiation and diffraction of water waves by a submerged sphere in finite depth. Ocean Engng.,18, 61-74.[8] Meng, F., et al. Modal analysis of a submerged spherical point absorber with asymmetric mass distribution.Renew. Energy 130, 223-237.[9] Shami, E.A., et al. 2021. Non-linear dynamic simulations of two-body wave energy converters via identificationof viscous drag coefficients of different shapes of the submerged body based on numerical wave tank CFD simulation.Renew. Energy, 179, 983-997.[10] Katsidoniotaki, E., et al. 2023. Valida
{"title":"Semi-analytical and CFD formulations of a spherical floater","authors":"Spyridon Mavrakos, Spyridon Zafeiris, Georgios Papadakis, Dimitrios Konispoliatis","doi":"10.36688/ewtec-2023-198","DOIUrl":"https://doi.org/10.36688/ewtec-2023-198","url":null,"abstract":"Today, humanity is facing the great pressure of fossil fuels exhaustion and environmental pollution. This obliges governments and industries to make accelerated efforts on producing green energy. The focus is spotted on marine environment which is a vast source of renewable energy. Among several classes of designs proposed for wave energy conversion, spherical Wave EnergyConverters (WECs) have received considerable attention. The problems of water wave diffraction and radiation by a sphere has been examined by a substantial amount of literature, i.e., [1]–[4], whereas in [5]–[8] linear hydrodynamic effects on a spherical WEC have been examined. All these research works are based on potential flow methodologies. Nevertheless, overthe last decade there has been a significant interest on Computational Fluid Dynamics CFD modelling due to its detailed results, focusing also to spherical WECs [9]–[10].In the present work a semi-analytical model is applied to solve the wave radiation problem around a spherical WEC (Figure 1), in the context of linear potential theory. The outcomes of the theoretical analysis are supplemented and compared with high fidelity CFD simulations (Figure 2 for a semi-submerged sphere). Furthermore, the two methodologies are compared with a theoretical approach for the hydrodynamic analysis of floating bodies with vertical axis as being presented in [11]. The method is based on the discretization of the flow field around the body using coaxial ring elements, which are generated from the approximation of the sphere’s meridian line by a stepped curve.Numerical results are given from the comparison of the three formulations, and some interesting phenomena are discussed concerning the viscous effects on the floater. \u0000[1] Havelock, T. H. 1955. Wave due to a floating sphere making periodic heaving oscillations. R. Soc. London,A231, 1-7.[2] Hulme, A. 1982. The wave forces acting on a floating hemisphere undergoing force periodic oscillation. J. FluidMech., 121, 443-463.[3] Wang, S. 1986. Motions of a spherical submarine in waves. Ocean Engng., 13, 249-271.[4] Wu, G.X. 1995. The interaction of water waves with a group of submerged spheres. Appl. Ocean. Res., 17, 165-184.[5] Srokosz, M.A. 1979. The submerged sphere as an absorber of wave power. J. Fluid Mech., 95, 717-741.[6] Thomas, G.P., Evans, D.V. 1981. Arrays of three-dimensional wave energy absorbers. J. Fluid Mech., 108, 67-88.[7] Linton, C.M. 1991. Radiation and diffraction of water waves by a submerged sphere in finite depth. Ocean Engng.,18, 61-74.[8] Meng, F., et al. Modal analysis of a submerged spherical point absorber with asymmetric mass distribution.Renew. Energy 130, 223-237.[9] Shami, E.A., et al. 2021. Non-linear dynamic simulations of two-body wave energy converters via identificationof viscous drag coefficients of different shapes of the submerged body based on numerical wave tank CFD simulation.Renew. Energy, 179, 983-997.[10] Katsidoniotaki, E., et al. 2023. Valida","PeriodicalId":201789,"journal":{"name":"Proceedings of the European Wave and Tidal Energy Conference","volume":"97 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115906665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yu Gao, Chenyu Zhao, Lars Johanning, Ajit C Pillai
Floating Offshore Wind Turbines (FOWT) can exploit the high energy density found in the offshore environment, with turbines now reaching up to 15 MW in size. At the same time, however, the energetic environment and the massive size of the device present significant challenges in the motion stabilization and mooring system. To overcome these challenges, a tuned mass damper (TMD) has been considered for integration in the FOWT for peak motion reduction. This paper investigates the baseline responses including motion, dynamic response, and tensile loading of the mooring line for a 15MW FOWT on a semi-submersible platform without TMD to identify the damageable motion and the impacts of the TMD on the motion response under wave-wind environmental loadings. The comprehensive analysis is conducted in a package for the dynamic analysis of offshore marine systems, named as Orcaflex. The dynamic and motion characteristics of the 15MW FOWT are analysed and compared under different environmental parameters. The wave and wind parameters are quantified by the 20-years statistical data of the Celtic Sea including both operational and extreme conditions (with a 50-year return period). Subsequently, the key parameters of TMD are investigated by configuring different combinations of mass, damping coefficients and stiffnesses. The preliminary results of the study show that the TMD system can successfully mitigate extreme motion characteristics, however this is strongly dependent on damping properties. Unsuitable TMD designs may increase the motion responses of FOWT and the tensile loading on the mooring line. Therefore, the TMD properties have to be adjusted based onsite environmental conditions). With this consideration, an active TMD with changeable damping properties will be conducted in future research.
