Dynamic Analysis of a 10 MW Floating Offshore Wind Turbine Considering the Tower and Platform Flexibility

Recently,semisubmersible floating offshore wind turbine technologies have received considerable attention.For the coupled simulation of semisubmersible floating offshore wind energy,the platform is usually considered a rigid model,which could affect the calculation accuracy of the dynamic responses.The dynamic responses of a TripleSpar floating offshore wind turbine equipped with a 10 MW offshore wind turbine are discussed herein.The simulation of a floating offshore wind turbine under regular waves,white noise waves,and combined wind-wave conditions is conducted.The effects of the tower and platform flexibility on the motion and force responses of the TripleSpar semisubmersible floating offshore wind turbine are investigated.The results show that the flexibility of the tower and platform can influence the dynamic responses of a TripleSpar semisubmersible floating offshore wind turbine.Considering the flexibility of the tower and platform,the tower and platform pitch motions markedly increased compared with the fully rigid model.Moreover,the force responses,particularly for tower base loads,are considerably influenced by the flexibility of the tower and platform.Thus,the flexibility of the tower and platform for the coupled simulation of floating offshore wind turbines must be appropriately examined.

Coupled Time-Domain Investigation on a Vertical Axis Wind Turbine Supported on a Floating Platform

The dynamic responses of a floating vertical axis wind turbine(VAWT)are assessed on the basis of an aero-hydro-mooring coupled model.The aerodynamic loads on the rotor are acquired with double-multiple stream tube method.First-and second-order wave loads are calculated on the basis of 3D potential theory.The mooring loads are simulated by catenary theory.The coupled model is established,and a numerical code is programmed to investigate the dynamic response of the semi-submersible VAWT.A model test is then conducted,and the numerical code is validated considering the hydrodynamic performance of the floating buoy.The responses of the floating VAWT are studied through the numerical simulation under the sea states of wind and regular/irregular waves.The effects of the second-order wave force on the motions are also investigated.Results show that the slow-drift responses in surge and pitch motions are significantly excited by the second-order wave forces.Furthermore,the effect of foundation motion on aerodynamic loads is examined.The normal and tangential forces of the blades demonstrate a slight increase due to the coupling effect between the buoy motion and the aerodynamic loads.

Capacity Optimization Configuration of Hydrogen Production System for Offshore Surplus Wind Power

To solve the problem of residual wind power in offshore wind farms,a hydrogen production system with a reasonable capacity was configured to enhance the local load of wind farms and promote the local consumption of residual wind power.By studying the mathematical model of wind power output and calculating surplus wind power,as well as considering the hydrogen production/storage characteristics of the electrolyzer and hydrogen storage tank,an innovative capacity optimization allocation model was established.The objective of the model was to achieve the lowest total net present value over the entire life cycle.The model took into account the cost-benefit breakdown of equipment end-of-life cost,replacement cost,residual value gain,wind abandonment penalty,hydrogen transportation,and environmental value.The MATLAB-based platform invoked the CPLEX commercial solver to solve the model.Combined with the analysis of the annual average wind speed data from an offshore wind farm in Guangdong Province,the optimal capacity configuration results and the actual operation of the hydrogen production system were obtained.Under the calculation scenario,this hydrogen production system could consume 3,800 MWh of residual electricity from offshore wind power each year.It could achieve complete consumption of residual electricity from wind power without incurring the penalty cost of wind power.Additionally,it could produce 66,500 kg of green hydrogen from wind power,resulting in hydrogen sales revenue of 3.63 million RMB.It would also reduce pollutant emissions from coal-based hydrogen production by 1.5 tons and realize an environmental value of 4.83 million RMB.The annual net operating income exceeded 6 million RMB and the whole life cycle NPV income exceeded 50 million RMB.These results verified the feasibility and rationality of the established capacity optimization allocation model.The model could help advance power system planning and operation research and assist offshore wind farm operators in improving economic and environmental benefits.

