利用闲置地块开发分散式风电的风机选址与选型研究

[目的]华南区域陆上集中式风电项目已得到广泛开发,充分利用村镇或厂区周边闲置地块发展分散式风电项目已然兴起,低风速分散式风电有望为国内风电市场带来新的增量空间.分散式风电机位选址正确与否,将直接影响电站的经济效益.由于村镇或厂区周边闲置地块一般没有实测风资源数据支持,这对分散式风电场开发、风机点位选址及风机选型提出了较...     

变速恒频风力发电系统及其控制技术研究

为了最大限度地利用风能,风力发电系统应采用变速恒频控制策略。分析了鼠笼异步发电系统、双馈发电系统、无刷双馈发电等变速恒频风力发电系统的原理、性能及特点,通过对比各种风力发电机和各种控制方法的优缺点,对未来风力发电机和风力发电控制技术的发展趋势做了展望: 风力发电机大型化;采用变桨距和变速恒频技术;风力发电机采用直接驱动;采用智能化控制等。     

Power generation efficiency analysis of offshore wind farms connected to a SLPC (single large power converter) operated with variable frequencies considering wake effects

This paper deals with the power generation efficiency analysis of a proposed offshore wind farm topology, consisting of a SLPC (single large power converter) that simultaneously controls a group of generators. This common converter can operate at a VF (variable frequency) or at a CF (constant frequency). The results are compared with the conventional onshore wind farm scheme, where individual power converters are connected to each turbine, guaranteeing maximum power generation for the entire wind farm. A methodology to analyze different wind speed and direction scenarios, and to compute the optimal electrical frequency for each one, is presented and applied to different case studies depending on the wind farm size. In order to obtain more realistic values of wind speeds, the wake effect amongst wind turbines is considered. A wake model considering single, partial and multiple wakes inside a wind farm and taking into account different wind directions, is presented. Both wind farm topologies are analyzed by means of simulations, taking into account both wind speed variability in wind farms and the number of wind turbines. The possible resulting benefits of simplifying the MPCs (multiple power converters) of each turbine, namely saving costs, reducing losses and maintenance and increasing the reliability of the system, are analyzed, focusing on the total power extraction. The SLPC-VF scheme is also compared with a CF scheme SLPC-CF, and it is shown that a significant power increase of more than 33% can be obtained with SLPC-VF.     

Dynamic modeling,design and simulation of a wind/fuel cell/ultra-capacitor-based hybrid power generation system

Recent research and development of alternative energy sources have shown excellent potential as a form of contribution to conventional power generation systems. In order to meet sustained load demands during varying natural conditions, different energy sources and converters need to be integrated with each other for extended usage of alternative energy. The paper focuses on the combination of wind, fuel cell (FC) and ultra-capacitor (UC) systems for sustained power generation. As the wind turbine output power varies with the wind speed: an FC system with a UC bank can be integrated with the wind turbine to ensure that the system performs under all conditions. We propose herein a dynamic model, design and simulation of a wind/FC/UC hybrid power generation system with power flow controllers. In the proposed system, when the wind speed is sufficient, the wind turbine can meet the load demand while feeding the electrolyzer. If the available power from the wind turbine cannot satisfy the load demand, the FC system can meet the excess power demand, while the UC can meet the load demand above the maximum power available from the FC system for short durations. Furthermore, this system can tolerate the rapid changes in wind speed and suppress the effects of these fluctuations on the equipment side voltage in a novel topology.     

Modeling and investigation of the wind resource in the gulf of Tunis,Tunisia

The development of wind energy conversion systems becomes one of the most important aims of many developing countries such as Tunisia. This is due to the reduction in wind turbine costs, and fossil fuel atmospheric pollution. The evaluation of wind power potential is necessary to estimate wind resource and therefore conduct the suitable decisions for the wind power generation projects, technical and economical feasibility. The presented work in this paper was to investigate the potential of wind resource in the Gulf of Tunis in Tunisia. The hourly mean wind speed and wind direction with a 10-min time step provided by the NRG (National Resources Group) weather station were used to analyze the wind speed characteristics and the wind power potential. Weibull parameters are estimated based on the most frequently used methods in which their accuracy was compared based on different goodness of fit tests. Those wind characteristics are required to give the picture of wind potential distribution in the Gulf of Tunis.     