{"title":"Hydrodynamic studies of a 15 MW semi-submersible FOWT to assess the suitability of the inclusion of a damper system","authors":"Yu Gao, Chenyu Zhao, Lars Johanning, Ajit C Pillai","doi":"10.36688/ewtec-2023-497","DOIUrl":"https://doi.org/10.36688/ewtec-2023-497","url":null,"abstract":"Floating Offshore Wind Turbines (FOWT) can exploit the high energy density found in the offshore environment, with turbines now reaching up to 15 MW in size. At the same time, however, the energetic environment and the massive size of the device present significant challenges in the motion stabilization and mooring system. To overcome these challenges, a tuned mass damper (TMD) has been considered for integration in the FOWT for peak motion reduction. This paper investigates the baseline responses including motion, dynamic response, and tensile loading of the mooring line for a 15MW FOWT on a semi-submersible platform without TMD to identify the damageable motion and the impacts of the TMD on the motion response under wave-wind environmental loadings. The comprehensive analysis is conducted in a package for the dynamic analysis of offshore marine systems, named as Orcaflex. The dynamic and motion characteristics of the 15MW FOWT are analysed and compared under different environmental parameters. The wave and wind parameters are quantified by the 20-years statistical data of the Celtic Sea including both operational and extreme conditions (with a 50-year return period).\u0000Subsequently, the key parameters of TMD are investigated by configuring different combinations of mass, damping coefficients and stiffnesses. The preliminary results of the study show that the TMD system can successfully mitigate extreme motion characteristics, however this is strongly dependent on damping properties. Unsuitable TMD designs may increase the motion responses of FOWT and the tensile loading on the mooring line. Therefore, the TMD properties have to be adjusted based onsite environmental conditions). With this consideration, an active TMD with changeable damping properties will be conducted in future research.","PeriodicalId":201789,"journal":{"name":"Proceedings of the European Wave and Tidal Energy Conference","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116361550","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A submerged transmission, fitted with a dynamic sealing system, in a wave energy converter (WEC) serves the purpose of transmitting the force, absorbed by a wave activated body, to an encapsulated power take-off (PTO) system, while preventing seawater from entering the capsule. Dry generator operation is generally a prerequisite for attaining long technical service life. Little attention seems to be devoted in publications to the study of dynamic sealing systems in WECs, and to test rigs for experimental verification and/or evaluation of the ability/performance of existing dynamic sealing systems in a controlled laboratory environment. This paper begins by presenting some of our earlier research within the focus area of dynamic sealing systems, incl. design considerations and typical operating conditions. This part also presents the 1st laboratory test rig, used for verifying the sealing ability of the piston rod mechanical lead-through design in the 1st and 2nd full-scale experimental WEC prototype from Uppsala University. In 2021 project DynSSWE (Dynamic Sealing Systems for Wave Energy) was initiated. Drawing from experience, the project includes development of a new test rig, representing a tool for further development of dynamic sealing systems. This paper introduces steps in the design and development process of that new test rig, enabling accelerated long-term test runs with a setup of multiple piston rod specimens. The test specimens’ will be surface treated differently with the aim of improving the prospects of a long maintenance free service life. Since the new test rig is in the design stage, seal testing results are not yet reported. The presented work is funded by the Swedish energy agency with the aim of improving subsystem performance in wave energy devices.
{"title":"Test rig for submerged transmissions in wave energy converters as a development tool for dynamic sealing systems","authors":"Anthon Jonsson, E. Strömstedt","doi":"10.36688/ewtec-2023-576","DOIUrl":"https://doi.org/10.36688/ewtec-2023-576","url":null,"abstract":"A submerged transmission, fitted with a dynamic sealing system, in a wave energy converter (WEC) serves the purpose of transmitting the force, absorbed by a wave activated body, to an encapsulated power take-off (PTO) system, while preventing seawater from entering the capsule. Dry generator operation is generally a prerequisite for attaining long technical service life. Little attention seems to be devoted in publications to the study of dynamic sealing systems in WECs, and to test rigs for experimental verification and/or evaluation of the ability/performance of existing dynamic sealing systems in a controlled laboratory environment. This paper begins by presenting some of our earlier research within the focus area of dynamic sealing systems, incl. design considerations and typical operating conditions. This part also presents the 1st laboratory test rig, used for verifying the sealing ability of the piston rod mechanical lead-through design in the 1st and 2nd full-scale experimental WEC prototype from Uppsala University. In 2021 project DynSSWE (Dynamic Sealing Systems for Wave Energy) was initiated. Drawing from experience, the project includes development of a new test rig, representing a tool for further development of dynamic sealing systems. This paper introduces steps in the design and development process of that new test rig, enabling accelerated long-term test runs with a setup of multiple piston rod specimens. The test specimens’ will be surface treated differently with the aim of improving the prospects of a long maintenance free service life. Since the new test rig is in the design stage, seal testing results are not yet reported. The presented work is funded by the Swedish energy agency with the aim of improving subsystem performance in wave energy devices.","PeriodicalId":201789,"journal":{"name":"Proceedings of the European Wave and Tidal Energy Conference","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117088679","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Wave energy is a rich and highly accessible renewable energy resource, that has largely been under-developed. Studies from the sector have tried to show the potential of benefits wave energy in “simple cases” or via small hybrid systems, the large scale incorporation of wave energy has not yet been fully investigated. Our approach uses a fully dynamic climate driven energy system model, which has undergone modifications to include wave energy converters and their associated dependencies. This study explores the system dynamics and important elements that will be used for large scale wave energy integration; in a fully coupled European Energy System. We explore the cost pathways of different wave energy converters, the impact of climate data, and the impact of transmission capacity expansion under cost-optimal configurations of a multi-renewable European power system. From this preliminary approach we aim to provide the boundary conditions, and assumptions that will govern the integration of wave energy into the European Energy System up to 2050.