Platform motion minimization using model predictive control of a floating offshore wind turbine

Wind turbines are installed offshore with the assistance of a floating platform to help meet the world’s increasing energy needs.However,the incident wind and extra incident wave disturbances have an impact on the performance and operation of the floating offshore wind turbine(FOWT)in comparison to bottom-fixed wind turbines.In this paper,model predictive control(MPC)is utilized to overcome the limitation caused by platform motion.Due to the ease of control synthesis,the MPC is developed using a simplified model instead of high fidelity simulation model.The performance of the controller is verified in the presence of realistic wind and wave disturbances.The study demonstrates the effectiveness of MPC in reducing platform motions and rotor/generator speed regulation of FOWTs.

Motion Performance and Mooring System of a Floating Offshore Wind Turbine

The development of offshore wind farms was originally carried out in shallow water areas with fixed （seabed mounted） structures. However, countries with limited shallow water areas require innovative floating platforms to deploy wind turbines offshore in order to harness wind energy to generate electricity in deep seas. The performances of motion and mooring system dynamics are vital to designing a cost effective and durable floating platform. This paper describes a numerical model to simulate dynamic behavior of a new semi-submersible type floating offshore wind turbine （FOWT） system. The wind turbine was modeled as a wind block with a certain thrust coefficient, and the hydrodynamics and mooting system dynamics of the platform were calculated by SESAM soRware. The effect of change in environmental conditions on the dynamic response of the system under wave and wind loading was examined. The results indicate that the semi-submersible concept has excellent performance and SESAM could be an effective tool for floating wind turbine design and analysis.

Dynamic Response of 6MW Spar Type Floating Offshore Wind Turbine by Experiment and Numerical Analyses

The floating offshore wind turbine(FOWT) is widely used for harvesting marine wind energy. Its dynamic responses under offshore wind and wave environment provide essential reference for the design and installation. In this study,the dynamic responses of a 6 MW Spar type FOWT designed for the water depth of 100 m are investigated by means of the wave tank experiment and numerical analysis. A scaled model is manufactured for the experiment at a ratio of65.3, while the numerical model is constructed on the open-source platform FAST(Fatigue, Aerodynamics,Structures, and Turbulence). Still water tests, wind-induced only tests, wave-induced only tests and combined windwave-current tests are all conducted experimentally and numerically. The accuracy of the experimental set-up as well as the loading generation has been verified. Surge, pitch and heave motions are selected to analyze and the numerical results agree well with the experimental values. Even though results obtained by using the FOWT calculation model established in FAST software show some deviations from the test results, the trends are always consistent. Both experimental and numerical studies demonstrate that they are reliable for the designed 6 MW Spar type FOWT.

A Novel Dynamics Analysis Method for Spar-Type Floating Offshore Wind Turbine

The dynamic behavior of floating offshore wind turbine (FOWT) is crucial for its design and optimization. A novel dynamics analysis method for the spar-type FOWT system is proposed in this paper based on the theorem of moment of momentum and the Newton’s second law. The full nonlinearity of the equations of motion (EOMs) and the full nonlinear coupling between external loads and the motions are preserved in this method. Compared with the conventional methods, this method is more transparent and it can be applied directly to the large-amplitude rotation cases. An in-house code is developed to implement this method. The capability of in-house code is verified by comparing its simulation results with those predicted by FAST. Based on the in-house code, the dynamic responses of a spar-type FOWT system are investigated under various conditions.

