基于功率区间划分的潮流能发电装置电能质量特性分析

在对中国自主研发的潮流能发电装置现场测试中获取的电能质量数据的基础上,提出功率区间划分的分析方法.以该装置的额定功率为基准划分功率区间,统计各功率区间的电能质量数据,独立分析各功率区间的电能质量特性,阐述产生电能质量问题的原因以及并网后对电网造成的影响.该方法的应用可提高潮流能发电装置电能质量特性分析的准确性,能辅助找...     

水平轴潮流能发电装置功率特性现场测试分析方法优化及应用

在分析中国水平轴潮流能发电装置研发现状及功率特性现场测试需求和水平轴潮流能发电装置功率特性现场测试分析方法研究成果的基础上,参考欧洲海洋能中心和国际电工委员会发布的潮流能发电装置功率特性测试规程,对水平轴潮流能发电装置功率特性现场测试分析方法进行了深入探讨,提出了水平轴潮流能发电装置能量捕获截面积计算优化方法、平均转换...     

基于时间序列的分布式光伏电站发电数据采集方法

由于当前方法对发电数据进行采集时,没有对发电数据的缺失值进行修复,存在缺失数据修复前数据采集精度差、与实际采集数据相差多的问题。该文提出一种基于时间序列的分布式光伏电站发电数据采集方法。根据光伏电站受到的不同影响,构建了负荷异常值类型的时间序列模型,利用该模型对异常数据负荷点进行剔除,由于剔除后的数据存在缺失值,因此对其进行修复;根据修复结果,采用BP神经网络对发电数据进行采集。实验结果表明,通过对该方法进行缺失数据修复前后对比测试、不同方法与实际指标数据采集测试,验证了该方法的有效性强、实用性高。     

基于实测资料的风、浪、流综合发电特性分析

风能、波浪能与潮流能装置联合发电能更大限度地获取海洋能、节约设备投资。文章基于实测资料,分析了江苏沿海大丰测站同步风速、浪高和潮流流速的时变特性,探究了风、浪、流和综合发电的理论发电功率的幅值稳定性、持续时间稳定性和同步相关性。研究结果表明,在不同时间窗下,综合发电的理论发电功率的幅值稳定性较低,持续稳定性最高,风能与波浪能理论发电功率的同步特性明显。该方法为我国近海可再生能源的综合利用提供了新思路。     

一种通用潮流能发电装置远程监控系统的设计与实现

为保证潮流能发电装置的稳定性与可靠性需配备实时或准实时监控系统,该文针对潮流能发电装置原理及实际工作情况,设计一种远程实时监控系统,通过该系统可实时监测潮流能发电装置运行过程中的各项基本参数,从而有效判断发电装置的工作状态。监控系统前端通过读取智能仪表实现数据采集,采用GPRS模块实现远程数据传输;监控系统后台使用PostgreSQL数据库实现数据存储。另外,使用LabVIEW软件设计人机界面,通过调用后台服务器数据可清晰直观地监测整个潮流能发电装置的运行情况。实际测试和应用表明,该监控系统能够可靠地把现场数据实时传输到后台数据库服务器中,验证该系统可作为监控潮流能发电装置工作状态的有效手段。     

直线发电机在流致振动潮流能发电装置中的应用研究

研制直线发电机,并与流致振动潮流能转换装置相结合,探索直线发电机在流致振动潮流能发电领域的应用可行性。通过理论分析推导出流致振动潮流能发电装置的有效发电功率,建立能量转换系统数学模型,在振子直径D为0.12 m、系统刚度k为600 N/m、流速v为0.50～0.75 m/s工况下计算该装置的振子振幅、频率及发电功率,并在相同工况下进行流致振动潮流能发电装置的水槽试验,试验结果与数值仿真结果的变化趋势基本吻合。     

CFD技术在潮流能发电装置设计中的应用

潮流能发电装置是潮流能发电系统的核心组成元素,发电装置的设计在很大程度上决定着整个发电系统的优劣,本文阐述了CFD技术在潮流发电装置设计开发中的优势及重要性,并结合实例,证明该方法在潮流能发电装置设计中的有效性。     