{"title":"Integration of wave energy into Energy Systems: an insight to the system dynamics and ways forward","authors":"G. Lavidas, Felix Delgado Elizundia, K. Blok","doi":"10.36688/ewtec-2023-157","DOIUrl":"https://doi.org/10.36688/ewtec-2023-157","url":null,"abstract":"Wave energy is a rich and highly accessible renewable energy resource, that has largely been under-developed. Studies from the sector have tried to show the potential of benefits wave energy in “simple cases” or via small hybrid systems, the large scale incorporation of wave energy has not yet been fully investigated. Our approach uses a fully dynamic climate driven energy system model, which has undergone modifications to include wave energy converters and their associated dependencies. \u0000This study explores the system dynamics and important elements that will be used for large scale wave energy integration; in a fully coupled European Energy System. We explore the cost pathways of different wave energy converters, the impact of climate data, and the impact of transmission capacity expansion under cost-optimal configurations of a multi-renewable European power system. From this preliminary approach we aim to provide the boundary conditions, and assumptions that will govern the integration of wave energy into the European Energy System up to 2050.","PeriodicalId":201789,"journal":{"name":"Proceedings of the European Wave and Tidal Energy Conference","volume":"98 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114508653","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jingyi Yang, Zhong You, Shanshan Cheng, Xinu Wang, Krishnendu Puzhukkil, Malcolm Cox, Rod Rainey, John Chaplin, Deborah Greaves
The Clam wave energy converter (WEC) is a floating device composed of two side plates connected by a hinge that closes and opens under interaction with wave crests and troughs. A linear power take-off (PTO) may be installed between the two side plates to convert the mechanical motions to electricity, or the volume change may be used to pump air between chambers and across an air turbine PTO. The basic concept has been discussed since 1978 and featured as part of the UK Wave Energy research programme [1]. Some simplified clam models have been built since then and preliminary investigations were conducted by Phillips [2] to understand the wave-structure interactions at the COAST laboratory, University of Plymouth. However, the simplified models were not enclosed and hence seawater can be trapped in the device. To further the investigation, we will design the outer shell of the clam model that is enclosed and thus suitable for use in the (adverse) marine environment. Since no enclosed flexible polyhedral structure can change its volume without bending or stretching of facets according to the bellows conjecture, the clam model must be strained when it is in motion. A portion of the wave energy will be consumed to deform the outer shell of the clam model and the rest can be captured by the PTO. Therefore, the design of the clam model will aim at minimising the strain on its facets while achieving the largest volumetric change of the device to maximise the power extraction by the PTO. Inspired by origami, we will construct the enclosed clam-type offshore device by connecting rigid panels and elastic membranes with rotational hinges. We model the rigid panels to rotate about the hinges without facet deformation and allow stretching on elastic membranes. The strain on the elastic material shall be minimised for better structural integrity and minimal energy loss. Satisfying all the design requirements, the best geometric design is obtained through an optimisation process. Based on the optimised geometry, a downscaled prototype will be built using rigid plywood and rubber membranes and tested under dynamic wave-induced loads to prove that the strain incurred is negligible in response to forces. References: [1] Peatfield, A. M., Duckers, L. J., Lockftt, F. P., Loughridge, B. W., West, M. J., & White, P. R. S. (1984). The SEA-Clam wave energy converter. In Energy Developments: New Forms, Renewables, Conservation (pp. 137-142). Pergamon. [2] Phillips, J. W. (2017). Mathematical and Physical Modelling of a Floating Clam-type Wave Energy Converter (Doctoral dissertation, University of Plymouth).
