共查询到19条相似文献,搜索用时 140 毫秒
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沿海风电场滩涂软土含水率高,压缩性大,必须对其加固才能进行风电基础施工。为研究硫氧镁水泥固化滩涂软土的加固机理及微观特性,开展了硫氧镁水泥复合固化剂加固滩涂软土的XRD试验以及不同初始含水量(w )、固化剂掺量(W g )和龄期(T )下固化滩涂软土的扫描电镜(SEM)试验,利用图像处理技术研究固化滩涂软土微观孔隙、微观颗粒形态以及接触面积率(R CA )受W g 、 w 和T 影响的规律。研究结果发现,固化滩涂软土主要由石英、5Mg(OH)2·MgSO4·7H2O相(简称5·1·7相)、白云石、叶腊石、M-F-A-S凝胶相以及少许CaO和MgO构成,固化机理包括改性硫氧镁水泥的水解和水化反应、离子交换及填充作用和碳酸化作用,固化滩涂软土微观孔隙可分为凝胶、接触和骨架3种类型,固体颗粒呈叶片状、颗粒状和凝块状3种形态。微观结构参数(R CA )与宏观力学参数,即初始切线模量E i 和强度指标(c 和φ )均随w 的增加而减小,随着W g 和T 的增加而增大。最后建立了固化滩涂软土的R CA 与E i 、 c 、 φ 之间的函数关系。 相似文献
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该文定量研究电子和质子辐射对太阳电池输出特性的影响。首先,证实作者前期工作得到的太阳电池输出电流-电压(I-V)模型仍适用于高能粒子辐射后的太阳电池;其次,由太阳电池输出电流-电压特征量定义一个等效电阻(R eq )。采用最小二乘方曲线拟合方法,找到能够定量描述太阳电池能量转化效率(PCE)与等效电阻(R eq )的关系,并且定量解释了经历电子和质子辐照的太阳电池的等效电阻(R eq )同辐照剂量的关系。最后,扩展这个模型用于定量描述太阳电池外量子效率(EQE )与入射光子能量(hν )的关系,经拟合验证,该模型与实验数据十分吻合,理论同实验结果的相关系数R 大于0.98,平均相对误差(ARE )小于3%。 相似文献
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设计一种太阳能热泵联合风电蓄热系统,并建立系统动态模型。为获得最大太阳辐照量和最小生命周期成本,使用4种不同优化算法对集热器倾角(CTA )、集热器方位角(CAA )、集热器面积(CA )、水箱容积(T V 1 、 T V 2 )、热泵功率(H P 1 、H P 2 )和电锅炉功率(BP )等关键参数进行优化。以乌鲁木齐某单位行政楼的供暖系统为对象进行算例分析。结果表明:Hooke-Jeeves方法优化效果最佳,CTA 为(φ - 6 ° )(φ 为当地纬度)、CAA 为( α - 2.5 ° ) (α = 0 ° 为正南朝向)时,可使系统获得最大采暖季辐照量;T V 2 / BP 为69.8 L/kW,T V 1 / CA 为86.4 L/m2,(H P 1 + H P 2 )/CA 为125.6 W/m2,系统生命周期成本最低,相比优化前,参数优化后的系统生命周期成本节省11.8%。 相似文献
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以近海风电伞式吸力锚基础为研究对象,进行室内水槽试验和数值模拟,研究波浪作用下伞式吸力锚基础周围冲刷演变机制,分别基于Raaijmakers和Myrhaug模型,提出随机波浪小Keulegan-Carpenter数(KC)情况下伞式吸力锚基础周围平衡冲刷深度预测模型。结果表明:随机波浪下,波峰时形成的旋涡体系主导冲刷过程,此时基础上游逆压梯度最大,这有利于波浪边界层充分分离,形成马蹄形旋涡,马蹄形旋涡和桩侧流线压缩导致筒裙上游两侧约45°圆心角位置剪切流速最大,筒裙和锚枝的设置保护了该位置床面土体,使得最大冲刷深度位置位于锚枝之间。当KC 采用K C s , p ,且K C s , p < 8 时,修正Raaijmakers模型预测的平衡冲刷深度S eq ' 与计算值具有较好的一致性,当K C s , p > 8 时,预测值与试验值之间的误差变大,修正Raaijmakers模型过分估计了平衡冲刷深度。当K C rms , a < 4 ,n = 10 时,修正Myrhaug平衡冲刷深度预测模型预测效果最好。 相似文献
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以园林废弃物为原料进行水热碳化制备固体生物燃料水热炭,研究不同温度、时间对水热炭燃料特性和燃烧行为的影响,利用燃烧动力学对水热炭燃烧过程及参数进行模拟计算。结果表明:制备的园林废弃物水热炭的燃料特性得到明显改善,且水热炭燃料特性受温度影响较为显著。水热炭热值范围为19.86~27.93 MJ/kg,达到与工业煤相当的水平。水热炭燃烧参数点火温度(T i )、燃尽温度(T f )和最大失重率温度(T m )随碳化温度的升高和时间的增加而增加,其失重量-失重速率(TG-DTG)曲线移向高温区,表明水热炭的热稳定性提高。水热炭燃烧反应过程的动力学拟合符合一级燃烧动力学线性模型(R 2 = 0.93 ~ 0.99 ),且水热炭具有较高的反应活化能(17.33~41.34 kJ/mol)。 相似文献
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利用中国5个气候区59个气象台站1981——2010年的日值气象数据,对比分析8个散总比和3个散射系数直散分离模型在中国不同气候区的适用性。采用判定系数(R 2 )、均方根误差(RMSE )、平均绝对误差(MABE )、平均误差(MBE )和全局性能系数(GPI )5个误差评价指标,确定各气候区最适宜的模型形式。以该模型为基础,建立适用于中国不同气候区的散总比和散射系数逐日直散分离通用模型。结果表明,除线性形式散射系数模型精度较差外,其他模型计算精度均较高,散总比和散射系数模型平均R 2 分别为0.85和0.62;基于晴空指数-日照百分率的二次多项式散总比模型和基于日照百分率三次多项式散射系数模型在不同气候区精度均最高;以该模型为基础建立中国不同气候区散总比和散射系数逐日直散分离通用模型,其平均R 2 分别为0.89和0.70。 相似文献
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以不同掺杂元素的高效双面p型PERC电池电性能参数在紫外辐照后的衰减特性为研究对象。硼元素掺杂和镓元素掺杂的双面PERC电池背面受紫外光辐照后,背面、正面效率均发生衰减,但两者背面效率衰减主要来自于I sc 衰减,而正面效率衰减主要来自于FF 衰减,U oc 在整个紫外辐照过程中表现稳定,背面衰减与紫外辐照后钝化层的折射率增大有关,而正面衰减可能与电池串阻增大有关。通过增加电池背面钝化层厚度优化紫外稳定的镓掺杂双面电池的紫外稳定性。优化后的电池在15 kWh/m2紫外辐照后,电池背面效率衰减仅为0.04%,同时其正面效率衰减相比于未加厚的电池下降0.32%,说明这种镓掺杂双面电池在户外光照下高稳定的潜力。 相似文献
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S.M. Alghuwainem 《Solar Energy Materials & Solar Cells》1997,46(3):249-257
