太阳能-煤炭互补的发电系统与互补方式

多能源综合互补利用系统是近年来能源系统的发展方向之一。该文进行了太阳能与煤炭互补的发电系统与互补方式研究。分析了太阳能热量用于不同容量燃煤机组不同受热面的热经济性,得出在大容量机组上利用太阳能满足水的汽化潜热吸热热经济性要优越于其他方式;利用技术成熟的抛物面槽式集热器收集太阳能热量,和国产300 MW机组进行互补发电系统的拟定;分析了在这种互补发电方式太阳能场的设计中,影响设计辐射强度选取的主要因素,并以3个地区的辐射资源为例进行研究,得出太阳能辐射资源与最佳设计太阳能辐射强度的关系。     

一种实用型的太阳能冰箱研究

本文介绍一种实用的太阳能冰箱。通过光伏电池转换，把太阳能转换成电能。我们在吸取国内外已有研究成果的基础上优化整个系统，使这种冰箱完全不用电网电能，并且可以连续工作。将白天太阳能转换成充裕的电能，既能使太阳能冰箱正常工作，又能向蓄电池充电，夜晚和下雨天则利用蓄电池的电能向冰箱供电。通过三个月的连续测试，可保证95％的正常使用率。     

Forecasting of solar irradiance with just‐in‐time modeling

PV power output mainly depends on solar irradiance, which is affected by various meteorological factors. Thus, it is required to predict solar irradiance in the future for the efficient operation of PV systems. In this paper we develop a novel approach for solar irradiance forecasting, in which we combine the black–box model (JIT modeling) with the physical model (GPV data). We investigate the predictive accuracy of solar irradiance over a wide controlled area of each electric power company by utilizing measured data from 44 observation points throughout Japan provided by JMA and 64 points around Kanto provided by NEDO. Finally, we propose an applied forecasting method of solar irradiance to deal with difficulties in compiling databases. We also consider the influence of different GPV default times on solar irradiance prediction. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 182(4): 19–28, 2013; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22338     

基于感应充电的电动车充电系统设计

简介了电动汽车发展的经济和技术背景,结合了现在电动车充电站结构及充电方式情况,用三维建模软件设计出以太阳能为主要充电来源的充电站大致结构。依据当今电动车充电方式所存在的弊端,结合超级电容技术设计出感应充电方式的理念,介绍了太阳能充电与电力系统之间的相互影响。然后,对人机交互应用等问题提出了研究意义。     

光电-光热区域综合能源系统太阳能消纳能力评估模型

合理评估太阳能消纳能力是支撑构建绿色、低碳、清洁的能源体系的重要环节。针对光电-光热区域综合能源系统太阳能消纳问题,提出了一种可充分考虑光照强度不确定性和系统安全运行约束的太阳能消纳能力鲁棒评估模型。首先,基于热力学第一定律构建了消纳能力评估指标;进而利用配电网二阶锥模型及线性热网能量流模型构建了两阶段鲁棒评估模型,提升了模型的可解性。最后,通过典型算例验证了太阳能综合利用可提高其消纳能力,并对光照强度波动、电网损耗、热电联产(CHP)机组类型、不确定度等因素对消纳能力的影响进行了分析。     

Energy Requirements for Electric Cars and Their Impact on Electric Power Generation and Distribution Systems

Assuming the availability of a high energy and power density battery of 100 Wh/lb and 100 W/lb by the 1980' s, the energy consumption and efficiency of electric and heat engine cars are compared on an equal basis. This is achieved by considering a reference electric car of 3150-lb weight similar in body construction, aerodynamics, and rolling resistance to a conventional heat engine car of equal weight, and comparing the performance of the two cars over the same driving modes. The reference electric car is then used as a baseline to evaluate the possible improvements in future electric cars. The energy consumption for an optimized 2000-lb electric car of driving range, comfort, and performance comparable to a conventional car is estimated. Assuming a gradual growth in electric car population leading to their widespread use by the 1990's, the impact on electric power generation and distribution systems is estimated. Though the analysis is based on a high energy and power density battery the results may be extrapolated to electric cars using lower performance batteries. It is noted that batteries with lower energy density can provide sufficient driving range to fulfill a significant portion of our transportation needs and their continued development and improvement will accelerate the achievement of the high energy-density goal [1].     

