基于DSP的交流电量采样及其实现

根据交流电量以及TI公司DSP的功能特点，介绍了基于TMS320LF2407的交流电量采样和计算方法，设计了采样与监控系统的软硬件，实现了实时、准确处理，在光伏并网发电系统中得到了很好的应用。     

DSP在电力参数检测系统中的应用

设计了一种基于TMS320F2812DSP电力参数实时检测系统。采用ADS8364对6路信号同时采样,利用复序列FFT算法得到各种电力参数,可由CAN总线与上位机实时传输数据,实现对电力系统的实时、准确的参数测量和数据分析。采用了硬件锁相环技术。可更加有效实现同步采样,提高了采样精度。     

基于DSP与GPRS的电能质量监测系统

获取广泛的电能质量实时监测数据具有重要的意义,但高成本和数据传输的不便限制了电能质量实时监测的范围。为此提出以GPRS作为数据传输通道组成电能质量监测系统,并使用单片DSP作为核心开发出低成本的电能质量实时监测终端,详细介绍了如何充分利用DSP的片内外围设备以简化系统硬件设计,同时介绍了软件的设计和在算法上进行的优化。     

基于DSP的柴油机振动信号小波降噪实时性研究

针对柴油机实时监测系统采集的振动信号采样频率高、实时降噪困难,而传统的实时性评价方法难以准确描述数字信号处理器(DSP)中所需降噪时间的问题,提出基于DSP的小波变换指令周期模型作为实时性的评价依据,对比不同小波算法的实时性优劣;根据采集的柴油机缸盖振动信号特征,提出基于变异系数定权法的综合评价指标,从降噪效果和实时性两个角度优选了小波基函数．结果表明：该模型与DSP中小波算法的实时性吻合较好,且优选的小波降噪参数能满足采样频率为25 kHz下的实时降噪需求．     

基于DSP的电能质量监测系统的设计

针对传统的单片机无法满足电能质量实时监测与分析的要求,介绍了一种基于DSP技术的电能质量监测系统设计,给出了前置滤波电路、A/D与 DSP的最小系统、同步锁相等电路图及系统的软件流程.调试结果表明,该系统具有较好的准确性和实用性,能适应目前电能质量监测市场发展的需求.     

基于DSP的柴油机实时监测系统软件设计

对一套基于Motoro1a16位DSP56F305电控柴油机实时监测系统进行了研究开发，与传统的MCU设计相比可以使综合性能得到提高。在发动机电控系统的运算速度和运算精度要求日益提高的今天，该实验室探讨了DSP的设计方向。本系统在X4115柴油机台架试验上做了柴油机性能多通道模拟信号采集试验；用信号发生器进行了多路数字信号仿真试验，实验效果良好。     

基于DSP的发动机测控系统

介绍了基于Motorola 16位DSP56F807的发动机测控系统，该系统的功能有数据采集、保存、实时监视和现场控制。系统开发主要包括：传感器信号处理电路，执行器功率驱动电路，电控系统软件设计，发动机测控系统上位机通信监控系统。通过实车试验，证明了该测控系统的实用性。     

基于DSP+CPLD模式的变电站电气设备在线监测采集系统

讨论了基于DSP CPLD模式的变电站电气设备在线监测采集系统。以断路器为例介绍了系统硬件结构、工作原理，提出利用DSP CPLD模式扩展系统外围器件，并分析了这种硬件结构的优势。最后得出结论。基于DSP CPLD模式的硬件系统将以其高速度、高集成度和高可靠性在电气设备在线监测中发挥重要作用。     

小波分析技术在汽轮机故障诊断中的应用

就小波分析技术在汽轮机故障诊断中故障特征提取和小波算法的硬件实现问题进行了深入研究.提出了基于小波能量分布的故障特征提取方法,并在转子试验台上进行了验证.对于小波分析算法的硬件实现,设计了一种基于DSP的小波算法.实践检验证明,该方法能够满足振动信号实时分析的需要.     

基于RTW和DSP的风力发电机组半实物仿真研究

在纯仿真环境下,风机控制器的开发周期长,而且难以反映其动静态特性及非线性因素,因此提出了一种基于DSP目标代码生成和计算机软件仿真相结合的新型半实物仿真方法。首先在Simulink下搭建好系统模型,然后根据目标DSP型号对控制算法模型添加相应内核、外设并选定参数,再利用Matlab的RTW(Real-Time Workshop)功能直接编译生成目标代码,使其在DSP中运行,以构成控制器实物模型,同时保持与Simulink中被控对象数学模型进行实时数据交换,从而完成半实物仿真平台的搭建。通过对1.5 MW双馈式风力发电机组控制系统的半实物仿真,不仅验证了该方法的快速性和简易性,还体现出这种方式同时具备了Matlab强大数据处理能力和DSP外设扩展简便的双重优势。     

