料仓内稠密粉体卸料流动特性研究

为了研究料仓内粉体卸料流动及混合特性,采用实验与模拟相结合的方法,利用粉体的溶解性质获得两种粉体卸料过程的混合曲线,并建立能够进行大规模数值计算颗粒间固相作用力的三维数学模型。该模型基于欧拉与拉格朗日相结合的方法,利用相邻网格间固相颗粒浓度梯度与颗粒平均速度梯度来描述颗粒间的固相作用力。结果表明:料仓半顶角与卸料口径对粉体卸料流率的影响的模拟结果与实验结果及Brown经验关联式预测值吻合较好。两种粉体卸料过程的混合指数随料仓半顶角的增加而减小,减小卸料口径时混合指数有所减小但减幅不大,表明增加料仓半顶角以及减小卸料口径均会促进两种粉体在卸料过程的混合。     

水平管道细粉高浓度分层流动阻力特性的试验研究

高浓度粉体输送由于人们对其优越性认识的深入而得到了广泛的研究。水平管内分层流动是高浓度粉体输送流型中最重要的形式 ,研究其阻力特性有着重要的意义。本文通过对近 5 0年来在这一领域内工作的回顾 ,分析了不同学者所获得的经验公式的利弊。在一高浓度气力输送试验台上的试验 ,获得了水平管道细粉高浓度分层流动的阻力公式 ,误差分析认为 ,该公式能够满足一般工程设计要求。     

水平管道细粉同浓度分层流动阻力特性的试验研究

高浓度粉体输送由于人们对其优越性认识的深入而得到了广泛的研究。水平管内分层流动是高浓度粉体输送流型中最重要的形式，研究其阻力特性有着重要的意义。本文通过对近５０年来在这一领域内工作的回顾，分析了不同学者所获得的经验公式的利弊。在一高浓度气力输送试验台上的试验，获得了水平管道细粉高浓度分层流动的阻力公式，误差分析认为，该公式能够满足一般工程设计要求。     

粉体荷电研究进展与煤粉荷电研究初探

综述了国内外粉体颗粒荷电科学和技术研究发展现状,给出煤粉颗粒的荷电机理、实验研究的目的、实验研究构想,提出煤粉荷电量、煤粉粒径及其分布、煤粉比电阻与介电常数的有效测量方法,对煤粉荷电的初步探索是后续煤粉电晕荷电强化燃烧研究的基础。     

电导法测量太阳池盐浓度分布的实验研究

对太阳池溶液浓度与电导的关系做了初步的实验测量和理论说明，并与用光学折射率法和比重计法测得的浓度做了比较。试图找出一种更为简便的太阳池盐浓度分布的测定方法。     

内燃机轴系纵/弯/扭振动动态测试方法的实验研究

本文提出了一个测量内燃机轴系纵 弯 扭振动的方法 ,并通过在一台发动机上进行的实验及对实验结果的分析得出了轴系三维振动的一些初步的结论     

高热流密度量热探针的设计与实验

以热等离子体射流冲击平板传热的热流密度测量为背景,分析比较了文献中报道过的各种测量高热流密度的量热探针的结构及实验方法;结合特定实验条件,设计了新型量热探针并对其测量高热流密度的方法误差进行了分析,描述了实际测量采用的方法,给出若干初步实验结果。     

内燃机轴系纵／弯／扭振动动态测试方法的实验研究

本文提出了一个测量内燃机轴系纵／弯／扭振动的方法,并通过在一台发动机上进行的实验及对实验结果的分析得出了轴系三难振动的一些初步的结论。     

1.5MW风力机叶片变形的分析

影响风力机叶片变形的载荷源主要是空气动力载荷、离心力载荷以及重力载荷。讨论了一种风力机叶片变形的计算方法,首先将叶片简化为悬臂梁进行初步分析并得出剪力和弯矩,然后进一步将悬臂梁离散化,通过对离散化节点的分析得出叶片各截面的变形。静载实验针对某1.5MW叶片的6个截面展开,测试了某叶片模型在其设计风速时各剖面的变形量。通过实验验证计算方法的可靠性,并对实验和计算结果进行对比分析。     