A solar cell array is inherently a nonlinear device consisting of several solar cell modules connected in series-parallel combinations to provide the desired DC voltage and current. At a fixed insolation level, the terminal voltage decreases nonlinearly as the load current increases. Due to this nonlinearity, it is difficult to determine analytically the operating point at which the output power is maximum; a condition required for maximum utilization efficiency of the array. Iterative techniques are normally used to determine this operating condition. These techniques are lengthy, time-consuming, and have to be repeated for any change in the array's parameters, temperature, and insolation level. In this paper, an accurate closed-form solution is derived in terms of the array's parameters and solar insolation level. This solution is useful to the system designer or researcher as a fast and accurate tool for system design and performance analysis. 相似文献
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In this paper the development of a new laboratory prototype for the emulation of a photovoltaic (PV) field is presented. The proposed system is based on a DC/DC step-down converter topology and allows to obtain the solar array I–V curves, taking into account the environmental changes in solar irradiance and cell temperature. The DC/DC converter control strategy is deduced by using a comprehensive mathematical model of the PV field whose parameters are obtained from the knowledge of: (a) maximum power point data, measured when the PV plant power converter is running, (b) open circuit voltage and short-circuit current, measured off-line. This approach allows the most accurate representation of the PV source. Computer simulations and experimental results demonstrate that the proposed circuit acts as a highly accurate and efficient laboratory simulator of the photovoltaic array electrical characteristics both in steady state and transient conditions. Partial shading and fluctuating conditions can be reproduced too. Moreover the dynamic behaviour of the proposed laboratory emulator is suitable to its effective connection to power electronic interface to the utility or to load through a DC/DC boost converter. 相似文献
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由于在飞行过程中,温度、辐照度和倾角变化都会对临近空间飞行器上太阳电池的输出功率及效率产生影响,该文利用太阳光模拟器及薄型晶体硅太阳电池,进行多组测量实验,得到在不同温度、辐照度和倾角条件下,太阳电池的短路电流、开路电压等参数,并通过与模型仿真结果进行对比,对已有太阳电池电模型进行修正,得到更接近真实飞行工况的临近空间飞行器用薄型晶体硅太阳电池的模型。最后,基于修正后的模型通过仿真对太阳电池阵列在临近空间的全天发电功率变化趋势进行预测,可为临近空间飞行器用太阳电池阵列设计与功率预测提供重要参考。 相似文献
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A novel on-line MPP search algorithm for PV arrays 总被引:3,自引:0,他引:3
A novel maximum power point (MPP) search algorithm for photovoltaic (PV) array power systems is introduced. The proposed algorithm determines the maximum power point of a PV array for any temperature and solar irradiation level using an online procedure. The method needs only the online values of the PV array output voltage and current, which can be obtained easily by using just current and voltage transducers. The algorithm requires neither the measurement of temperature and solar irradiation level nor a PV array model that is mostly used in look-up table based algorithms. Satisfactory results were obtained with the proposed algorithm in a laboratory prototype implementation scheme consisting of a PV array computer emulation model, a chopper controlled permanent magnet DC motor, and a DT2827 data acquisition board with the ATLAB software drivers for interfacing 相似文献
