GPS授时与卫星定位技术在太阳跟踪系统中的应用

采用太阳跟踪系统能大大地提高太阳能电池板的光电转换效率,本文采用GS - 87模块,取得当地经纬度和时间,然后根据天文轨迹算法,精确计算出太阳的定位跟踪参数,即高度角和方位角,从而得出太阳的准确位置,实现太阳轨迹的跟踪.     

CPV系统中太阳能转换效率分析方法的探讨

太阳能转换效率是评价太阳能系统优劣的重要指标。在聚光光伏系统中,太阳能转换效率受太阳跟踪误差的影响较大。文章分析了太阳跟踪误差与太阳能转换效率之间的关系,提出了基于跟踪误差的太阳能转换效率误差分析法,填补了光伏产业中缺少太阳能转换效率评定标准的空白。文章以北京地区某日全天太阳光照辐射量数据为例,采用了两种经典的太阳位置算法,对文章所提出的误差分析法进行了验证说明。理论分析和验证表明,误差分析法可以作为评价太阳能系统能量转换效率的评定依据。     

太阳能智能追光装置设计

针对太阳能发电系统中双轴跟踪系统能大幅提高太阳能利用率问题,结合光电探测器与太阳位置算法,采用32位ARM嵌入式微处理器,以步进电机为执行机构实现太阳能智能追光装置的设计.实践表明,跟踪精度可满足太阳能发电系统的要求且性能稳定可靠.     

太阳能自动跟踪发电系统的创新设计

针对现有太阳能光伏发电装置能量转换效率较低的缺陷,设计了一种新型太阳能光伏发电系统——双轴自动跟踪发电系统。研制了光电传感器,分析了光电传感器的工作原理;设计了系统的信号处理及控制电路。该系统能使太阳电池板在晴天始终保持与太阳光线垂直,在夜晚、阴天或太阳光辐照度低于工作照度时自动关机。为了得到该系统的发电功率随时间和天气变化的情况,进行了实验研究,最终得到光伏发电功率随时间和天气变化的规律。     

基于PLC的双轴闭环太阳能跟踪模型

针对目前太阳能跟踪系统存在的问题,分析了现存的几种太阳能跟踪方法的优劣;设计了一套基于方位角和高度角的太阳能跟踪系统,解决了现阶段大多数跟踪系统存在的问题;制作了一套基于ABB PLC的太阳能跟踪模型,并对模型进行了系统测试,测试显示该跟踪系统能提供精度可达0.001°的太阳定位,自动实现了不同要求的跟踪计算和不同条件下的模式转换.     

基于七点法太阳定位器的自动跟踪系统研究

为提高光伏系统的转换效率,基于七点法太阳定位器的结构与原理,分析了其精度,设计了七点法太阳定位器的自动跟踪系统,推导了自动跟踪系统的控制模型和传递函数,并阐明了控制策略.试验结果表明,该自动跟踪系统克服了主动式的误差累积和被动式易受天气影响的缺点,具有跟踪范围广、结构简单、控制方便等优点,提高了太阳能利用率.     

全天候太阳方位跟踪控制系统的设计

采用光感跟踪与时间跟踪相结合的方法,设计了全天候太阳方位跟踪控制系统。该系统包括监测装置、跟踪方式转换控制模块和双跟踪方式控制模块。监测装置监测天气状态为跟踪方式转换控制模块提供判断依据,跟踪方式转换控制模块发出指令启动相关跟踪方式,控制传动及支撑装置的运动,以改变太阳能电池板采光面的位置。系统的跟踪精度高,跟踪能耗低。     

飞雕太阳能收集与高温储能技术装置制作

太阳能热开发利用中有三个需要同时解决的问题:精确简洁地自动跟踪太阳,实时以最大面积采光;将收集到的太阳能转移到固定的地方;实现高温高效的储存或利用。目前的太阳灶或太阳能热发电系统都是在其中某个问题上存在较大的缺陷。为此设计并试制了装置:通过自动跟踪系统分别对太阳的两个运动方向进行相对独立的精确简洁的跟踪,实现凹面镜保持实时以最大采光面积采光;利用光能传输管在系统跟踪太阳的同时定向输出光能;最终光能在储热容器中转换为热能进行高温储存或利用。根据样机的制作结果及试验,该装置可同时有效解决上述三个问题,集成了太阳灶与太阳能热水器的功能,也可用于规模化的太阳能热发电。     

碟式太阳能直接跟踪传感器设计及其应用

为克服碟式太阳能间接跟踪光斑偏心问题,设计一种专门用于高强度光探测和光敏转换的太阳能跟踪传感器,对聚焦光斑进行直接跟踪。采用二级或者多级分隔的光导材料隔绝聚焦光斑的高温,光电传感器对比测量使聚焦光斑汇集到集热器中心,实现跟踪系统最大效率的利用太阳能。实验结果表明:传感器设计方法可行、可有效隔绝光斑的高温。通过Matlab分析每级光导材料光斑温度衰减系数为0.32,此传感器跟踪运行稳定,可提高跟踪精度。该研究为提高碟式太阳能自动跟踪精度提供一种方法。     

