Developing and applying a GIS-assisted approach to evaluate visual impact in wind farms

Wind energy represents one of the most important renewable resources. Wind energy is a clean, renewable and its benefits are considered greater than the disadvantages. However, even though wind farms represent environmentally friendly projects, they frequently generate public resistance.One of the main disadvantages of wind farm construction projects is their poor aesthetic integration into the landscape. On the other hand, landscape impact of wind farms could be minimised if the visual impact is previously evaluated.As regards with the European legislation, the procedure of environmental impact assessment study is necessary before a wind farm project could be established. In contrast, there is not an objective methodology to assess the visual impact of wind farms.The aim of this work was to develop a methodology to predict and evaluate, before its construction, the visual impact of wind farms, taking into account the visualscape from different observation points.Proposed methodology could help to determine and evaluate the best location for new wind farm projects. Moreover, this method could be used as a consulting tool for public organization and private institutions, being quick, concise and clear.     

海上风电场对鸟类的影响及其危害预防

目的 风能作为公认的最成熟的可再生能源技术之一,近年来发展迅速。中国在近年开发了大量的海上风电项目。但风电场对环境,尤其是对鸟类的影响引发了人们大量的担忧和研究。在碳达峰实现之前,我国的海上风能产业将持续增长,需要全面了解风电场对鸟类的影响。 方法 通过总结现有研究,对海上风电场引起的鸟类问题进行了综述,并讨论了可将对鸟类不利环境影响降至最低的预防和缓解措施。 结果 研究表明：危害鸟类生存的风电问题主要有风力涡轮机叶片撞击和风机运行噪音两方面的原因,尚无明确的证据表明鸟类会受到电磁场的影响。风电场的运行可能造成鸟类栖息地的变迁、繁殖和交流的受阻以及种群结构的改变等。人们可以通过风电场选址、风电场形态及风机叶片和桩机结构设计、遥感与视频监控等方式减少风电场对鸟类的不利影响。 结论 对风电场鸟类开展更加深入的研究,将有利于我们掌握海上风电场开发建设及运营相关的鸟类生态学基本规律,形成降低生态环境负面影响的科学决策。     

Spanish method of visual impact evaluation in wind farms

The present Spanish laws on the procedure to evaluate the environmental impact of wind farms are ambiguous, especially those pertaining to visual impact. There is no specific national law but only regional laws. The main targets of these laws are the conservation of the environment (protected animals and plants), and the noise generated. The focus of this paper, the visual impact, is not taken into account in a direct way in these laws.This work develops a methodology to predict, before its construction, the visual impact that a wind farm can have. This could be used as a consulting tool to analyze and evaluate wind projects, both government-run and private.The developed methodology is quick, concise and clear.     

海上风电场对鸟类的影响及其危害预防

[目的]风能作为公认的最成熟的可再生能源技术之一,近年来发展迅速.中国在近年开发了大量的海上风电项目.但风电场对环境,尤其是对鸟类的影响引发了人们大量的担忧和研究.在碳达峰实现之前,我国的海上风能产业将持续增长,需要全面了解风电场对鸟类的影响.[方法]通过总结现有研究,对海上风电场引起的鸟类问题进行了综述,并讨论了可将...     

Dynamic models of wind farms with fixed speed wind turbines

The increasing wind power penetration on power systems requires the development of adequate wind farms models for representing the dynamic behaviour of wind farms on power systems. The behaviour of a wind farm can be represented by a detailed model including the modelling of all wind turbines and the wind farm electrical network. But this detailed model presents a high order model if a wind farm with high number of wind turbines is modelled and therefore the simulation time is long. The development of equivalent wind farm models enables the model order and the computation time to be reduced when the impact of wind farms on power systems is studied. In this paper, equivalent models of wind farms with fixed speed wind turbines are proposed by aggregating wind turbines into an equivalent wind turbine that operates on an equivalent wind farm electrical network. Two equivalent wind turbines have been developed: one for aggregated wind turbines with similar winds, and another for aggregated wind turbines under any incoming wind, even with different incoming winds.The proposed equivalent models provide high accuracy for representing the dynamic response of wind farm on power system simulations with an important reduction of model order and simulation time compare to that of the complete wind farm modelled by the detailed model.     

Development of a decision support system for setting up a wind energy policy across the Walloon Region (southern Belgium)

Wallonia (the region covering southern Belgium) is committed to making a significant increase in its wind-powered electricity production capacity by 2010. Therefore, a decision support system designed to evaluate and map environmental and landscape constraints fundamental to the building of wind farms was developed for the whole Walloon Region (17,000 km²). This system is a geodatabase using 40 criteria (landscape or environmental) corresponding to three constraint levels (exclusion, highly sensitive and sensitive). This geodatabase also has analysis functions developed in the ArcGIS 9 software environment that are used to update the overall constraints map, to analyse sensitivity with respect to constraint criteria-defining parameters as well as to perform full diagnostic studies on wind farm projects.     