Clam波浪能转换器(Clam wave energy converter, WEC)是由两个侧板组成的浮动装置，通过铰链连接，在波峰和波谷的相互作用下关闭和打开。线性动力输出(PTO)可以安装在两个侧板之间，以将机械运动转换为电力，或者体积变化可以用于在室之间和穿过空气涡轮PTO泵送空气。自1978年以来，基本概念一直在讨论，并作为英国波浪能源研究计划[1]的一部分。从那时起，一些简化的蛤蜊模型已经建立，普利茅斯大学海岸实验室的Phillips b[2]进行了初步调查，以了解波浪-结构相互作用。然而，简化模型没有封闭，因此海水可能被困在装置中。为了进一步调查，我们将设计封闭的蛤蜊模型外壳，从而适合在(不利的)海洋环境中使用。由于根据波纹管猜想，任何封闭的柔性多面体结构都不能在不弯曲或不拉伸表面的情况下改变其体积，因此蛤模型在运动时必须受到应变。波浪能量的一部分将被消耗来变形蛤模型的外壳，其余的可以被PTO捕获。因此，蛤蜊模型的设计将旨在最大限度地减少其侧面的应变，同时实现设备的最大体积变化，以最大限度地提高PTO的功率提取。受折纸的启发，我们将通过旋转铰链连接刚性面板和弹性膜来构建封闭的蛤蜊式海上装置。我们对刚性面板进行建模，使其围绕铰链旋转而不产生关节面变形，并允许在弹性膜上拉伸。弹性材料上的应变应最小化，以获得更好的结构完整性和最小的能量损失。在满足所有设计要求的情况下，通过优化过程获得最佳的几何设计。基于优化的几何形状，将使用刚性胶合板和橡胶膜建造一个缩小尺寸的原型，并在动态波浪诱导载荷下进行测试，以证明所产生的应变在力的响应中可以忽略不计。参考文献:[1]Peatfield, A. M.， Duckers, L. J.， Lockftt, F. P.， Loughridge, B. W.， West, M. J, and White, P. R. S.(1984)。SEA-Clam波浪能量转换器。能源发展:新形式，可再生能源，保护(第137-142页)。帕加马。J. W.菲利普斯(2017)。浮蛤式波浪能量转换器的数学与物理建模(博士论文，英国普利茅斯大学)。
{"title":"Origami-adapted clam design for wave energy conversion","authors":"Jingyi Yang, Zhong You, Shanshan Cheng, Xinu Wang, Krishnendu Puzhukkil, Malcolm Cox, Rod Rainey, John Chaplin, Deborah Greaves","doi":"10.36688/ewtec-2023-329","DOIUrl":"https://doi.org/10.36688/ewtec-2023-329","url":null,"abstract":"The Clam wave energy converter (WEC) is a floating device composed of two side plates connected by a hinge that closes and opens under interaction with wave crests and troughs. A linear power take-off (PTO) may be installed between the two side plates to convert the mechanical motions to electricity, or the volume change may be used to pump air between chambers and across an air turbine PTO. The basic concept has been discussed since 1978 and featured as part of the UK Wave Energy research programme [1]. Some simplified clam models have been built since then and preliminary investigations were conducted by Phillips [2] to understand the wave-structure interactions at the COAST laboratory, University of Plymouth. However, the simplified models were not enclosed and hence seawater can be trapped in the device. To further the investigation, we will design the outer shell of the clam model that is enclosed and thus suitable for use in the (adverse) marine environment. \u0000Since no enclosed flexible polyhedral structure can change its volume without bending or stretching of facets according to the bellows conjecture, the clam model must be strained when it is in motion. A portion of the wave energy will be consumed to deform the outer shell of the clam model and the rest can be captured by the PTO. Therefore, the design of the clam model will aim at minimising the strain on its facets while achieving the largest volumetric change of the device to maximise the power extraction by the PTO. \u0000Inspired by origami, we will construct the enclosed clam-type offshore device by connecting rigid panels and elastic membranes with rotational hinges. We model the rigid panels to rotate about the hinges without facet deformation and allow stretching on elastic membranes. The strain on the elastic material shall be minimised for better structural integrity and minimal energy loss. Satisfying all the design requirements, the best geometric design is obtained through an optimisation process. Based on the optimised geometry, a downscaled prototype will be built using rigid plywood and rubber membranes and tested under dynamic wave-induced loads to prove that the strain incurred is negligible in response to forces. \u0000 \u0000References: \u0000[1] Peatfield, A. M., Duckers, L. J., Lockftt, F. P., Loughridge, B. W., West, M. J., & White, P. R. S. (1984). The SEA-Clam wave energy converter. In Energy Developments: New Forms, Renewables, Conservation (pp. 137-142). Pergamon. \u0000[2] Phillips, J. W. (2017). Mathematical and Physical Modelling of a Floating Clam-type Wave Energy Converter (Doctoral dissertation, University of Plymouth).","PeriodicalId":201789,"journal":{"name":"Proceedings of the European Wave and Tidal Energy Conference","volume":"94 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116240532","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
James McVey, John Zaengle, Robert Cavagnaro, Michelle Fenn, Brittnee Lommers, Chris Rumple
Cross-flow tidal turbines are an attractive option for powering remote or off-grid applications because of their simplicity as compared to axial-flow turbines. For instance, when oriented vertically, they harvest power from any current direction with a single degree of freedom and no yaw mechanism. Additive manufacturing (AM) offers an opportunity to print parts out of a wide variety of materials that can result in components that are lighter, stronger and/or less expensive to produce than with traditional manufacturing techniques. When coupled with cross-flow turbine rotors, which require critical features (blade-strut, strut-shaft connections) to be both structurally stiff and hydrodynamically shaped, which can be challenging for typical fabrication processes, AM offers the ability to do both well. This paper describes work on the feasibility of using advanced AM techniques to fabricate small cross-flow turbine rotors for applications at sea and near remote coastal communities. AM materials were categorized into 3 classes – plastics, metals, and ceramics – and reviewed for suitability based on a set of engineering requirements and criteria related to turbine characteristics, material properties, and AM process capabilities. Two plastics and two metals were selected to undergo further testing: Essentium CF25, CarbonX Ult 9085, Titanium Ti-6Al-4V, and Inconel 718. Testing is conducted in three phases: the first is a long-term, 5-month submersion test in the seawater tanks