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太阳能光伏发电最大功率跟踪控制器的研究 总被引:1,自引:1,他引:0
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。 相似文献
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Hongmei Tian Fernando Mancilla-David Kevin Ellis Eduard Muljadi Peter Jenkins 《Solar Energy》2012,86(9):2695-2706
This paper presents a modified current–voltage relationship for the single-diode model. The single-diode model has been derived from the well-known equivalent circuit for a single photovoltaic (PV) cell. A cell is defined as the semiconductor device that converts sunlight into electricity. A PV module refers to a number of cells connected in series and in a PV array, modules are connected in series and in parallel. The modification presented in this paper accounts for both parallel and series connections in an array. Derivation of the modified current–voltage relationships begins with a single solar cell and is expanded to a PV module and finally an array. Development of the modified current–voltage relationship was based on a five-parameter model, which requires data typically available from the manufacturer. The model accurately predicts voltage–current (V–I) curves, power–voltage (P–V) curves, maximum power point values, short-circuit current and open-circuit voltage across a range of irradiation levels and cell temperatures. The versatility of the model lies in its accurate prediction of the aforementioned criteria for panels of different types, including monocrystalline and polycrystalline silicon. The model is flexible in the sense that it can be applied to PV arrays of any size, as well as in simulation programs such as EMTDC/PSCAD and MatLab/Simulink. Accuracy of the model was validated through a series of experiments performed outdoors for different configurations of a PV array. 相似文献
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Solar photovoltaics (PVs) have nonlinear voltage–current characteristics, with a distinct maximum power point (MPP) depending on factors such as solar irradiance and operating temperature. To extract maximum power from the PV array at any environmental condition, DC–DC converters are usually used as MPP trackers. This paper presents the performance analysis of a coupled inductor single-ended primary inductance converter for maximum power point tracking (MPPT) in a PV system. A detailed model of the system has been designed and developed in MATLAB/Simulink. The performance evaluation has been conducted on the basis of stability, current ripple reduction and efficiency at different operating conditions. Simulation results show considerable ripple reduction in the input and output currents of the converter. Both the MPPT and converter efficiencies are significantly improved. The obtained simulation results validate the effectiveness and suitability of the converter model in MPPT and show reasonable agreement with the theoretical analysis. 相似文献
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基于光伏发电系统的物理模型研究,在matlab/simulink中开发了包含光伏阵列模型、光伏阵列的最大功率跟踪(MPPT)模块、DC/DC升压电路和采用电压及电流环控制的逆变系统在内的动态仿真模型,并建立了基于电压型逆变器的暂态数学模型;并通过仿真得到了并网光伏发电系统辐射强度突变和发生短路时的暂态运行特性,为深入研究并网光伏发电系统的暂态特性建立了基础。 相似文献