Numerical investigation of the coupled aero-hydrodynamic performances of a semi-submersible floating offshore wind turbine with inclined columns

Numerical investigations of floating platforms with different outer column inclined angles under two operating conditions of regular wave and irregular wave are presented in this paper.A coupled aero-hydrodynamic computational fluid dynamics in-house solver FOWT-UALM-SJTU is applied for the calculation.First,the validation for wave and wind generation are conducted to determine mesh distribution strategy.Based on these,the hydrodynamic motion response,aerodynamic performance and wake flow are analyzed to explore the impact of inclined angle.Conduct spectral analysis on the motion response under wave action,discuss the aerodynamic attack angle and inflow wind velocity along the blade spanwise direction in detail,reveal different trends in wake development and recovery.The results show that for the regular wave condition with the increase of inclined angles,the equilibrium position of surge motion is constantly rising,while pitch is decreasing.The maximum root mean square(rms)value occurs at angle=30°,compared with the original OC4 FOWT,the rms in power and thrust increase 0.35%,0.71%.And there are two low regions of attack angle and high regions of axial inflow velocity,corresponding to aerodynamic loads.The spectral analysis indicates that the natural frequency of pitch motion will increase with inclined angle.Besides,from the middle to far region of wake flow,the velocity recovery of FOWT with inclined angle will become faster,which is beneficial for downstream turbines to enhance more wind energy.

Coupled dynamic response analysis of multi-column floating offshore wind turbine with low center of gravity

To realize the application of the floating offshore wind turbine(FOWT)from deep to relatively shallow waters,a new concept of multi-column floating wind turbine platform with low center of gravity(CG)is designed and validated.The multi-column low CG platform is designed to support a 6MW wind turbine class and operated at a water depth of 50m in the South China Sea.The frequency domain software WADAM and time domain software NREL-FAST are used to simulate coupled dynamic responses of the floating wind turbine system with second-order wave loads considering.The dynamic behaviors of multi-column low CG FOWT system under normal operation and parked conditions are presented.The influence of second-order wave force on the motion responses of the multi-column platform,fore-aft force and moment of the tower base and mooring force are researched respectively.The results demonstrate that the coupled dynamic responses at rated operating condition and extreme condition meet the normal operating requirements and extreme survival requirements of FOWT system in the shallow water(50m)of South China Sea.In addition,it is found that,the wave frequency response gradually replaces the second-order low frequency response as the main influencing factor of the coupled dynamic response of the FOWT system with the increasing severity of the sea states.However,in general,the magnitude of second-order low frequency response increases with the increasing severity of the design load case.Thus,in the subsequent design of the shallow water FOWT system,the second-order effects should be paid enough attention.

海上风电机组DeepCWind平台系泊缆布置及断裂仿真分析

以NREL 5 MW风电机组和OC4-DeepCWind半潜式浮式平台为研究对象,运用ANSYS/AQWA水动力分析软件和OPENFAST仿真分析软件进行风电机组气动、水动和系泊系统的时域耦合运动分析,研究不同系泊缆数量、角度布置形式及系泊缆断裂等因素对浮式风电机组动态响应和系泊缆张力的影响。结果表明:增大系泊缆的布置角度可提高浮式风电机组平台的稳定性,但同时增大了系泊缆张力,导致安全系数降低;迎浪侧系泊缆断裂瞬态情况下,浮式平台产生明显的运动响应波动,系泊缆布置角度的增大使浮式平台的稳定性急剧降低。

Research on hydraulic wind turbine semi-physical simulation platform

According to a research on the 30kVA simulation experimental platform of hydraulic wind tur- bine, its basic structure, composition and operation principle are expounded in this paper. An in- verter motor is used to simulate the wind turbine, while a similarity calculation method is applied be- tween the small and large wind turbine. A fixed displacement pump-variable motor closed loop is used as the main transmission system, and a self-excited synchronous generator generates electricity through the grid connection. The experiment and simulation study on the speed and power control of the hydraulic wind turbine is conducted, based on the experimental platform, thus correctness and progressiveness of the experiment platform is further verified. The experimental platform study lays a foundation for further research on the characteristics of hydraulic wind turhln~