at PNNL-Sequim to study corrosion, water uptake, and biofouling potential; in the second, materials are tensile tested on a load frame to find their failure parameters to compare to material standards; the third test is a fatigue test consisting of cyclically loading test parts with a known force on the order of that exerted on rotor blades in a 1.5 m/s current flow. These tests are designed to discern the suitability of AM materials since their properties from 3D printing processes are known to vary from published parameters. The test samples undergoing submersion testing will be tension tested and compared to control samples not subjected to extended seawater immersion. For fatigue life testing, a small rotor is expected to complete 100 million cycles over the course of a year-long lifespan, but for the case herein is restricted to 1 million for a preliminary performance evaluation. The first 10k cycles are run on an MTS 312.21 load frame at a rate of 0.2 Hz, with the remaining on a custom-built cyclic-deflection test rig at 0.8 Hz.
{"title":"Critical Feature and Seawater Testing of Cross-Flow Rotor Components Fabricated with Additive Manufacturing","authors":"James McVey, John Zaengle, Robert Cavagnaro, Michelle Fenn, Brittnee Lommers, Chris Rumple","doi":"10.36688/ewtec-2023-222","DOIUrl":"https://doi.org/10.36688/ewtec-2023-222","url":null,"abstract":"Cross-flow tidal turbines are an attractive option for powering remote or off-grid applications because of their simplicity as compared to axial-flow turbines. For instance, when oriented vertically, they harvest power from any current direction with a single degree of freedom and no yaw mechanism. Additive manufacturing (AM) offers an opportunity to print parts out of a wide variety of materials that can result in components that are lighter, stronger and/or less expensive to produce than with traditional manufacturing techniques. When coupled with cross-flow turbine rotors, which require critical features (blade-strut, strut-shaft connections) to be both structurally stiff and hydrodynamically shaped, which can be challenging for typical fabrication processes, AM offers the ability to do both well. This paper describes work on the feasibility of using advanced AM techniques to fabricate small cross-flow turbine rotors for applications at sea and near remote coastal communities. \u0000AM materials were categorized into 3 classes – plastics, metals, and ceramics – and reviewed for suitability based on a set of engineering requirements and criteria related to turbine characteristics, material properties, and AM process capabilities. Two plastics and two metals were selected to undergo further testing: Essentium CF25, CarbonX Ult 9085, Titanium Ti-6Al-4V, and Inconel 718. Testing is conducted in three phases: the first is a long-term, 5-month submersion test in the seawater tanks at PNNL-Sequim to study corrosion, water uptake, and biofouling potential; in the second, materials are tensile tested on a load frame to find their failure parameters to compare to material standards; the third test is a fatigue test consisting of cyclically loading test parts with a known force on the order of that exerted on rotor blades in a 1.5 m/s current flow. These tests are designed to discern the suitability of AM materials since their properties from 3D printing processes are known to vary from published parameters. The test samples undergoing submersion testing will be tension tested and compared to control samples not subjected to extended seawater immersion. For fatigue life testing, a small rotor is expected to complete 100 million cycles over the course of a year-long lifespan, but for the case herein is restricted to 1 million for a preliminary performance evaluation. The first 10k cycles are run on an MTS 312.21 load frame at a rate of 0.2 Hz, with the remaining on a custom-built cyclic-deflection test rig at 0.8 Hz.","PeriodicalId":201789,"journal":{"name":"Proceedings of the European Wave and Tidal Energy Conference","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116242723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Payam Aboutalebi, A. Garrido, I. Garrido, Dong Trong Nguyen, Zhen Gao
Marine structures like Floating Wind Turbine (FWT) is exposed to the oncoming waves and wind that can cause oscillatory motions within the system. These undesired oscillations can have negative impacts on the efficiency of the system, reduce its lifespan, hinder energy extraction, increase stress levels, and raise maintenance costs. To mitigate these negative impacts, the integration of Wave Energy Converters (WECs) into the FWT system has been proposed. This hybrid system may be capable of extracting coupled wind-wave energy and transferring electrical power to the shared grid. This paper presents an investigation of the use of Oscillating Water Columns (OWCs), a type of WECs, within a FWT system. The purpose of using an OWC to increase the hydrodynamic damping and reduce the resonant motions of the floating wind turbines under environmental loads, including both wind and wave loads. This is because the wave energy from OWC would be very small as compared to the wind energy. However, OWCs can provide a damping source for reducing the resonant motions of the floater, especially the pitch resonant motions. This would be very beneficial for the power performance of the floating wind turbine and the structural design of the floater. The purpose of this paper is to redesign the original FWT platform to accommodate the additional OWCs by considering the hydrostatic stability and hydrodynamics since the new elements, the OWCs, can significantly change the response