Multi-stage Stochastic Optimal Operation of Energy-efficient Building with Combined Heat and Power System

Abstract

Due to the integration of volatile renewable energy and random energy consumption in the building grid, uncertainties have become a big concern for the operation of energy-efficient buildings. To minimize energy usage expenses under uncertainty, it is necessary to determine the optimal power production for a building from various energy sources, including the electric grid, battery, and combined heat and power with a boiler unit. This article presents a multi-stage mixed-integer stochastic programming model for optimal operation of energy-efficient building systems considering controllable electric and thermal loads. Taking into account the randomness of non-controllable electric and thermal loads, as well as solar power generations through the multi-stage scenario tree, the operation of energy-efficient buildings will be more robust against changes in uncertain variables. With information of uncertainties updated hourly, the rolling scheduling method is introduced to determine an adaptive power output of electric grid, charging/discharging status of the battery, and operation of combined heat and power with a boiler unit. The simulation results offer a set of adaptive decision solutions within the scheduling horizon.     

AXIAL FLUX WHEEL MACHINES FOR ELECTRIC VEHICLES

ABSTRACT

Several possible solutions for axial flux wheel motor drives for Electric Vehicles (EVs) are invesligated. As a case study, a small electric city car has been chosen and a 10 kW motor for each wheel has been selected for the comparison between the different motors types. Among die different solutions, die axial flux interior PM motors seem to be the best compromise in terms of efficiency, weight, compactness and capability characteristics.     

考虑光伏出力间歇性的微电网故障辨识方法

在光伏高比例接入的孤岛微电网中,太阳辐照度变化将导致光伏出力明显波动,继而影响微电网线路故障电流变化趋势。对于不同辐照度光伏出力,如何准确完成微电网故障辨识是微电网故障保护研究面临的一个重要问题。针对这一问题,首先建立了含有光伏发电的典型微网模型,分析了孤岛模式下太阳辐照度变化对网内故障电流的影响;然后利用快速小波能量熵(wavelet energy entropy,WEE)算法提取线路故障电流的暂态特征,继而选取简洁清晰的暂态特征并构建故障综合样本集;最后,利用典型故障样本集对极限学习机进行训练,形成一种新的考虑光伏出力间歇性的微网故障辨识方法。算例仿真结果表明所提方法既能精确提取不同辐照度下微网故障的暂态特征,又可准确地实现故障辨识,为微电网故障分析和保护提供了技术支持。     

太阳能电动车混合储能系统的能量管理策略研究

论文提出了一种适用于太阳能电动车的混合动力储能系统方案,给出了该系统的能量管理控制算法,其核心是分配、协调和优化太阳能、蓄电池和超级电容的能量。该系统包含太阳能电池板、boost变换器、蓄电池、超级电容、双向DC／DC变换器和直流无刷电动机。文中提出了一种新的双向DC／DC变换器的控制方法,能够充分利用超级电容的快速充...     

Moment performance of photovoltaic/thermal hybrid panel (numerical analysis and exergetic evaluation)

A photovoltaic/thermal hybrid panel (PV/T) is a high‐efficiency energy converter which supplies electrical energy and thermal energy from solar energy. In this paper, we report characteristics of two PV/T types under various environmental conditions and fluid flow rates, using numerical analysis. We found photovoltaic efficiencies to be 9.61% for PV/T_A and 10.56% for PV/T_B at T _c = 25 °C; thermal ones were 52.11% for PV/T_A and 40.14% for PV/T_B at T_f = 40 °C, I_rr = 800 W/m². From these results, we propose some design points to construct the optimum structure of PV/T. Next, we adopted exergetic evaluation to study electrical energy and thermal energy quantitatively. As a result, we could confirm the existence of flow rate maximizing the total efficiency (optimum flow rate) on some environmental condition, and could define the optimum operating condition. Moreover, we compare exergetic efficiencies on optimum operating conditions (maximum exergetic efficiency) under various environmental conditions with PV, PV/T_A, and PV/T_B. A rise of maximum exergetic efficiency with increasing irradiance yielded –3.6%/kW ⋅ m^–2, +3.6%/kW ⋅ m², and +1.4%/kW ⋅ m², respectively. Nevertheless, we could confirm a hybridizing advantage of high irradiance. © 2000 Scripta Technica, Electr Eng Jpn, 133(2): 43–51, 2000     