Floating Wind Turbine Motion Suppression Using an Active Wave Energy Converter

This paper proposes a new concept of an actively-controlled wave energy converter for suppressing the pitch and roll motions of floating offshore wind turbines.The wave energy converter consists of several floating bodies that receive the wave energy,actuators that convert the wave energy into electrical energy and generate the mechanical forces,and rigid bars that connect the floating bodies and the wind turbine platform and deliver the actuator forces to the platform.The rotational torques that are required to minimize the platform pitch and roll motions are determined using a linear quadratic regulator.The torques determined in this manner are realized through the actuator forces that maximize the wave power capture as well.The performance of the proposed wave energy converter in simultaneously suppressing the platform pitch and roll motions and extracting the wave energy is validated through simulations.

海上油气平台不稳定电源与储能联合配置优化策略

针对海上油气平台集群接入不稳定电源与储能的联合配置问题,结合海上风电、光伏特点及已有的拓扑结构,提出了三阶段风机/光伏/储能阶段式联合配置策略,介绍嵌入潮流计算的阶段式粒子群算法。第一阶段通过LightGBM网络预测模型得到风机光伏的时序预测发电功率,再以投资建设经济性和潮流稳定性为目标优化每个节点的风机/光伏容量;第二阶段针对不稳定电源配置后的配电网,提出了基于电压和损耗灵敏度为指标的集群划分方法,将配电网集群划分为若干个子集群;第三阶段根据划分后的子集群,以储能容量、配电网损耗和节点电压波动为目标为每个子集群内配置储能。以渤海油田某10 kV实际油气平台配电网为例,设立燃气机出力功率自定义和经济性自定义两种方案来验证联合配置优化决策的合理性。结果表明,两种配置策略都可以有效地提升海上油气平台配电网的潮流稳定性,提高新能源的渗透率。本文研究验证了海上分散式风机/光伏发电工程的可行性,有利于实现未来海上油气平台的“零碳”建设。

风电接入远海油气平台的规划方法

海上风电直供远海油气平台可降低发电成本和碳排放,但传统规划方法不适用于远海油气平台的负荷特性。在考虑海上油田电力系统燃气透平机组与负荷特性的基础上,建立计及风-燃-荷功率动态匹配特性的扩展概率潮流模型,提出适用于远海油气平台的风机规划方法。采用所提潮流计算方法,在满足远海油田电力系统的电压、线路载流量等约束条件下,以年发电成本与年碳排放量的综合成本最低为目标建立规划模型,并采用粒子群优化算法对模型进行求解。以我国某远海油田电力系统为例,提出针对远海油田电力系统特点的风电接入方案,算例结果表明,所提规划方法具有可行性。

风电供能海上平台孤网负荷侧调频策略研究

大量风力发电接入远海油气平台对系统频率稳定造成了负面影响。在实际生产中,以注水泵为代表的可调节负荷和部分生产负荷占总负荷的30%,且其功率变化甚至启停对生产影响不大。该类负荷在以往的研究中不直接参与海上平台的调频,但调频潜力极大,且响应速度较快。在不影响海上平台生产的同时,既可以提供适量的风电消纳、提供快速的频率响应支撑,又可以跟随系统频率调整自身转速、调节所需有功。该文提出一种海上平台的可调节负荷跟随系统频率或跟随风电出力的调频控制策略,通过分析跟随燃机和跟随风电出力的速度给定方法,研究各控制参数及客观因素对调频效果的影响。仿真结果表明,该策略充分利用可调节负荷的调频容量,有效改善了海上平台频率特性,为提高风电渗透率、实现“双碳”目标提供了技术参考。