Ash-forming elements in four Scandinavian wood species. Part 1: Summer harvest

Woody biomass in Finland and Sweden comprises mainly four wood species: spruce, pine, birch and aspen. To study the ash, which may cause problems for the combustion device, one tree of each species were cut down and prepared for comparisons with fuel samples. Well-defined samples of wood, bark and foliage were analyzed on 11 ash-forming elements: Si, Al, Fe, Ca, Mg, Mn, Na, K, P, S and Cl. The ash content in the wood tissues (0.2–0.7%) was low compared to the ash content in the bark tissues (1.9–6.4%) and the foliage (2.4–7.7%). The woods’ content of ash-forming elements was consequently low; the highest contents were of Ca (410–1340 ppm) and K (200–1310), followed by Mg (70–290), Mn (15–240) and P (0–350). Present in the wood was also Si (50–190), S (50–200) and Cl (30–110). The bark tissues showed much higher element contents; Ca (4800–19,100 ppm) and K (1600–6400) were the dominating elements, followed by Mg (210–2400), P (210–1200), Mn (110–1100) and S (310–750), but the Cl contents (40–330) were only moderately higher in the bark than in the wood. The young foliage (shoots and deciduous leaves) had the highest K (7100–25,000 ppm), P (1600–5300) and S (1100–2600) contents of all tissues, while the shoots of spruce had the highest Cl contents (820–1360) and its needles the highest Si content (5000–11,300). This paper presented a new approach in fuel characterization: the method excludes the presence of impurities, and focus on different categories of plant tissues. This made it possible to discuss the contents of ash element in a wide spectrum of fuel-types, which are of large importance for the energy production in Finland and Sweden.     

NEXT GENERATION ENGINEERED MATERIALS FOR ULTRA SUPERCRITICAL STEAM TURBINES

正1 ABSTRACT To reduce the effect of global warming on our climate,the levels of CO2emissions should be reduced.One way to do this is to increase the efficiency of electricity production from fossil fuels.This will in turn reduce the amount of CO2emissions for a given power output.Using US practice for efficiency calculations,then a move from a typical US plant running at 37%efficiency to a 760℃/38.5 MPa(1 400/5 580 psi)plant running at 48%efficiency would reduce CO2emissions by 170kg/MW.hr or 25%.     

Contents in Volume 23,2014

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Aerodynamic performance effects of leading-edge geometry in gas-turbine blades

The purpose of this paper is to illustrate the advantages of the direct surface-curvature distribution blade-design method, originally proposed by Korakianitis, for the leading-edge design of turbine blades, and by extension for other types of airfoil shapes. The leading edge shape is critical in the blade design process, and it is quite difficult to completely control with inverse, semi-inverse or other direct-design methods. The blade-design method is briefly reviewed, and then the effort is concentrated on smoothly blending the leading edge shape (circle or ellipse, etc.) with the main part of the blade surface, in a manner that avoids leading-edge flow-disturbance and flow-separation regions. Specifically in the leading edge region we return to the second-order (parabolic) construction line coupled with a revised smoothing equation between the leading-edge shape and the main part of the blade. The Hodson–Dominy blade has been used as an example to show the ability of this blade-design method to remove leading-edge separation bubbles in gas turbine blades and other airfoil shapes that have very sharp changes in curvature near the leading edge. An additional gas turbine blade example has been used to illustrate the ability of this method to design leading edge shapes that avoid leading-edge separation bubbles at off-design conditions. This gas turbine blade example has inlet flow angle 0°, outlet flow angle −64.3°, and tangential lift coefficient 1.045, in a region of parameters where the leading edge shape is critical for the overall blade performance. Computed results at incidences of −10°,   −5°,   +5°,   +10° are used to illustrate the complete removal of leading edge flow-disturbance regions, thus minimizing the possibility of leading-edge separation bubbles, while concurrently minimizing the stagnation pressure drop from inlet to outlet. These results using two difficult example cases of leading edge geometries illustrate the superiority and utility of this blade-design method when compared with other direct or inverse blade-design methods.     

Hydrogen production by steam-gasification of carbonaceous materials using concentrated solar energy – V. Reactor modeling,optimization, and scale-up

A chemical reactor for the steam-gasification of carbonaceous particles (e.g. coal, coke) is considered for using concentrated solar radiation as the energy source of high-temperature process heat. A two-phase reactor model that couples radiative, convective, and conductive heat transfer to the chemical kinetics is applied to optimize the reactor geometrical configuration and operational parameters (feedstock's initial particle size, feeding rates, and solar power input) for maximum reaction extent and solar-to-chemical energy conversion efficiency of a 5 kW prototype reactor and its scale-up to 300 kW. For the 300 kW reactor, complete reaction extent is predicted for an initial feedstock particle size up to 35 μm at residence times of less than 10 s and peak temperatures of 1818 K, yielding high-quality syngas with a calorific content that has been solar-upgraded by 19% over that of the petcoke gasified.     