生态系统理念在海上风电项目管理中的应用研究

  [目的]  中国海上风电行业已迈入快速发展期,如何创新项目开发管理模式,有效应对海上风电造价高、界面多、工期长等问题,实现成本降低、效能提升,是推动海上风电行业健康快速发展的重要保障。  [方法]  通过将生态系统理念应用到海上风电场项目开发建设和运营管理中,探索构建海上风电场生态系统,以搭建风电场神经网络为核心,提高整体关联效能,实现最优开发目标;利用层次分析法对系统影响因子权重进行定量分析。  [结果]  通过海上风电场生态系统的构建,使海上风电场具备信息快速的收集、存储、共享、分析和反馈调节功能,降本增效,提升风电场稳定性。  [结论]  生态系统的引入为海上风电项目的开发管理和提供了新的思路,借助人工智能技术等前沿科技的发展,海上风电场生态系统也将不断完善和广泛应用。     

Aggregated dynamic model for wind farms with doubly fed induction generator wind turbines

As a result of increasing wind farms penetration in power systems, the wind farms begin to influence power system, and thus the modelling of wind farms has become an interesting research topic. Nowadays, doubly fed induction generator based on wind turbine is the most widely used technology for wind farms due to its main advantages such as high-energy efficiency and controllability, and improved power quality. When the impact of a wind farm on power systems is studied, the behavior of the wind farm at the point common coupling to grid can be represented by an equivalent model derived from the aggregation of wind turbines into an equivalent wind turbine, instead of the complete model including the modelling of all the wind turbines. In this paper, a new equivalent model of wind farms with doubly fed induction generator wind turbines is proposed to represent the collective response of the wind farm by one single equivalent wind turbine, even although the aggregated wind turbines operate receiving different incoming winds. The effectiveness of the equivalent model to represent the collective response of the wind farm is demonstrated by comparing the simulation results of equivalent and complete models both during normal operation and grid disturbances.     

Adding wind power to a wind-rich grid: Evaluating secondary suitability metrics

As the quantity of renewable electricity generation from wind farms increases in a region, the costs associated with integrating it into the broader electricity system also grow. This is primarily due to the need for dispatchable generators that vary power output to compensate for wind farm power variations. Such “balancing services” are an economic cost to the system that is typically not passed on to wind farms. We propose including the use of technical merits other than capacity factor and cost of energy for evaluating new wind farm sites and present a new graphical geospatial method, with the intention of identifying sites that minimize the need for additional electricity balancing service and transmission congestion. Specifically, locations with low correlation to existing wind farms, locations with high correlation to load, locations with high characteristic power time-shift from existing wind farms, and locations that relieve or do not negatively impact electricity transmission congestion are identified. A geospatial Venn diagram-based method of visualization is presented. These methods will equip regional planners with new tools to encourage wind farm development in areas that benefit the electricity grid beyond the lowest bid price.     

Guidelines for assessment of investment cost for offshore wind generation

Offshore wind generation represents a key element for development of renewable energy, thanks to higher availability of energy source and lower presence of constraints. However, the feasibility of offshore wind farms has to be carefully evaluated, due to remarkable economical efforts required. In this paper, economic issues concerning costs in pre-investment and investment stages for offshore wind farms exploiting alternating-current transmission system are analysed. Single cost centres are detailed, taking into account technical features and current equipment exploitation. The aim is to formulate a general model to evaluate the total investment depending on wind farm layout. The model is employed to determine the most suitable connection solution for a 150-MW test wind farm, accounting for different connection schemes and the presence of an offshore or onshore substation. Further tests are run to evaluate cost variation for larger wind farms with different nominal voltage levels.     

A geographic analysis of wind turbine placement in Northern California

The development of new wind energy projects requires a significant consideration of land use issues. An analytic framework using a Geographic Information System (GIS) was developed to evaluate site suitability for wind turbines and to predict the locations and extent of land available for feasible wind power development. The framework uses rule-based spatial analysis to evaluate different scenarios. The suitability criteria include physical requirements as well as environmental and human impact factors. By including socio-political concerns, this technique can assist in forecasting the acceptance level of wind farms by the public. The analysis was used to evaluate the nine-county region of the Greater San Francisco Bay Area. The model accurately depicts areas where large-scale wind farms have been developed or proposed. It also shows that there are many locations available in the Bay Area for the placement of smaller-scale wind turbines. The framework has application to other regions where future wind farm development is proposed. This information can be used by energy planners to predict the extent that wind energy can be developed based on land availability and public perception.     