of the platform. The redesign of the original FWT involves the integration of OWCs within two out of three columns of an existing semisubmersible platform for a 12 MW FWT. To do this, two moonpools, which are consistent with OWC air chambers, have been created within two columns of the FWT. The water ballast was designed for the columns with and without OWCs. After that the redesign is done hydrostatic stability and hydrodynamics analyses are evaluated. The hydrodynamics properties are discussed in terms of the hybrid platform response as compared to the original platform. The hybrid platform was modeled using GeniE and the hydrostatic stability and hydrodynamics of the system was evaluated by HydroD, tools developed and marketed by DNV. The results of this study demonstrate the potential benefits of integrating OWCs within a FWT system in terms of reducing the platform oscillatory motion.
{"title":"Hydrodynamic and Static Stability Analysis of a Hybrid Offshore Wind-Wave Energy Generation","authors":"Payam Aboutalebi, A. Garrido, I. Garrido, Dong Trong Nguyen, Zhen Gao","doi":"10.36688/ewtec-2023-628","DOIUrl":"https://doi.org/10.36688/ewtec-2023-628","url":null,"abstract":"Marine structures like Floating Wind Turbine (FWT) is exposed to the oncoming waves and wind that can cause oscillatory motions within the system. These undesired oscillations can have negative impacts on the efficiency of the system, reduce its lifespan, hinder energy extraction, increase stress levels, and raise maintenance costs. To mitigate these negative impacts, the integration of Wave Energy Converters (WECs) into the FWT system has been proposed. This hybrid system may be capable of extracting coupled wind-wave energy and transferring electrical power to the shared grid. This paper presents an investigation of the use of Oscillating Water Columns (OWCs), a type of WECs, within a FWT system. The purpose of using an OWC to increase the hydrodynamic damping and reduce the resonant motions of the floating wind turbines under environmental loads, including both wind and wave loads. This is because the wave energy from OWC would be very small as compared to the wind energy. However, OWCs can provide a damping source for reducing the resonant motions of the floater, especially the pitch resonant motions. This would be very beneficial for the power performance of the floating wind turbine and the structural design of the floater. The purpose of this paper is to redesign the original FWT platform to accommodate the additional OWCs by considering the hydrostatic stability and hydrodynamics since the new elements, the OWCs, can significantly change the response of the platform. The redesign of the original FWT involves the integration of OWCs within two out of three columns of an existing semisubmersible platform for a 12 MW FWT. To do this, two moonpools, which are consistent with OWC air chambers, have been created within two columns of the FWT. The water ballast was designed for the columns with and without OWCs. After that the redesign is done hydrostatic stability and hydrodynamics analyses are evaluated. The hydrodynamics properties are discussed in terms of the hybrid platform response as compared to the original platform. The hybrid platform was modeled using GeniE and the hydrostatic stability and hydrodynamics of the system was evaluated by HydroD, tools developed and marketed by DNV. The results of this study demonstrate the potential benefits of integrating OWCs within a FWT system in terms of reducing the platform oscillatory motion. \u0000 ","PeriodicalId":201789,"journal":{"name":"Proceedings of the European Wave and Tidal Energy Conference","volume":"60 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114090870","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Modeling oscillating surge wave energy converter (OSWEC) systems to accurately predict their behavior has been a notoriously difficult challenge for the wave energy field. This is particularly challenging in realistic sea states where nonlinear WEC dynamics are common due to complex fluid-structure interaction, breaking waves, and other phenomena. Common modeling techniques for OSWECs include using potential flow theory to linearize the governing equations and ease computations, or using CFD to solve the full Navier-Stokes equations coupled with rigid body motion. However, both of these options have significant limitations. Potential flow theory breaks down in realistic sea conditions where nonlinear WEC dynamics are present, and CFD is often too computationally expensive for many applications such as real-time state prediction and optimal control, two areas of active research in the wave energy field. In particular, OSWEC dynamics are dominated by diffractive and viscous forces, often making common assumptions and linearization approximations (including small-body approximations) unreasonable, and CFD computationally intractable. To bridge this gap in modeling methods, we propose using Sparse Identification of Nonlinear Dynamics (SINDy) to build nonlinear reduced-order models (ROMs) that describe OSWEC behavior in response to large-amplitude regular waves. SINDy is an equation-free, data-driven algorithm that identifies dominant nonlinear functions present in system state dynamics using a library of nonlinear functions created from time series measurement data. The result is an ordinary differential equation (ODE) in time that can be solved from an initial condition to model and predict time behavior of the states. SINDy is parsimonious, meaning it uses a sparsity-promoting hyperparameter with the goal of only including the minimum number of terms