基于Matlab/Simulink的风力机性能仿真研究

随着风力发电技术的发展,变速风力发电技术成为了风力发电发展的趋势。风力机作为变速风力发电机组的重要部分,其性能影响到风力发电机组的整体性能。根据变速风力机的静态性能特点,采用Matlab／Simulink软件对其进行建模,并给变速风力发电机组风力机输入模拟变速风速进行仿真研究,给出了风力机的静态性能数据和仿真波形。结果表明：通过调节影响风力机性能的各因素,保持发电机的转速与主导风速之间特定的最优比例系数,使得风力机保持在最佳叶尖速比下运行,跟随变速风速可实现最大风能捕获;对变速风力机的静态性能研究建模方法是正确可行的。     

Investigation on wind power potential on Hong Kong islands—an analysis of wind power and wind turbine characteristics

This paper discusses the potential for electricity generation on Hong Kong islands through an analysis of the local weather data and typical wind turbine characteristics. An optimum wind speed, u_op, is proposed to choose an optimal type of wind turbine for different weather conditions. A simulation model has been established to describe the characteristics of a particular wind turbine. A case study investigation allows wind speed and wind power density to be obtained using different hub heights, and the annual power generated by the wind turbine to be simulated. The wind turbine's capacity factor, being the ratio of actual annual power generation to the rated annual power generation, is shown to be 0.353, with the capacity factor in October as high as 0.50. The simulation shows the potential for wind power generation on the islands surrounding Hong Kong.     

Some of the design and methodology considerations in wind resource assessment

Owing to the increasing power demand and the environmental concerns of the conventional power sources, power generation from wind is receiving due attention from majority of power planners. Since wind is an intermittent energy source and to find the economic viability of wind project, a proper wind resource assessment (WRA) and analysis of the data collected is very important. An extensive literature survey on WRA is carried out and the different techniques of WRA are discussed. The methodology includes discussions on preliminary wind survey to choose the best site for installing wind data instruments, selecting the optimum wind turbine suitable for a site and the uncertainties involved in estimating the wind speed using the different WRA techniques.     

A novel small scale efficient wind turbine for power generation

A ‘proof of concept’ study of a novel wind turbine that overcomes some of the deficiencies and combines the advantages of the conventional horizontal and vertical axis wind turbines is presented in this paper. The study conducted using computational fluid dynamics and wind tunnel tests clearly demonstrate that such a proposition is feasible and a low cost, low noise, safe and easy to operate but enhanced performance wind turbine for small scale power generation in low wind speed is viable.     

Impact of wind power in autonomous power systems—power fluctuations—modelling and control issues

This paper describes a detailed modelling approach to study the impact of wind power fluctuations on the frequency control in a non‐interconnected system with large‐scale wind power. The approach includes models for wind speed fluctuations, wind farm technologies, conventional generation technologies, power system protection and load. Analytical models for wind farms with three different wind turbine technologies, namely Doubly Fed Induction Generator, Permanent Magnet Synchronous Generator and Active Stall Induction Generator‐based wind turbines, are included. Likewise, analytical models for diesel and steam generation plants are applied. The power grid, including speed governors, automatic voltage regulators, protection system and loads is modelled in the same platform. Results for different load and wind profile cases are being presented for the case study of the island Rhodes, in Greece. The scenarios studied correspond to reference year of study 2012. The effect of wind fluctuations in the system frequency is studied for the different load cases, and comments on the penetration limits are being made based on the results. Copyright © 2010 John Wiley & Sons, Ltd.     