聚光型太阳能光电光热一体化装置研制

综合采用太阳跟踪聚光技术和热工原理,设计加工了一种聚光型光电光热一体化装置,并对其进行了实验研究。结果表明,采用层压技术将电池片与热交换器组合在一起,不仅可有效降低电池片的工作温度、确保其光电转换效率、延长其使用寿命,而且可获得一定温度的热水。通过集热板的二次加热,可获得更高温度的热水,从而实现高效、低成本太阳能光电-光热的综合利用。同时,研究还表明,气候条件或空气质量对实际聚光比影响较明显,但对该装置的光电转换效率以及所获得的热水温度无显著影响。     

Development and performance analysis of a two‐axis solar tracker for concentrated photovoltaics

This study presents a two‐axis solar tracking system equipped with a small concentrator module for electricity generation through a multijunction solar cell. The system can accurately track the sun without the need of calibration for an extended period and operate as a stand‐alone system. High‐precision solar tracking was achieved by a combination of open‐loop and closed‐loop controls. A camera tracking sensor was introduced as a feedback device in closed‐loop control. Two different types of solar concentrator modules were designed and fabricated. Their concentration ratios were analyzed against solar tracking errors by means of ray tracing software. One is made up of a paraboloidal primary concentrator and a paraboloidal secondary reflector, whereas the other has a paraboloidal primary concentrator and a hyperboloidal secondary reflector. Both modules showed an almost identical concentration ratio of 610 provided that the solar tracker is pointing perfectly at the sun. However, their performance differs considerably when tracking error is present. The maximum power output was obtained near solar noon with multijunction cells, whose average solar conversion efficiency was 21%, much higher than that of conventional photovoltaic systems. Copyright © 2015 John Wiley & Sons, Ltd.     

Design and testing of a separate-type lighting system using solar energy and cold-cathode fluorescent lamps

This paper presents a solar-powered lighting system, using cold-cathode fluorescent-lamps (CCFLs), with its battery-charging circuit and lamp-ignition circuit being separated so that its solar panels can be installed at any distance deemed necessary away from the lighting site in order to receive the maximum solar energy available. This system adopts the maximum-power point tracking (MPPT) method to control the power output of the solar panels and uses the zero-voltage switching (ZVS) DC–DC converter, as the charging circuit, to increase the panels’ power generation efficiency and the charging circuit’s conversion efficiency. The electronic ballast circuit for the CCFL is constructed with a half-bridge inverter, a resonant inductor, and a Rosen-type piezoelectric transformer, which forms a piezoelectric resonant-type inverter: to simplify the circuitry and to improve the power conversion efficiency, the ballast circuit is designed to directly step up the battery voltage in igniting the lamp. We also establish the transmission-parameter model for the piezoelectric resonant-type inverter to provide the base for the electric-power circuit design. Our experimental results indicate that the proposed system possesses some advantages, such as greater energy efficiency, circuitry simplicity, and so on, and is suitable for night lighting in house yards, parks and advertising panels.     

太阳能光伏发电最大功率跟踪控制器的研究

针对目前太阳能发电系统效率低、铅酸蓄电池使用寿命短等问题,利用微控制器MC9S08QG8设计一种太阳能控制器。该控制器采用升降压式DC/DC转换电路、利用电压扰动法实现最大功率点跟踪,使太阳能电池始终保持最大功率输出;控制器还能实时测量蓄电池的端电压,对蓄电池进行充放电保护。该控制器软硬件结合、可靠性高,提高了太阳能发电系统的效率,延长了蓄电池的使用寿命。     

Development status of high-efficiency HIT solar cells

This paper describes the development status of high-efficiency heterojunction with intrinsic thin-layer (HIT) solar cells at SANYO Electric. Presently, the conversion efficiency of our standard HIT solar cell has reached a level of 23.0% for a practical size of (100.4 cm²) substrate. On the other hand, we have developed special technologies for effectively using thinner substrates for HIT solar cells. Surprisingly, we have achieved a quite high open circuit voltage (V_oc) of 743 mV, and a high conversion efficiency of 22.8% using only a 98-μm-thick substrate. A 98-μm-thick cell also exhibits a good temperature coefficient, and allows the thickness of the substrate to be reduced by more than 50% while maintaining its efficiency. These results suggest that the HIT solar cell has the potential to further improve cost-performance.     