典型建筑结构中烟气毒物迁移的实验及数值分析

建筑火灾中致人死亡的因素除了热以外，更多的是因为烟气的毒性．通过实验系统研究了典型侧间一走廊建筑结构中的烟气浓度场的分布以及烟气迁移到远距离处的特征，并结合数值分析，讨论了建筑结构形式对烟气毒物迁移的影响．实验中发现，由于建筑结构的影响，离火源近的点烟气毒物的浓度反而比远点低，并对此现象进行了初步的分析．     

Analysis and control of wind-driven self-excited induction generators connected to the grid through power converters

The analysis of the wind-driven self-excited induction generators (SEIGs) connected to the grid through power converters has been developed in this paper. For this analysis, a method of representing the grid power as equivalent load resistance in the steady-state equivalent circuit of SEIG has been formulated. The technique of genetic algorithm (GA) has been adopted for making the analysis of the proposed system simple and straightforward. The control of SEIG is attempted by connecting an uncontrolled diode bridge rectifier (DBR) and a line commutated inverter (LCI) between the generator terminals and three-phase utility grid. A simple control technique for maximum power point tracking (MPPT) in wind energy conversion systems (WECS), in which the firing angle of the LCI alone needs to be controlled by sensing the rotor speed of the generator has been proposed. The effectiveness of the proposed method of MPPT and method of analysis of this wind-driven SEIG-converter system connected to the grid through power converters has been demonstrated by experiments and simulation. These experimental and simulated results confirm the usefulness and successful working of the proposed system and its analysis.     

A heuristic method of variable selection based on principal component analysis and factor analysis for monitoring in a 300 kW MCFC power plant

In a commercialized 300 kW molten carbonate fuel cell (MCFC) power plant, a univariate alarm system that has only upper and lower limits is usually employed to identify abnormal conditions in the system. Even though univariate alarms have already been adopted for system monitoring, this simple monitoring system is limited for using in an extended monitoring system for fault diagnosis. Therefore, based on principal component analysis (PCA), a recursive variable grouping method for a multivariate monitoring system in a commercialized MCFC power plant is presented in this paper. In terms of development, since a principal component analysis model that contains all system variables cannot isolate a system fault, heuristic recursive variable selection method using factor analysis is presented here. To verify the performance of the fault detection, real plant operations data are used. Furthermore, comparison between type 1 and type 2 errors for four different variable groups demonstrates that the developed heuristic method works well when system faults occur. These monitoring techniques can reduce the number of false alarms occurring on site at MCFC power plant.     

Research on a power quality monitoring technique for individual wind turbines

The extensive deployment of megawatt-scale wind turbines is bringing more challenges to the safety and stability of electric grid than ever before. This is not only because of the unstable wind over time but the increased risk of power quality pollution by defective wind turbines particularly when the turbines today are still experiencing various reliability issues. To prevent the power quality pollution by defective turbines, a new power quality monitoring technique dedicated for individual wind turbines is developed in this paper, so that the quality of the power generated by an individual turbine can be monitored by the wind turbine condition monitoring system. Through simulated and physical experiments on a specially designed test rig, some encouraging results have been achieved. It has been shown that the proposed technique is not only valid for monitoring the power quality of an individual wind turbine, but helpful in detecting the mechanical and electrical faults occurring in the wind turbines.     