Design and evaluation of PV-wind hybrid system with hydroelectric pumped storage on the National Power System of Egypt

National and international policies encourage increased penetration of solar and wind energy into electrical networks in order to reduce greenhouse gas emission. Solar radiation and wind speed variations complicate the integration of wind and solar generation into power systems and delay the transition of these sources from centralized to distributed energy sources. The increased penetration of nontraditional energy sources into the electric grid stimulates the demand for large capacities in the field of energy storage. A mathematical model, which describes the operation of a proposed hybrid system, including solar PV, wind energy, and a pumped storage hydroelectric power plant is developed in this paper. This hydropower plant utilizes seawater as a lower reservoir, and only a tank has to be built in order to reduce the installation cost of the storing system. The pumped storage power plant used for compensation of the variation of the output energy from the PV and wind power plants by discharging water from the upper reservoir, which is previously pumped in the case of surplus energy from PV and wind turbine power plants. The impact of the proposed system on the grid utility is investigated in accordance with the values of energy exchange (deficits and surpluses of energy) between the considered hybrid system and the grid. The optimum design is determined by the pump and turbine capacities, upper reservoir volume, and the volume of water left in the tank for emergencies. Different scenarios of the optimum operations are presented for analysis. The results obtained from the examined scenarios indicate the ability of such a hybrid energy system to reduce the exchange of energy with the grid. This paper indicates the technical feasibility of seawater pumped-storage hydropower plant for increasing the Egyptian national grid’s ability to accept high integration of renewable energy sources.     

小型Savonius风机的创新设计与仿真分析

Savonius风机是一种典型的垂直轴风力机。针对传统风机的发电机部分采用转子、定子一动一静的设计布局,提出了一种新型的发电机结构,从而提高风机发电效率。通过有限元分析软件ANSYS／CFX,对风力机模型进行流体分析,计算Savonius风力机的效率,验证本设计分析方法的正确性。     

Wind farm investment risks under uncertain CDM benefit in China

China has set an ambitious target to increase its wind power capacity by 35 GW from 2007 to 2020. The country’s hunger for clean power provides great opportunities for wind energy investors. However, risks from China’s uncertain electricity market regulation and an uncertain energy policy framework, mainly due to uncertain Clean Development Mechanism (CDM) benefits, prevent foreign investors from investing in China’s wind energy. The objectives of this paper are to: (1) quantify wind energy investment risk premiums in an uncertain international energy policy context and (2) evaluate the impact of uncertain CDM benefits on the net present values of wind power projects. With four scenarios, this study simulates possible prices of certified emissions reductions (CERs) from wind power projects. Project net present values (NPVs) have been calculated. The project risk premiums are drawn from different and uncertain CER prices. Our key findings show that uncertain CDM benefits will significantly affect the project NPVs. This paper concludes that the Chinese government needs revising its tariff incentives, most likely by introducing fixed feed-in tariffs (FITs), and re-examining its CDM-granting policy and its wind project tax rates, to facilitate wind power development and enable China to achieve its wind energy target.     

Promotion strategy of clean technologies in distributed generation expansion planning

Distributed generation expansion planning (DGEP) has been frequently reported in the literature around the world. In this scope, renewable technologies which are considered as a kind of distributed generations are developing due to their environmental benefits. However, only a few renewable energies have proven to be competitive so far, while their economic viability is also limited to certain regions of the world. In this paper, an encouraging mechanism is proposed in favor of clean technologies in the planning process. This mechanism is defined based on a grant function of emission not polluted which is paid to DG owners to promote renewable and clean technologies. In the planning process, a multi-objective optimization algorithm is applied to produce a Pareto set of optimal planning schemes by taking into account different objective functions (cost and grant functions). The best planning scheme among the Pareto set is chosen based on a composite utility which are obtained through a Monte Carlo simulation of uncertain situations. Distributed generation technologies which are considered in this paper are conventional and renewable technologies, namely photovoltaic (PV), wind turbine (WT), fuel cell (FC), micro turbine (MT), gas turbine (GT), and reciprocal engine (RE). To assess the ability of the proposed method, a typical distribution system is used for expansion planning under two environmental scenarios.     