Aesthetic impact assessment of solar power plants: An objective and a subjective approach

Solar energy for the production of electric energy is one source of renewable energy which is experiencing most development in recent years. In countries with high solar radiation indices, as is the case of Spain, expectations of installation of large solar power plants are increasing. Most solar power plants are located in rural environments, where the landscape has remained practically unaltered ever since extensive agriculture was introduced. Because of this, one of the most significant environmental impacts of this type of installation is the visual impact derived from the alteration of the landscape. In this work, an indicator is proposed for the quantification of the objective aesthetic impact, based on four criteria: visibility, colour, fractality and concurrence between fixed and mobile panels. The relative importance of each variable and the corresponding value functions are calculated using expert contribution. A study of the subjective aesthetic impact is then carried out using the semantic differential method, to obtain the perception of a sample of individuals of the initial landscapes and of the landscapes altered through the installation of a solar power plant. The indicator and the study of public perception are applied to five real solar power plants, to test their reliability. Subsequently, a different group of individuals is used to determine preferences between the five solar power plants. The study proves that the combined use of objective indicator and subjective study, faithfully explains user preferences corresponding to the combined comparisons of the five cases. It is concluded that the tools proposed for the evaluation of the aesthetic impact of solar power plants are useful for the selection of optimal plant location and most adequate use of panel technology, to minimise aesthetic impact.     

Cuckoo search for wind farm optimization with auxiliary infrastructure

This paper focuses on the optimization problem of a wind farm layout. This area of research is currently receiving widespread attention, as optimal positioning of the turbines promotes the financial viability of the wind farm and enhances the competitiveness of wind projects in the energy market. In this work, cuckoo search (CS), a modern population‐based metaheuristic optimization algorithm, is used. The objective is to find the turbine layout and types that maximize the net present value of the wind farm, while constraints on the turbine positions have to be met. The following constraints are considered: Firstly, the minimum distance between turbines for safe operation; secondly, a realistic wind farm shape including forbidden zones for installation and the existing infrastructure. Furthermore, the optimization of the wind farm includes an algorithm to find the least expensive layout of the wind farm roads and the electrical collector system. The algorithm is based on Dijkstra's shortest path and Prim's minimum spanning tree algorithms. The test results indicate that the infrastructure cost has a significant effect on the optimum wind farm solution. A genetic algorithm, commonly applied to wind farm micro‐siting problems, is used to benchmark the performance of the CS. The results show that the CS is capable of consistently finding better solutions than the genetic algorithm.     

Monte Carlo analysis of wind farm surge arresters risk of failure due to lightning surges

This paper presents a Monte Carlo procedure intended for the assessment of the metal-oxide (MO) surge arresters risk of failure in onshore wind farms. It focuses on the energy withstand (absorption) capability of the MO surge arresters in relation to lightning surges and in terms of their risk of failure assessment. Presented methodology accounts for the fact that the lightning itself is stochastic in nature and that the MO surge arrester energy capability is a statistical quantity. The well-known backsurge phenomenon is employed as a means for studying the MO surge arresters energy stresses due to lightning surge transients (in onshore wind farms), where the associated transient (i.e. high-frequency) models of particular wind farm components feature prominently. Necessary numerical simulations are carried-out with the well-known EMTP-ATP software package. This procedure could be seen as beneficial in selection of the optimal MO surge arrester energy withstand capability for wind farm projects situated in areas marked with high keraunic levels and/or having high soil resistivity.     

ENDOW (efficient development of offshore wind farms): modelling wake and boundary layer interactions

While experience gained through the offshore wind energy projects currently operating is valuable, a major uncertainty in estimating power production lies in the prediction of the dynamic links between the atmosphere and wind turbines in offshore regimes. The objective of the ENDOW project was to evaluate, enhance and interface wake and boundary layer models for utilization offshore. The project resulted in a significant advance in the state of the art in both wake and marine boundary layer models, leading to improved prediction of wind speed and turbulence profiles within large offshore wind farms. Use of new databases from existing offshore wind farms and detailed wake profiles collected using sodar provided a unique opportunity to undertake the first comprehensive evaluation of wake models in the offshore environment. The results of wake model performance in different wind speed, stability and roughness conditions relative to observations provided criteria for their improvement. Mesoscale model simulations were used to evaluate the impact of thermal flows, roughness and topography on offshore wind speeds. The model hierarchy developed under ENDOW forms the basis of design tools for use by wind energy developers and turbine manufacturers to optimize power output from offshore wind farms through minimized wake effects and optimal grid connections. The design tools are being built onto existing regional‐scale models and wind farm design software which was developed with EU funding and is in use currently by wind energy developers. Copyright © 2004 John Wiley & Sons, Ltd.     

