基于SVM的断路器状态监视诊断方法研究

提出了一种基于支持向量机(SVM)的断路器监视诊断方法,通过对断路器故障时的特性参数向量进行训练推理,实现断路器在线监视诊断,并用实例验证了该方法的准确性和快速性。     

pn Junction depth impact on short circuit current of solar cell

The effect of position of pn junction on output current for both micro-rectangular texturing and planar surface in solar cell has been investigated by ray tracing. In geometric optic modeling, this includes finding the effect of position of pn junction on improving the efficiency. The importance of pn junction position in the textured surface of solar cells has been confirmed using the ATLAS software. Texturing improves the efficiency but the effectiveness increases with the depth of pn junction. A textured solar cell with 40 μm depth of pn junction has the 3 times more efficiency than the same non-textured solar cell.Introducing the current variation in the voltage 0.25 V for two surfaces supports this conclusion.     

Satellite-based snow identification and its impact on monitoring photovoltaic systems

Earth observation allows the separation of snow cover and cloudiness using multispectral measurements. Several satellite-based snow monitoring services are available, ranging from regional to world-wide scales. Using these data enables photovoltaic (PV) plant management to differentiate between failures due to snow coverage on a PV system and other error sources. Additionally, yield estimates for solar siting are improved. This paper presents a validation study from January to April 2006 comparing satellite-based datasets with ground measurements from German and Swiss meteorological stations. A false alarm rate, an error due to irradiance underestimation, the availability of daily data, and the classification accuracy are introduced as quality metrics. Compared to Switzerland, generally a higher accuracy is found in all datasets for Southern Germany. The most significant difference among the datasets is found in the error pattern shifting from too much snow (which results in an error due to underestimation of irradiance) to too little snow detection, causing a false alarm in PV monitoring.Overall, the data records of the Land Surface Analysis Satellite Application Facility (LSA SAF), the German Aerospace Center (DLR) and the Interactive Multisensor Snow and Ice Mapping System (IMS) are found to be most suitable for solar energy purposes. The IMS dataset has a low false alarm rate (4%) and a good data availability (100%) making it a good choice for power plant monitoring, but the error due to underestimation relevant in site auditing is large with 59%. If a cumulative snow cover algorithm is applied to achieve information every day as needed both for power plant monitoring and site auditing, both the DLR and the LSA SAF datasets are comparable with classification accuracies of 70%, false alarm rates of 37% and 34%, respectively, and errors due to irradiance underestimation in 26% and 27% of all coincidences.     

基于MCGS的光伏电站数据监测系统的设计与实现

光伏电站数据监测系统以工业控制组态软件MCGS为开发平台,以数据的获取、传输、变换、输出为主线进行程序设计,开发了电站监测计算机数据采集与处理程序.系统程序设计有数据存储、电站数据及曲线动态显示、报警信息查询、自动生成电站系统运行日报表、报表打印等功能.电站数据监测系统采用了分布式数据采集的结构模式,利用传感器、交送器分别对太阳能辐射强度,光伏组件发电数据,以及蓄电池的充放电等重要数据进行采集,最后利用RS-485总线结构模式将采集到的数据传送至监测系统计算机中进行统计与处理.     

基于3D虚拟现实技术的风电场全数字化巡检及监测平台

提出了基于3D虚拟现实技术的风电场全数字化巡检及监测平台的构建方案。该方案利用虚拟现实技术,对风电场全部设备进行3D数字化建模;应用远程通信技术,将风电场运行的状态数据、指标参数引入到巡检与监测平台。在此基础上,设计了系统的硬件结构,构建了信息的有效性检测模型,并建立风电机组的故障失效模式、影响及后果分析模型;结合状态数据、指标参数与分析模型,实现风电场设备故障诊断;同时,将诊断结果提示给工作人员,确保在中控室便能实现风电场的巡检、监测与故障诊断。     

Design and implementation of PLC-based monitoring control system for induction motor

The implementation of a monitoring and control system for the induction motor based on programmable logic controller (PLC) technology is described. Also, the implementation of the hardware and software for speed control and protection with the results obtained from tests on induction motor performance is provided. The PLC correlates the operational parameters to the speed requested by the user and monitors the system during normal operation and under trip conditions. Tests of the induction motor system driven by inverter and controlled by PLC prove a higher accuracy in speed regulation as compared to a conventional V/f control system. The efficiency of PLC control is increased at high speeds up to 95% of the synchronous speed. Thus, PLC proves themselves as a very versatile and effective tool in industrial control of electric drives.     