5 MW双馈风电机组低电压穿越的仿真分析

针对海上风力发电机组安全可靠运行要求的发展趋势,本文在阐述双馈风电机组控制原理的基础上,建立了双馈发电机及其变流器的控制模型。其次,在分析电力系统对并网风电机组低电压穿越原理基础上,比较分析了双馈风电机组低电压穿越的各种控制技术方案。最后,结合海上用5.0 MW双馈风力发电机组电气参数,对2种典型低电压穿越的转子电路保护措施进行了仿真比较。分析结果表明,采用二极管整流桥加IGBT和保护电阻构成斩波器的措施具有较好的暂态控制效果。     

基于Matlab/Simulink的永磁直驱风力发电机组建模和仿真研究

以永磁直驱风力发电机组为研究对象,建立了包括风力机、传动部分、永磁直驱发电机、矢量控制策略、最大风能捕获策略的整体数学模型;应用Matlab/Simulink工具,以建立的数学模型为基础搭建了永磁直驱风力发电机组仿真模型,并以两次阶跃风速为例对所建模型并网后运行特性进行了仿真研究。实现了永磁直驱风力发电机组的最大风能捕获和功率解耦控制,仿真结果表明,永磁直驱风力发电机组具有良好的运行特性,同时验证了所建模型的正确性和有效性。     

Optimal distributed energy resources planning in a competitive electricity market: Multiobjective optimization and probabilistic design

This paper presents a probabilistic multiobjective framework for optimal distributed energy resources (DERs) planning in the distribution electricity networks. The proposed model is from the distribution company (DISCO) viewpoint. The projected formulation is based on nonlinear programming (NLP) computation. The proposed design attempts to achieve a trade-off between minimizing the monetary cost and minimizing the emission of pollutants in presence of the electrical load as well as electricity market prices uncertainties. The monetary cost objective function consists of distributed generation (DG) investment and operation cost, payment toward loss compensation as well as payment for purchased power from the network. A hybrid fuzzy C-mean/Monte-Carlo simulation (FCM/MCS) model is used for scenario based modeling of the electricity prices and a combined roulette-wheel/Monte-Carlo simulation (RW/MCS) model is used for generation of the load scenarios. The proposed planning model considers six different types of DERs including wind turbine, photovoltaic, fuel cell, micro turbine, gas turbine and diesel engine. In order to demonstrate the performance of the proposed methodology, it is applied to a primary distribution network and using a fuzzified decision making approach, the best compromised solution among the Pareto optimal solutions is found.     

大型风电机组功率曲线的分析与修正

讨论了风电机组不同情况下的功率曲线定义,分析了功率曲线绘制过程中的风速处理方法,可以适用于绘制风力发电机组静、动态功率曲线;讨论了影响机组功率曲线的各种因素,并给出了影响因子,使得根据功率曲线进行风场发电量的计算可以取得更可靠的结果。     

基于网格-坐标化遗传算法的风电场布局优化

采用Jensen尾流模型来描述风电机组间尾流的干扰效应。首先基于网格化的改进遗传算法获得风电机组的数量和布局初始位置,再通过坐标化遗传算法对风电机组位置进行进一步调整优化,从而提高单位成本的发电量。根据所提出的方法,在3种不同的风场（定风向定风速、定风速变风向和变风速变风向）下,针对2 km×2 km的标准风场区域进行风电机组布局优化,再将其应用到不规则的实际案例,对比分析表明所提出的方法能有效提高发电量。     

Dynamic modeling of a hybrid wind/solar/hydro microgrid in EMTP/ATP

Microgrids are LV or MV electric networks which utilize various distributed generators (DG) to serve local loads. In this paper, dynamic models of the main distributed generators including photovoltaic (PV) cell, wind turbine, hydro turbine as well as the equivalent power electronic interfaces, battery unit of PV and excitation system of hydro turbine have been made in ElectroMagnetic Transient Program/Alternative Transient Program (EMTP/ATP) software package. Control strategies based on active power/frequency and reactive power/voltage droops for the power control of the inverters have been also developed. Case studies have been carried out in a distribution network to investigate the dynamic behavior of the micro-sources in both steady state and fault scenarios. Simulation results verify the feasibility of the proposed models.