漂浮式海上风力机自适应超螺旋滑模桨距控制

针对额定风速以上漂浮式海上风力机系统的输出功率稳定、浮式平台运动和疲劳载荷抑制任务目标,考虑系统非线性和模型参数摄动及风浪扰动,提出一种基于自适应超螺旋二阶滑模和干扰观测补偿的桨距角鲁棒控制方案。首先,实现漂浮式海上风力机的仿射非线性不确定系统建模;其次,构建考虑风力机额定转速和平台纵摇的滑模函数,设计控制增益自适应调节的超螺旋二阶滑模控制律;再次,采用干扰观测器补偿模型参数摄动和风浪扰动不确定项;最后,基于FAST与Matlab/Simulink在不同风浪环境下进行仿真,验证所提方案有效性和优越性。时域和频域仿真结果表明,与传统比例积分控制方案相比,所提方案对稳定风力机系统输出功率、抑制浮式平台运动及减少塔基载荷具有更好的控制效果。

漂浮式海上风电离网制氢联合仿真实验平台

海上风电制氢有助于解决海上风电消纳和远海输电难题,但目前的仿真缺乏海上环境对制氢影响的模拟,限制了相关研究与教学发展,因此亟需开发充分考虑海洋环境载荷的海上风电离网制氢仿真实验平台。该文将风机一体化仿真工具FAST和MATLAB/Simulink电力系统工具箱相结合,实现海上风机与发电机的联合仿真,在MATLAB内部通过设计接口实现电力系统与数学模型的两工具箱的联合仿真,以此构建两软件三工具箱联合的海上风电离网制氢一体化仿真实验平台。仿真结果表明,该平台能实现漂浮式海上风电离网制氢联合仿真,可为海上风电制氢有关研究和实验教学提供有力支撑。

漂浮式海上风力机三维尾流模型研究

针对漂浮式海上风电机组接地系统所处的深海环境及特殊的系泊系统,综合考虑纵荡运动对入流风速和尾流区域膨胀的影响,基于二维BP工程尾流模型,提出一种三维尾流模型(3Dksg_BP),将该模型用于全尾流区域横向和垂向风速剖面的预测。预测结果与风洞实验数据对比发现,下游1.7D、2.3D、5.0D和10.0D(D为风轮直径)等位置的预测精度均不低于97.6%。基于3Dksg_BP,研究不同频率和振幅下的纵荡运动对尾流造成的影响,结果表明:纵荡运动对尾迹的影响随频率和振幅的增大而增大,且随着下游距离的增加,纵荡运动对尾迹的影响逐渐减小。

浮式风机平台设计研究综述

大力发展风力发电技术是国家推动能源低碳转型、实现“双碳”目标的核心路径。随着陆上风电和近海风电资源开发逐渐饱和,风电开发从近岸走向深远海成为风电行业发展必然的趋势,而浮式风机平台的研发与优化是推进海上风电向深远海区域发展的关键。基于对国内外浮式风机平台发展现状的研究,进一步分析浮式风机平台设计中气动载荷、水动力载荷、系泊系统、耦合分析方法以及常用数值模拟工具的研究现状,重点梳理以提升结构稳性和降低成本为驱动的浮式风机平台的关键技术思路及构型特点,总结浮式风机平台优化的研究现状,以及其设计中存在的问题与挑战,以期为相关领域研究人员提供技术参考。

基于改进无模型自适应控制的漂浮式海上风机转矩-变桨协调控制策略研究

针对漂浮式海上风机建模困难、频繁变桨造成的严重疲劳损伤等问题,提出一种基于改进无模型自适应控制的转矩-变桨协调控制策略。该策略不依赖漂浮式海上风机的数学模型,通过集成迭代学习控制策略改进无模型自适应控制方法,设计发电机电磁转矩和桨距角作为控制变量的多输入多输出控制器进行协调控制,允许非零度桨距角下风机用做动能缓冲,在平滑输出功率的同时减少变桨动作量。为证明所提出控制策略的有效性,在多种风场景下,与增益调度PI控制等方法进行了对比实验。结果表明:所提出的控制策略使漂浮式海上风机在满足发电功率平稳性的同时减缓了漂浮平台的俯仰运动,可有效降低漂浮式海上风机的疲劳载荷。