to capture dominant dynamics, resulting in interpretable and generalizable results that are not overfit to the data. Using the discovered ROMs and integrating in time, not only can SINDy provide time series models and future state predictions of OSWEC dynamics, it can also give insights into which variables are critical in describing the underlying dynamics of the state. In this study, we use SINDy to describe the nonlinear dynamics of a lab-scale OSWEC in a wave tank subjected to large-amplitude regular waves. We use nonlinear simulation data to generate kinematic, force, and torque data and use it as input to SINDy to identify ODEs that describe the measurement variables in time. We then integrate the ODEs to recreate the time series as well as predict future system behavior. We directly compare the resulting time series to the original data input to assess the accuracy of the SINDy model. We also interpret the dominant terms in the ODEs to gain insight on underlying mechanisms of the observed nonlinearity. Early results show SINDy is a promising tool for modeling nonlinear OSWEC dynamics. We are
{"title":"Nonlinear WEC modeling using Sparse Identification of Nonlinear Dynamics (SINDy)","authors":"Brittany Lydon, Brian Polagye, Steven Brunton","doi":"10.36688/ewtec-2023-383","DOIUrl":"https://doi.org/10.36688/ewtec-2023-383","url":null,"abstract":"Modeling oscillating surge wave energy converter (OSWEC) systems to accurately predict their behavior has been a notoriously difficult challenge for the wave energy field. This is particularly challenging in realistic sea states where nonlinear WEC dynamics are common due to complex fluid-structure interaction, breaking waves, and other phenomena. Common modeling techniques for OSWECs include using potential flow theory to linearize the governing equations and ease computations, or using CFD to solve the full Navier-Stokes equations coupled with rigid body motion. However, both of these options have significant limitations. Potential flow theory breaks down in realistic sea conditions where nonlinear WEC dynamics are present, and CFD is often too computationally expensive for many applications such as real-time state prediction and optimal control, two areas of active research in the wave energy field. In particular, OSWEC dynamics are dominated by diffractive and viscous forces, often making common assumptions and linearization approximations (including small-body approximations) unreasonable, and CFD computationally intractable. \u0000To bridge this gap in modeling methods, we propose using Sparse Identification of Nonlinear Dynamics (SINDy) to build nonlinear reduced-order models (ROMs) that describe OSWEC behavior in response to large-amplitude regular waves. SINDy is an equation-free, data-driven algorithm that identifies dominant nonlinear functions present in system state dynamics using a library of nonlinear functions created from time series measurement data. The result is an ordinary differential equation (ODE) in time that can be solved from an initial condition to model and predict time behavior of the states. SINDy is parsimonious, meaning it uses a sparsity-promoting hyperparameter with the goal of only including the minimum number of terms to capture dominant dynamics, resulting in interpretable and generalizable results that are not overfit to the data. Using the discovered ROMs and integrating in time, not only can SINDy provide time series models and future state predictions of OSWEC dynamics, it can also give insights into which variables are critical in describing the underlying dynamics of the state. \u0000In this study, we use SINDy to describe the nonlinear dynamics of a lab-scale OSWEC in a wave tank subjected to large-amplitude regular waves. We use nonlinear simulation data to generate kinematic, force, and torque data and use it as input to SINDy to identify ODEs that describe the measurement variables in time. We then integrate the ODEs to recreate the time series as well as predict future system behavior. We directly compare the resulting time series to the original data input to assess the accuracy of the SINDy model. We also interpret the dominant terms in the ODEs to gain insight on underlying mechanisms of the observed nonlinearity. \u0000Early results show SINDy is a promising tool for modeling nonlinear OSWEC dynamics. We are","PeriodicalId":201789,"journal":{"name":"Proceedings of the European Wave and Tidal Energy Conference","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114911196","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Blanco, G. Navarro, J. Nájera, M. Lafoz, J. Sarasúa, Hilel García, G. Martínez-Lucas, J. Pérez-Díaz, Isabel Villalba
In general terms, the variable penetration of RE in power systems has some inherent drawbacks, such as lack of manageability and resource variability [1]. Medium (in the range of minutes) and short term (in the range of seconds) variability has a negative impact on system reliability, causing a deterioration of system frequency quality in both interconnected and, moreover, isolated systems [1-2]. Specifically, the variability of the wave energy resource is medium- and short-term. Therefore, although wave energy could be very suitable to be integrated in islands due to its location, the variable nature of wave energy could negatively impact the stability of the power grid [3]. The case study of the work focuses on the island of El Hierro (Canary Islands, Spain). It is an isolated electrical system with a very high penetration of renewable energy sources. The generation of the electrical system is composed of a wind farm, a pumped hydroelectric power plant and