低流速潮流能捕获系统叶轮的研究

提出一种低流速下总体发电量高的潮流能捕获系统,以实现深水网箱的能量自给。建立一个潮流半月周期内叶轮的总体发电量数学模型,对S型和H型2种不同叶轮的性能进行分析比较,得出S型叶轮在潮流流速较低时能自启动且总发电量较高;并对该叶轮结构参数进行优化,提高其在低流速时的功率系数。试验结果表明,该种潮流能发电装置能充分利用低流速潮流能为深水网箱供给能量,具有良好的使用效益。     

低流速水平轴潮流能发电装置桨叶的研究

提出一种桨叶设计流速的计算方法,使以此设计的桨叶在一个变化的流速范围内获得较好的捕能效率。首先,对实验地点的海水流速变化进行测试分析,通过计算确定桨叶的设计流速;其次,在叶素动量理论的基础上采用Wilson的优化设计法,通过Matlab软件计算8 kW水平轴潮流能发电装置的桨叶外形参数,并对其在不同流速下性能进行数字预测。最后,在实际海况下对捕能装置进行测试,实验结果表明捕能装置性能和数字预测基本一致,验证了设计方法的正确性和有效性。     

斋堂岛海域潮流特性分析与微观选址

利用VBA编程技术提取海图的水深数据建立Delft3D模型,模拟并分析斋堂岛海域潮流特性;根据潮流仿真结果结合FLUX方法进行潮流能发电装置的微观选址,并评估其资源可开发量。结果表明:VBA编程技术提取的水深数据与原数据吻合良好;斋堂岛海域最大潮流速度2.1 m/s,发生在大潮期落潮阶段;斋堂岛南部35.613°N,119.936°E处安放发电装置,该位置资源可开发量可达520 kW。     

Variability and phasing of tidal current energy around the United Kingdom

Tidal energy has the potential to play a key role in meeting renewable energy targets set out by the United Kingdom (UK) government and devolved administrations. Attention has been drawn to this resource as a number of locations with high tidal current velocity have recently been leased by the Crown Estate for commercial development. Although tides are periodic and predictable, there are times when the current velocity is too low for any power generation. However, it has been proposed that a portfolio of diverse sites located around the UK will deliver a firm aggregate output due to the relative phasing of the tidal signal around the coast. This paper analyses whether firm tidal power is feasible with ‘first generation’ tidal current generators suitable for relatively shallow water, high velocity sites. This is achieved through development of realistic scenarios of tidal current energy industry development. These scenarios incorporate constraints relating to assessment of the economically harvestable resource, tidal technology potential and the practical limits to energy extraction dictated by environmental response and spatial availability of resource. The final scenario is capable of generating 17 TWh/year with an effective installed capacity of 7.8 GW, at an average capacity factor of 29.9% from 7 major locations. However, it is concluded that there is insufficient diversity between sites suitable for first generation tidal current energy schemes for a portfolio approach to deliver firm power generation.     

底铰摆式波浪能装置群水动力性能研究

对常水深等厚度底铰摆式波浪能装置群,为减少多个装置物面上的网格数量,采用变量分离法将三维空间速度势表示成二维平面速度势和垂向特征函数相乘的形式,并利用二维格林函数法求解平面绕射势和辐射势,解决波浪与波浪能装置群之间的相互作用问题。利用所建立的数值模型分析波浪发电场装置之间的间距对各装置波能俘获效率、波浪发电场平均俘获效率及总输出功率随时间变化的波动率的影响。与单个孤立底铰摆式波能转换装置比较,以阵列形式布置的装置群,其总输出功率随时间变化的波动率在大部分波浪周期范围可明显降低,其降低程度主要与沿波浪传播方向的装置间距有关。     

Numerical analysis of the characteristics of vertical axis tidal current turbines

Tidal current is considered to be one of the promising alternative green energy resources. Tidal current turbines are devices used for harnessing tidal current energy. The development of a standard for tidal current turbine design is a very important step in the commercialization of tidal current energy as the tidal current industry is growing rapidly, but no standard for tidal current turbines has been developed yet. In this paper, we present our recent efforts in the numerical simulation of the characteristics (e.g., power output, torque fluctuation, induced velocity, and acoustic emission) of tidal current turbines related to the development of the standard. The relationship between the characteristics and the parameters of an example turbine are extensively discussed and quantified. The findings of this paper are expected to be helpful in developing the standards for tidal current turbines in the near future.     