Solar-driven high temperature hydrogen production via integrated spectrally split concentrated photovoltaics (SSCPV) and solar power tower

Hydrogen production can be achieved via combined concentrated photovoltaic (CPV) and concentrated solar power (CSP) in which concentrated radiation is spectrally split and then converted in a photovoltaic receiver and a thermal absorber. This study thus proposes an innovative solar process design integrating both thermal and quantum components of solar energy while providing a complete assessment of its global performance to demonstrate its practical interest. A stand-alone solar-to-hydrogen path was modeled and numerically simulated, which was both electrically and thermally supplied by a solar power generation unit to feed the electrolyzer power utilization unit with enhanced solar-to-hydrogen conversion efficiency. Following balance of plant (BoP), the heliostat field and cavity receiver were designed to match the entire system in which the receiver only intercepts a definite range of infrared wavelength while the rest is converted by separately insulated PV cells. Moreover, dichroic reflectors and optimum cutoff wavelength were applied to fulfill separate optimization and heat load reduction of each solar cell. Finally, the solid oxide electrolysis cell (SOEC) was designed to utilize the generated thermal and electrical power appropriately. In best case scenario, a solar-to-hydrogen conversion efficiency of 36.5% was achieved under 899 W/m² direct normal irradiance (DNI) and 1000 suns concentration. The solar plant outputs at this operating point were 850 g/h H₂ and 6754 g/h O₂. Further improvement in efficiency can be achieved through alignment in regard to the site location and annual insolation variation.     

Design,simulation and experimental study of a directly-irradiated solar chemical reactor for hydrogen and syngas production from continuous solar-driven wood biomass gasification

The use of concentrated solar energy as the high-temperature heat source for the thermochemical gasification of biomass is a promising prospect for producing CO₂-neutral chemical fuels (syngas). The solar process saves biomass resource because partial combustion of the feedstock is avoided, it increases the energy conversion efficiency because the calorific value of the feedstock is upgraded by the solar power input, and it also reduces the need for downstream gas cleaning and separation because the gas products are not contaminated by combustion by-products. A new concept of solar spouted bed reactor with continuous biomass injection was designed in order to enhance heat transfer in the reactor, to improve the gasification rates and gas yields by providing constant stirring of the particles, and to enable continuous operation. Thermal simulations of the prototype were performed to calculate temperature distributions and validate the reactor design at 1.5 kW scale. The reliable operation of the solar reactor based on this new design was also experimentally demonstrated under real solar irradiation using a parabolic dish concentrator. Wood particles were continuously gasified at temperatures ranging from 1100 °C to 1300 °C using either CO₂ or steam as oxidizing agent. Carbon conversion rates over 94% and gas productions over 70 mmol/g_biomass were achieved. The energy contained in the biomass was upgraded thanks to the solar energy input by a factor of up to 1.21.     

聚热式太阳能蒸汽发生系统性能研究

为提高汽化温度,获得较高产蒸汽效率,根据聚热集能及局域加热的原则,设计并搭建无需复杂聚光元件,经济可靠的聚热式太阳能蒸汽发生系统。聚热式太阳能蒸汽发生系统中,顶部热损远高于底部和侧面热损的总和,采用双层玻璃盖板,可减少41%的顶部热损。实验表明:采用聚热集能及双层玻璃盖板减少热损可使水汽化温度达到沸点(94℃)。典型晴天下,8 m²聚热式太阳能蒸汽发生系统的日产蒸汽量4.03 kg,工作温度120~140℃时,太阳能转换效率为9%。     

Experimental study on sulfur trioxide decomposition in a volumetric solar receiver–reactor

Process conditions for the direct solar decomposition of sulfur trioxide have been investigated and optimized by using a receiver–reactor in a solar furnace. This decomposition reaction is a key step to couple concentrated solar radiation or solar high‐temperature heat into promising sulfur‐based thermochemical cycles for solar production of hydrogen from water. After proof‐of‐principle a modified design of the reactor was applied. A separated chamber for the evaporation of the sulfuric acid, which is the precursor of sulfur trioxide in the mentioned thermochemical cycles, a higher mass flow of reactants, an independent control and optimization of the decomposition reactor were possible. Higher mass flows of the reactants improve the reactor efficiency because energy losses are almost independent of the mass flow due to the predominant contribution of re‐radiation losses. The influence of absorber temperature, mass flow, reactant initial concentration, acid concentration, and residence time on sulfur trioxide conversion and reactor efficiency has been investigated systematically. The experimental investigation was accompanied by energy balancing of the reactor for typical operational points. The absorber temperature turned out to be the most important parameter with respect to both conversion and efficiency. When the reactor was applied for solar sulfur trioxide decomposition only, reactor efficiencies of up to 40% were achieved at average absorber temperature well below 1000°C. High conversions almost up to the maximum achievable conversion determined by thermodynamic equilibrium were achieved. As the re‐radiation of the absorber is the main contribution to energy losses of the reactor, a cavity design is predicted to be the preferable way to further raise the efficiency. Copyright © 2009 John Wiley & Sons, Ltd.     

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。