conventional generation by means of a diesel power plant. In a previous analysis [4], the integration of energy storage systems based on flywheels was analyzed. Based on this previous analysis, the manuscript studies the influence of the integration of the wave energy park in the electrical system of El Hierro. On the one hand, a wave farm will be proposed to evaluate the generated power and its associated oscillation [5]. The wave energy resource at different locations along the coast of El Hierro will be taken into account. On the other hand, an aggregated inertial dynamic mode of the electrical power system will be used to evaluate the impact of the generated power on the electrical frequency and the aging/degradation effects of the hydropumping elements. The Spanish Grid Code will be taken into account regarding frequency regulation mechanisms in isolated systems. The degradation of the hydraulic pumping systems due to additional frequency regulation stresses and electrical frequency deterioration will be calculated and evaluated in relation to the penetration of wave energy into the system, with and without the flywheel energy storage plant. This will allow quantification of certain technical limits to wave energy penetration in isolated systems and to draw conclusions with reference to the size of such a power system. [1] R. S. Kaneshiro et al. “Hawaii Island (Big Island) Wind Impacts” Proc. of Workshop on Active Power Control from Wind Power, Broomfield, CO, USA, 2013. [2] H. R. Iswadi et al. “Irish power system primary frequency response metrics during different system non synchronous penetration,” IEEE Eindhoven PowerTech 2015, doi: 10.1109/PTC.2015.7232425. [3] Isabel Villalba et al. “Wave farms grid code compliance in isolated small power systems,” IET Renewable Power Generation, 2019, doi: 10.1049/iet-rpg.2018.5351. [4] Hilel Garcia-Pereira et al. “Comparison and Influence of Flywheels Energy Storage System Control Schemes in the Frequency Regulation of Isolated Power Syst
{"title":"Wave Farms Integration in a 100% renewable isolated small power system -frequency stability and grid compliance analysis.","authors":"M. Blanco, G. Navarro, J. Nájera, M. Lafoz, J. Sarasúa, Hilel García, G. Martínez-Lucas, J. Pérez-Díaz, Isabel Villalba","doi":"10.36688/ewtec-2023-215","DOIUrl":"https://doi.org/10.36688/ewtec-2023-215","url":null,"abstract":"In general terms, the variable penetration of RE in power systems has some inherent drawbacks, such as lack of manageability and resource variability [1]. Medium (in the range of minutes) and short term (in the range of seconds) variability has a negative impact on system reliability, causing a deterioration of system frequency quality in both interconnected and, moreover, isolated systems [1-2]. Specifically, the variability of the wave energy resource is medium- and short-term. Therefore, although wave energy could be very suitable to be integrated in islands due to its location, the variable nature of wave energy could negatively impact the stability of the power grid [3]. \u0000The case study of the work focuses on the island of El Hierro (Canary Islands, Spain). It is an isolated electrical system with a very high penetration of renewable energy sources. The generation of the electrical system is composed of a wind farm, a pumped hydroelectric power plant and conventional generation by means of a diesel power plant. \u0000In a previous analysis [4], the integration of energy storage systems based on flywheels was analyzed. Based on this previous analysis, the manuscript studies the influence of the integration of the wave energy park in the electrical system of El Hierro. \u0000On the one hand, a wave farm will be proposed to evaluate the generated power and its associated oscillation [5]. The wave energy resource at different locations along the coast of El Hierro will be taken into account. On the other hand, an aggregated inertial dynamic mode of the electrical power system will be used to evaluate the impact of the generated power on the electrical frequency and the aging/degradation effects of the hydropumping elements. The Spanish Grid Code will be taken into account regarding frequency regulation mechanisms in isolated systems. \u0000The degradation of the hydraulic pumping systems due to additional frequency regulation stresses and electrical frequency deterioration will be calculated and evaluated in relation to the penetration of wave energy into the system, with and without the flywheel energy storage plant. This will allow quantification of certain technical limits to wave energy penetration in isolated systems and to draw conclusions with reference to the size of such a power system. \u0000[1] R. S. Kaneshiro et al. “Hawaii Island (Big Island) Wind Impacts” Proc. of Workshop on Active Power Control from Wind Power, Broomfield, CO, USA, 2013. \u0000[2] H. R. Iswadi et al. “Irish power system primary frequency response metrics during different system non synchronous penetration,” IEEE Eindhoven PowerTech 2015, doi: 10.1109/PTC.2015.7232425. \u0000[3] Isabel Villalba et al. “Wave farms grid code compliance in isolated small power systems,” IET Renewable Power Generation, 2019, doi: 10.1049/iet-rpg.2018.5351. \u0000[4] Hilel Garcia-Pereira et al. “Comparison and Influence of Flywheels Energy Storage System Control Schemes in the Frequency Regulation of Isolated Power Syst","PeriodicalId":201789,"journal":{"name":"Proceedings of the European Wave and Tidal Energy Conference","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114659816","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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