变占空比三态Boost功率因数校正电路研究

为提高新能源并网等系统中变换器的功率因数,该文提出三态Boost变换器的变占空比控方案。通过分析电感电流参考值,推导出开关管的占空比表达式;根据输出电容上的二次谐波电压得到电压的纹波大小。相比于传统的定占空比控制方法,变占空比控制能够在较宽的输入电压范围内实时调整占空比,使电流跟踪电压变化,从而提高功率因数,降低输出电压纹波且不随输入电压变化。通过仿真和实验验证了理论分析的正确性以及控制的有效性。     

储能系统双向Buck-Boost变换器控制策略研究

为应对可再生能源出力波动引起储能系统功率流动方向的频繁变化,提出一种基于自抗扰控制和模型预测控制（ADRC+MPC）的储能系统双向Buck-Boost变换器控制策略。其中模型预测控制方法应用于电流内环,无需进行参数整定的同时,也提高了系统的响应速度;采用自抗扰控制策略的电压外环,通过在高频段降阶简化控制对象,达到降低自抗扰控制器复杂度的目的。仿真和样机实验显示当电感电流与输出电压参考值突变时,系统可分别在0.2与30 ms内迅速调整到给定值;当负载与电源电压突变时,系统能在20 ms内恢复稳定。实验结果证明该文提出的控制方法优于PI+MPC策略,具有响应速度快、超调量和波动幅度小的特点。     

多输入交错并联Boost变换器功率分配控制策略

针对功率分配底层功能提出一种新型控制策略,该控制策略在传统的双闭环平均电流均流法上加以改进。首先电流内环修改为功率内环,将电压外环的输出除以输入电压再乘以功率分配系数作为新的功率给定值来实现功率分配功能。同时将自抗扰技术应用到电压外环提高母线电压的响应速度。最后基于模块化思想并利用氮化镓功率开关器件,搭建一台三输入交错并联Boost实验样机,其额定功率为1500 W,额定工作频率为500 kHz,峰值效率为98.3%。实验验证结果表明,在相同输入电压或不同输入电压的情况下均能实现功率分配功能,并具有良好的动态响应。     

Zero sequence method for energy recovery from a variable-speed windturbine generator

An innovative power conversion system to convert energy from a variable-frequency wind-powered induction generator to a fixed frequency output is presented. A standard six-switch DC link current regulated pulse width modulated (CRPWM) inverter is simultaneously modulated with two current components. A three-phase balanced current component at the induction generator's optimum operating frequency transfers energy from the generator to the converter. A single phase zero sequence current component at a fixed 60 Hz frequency transfers energy from the converter through a zero sequence filter to the load. Unity power factor output is shown both in simulation and experiment, though any arbitrary power factor output may be readily commanded. Maximum power capture for a variable-speed wind turbine is achieved using proven control techniques. This method uses only half of the active power switching devices of conventional conversion methods. Simulation and experimental verification are shown     

The role of tidal asymmetry in characterizing the tidal energy resource of Orkney

When selecting sites for marine renewable energy projects, there are a wide range of economical and practical constraints to be considered, from the magnitude of the resource through to proximity of grid connections. One factor that is not routinely considered in tidal energy site selection, yet which has an important role in quantifying the resource, is tidal asymmetry, i.e. variations between the flood and ebb phases of the tidal cycle. Here, we present theory and develop a high-resolution three-dimensional ROMS tidal model of Orkney to examine net power output for a range of sites along an energetic channel with varying degrees of tidal asymmetry. Since power output is related to velocity cubed, even small asymmetries in velocity lead to substantial asymmetries in power output. We also use the 3D model to assess how tidal asymmetry changes with height above the bed, i.e. representing different device hub heights, how asymmetry affects turbulence properties, and how asymmetry is influenced by wind-driven currents. Finally, although there is minimal potential for tidal phasing over our study site, we demonstrate that regions of opposing flood- versus ebb-dominant asymmetry occurring over short spatial scales can be aggregated to provide balanced power generation over the tidal cycle.