汽轮机数字电液调节系统挂闸异常的技术完善

分析了200MW汽轮机数字电液调节系统在运行中存在的挂闸异常问题,采取了相应的技术处理措施,且运行实践效果良好。     

新型高压共轨ECU升压模块的数字化开发与优化

为了提高喷油器电磁阀的响应速率,提出了一种基于CPLD(复杂可编程逻辑器件)应用于高压共轨ECU的数字升压模块。鉴于该升压电路结构参数多,其升压电压的恢复响应要求高等特征,基于Pspice建立了升压电路的仿真模型,研究了不同电路参数下升压模块的输出特性,全面优化了该升压模块的性能。结果显示,该升压模块的最大转换效率可以达90%以上。在柴油发动机上对ECU的试验表明,升压电压最大波动不超过10%,其恢复时间仅为1.3ms,功率管最大温升仅为41℃,满足整机运行范围内ECU的需求。     

Trace metal chemistry and silicification of microorganisms in geothermal sinter, Taupo Volcanic Zone, New Zealand

As part of a pilot study investigating the role of microorganisms in the immobilisation of As, Sb, B, Tl and Hg, the inorganic geochemistry of seven different active sinter deposits and their contact fluids were characterised. A comprehensive series of sequential extractions for a suite of trace elements was carried out on siliceous sinter and a mixed silica-carbonate sinter. The extractions showed whether metals were loosely exchangeable or bound to carbonate, oxide, organic or crystalline fractions. Hyperthermophilic microbial communities associated with sinters deposited from high temperature (92–94°C) fluids at a variety of geothermal sources were investigated using SEM. The rapidity and style of silicification of the hyperthermophiles can be correlated with the dissolved silica content of the fluid. Although high concentrations of Hg and Tl were found associated with the organic fraction of the sinters, there was no evidence to suggest that any of the heavy metals were associated preferentially with the hyperthermophiles at the high temperature (92–94°C) ends of the terrestrial thermal spring ecosystems studied.     

Assessment methods of material ageing using Sdobyrev''s creep rupture model

The physical aspects of the activation energy, in higher and high temperatures, of the metal creep process were examined. The research results of creep-rupture in a uniaxial stress state and the criterion of creep-rupture in biaxial stress states, at two temperatures, are then presented. For these studies creep-rupture, taking case iron as an example the energy and pseudoenergy activation was determined. For complex stress states the criterion of creep-rupture was taken to be Sdobyrev's, i.e. σ_red = σ₁ β + (1 − β)σ_i, where: σ₁-maximal principal stress, σ_i-stress intensity, β-material constant (at variable temperature β = β(T)). The methods of assessment of the material ageing grade are given in percentages of ageing of new material in the following mechanical properties: 1) creep strength in uniaxial stress state, 2) activation energy in uniaxial stress state, 3) criterion creep strength in complex stress states, 4) activation pseudoenergy in complex stress states. The methods 1) and 3) are the relatively simplest because they result from experimental investigations only at nominal temperature of the structure work, however, for methods 2) and 4) it is necessary to perform the experimental investigations at least at two temperatures.     

Production of hydrogen from sewage biosolids in a continuously fed bioreactor: Effect of hydraulic retention time and sparging

Hydrogen was produced from primary sewage biosolids via mesophilic anaerobic fermentation in a continuously fed bioreactor. Prior to fermentation the sewage biosolids were heated to 70 °C for 1 h to inactivate methanogens and during fermentation a cellulose degrading enzyme was added to improve substrate availability. Hydraulic retention times (HRT) of 18, 24, 36 and 48 h were evaluated for the duration of hydrogen production. Without sparging a hydraulic retention time of 24 h resulted in the longest period of hydrogen production (3 days), during which a hydrogen yield of 21.9 L H₂ kg⁻¹ VS added to the bioreactor was achieved. Methods of preventing the decline of hydrogen production during continuous fermentation were evaluated. Of the techniques evaluated using nitrogen gas to sparge the bioreactor contents proved to be more effective than flushing just the headspace of the bioreactor. Sparging at 0.06 L L min⁻¹ successfully prevented a decline in hydrogen production and resulted in a yield of 27.0  L H₂ kg⁻¹ VS added, over a period of greater than 12 days or 12 HRT. The use of sparging also delayed the build up of acetic acid in the bioreactor, suggesting that it serves to inhibit homoacetogenesis and thus maintain hydrogen production.