Government management and implementation of national real-time energy monitoring system for China large-scale public building

The supervision of energy efficiency in government office buildings and large-scale public buildings (GOBLPB) is the main embodiment for government implementation of Public Administration in the fields of resource saving and environmental protection. It is significant for China government to achieve the target: reducing building energy consumption by 11 million ton standard coal before 2010. In the framework of a national demonstration project concerning the energy management system, Shenzhen Municipality has been selected for the implementation of the system. A data acquisition system and a methodology concerning the energy consumption of the GOBLPB have been developed. This paper summarizes the various features of the system incorporated into identifying the building consumes and energy saving potential. This paper also defines the methods to achieve the real-time monitoring and diagnosis: the meters installed at each building, the data transmitted through internet to a center server, the analysis and unification at the center server and the publication through web. Furthermore, this paper introduces the plans to implement the system and to extend countrywide. Finally, this paper presents some measurements to achieve a common benefit community in implementation of building energy efficiency supervisory system on GOBLPB in its construction, reconstruction or operation stages.     

Methods of determining the influence of quality assurance on the reliability of primary components of a PWR

Two failure modes of two different primary components of a PWR are considered: (i) brittle fracture of the reactor pressure vessel and (ii) leakage of the main coolant pipe.The influence of quality assurance on the reliability of these components is evaluated for the following cases: (a) pre-service and in-service ultrasonic inspections and (b) pre-service and in-service hydro-tests.The influence of these different actions on reliability is studied by comparing the estimated reliabilities with and without such actions, the results being presented as relative numbers.By introducing a detection probability of the ultrasonic inspection, the effect on the initial defect distribution—and thus on reliability—can be estimated. This effect on reliability is strongly dependent on the shape of the assumed detection probability. Using that of the Marshall report,¹ the failure probability of the component in question decreases by a factor of approximately 100.The influence of the hydro-test on reliability turns out to be very dependent on the time which has passed since the test. Generally speaking, the effect during the first years after the test is very considerable whereas it strongly decreases thereafter.Taking into account the short intervals between the in-service inspections (for example, four years), the reliability of the components considered can be shown to be extremely high.     

机车走行部旋转部件在线实时监控的研究与应用--以冲击频谱分析为核心的诊断技术的研讨和实践

指出走行部是机车安全、快速运行的关键部位 ,走行部件更是大事故的突发、多发部件。介绍了运用以冲击频谱分析为核心的诊断技术对机车走行部旋转部件进行在线实时诊断的理论和实践 ,为确保机车走行部运行安全提供了全新的思路。     

The impact of plug-in vehicles on greenhouse gas and criteria pollutants emissions in an urban air shed using a spatially and temporally resolved dispatch model

With the introduction of plug-in vehicles (PEVs) into the light-duty vehicle fleet, the tail-pipe emissions of GHGs and criteria pollutants will be partly transferred to electricity generating units. To study the impact of PEVs on well-to-wheels emissions, the U.S. Western electrical grid serving the South Coast Air Basin (SoCAB) of California is modeled with both spatial and temporal resolution at the level of individual power plants. Electricity load is calculated and projected for future years, and the temporal electricity generation of each power plant within the SoCAB is modeled based on historical data and knowledge of electricity generation and dispatch.Due to the efficiency and pollutant controls governing the performance of the Western grid, the deployment of PEVs results in a daily reduction of greenhouse gases (GHGs) and tail-pipe emissions, especially in the critical morning and afternoon commute hours. The extent of improvement depends on charging scenarios, future grid mix, and the number and type of plug-in vehicles. In addition, charging PEVs using wind energy that would otherwise be curtailed can result in a substantial emissions reduction. Smart control will be required to manage PEV charging in order to mitigate renewable intermittencies and decrease emissions associated with peaking power production.     

