塔式太阳能光热电站控制系统研究

  目的  旨在解决塔式太阳能光热电站控制领域的难点问题。  方法  首先基于太阳位置计算天文算法,发明了一种高精度,易于工程实现的定日镜跟踪控制算法;其次对定日镜场控制系统的主要控制技术进行了研究,包括系统架构、硬件与软件设计方案、基于图像处理的反馈测量方案;最后对电站的全厂控制系统进行了整体设计规划并提出了镜场控制系统与DCS主控系统之间的信号接口。  结果  可大幅度降低工程成本,缩短建设周期。  结论  研究成果体系完整、易于工程实现,可用较低的工程造价满足塔式光热电站控制精度的要求。     

摩洛哥NOORIII塔式电站定日镜面积达178m~2创下记录

正北极星太阳能光伏网11月21日报道,在建中的摩洛哥NOORIII塔式光热电站在定日镜的商业化应用方面将创下记录,其采用的单台定日镜面积达178 m~2,是Sener设计的最新一款定日镜,也是目前已商业化应用的定日镜的最大尺寸.该电站总计将安装7 400台定日镜,总采光面积约1 317 200 m~2.在已建成的塔式电站中采用最大的定日镜面积的为南非Khi solar one水工质塔式电站,其采用的是     

西西里上的太阳能热电站

1980年12月,意大利西西里岛上建成了世界上第一座太阳能热电站。此电站主要分为两部分:一是定日镜系统,二是中心接收器系统(见图)。电站共有182块定日镜,总面积为6200平方米。其中大部分为曲面聚光镜,它     

塔式太阳能热发电镜场定日镜清洗装置设计

设计了一种应用于塔式太阳能热发电镜场的定日镜清洗装置。该定日镜清洗装置具备自动循迹、根据镜面自动调整清洗面角度、自动进行清洗水流控制的功能,并采用无线通信技术实现清洗装置与镜场控制系统间的信息交互,保证清洗完毕的定日镜立即恢复为正常运营状态,尽量减少镜场能量损失。通过实际测试,该清洗系统能够有效地实现预定的控制功能和清洗功能,其清洗装置通过一次清洗可将镜面清洁度从0.85提高到0.95。     

塔式太阳能热发电中定日镜的精度检测方法

介绍了塔式太阳能热发电中定日镜精度检测的常用方法,包括对定日镜关键零部件及定日镜整体的精度检测。定日镜关键零部件主要包括减速机、推杆(含电动及液压推杆),其精度检测是采用专用的测试工装进行;定日镜整体精度检测主要包括定日镜跟踪准确度及定日镜面形精度检测,均采用图像处理技术进行。通过这些检测方法可保证工程应用中的定日镜能够达到设计要求,起到良好的聚光作用。     

塔式光热电站定日镜跟踪精度校正技术研究

为提高光热电站定日镜校正合格率,从定日镜跟踪精度校正的必要性出发,结合塔式光热电站定日镜控制系统及光斑校正系统对校正的理论依据、校正策略等进行了研究,分析了风速、云层及太阳直接辐射（DNI）、镜面清洁系数、校正系统及临时局域网的稳定性等因素对校正结果的影响,并提出了具体的应对策略。研究表明,当风速小于5 m/s、DNI值大于800 W/m²、镜面清洁系数超过0.7时定日镜跟踪精度的校正合格率能够达到60%以上。     

专利信息

<正>太阳能热利用一种定日镜传动装置专利申请号:CN200820122275.2公开号:CN201232734申请人:杭州工电能源科技有限公司本实用新型为一种定日镜传动装置,涉及一种塔式太阳能集热电站的定日镜传动装置。该装置由上组件和下组件组成,上组件为仰卧角调整传动机     

塔式太阳能定日镜高精度传动系统设计

介绍了一种应用于塔式太阳能热发电的定日镜高精度传动系统,通过该传动系统定日镜可以得到良好的重复定位精度;结合定日镜运动模型的校正算法控制系统,将定日镜转动的定位精度进行测量与补偿,从而得到准确的定位精度与重复定位精度。保证了定日镜跟踪系统追日长久稳定性。该系统对各零部件的精度要求低,具有跟踪精度高、制造成本低等优点。     

塔式太阳能热发电中定日镜的设计及性能分析

提出一种基于水平轴和方位轴、具有二维空间转动、实现两轴静平衡的定日镜结构设计方法,实现塔式太阳能热发电中定日镜高精度跟踪系统、低负荷运转及低成本施工和制作.该定日镜水平轴传动采用电动推杆传动,垂直轴传动采用一齿差传动,水平轴和垂直轴转动的轴线均通过重心,从而实现两轴静平衡;设计了两片间隔式反射镜支架结构,使其结构满足太阳能反射镜子支架转动要求以及反射光斑满足校正要求.通过仿真计算,对光斑、输入输出角度关系及成本进行了分析,论证了该定日镜的可行性.     