Off/on-line FRA condition monitoring technique for powertransformer

This letter presents a novel and sensitive frequency response analysis (FRA) technique for off/on-line condition monitoring of expensive power apparatus. The main objective is to investigate the applicability of this predictive maintenance technique to diagnosing power transformer failures, to characterize the transformer in a frequency plane for safe operation, and to develop on-line monitoring technique. The effectiveness of this technique is demonstrated on a 2.5 MVA transformer housed at the High Voltage Laboratory of Pacific Power International (PPI) and then tested on three field transformers. The on-line technique is verified on a single-phase high voltage transformer. This study shows that FRA results are very sensitive to faults. The configuration of the measurement set up, frequency range and terminations play a greater role in getting reproducible, fault-indicating results. The interpretation of the voluminous data and analysis relevant to the faults opens a gateway to develop smart power apparatus     

Fuel sensor-less control of a liquid feed fuel cell under dynamic loading conditions for portable power sources (II)

This work presents a new fuel sensor-less control scheme for liquid feed fuel cells that is able to control the supply to a fuel cell system for operation under dynamic loading conditions. The control scheme uses cell-operating characteristics, such as potential, current, and power, to regulate the fuel concentration of a liquid feed fuel cell without the need for a fuel concentration sensor. A current integral technique has been developed to calculate the quantity of fuel required at each monitoring cycle, which can be combined with the concentration regulating process to control the fuel supply for stable operation. As verified by systematic experiments, this scheme can effectively control the fuel supply of a liquid feed fuel cell with reduced response time, even under conditions where the membrane electrolyte assembly (MEA) deteriorates gradually. This advance will aid the commercialization of liquid feed fuel cells and make them more adaptable for use in portable and automotive power units such as laptops, e-bikes, and handicap cars.     

A line outage study for prediction of static voltage collapse

A simple but useful technique is proposed to study steady-state line outage and hence voltage collapse of the system. Voltage collapse prediction can be performed through the study of line outages, though techniques for nodal-based prediction or critical-node identification are frequently proposed. Experimentally, it was proven that both line outage and system voltage collapse take place simultaneously. In fact, line outages can be treated as the secondary cause of voltage collapse. A scalar index called line-stability index for each line is calculated based on the power flow through the line. The line-stability index may have a value that varies from zero (no power flows through the line) to one (maximum power flows through the line). Any line exceeding the maximum limit of stability index (1.00) can cause system-wide voltage collapse. The proposed technique is tested on a six-bus standard test system, and encouraging results are observed. The results obtained indicate that the technique has the potential to be used as a tool for system monitoring and future load planning     

Application of AI techniques in monitoring and operation of power systems

In recent years, the artificial intelligence (AI) technology is becoming more and more popular in many areas due to its amazing performance. However, the application of AI techniques in power systems is still in its infancy. Therefore, in this paper, the application potentials of AI technologies in power systems will be discussed by mainly focusing on the power system operation and monitoring. For the power system operation, the problems, the demands, and the possible applications of AI techniques in control, optimization, and decision making problems are discussed. Subsequently, the fault detection and stability analysis problems in power system monitoring are studied. At the end of the paper, a case study to use the neural network (NN) for power flow analysis is provided as a simple example to demonstrate the viability of AI techniques in solving power system problems.     

130t_h煤粉锅炉风_粉在线监测系统的应用和研究

基于气，固两相流理论，考虑了风一煤合流过程中的压力损失影响，运用能量法提出了一种测量一次风管中风－粉混合后煤粉浓度的方法，并介绍了利用动态链接库技术对一次风管中煤粉学，风速实现在线，实时监测的过程和方法。此在线监测系统在热力厂现场应用中取得了很好的效果。     

能量分析与一次风煤粉浓度测量

在火力发电厂的锅炉运行中，煤粉燃烧器的一次风煤粉流量的均匀性对锅炉的安全经济运行起着重要的作用。一次风煤粉浓度的准确测量一直是工程技术上的前沿问题，尤其是对乏气送粉锅炉进行煤粉浓度监测更是缺乏有效的方法。通过对一次风气流与煤粉颗粒混合过程的分析，从开放系统的能量方程出发，确立了乏气送粉锅炉一次风煤粉浓度的测量方法，并成功应用于生产实践，为一次风煤粉浓度在线监测提供了新的途径。     

水轮发电机组测试系统实用数据压缩方法研究

充分利用基于提升算法的第二代小波的优点，对水轮发电机组在线监测与性能试验系统的大量数据实现了动态压缩存储。压缩效果比通用压缩软件高出近一倍的结果表明这种压缩方法具有很大的发展潜力。