Parametric analysis and assessment of the photovoltaics' landscape integration: Technical and legal aspects

The increasing spread of photovoltaic (PV) systems occurring nowadays does not always keep pace with respective legislative initiatives, especially those regarding a specific relation between PV systems, the natural environment and landscape. As a result of this differentiation, the existence of legislative gaps or omissions is noticed. Thus, while the development of Renewable Energy Sources (RES) is actively promoted by the government in general, from a legal point of view there are no equivalent preventive measures for the protection and preservation of physical environment and landscape aesthetics, at least in all types of RES, with the exception of wind farms. In fact, in the case of PV systems, there is no specific legal framework, which would regulate their integration in the environment, and in particular into landscape.The work analyzes a method for assessment of aesthetic impact caused by PV plants. The method is developed in MATLAB and based on the use of a PV plant photo and the quantification of three parameters: visibility, color and fractality. Purpose of this work is to propose this method as an applicable integration rule of PV systems into landscape, aiming to reduce its aesthetic downgrading, contributing thereby to sustainability.Additionally, in an interdisciplinary approach, the suggested method restores the issue of the explicit legislative provision of specific rules and criteria regarding the PV systems integration into landscape.     

Centralised power control of wind farm with doubly fed induction generators

At the moment, the control ability of wind farms is a prime research concern for the grid integration of large wind farms, due to their required active role in the power system. This paper describes the on-going work of a research project, whose overall objective is to analyse and assess the possibilities for control of different wind farm concepts. The scope of this paper is the control of a wind farm made up exclusively of doubly fed induction generators. The paper addresses the design and implementation issues of such a controller and focuses on the ability of the wind farm control strategy to regulate the wind farm power production to the reference power ordered by the system operators. The presented wind farm control has a hierarchical structure with both a central control level and a local control level. The central wind farm control level controls the power production of the whole farm by sending out reference power signals to each individual wind turbine, while the local wind turbine control level ensures that the reference power signal send by the central control level is reached. The performance of the control strategy is assessed and discussed by means of simulations illustrated both at the wind farm level and at each individual wind turbine level.     

基于偏航尾流模型的风电场功率协同优化研究

为减小风电场尾流效应的影响,提升风电场整体发电量,提出一种基于偏航尾流模型的风电场功率协同优化方法。首先建立风电场偏航尾流模型,该模型包括用于计算单机组尾流速度分布的Jensen-Gaussian尾流模型、尾流偏转模型及多机组尾流叠加模型,对各机组风轮前来流风速进行求解;再根据来流风速计算风电场输出功率,并以风电场整体输出功率最大为优化目标,利用拟牛顿算法协同优化各机组轴向诱导因子和偏航角度。以4行4列方形布置的16台NREL-5 MW风电机组为对象进行仿真研究。结果表明,所提出的基于偏航尾流模型的风电场功率协同优化方法能显著提升风电场整体输出功率。     

Active power variation in wind farms by varying the number of wind turbine units

Aggregated representation of wind turbine units in the wind farm has been normally adopted for modelling and analysis of dynamic performance, with power variation obtained by change of wind speed in the literature. This paper presents a different scenario of power variation of wind farms by the addition and removal of turbines in wind farms and its implication in modelling and stability of wind farms. The steady-state and dynamic stability with the aggregated model of the wind farm has been analysed with variation in the number of turbine units and has been corroborated with time domain simulation in DIgSILENT Power Factory software. It has been concluded that the variation in the number of wind turbines generators connected to the same transmission line has a minimal impact on the stability in nonseries-compensated line; however, significant impact on the stability has been observed in series-compensated system.     

Dependence of optimal wind turbine spacing on wind farm length

Recent large eddy simulations have led to improved parameterizations of the effective roughness height of wind farms. This effective roughness height can be used to predict the wind velocity at hub‐height as function of the geometric mean of the spanwise and streamwise turbine spacings and the turbine loading factors. Recently, Meyers and Meneveau used these parameterizations to make predictions for the optimal wind turbine spacing in infinitely large wind farms. They found that for a realistic cost ratio between the turbines and the used land surface, the optimal turbine spacing may be considerably larger than that used in conventional wind farms. Here, we extend this analysis by taking the length of the wind farm, i.e. the number of rows in the downstream direction into account and show that the optimal turbine spacing strongly depends on the wind farm length. For small to moderately sized wind farms, the model predictions are consistent with spacings found in operational wind farms. For much larger wind farms, the extended optimal spacing found for infinite wind farms is confirmed. Copyright © 2015 John Wiley & Sons, Ltd.