基于跟踪轴参考位错位法的定日镜自动纠偏系统

以北京延庆塔式太阳能热发电站的定日镜场自动纠偏系统为研究对象,基于跟踪轴参考位错位法提出定日镜自动纠偏流程以及定日镜两旋转轴参考位偏差量的计算方法。利用迭代的方法,依据这两个方向上的偏差在短时间内修正定日镜的跟踪角度,直至偏差小于纠偏阈值。在每个定日镜跟踪角度修正过程中,两个方向的偏差被用于产生一个临时的对称目标点,并利用定日镜跟踪角度计算公式计算此目标点对应的跟踪角度。利用定日镜场两台定日镜进行实验,实验结果显示定日镜自动纠偏系统可减小定日镜的跟踪误差。     

Multi-tower solar array

The multi-tower solar array (MTSA) is a new concept of a point focussing two-axis tracking concentrating solar power plant. The MTSA consists of several tower-mounted receivers which stand so close to each other that the heliostat fields of the towers partly overlap. Therefore, in some sectors of the heliostat field neighbouring heliostats are alternately directed to the receivers on different towers. This allows the MTSA to use radiation which would usually remain unused by a conventional solar tower system due to mutual blocking of the heliostats and permits an MTSA to obtain a high annual ground area efficiency (efficiency of usage of ground area). In the sectors close to the towers, where the shading effect predominates, all heliostats are directed to the nearest tower. In sectors further away from the towers, the heliostats are alternately directed to the receivers on two, three, or four different towers. To reduce dilution of the radiation from the field, the number of towers the heliostats in a specific region can be directed to may be limited to two, which causes almost no losses in the annual ground area efficiency.     

塔式太阳能热发电系统镜场调度方法的研究

提出一种塔式太阳能热发电系统中定日镜调度的方法。根据太阳、定日镜和接收面的光学成像关系,考虑太阳位置、镜面反射率和能见度等因素给出了镜场光能转换效率的计算方法,同时结合定日镜场状态及热力系统所需光功率建立了镜场调度模型。该文将定日镜的调度转化为一个0-1背包问题,设计了一种混合遗传算法来对其求解。采用该调度方法可得到各时刻转换效率最高时所需调用的定日镜数量及其分布,并可调整定日镜瞄准接收靶上分布的目标点,使吸热器上能流分布均匀,降低峰值能流密度,避免过热故障。仿真算例结果表明了该方法的有效性。     

Range of motion study for two different sun-tracking methods in the application of heliostat field

Since the beginning of the history in the application of heliostats, the sun-tracking method is generally implemented using the Azimuth-Elevation method. Although Spinning-Elevation method was first proposed by Ries et al. and then popularized by Chen et al., it is still not widely applied in a large scale solar energy application especially in central tower system. This paper will study in more detail the implementation of the Spinning-Elevation method in the central tower system for a comparison to that of the typical Azimuth-Elevation method. The annual accumulated angles of the two different sun-tracking methods were analyzed in details for both the cases of a single heliostat and the heliostat field.     

An optimization tool to design the field of a solar power tower plant allowing heliostats of different sizes

The design of a solar power tower plant involves the optimization of the heliostat field layout. Fields are usually designed to have all heliostats of identical size. Although the use of a single heliostat size has been questioned in the literature, there are no tools to design fields with heliostats of several sizes at the same time. In this paper, the problem of optimizing the heliostat field layout of a system with heliostats of different sizes is addressed. We present an optimization tool to design solar plants allowing two heliostat sizes. The methodology is illustrated with a particular example considering different heliostat costs. Copyright © 2017 John Wiley & Sons, Ltd.     

A new method for the design of the heliostat field layout for solar tower power plant

A new method for the design of the heliostat field layout for solar tower power plant is proposed. In the new method, the heliostat boundary is constrained by the receiver geometrical aperture and the efficiency factor which is the product of the annual cosine efficiency and the annual atmospheric transmission efficiency of heliostat. With the new method, the annual interception efficiency does not need to be calculated when places the heliostats, therefore the total time of design and optimization is saved significantly. Based on the new method, a new code for heliostat field layout design (HFLD) has been developed and a new heliostat field layout for the PS10 plant at the PS10 location has been designed by using the new code. Compared with current PS10 layout, the new designed heliostats have the same optical efficiency but with a faster response speed. In addition, to evaluate the feasibility of crops growth on the field land under heliostats, a new calculation method for the annual sunshine duration on the land surface is proposed as well.     