太阳能辅助燃煤机组发电系统集热温度优化

为研究集热器工作温度对太阳能辅助燃煤机组发电系统中太阳能发电效率、成本的影响,从热力学第二定律出发,对用于太阳能辅助燃煤机组回热系统不同集成方式下太阳能热发电的火用效率进行分析,得出系统中太阳能发电的火用效率与集热器瞬时热效率及汽轮机抽汽效率之间的关系表达式,并结合LS-2槽式集热器(一种典型槽式集热器)的测试结果,对不同辐照条件下不同替代方式的热性能进行了比较。在此基础上,以太阳集热场辅助300MW燃煤机组发电系统为例对太阳能子系统的火用效率和发电成本(levelizedelectricity costs,LEC)进行分析,结果表明,当太阳直射辐射(direct normal irradiance,DNI)从300变化到1 000 W/m2时,对应的集热器最佳工作温度从277变化到317℃。     

太阳逐日曝辐量预测建模方法研究

建立一种太阳逐日辐射能量预测的小波过程神经网络等效模型。将神经网络与傅里叶变换以及小波多尺度分解相结合,构建了太阳逐日曝辐量的短期预测和中长期预测问题的两种实时在线预测模型,以提高预测精度。将太阳逐日辐射能量混沌时间序列进行相空间重构,其维数作为网络输入数据的傅里叶变换长度,以得到的傅里叶变换系数作为神经网络的输入,避免输入随意性导致预测结果不一定是其解空间的表达问题;通过小波多尺度分解使太阳逐日曝辐量在一定尺度上表现出准平稳性,以此确定神经网络隐层节点数,以减小试凑性造成的误差。将日照百分比、云量与太阳逐日曝辐量的时间序列同时作为输入量,对两种模型进行学习训练和预测分析。仿真结果表明,2种预测模型可在不同的时间尺度上有效地预测太阳逐日曝辐量,且能有效地实时在线递推预测太阳逐日辐射能量。     

Domain behavior in lead zirconate titanate (PZT) thin film capacitors

Abstract

Domain behavior based on surface energy and volumetric free energy was discussed in relation to imprint. Surface enery and volumetric free energy result in net free energy, which determines the critical size for domain growth. If a domain size is greater than the critical size, they will grow spontaneously under a constant electric field or even under zero electric field. Sometimes, they can grow to the extent that they dominate reverse domains. This phenomenon appears to be polarization reversal under zero voltage bias. Spontaneous domain growth either under zero electric field or a constant electric field was demonstratred. This phenomenon can be partly a source of asymmetric imprint mechanism.     

城市轨道交通车辆段电气节能设计

针对城市轨道交通车辆段电气设备耗电量大的问题,从照明系统、动力系统、太阳能新技术应用、运营管理等环节着手,详细论述了目前城市轨道交通车辆段电气领域所运用的各种节能方法,以实现电气节能的最佳综合效益。     

CDMA直放站独立光伏供电系统的优化设计

用太阳能光伏给远离市区的直放站提供电能,不但节约能源、清洁,而且便捷,不需要从数十里远的地方架设电线,有利于保护环境,减少投资.用太阳能光伏作为独立供电系统,首先要解决的是系统的最优设计问题:太阳电池板安装的最佳倾角;对-定功率的用电器配多大功率的太阳电池板;按照系统设计的工作要求如何配套电瓶的容量;选择相应的充电放电...     