柴油机虚拟检修系统中的关键技术研究

为了实现在虚拟环境下的柴油机检修和对柴油机检修人员的培训,采用虚拟样机技术与数据库技术相结合,开发了一款以柴油机检修手册为基础的检修系统。应用VC 6 0编程技术,开发了针对Pro/E输出的OBJ图形文件的后处理器。引入OpenGL图形接口,实现对柴油机三维模型的显示,通过提取存储在数据库中的装配信息最终实现虚拟装配。     

Application of geographical information system to site selection of small run-of-river hydropower project by considering engineering/economic/environmental criteria and social impact

In the process of site selection of a small run-of-river hydropower project in Thailand, some problems are addressed as follows: the accessibility of the possible sites which are mostly located in rural and mountainous areas, the large amount of data required, and the lack of participation of the local people living nearby. In order to cope with these problems, this study proposes a new method to select feasible sites of small run-of-river hydropower projects by using Geographic Information System (GIS) technology. A combination of engineering, economic, and environmental criteria, as well as social impact is employed in this study. The selected study area is the upper Nan river basin situated in the north of Thailand. For the engineering criteria, the project locations are found by GIS in visual basic platform, and then economic evaluations of the selected projects are performed. Next, the environmental parameters are used to rank the projects by total weighted scores. Finally, a social impact study at the potential sites is conducted based on the public participation process, i.e. questionnaire survey and focus group discussions. The applicability of the proposed method is verified by the results of site selection of the small hydropower projects located on the Nan river basin in Thailand. This case study can be the model for the process of site selection of similar projects.     

The impact of the life cycle analysis methodology on whether biodiesel produced from residues can meet the EU sustainability criteria for biofuel facilities constructed after 2017

This paper considers biodiesel production from residues; tallow and used cooking oil (UCO). The tallow system is more complex involving two processes. The first process is rendering in which tallow (animal fat) and Meat and Bone Meal (MBM) are produced from the slaughter of cattle. MBM is assumed as a thermal energy source for cement manufacture and thus is not used for biodiesel production. The second process is biodiesel production from tallow. Three methodologies are employed to examine sustainability of the biodiesel. The no allocation approach assigns all the parasitic demands to the tallow; thus all energies required to make both MBM and tallow are associated with the tallow biodiesel. The resulting energy balance is negative. The substitution approach allocates the energy in MBM (used to produce cement) to tallow biodiesel. This results in the net energy being greater than the gross energy. The allocation by energy content method divides the parasitic demands of the rendering process between tallow and MBM by energy content. The parasitic demands of the biodiesel process are divided by energy content of the biodiesel, glycerol and K-fertiliser. For tallow biodiesel this yielded a net energy value of 38.6% of gross energy. The same method generated a net energy value of 67% for UCO biodiesel. More importantly the recommended method (allocation by energy content) generated a value of 54% greenhouse gas (GHG) emission savings for tallow and a value of 69% for UCO. Plants commencing after 2017, need to have a 60% GHG emission savings, to be considered sustainable. Thus a facility treating both feedstocks would need to treat a maximum of 60% tallow to be considered sustainable after 2017.     

Investigation of yield strength and single cycle overload on crack closure

Crack closure experiments were performed on 6063-T6 and 6061-T6 aluminium alloys, using a crack opening displacement gauge, for various overload ratios (1·67, 1·88 and 2·06). On the basis of these experiments some relationships are developed. The delay period after application of a single overload increases with increase in the magnitude of overload. The retardation is decreased with increase in prestrain for the same overload ratio. After the overload cycle the increase in U values is less in prestrained material than in the as-received material. Crack growth rate also decreases after application of an overload cycle; it attains a constant amplitude crack growth rate and crack closure value after a certain number of cycles. For the same stress ratio, the delay period in the 6063-T6 alloy was found to be more than in the 6061-T6 alloy. The experimental results when plotted on log-log graph paper, show that N_D/N_CAL vs overload ratio and crack length (when U = U_min) vs overload ratio fit a straight line, from which the power laws are developed.     

Lewis因子及其对饱和器数值模拟的影响

讨论了Lewis因子和Lewis数两个不同概念的区别和联系,Lewis因子,也叫Lewis关系,表示蒸发过程中传热和传质的对比关系;建立了饱和器的一维数学模型,通过数值计算分析了Lewis因子对饱和器数值模拟结果的影响.