A new code for the design and analysis of the heliostat field layout for power tower system

A new code for the design and analysis of the heliostat field layout for power tower system is developed. In the new code, a new method for the heliostat field layout is proposed based on the edge ray principle of nonimaging optics. The heliostat field boundary is constrained by the tower height, the receiver tilt angle and size and the heliostat efficiency factor which is the product of the annual cosine efficiency and the annual atmospheric transmission efficiency. With the new method, the heliostat can be placed with a higher efficiency and a faster response speed of the design and optimization can be obtained. A new module for the analysis of the aspherical heliostat is created in the new code. A new toroidal heliostat field is designed and analyzed by using the new code. Compared with the spherical heliostat, the solar image radius of the field is reduced by about 30% by using the toroidal heliostat if the mirror shape and the tracking are ideal. In addition, to maximize the utilization of land, suitable crops can be considered to be planted under heliostats. To evaluate the feasibility of the crop growth, a method for calculating the annual distribution of sunshine duration on the land surface is developed as well.     

Design and evaluation of esolar’s heliostat fields

Central receiver concentrating solar power plants offer significant performance advantages over line-focus systems. However, the high cost of the heliostat field remains a barrier to the widespread adoption of such plants. eSolar has approached the problem of heliostat field cost by emphasizing small size, low cost, easy installation, and high-volume manufacturing of heliostat field components.During 2008 and 2009, eSolar designed, constructed, and began operation of its demonstration facility, which comprises two towers each with heliostat subfields to the north and the south. These heliostat fields are composed of large numbers of small heliostats, creating an arrangement unlike other central receiver plants. This paper describes the design, construction, startup, and testing of these heliostat fields, showing that they perform well and represent a viable alternative to more traditional fields of large heliostats.     

Improving the optical efficiency of a concentrated solar power field using a concatenated micro-tower configuration

The concatenated micro-tower (CMT) is a new configuration for concentrated solar power plants that consists of multiple mini-fields of heliostats. In each mini-field, the heliostats direct and focus sunlight onto designated points along an insulated tube, where thermal receivers are located. The heat transfer fluid, flowing through a multitude of discrete receivers, is combined and directed towards a single power block. The key advantages of CMT are its dual-axis tracking system and dynamic receiver allocation, i.e., the ability of each heliostat to direct sunrays towards receivers from adjacent mini-fields throughout the day according to their optical efficiency. Here we compare between the annual optical efficiencies of a conventional trough, large tower, and CMT configuration, all located at latitude 36 N. For each configuration, we calculated the annual optical efficiency based on the cosine factor and atmospheric transmittance. CMT’s dynamic receiver allocation provides more uniform electricity production during the day and throughout the year and improves the annual optical efficiency by 12-19% compared to conventional trough and large tower configurations.     

An artificial vision-based control system for automatic heliostat positioning offset correction in a central receiver solar power plant

This paper presents the development of a simplified and automatic heliostat positioning offset correction control system using artificial vision techniques and common CCD devices. The heliostats of a solar power plant reflect solar radiation onto a receiver (in this case, a volumetric receiver) placed at the top of a tower in order to provide a desired energy flux distribution correlated with the coolant flow (in this case air mass flow) through the receiver, usually in an open loop control configuration. There exist error sources that increase the complexity of the control system, some of which are systematic ones, mainly due to tolerances, wrong mirror facets alignment (optical errors), errors due to the approximations made when calculating the solar position, etc., that produce errors (offsets) in the heliostat orientation (aiming point). The approximation adopted in this paper is based on the use of a B/W CCD camera to correct these deviations in an automatic way imitating the same procedure followed by the operators. The obtained images are used to estimate the distance between the sunbeam centroid projected by the heliostats and a target placed on the tower, this distance thus is used for low accuracy offset correction purposes. Basic threshold-based image processing techniques are used for automatic correction.     

An experimental and numerical study of the gap effect on wind load on heliostat

The main handicap of the concentrating solar power technology is still the higher cost compared with the conventional coal power plant. Heliostat arrays cause about 40% of the costs of central receiver power plants. The cost reduction of heliostats is of crucial importance to central receiver power plants. The reduction of wind load on heliostats will decrease the structural requirement for heliostats, and then cut the cost of heliostats. In this paper, different gap sizes (0–40 mm) between the facets of the heliostats were studied experimentally and numerically. Both of the results showed that the wind load increases slightly with the increase of gap size (0–40 mm). The result of the numerical simulation shows the flow pattern through the gap resembles a jet flow which does not affect the static pressure on the windward surface but does decrease the static pressure on the leeward surface of the facets. Consequently it increases the total drag force on the heliostat. However, the absolute increment of the wind load is very small compared with the overall wind load on the heliostat structure. It is not necessary to take account of the gap size effects on the wind load during the design process of heliostat.