A Hydrogen Management Method in Residential Distributed Generation Systems with Photovoltaic Cells and Hydrogen‐Storage Type Fuel Cells

Recently, renewable energy has been attracting attention as a result of global warming and the depletion of fossil fuels. Photovoltaic (PV) systems have spread rapidly around the world because they generate electric power quietly and can be installed in many places. The output power generated in a PV system fluctuates with changes in solar irradiance and panel temperature. The reverse flow of surplus power in output spikes may have a negative effect on electric power quality, such as on the frequency and voltage in a power system. A residential distributed generation (DG) system composed of a fuel cell (FC) unit, an electrolyzer (EL) unit, and a PV system has been proposed in order to resolve these problems. In order to operate this system without interruption, the hydrogen storage volume must be managed. This paper proposes a novel hydrogen management method for a residential DG system with PV cells and hydrogen‐storage type FCs. The hydrogen storage volume is maintained at the preset frequency by operating the FC unit and the EL unit. Models of the PV, FC, and EL were constructed for a simulation. In the simulation, we showed that the proposed management method is viable for a residential DG system with PV cells and hydrogen‐storage FCs.     

Maximum Power Point Tracking Using Disturbance Observer-Based Sliding Mode Control for Estimation of Solar Array Voltage

Abstract

The output power of solar panel in photovoltaic systems is affected by changes in environmental and load conditions. Most currently developed MPPT control algorithms require measurements of panel output voltage, output current, and converter output voltage. In this paper, a new scheme that can cater to uncertainties in the environmental and load condition, is developed using a disturbance observer-based sliding mode control (DOSMC). The proposed DOSMC scheme obviates the need of using a panel output voltage sensor. The proposed scheme does not use a discontinuous control, thereby overcoming the problems of chatter normally associated with the conventional sliding mode control (SMC). The stability is proven in the sense of ultimate boundedness. The proposed scheme is validated by extensive simulation and laboratory experimentation under various scenarios of irradiation, temperature, and load conditions and compared with two existing popular schemes.     

Towards the establishment of maximum PV generation limits due to power quality constraints

The solar irradiance dependent level of harmonic distortion due to PV generation is investigated through a combination of experimental and simulation studies. The expected growth of connection densities of PV systems in distribution networks coupled to the environmental conditions and in particular the fluctuations in solar irradiance can lead to undesirable variations of power and supply quality. In order to be able to predict the harmonic pollution due to PV generation, measurements of power quality indices were carried out at the output of a PV system for a period of 2 weeks. Then, a typical distribution system was modeled using the statistically obtained outcome of the measurements from the PV system. From the simulation of the chosen distribution system we obtained results for voltage distortion and categorized them based on solar irradiance levels. The procedure was then validated using the EN50160 analysis approach. The most extreme case, the high solar irradiance condition, was subsequently used for the simulation of different concentration scenarios, in order to assess the concentration limits set by power quality indices and the results are presented.     

风光氢联合式独立发电系统的建模及仿真

提出了一种独立使用的风光氢联合式独立发电系统，该系统由风力发电、太阳能发电、氢能系统(包括电解水制氢、燃料电池系统、超级电容等)及其他系统单元组成。各单元通过2条直流总线联接，并采用功率流控制。由于风力发电与太阳能发电所输出的功率随风速和日照的变化而变化，因此采用燃料电池系统与超级电容堆与风光发电系统配合使用，以保证系统在任何条件下都具有可靠的供电性能。当风能与太阳能充足时，风机与光伏阵列可满足负荷的需要，同时还可向电解池供电；如果不能满足负荷的需要则由燃料电池提供额外的电能，同时由超级电容在短时期内向负荷提供燃料电池最大功率以外的那部分电能。最后在Matlab环境下建立了系统仿真模型，并以西藏边远村落为例对该系统的动态响应进行了仿真分析，仿真结果表明本文提出的供电系统可以用于以西藏为典型代表的风速和光能变化较大的边远地区。