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《水电能源科学》2021,39(5):165-168,188
针对水电站监控系统与机组调速器缺乏一次调频协调配合策略,且一次调频不能有效避开机组振动区等问题,提出了一种水电机组一次调频协调控制策略,即根据机组振动区范围、最大最小负荷限值和实际发电功率确定机组的调频裕量;根据机组的实际频差和调频裕量确定调频功率修正值和调频频差修正值;根据调频频差修正值和机组运行工况变换调速器开度模式PID的控制偏差;根据调频功率修正值补偿监控系统功率给定值,由监控系统完成一次调频闭环控制。现场试验与仿真试验对比结果表明,该策略实现了水电站监控系统与机组调速器在一次调频过程中的协调控制,并能有效避开机组振动区,为改进水电机组的一次调频控制提供了有益参考。 相似文献
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针对当代电力系统中水轮机调速器已成为水轮机控制系统的控制核心,依据福建电网大量水电站一次调频试验结果,论述了水轮机调速器与电网负荷频率控制间的关系,分析了调速器在电网一次调频中的作用、静态与动态特性,提出了福建电网水电机组并网工况下调速器PID参数整定范围及机组功率控制模式. 相似文献
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为减少水电机组一次调频合格率低、实际积分电量经常不达标问题,提出了增强型一次调频的频差算法,借助建模仿真的方法对增强型一次调频的动态响应过程进行模拟,并将增强型与普通型一次调频的反调效果、动态响应指标、功率积分电量、调频频繁动作进行比较。结果表明,增强型一次调频由于其频差算法的不同,在网频超出频率死区后,其频差Δf有大小为Ef的阶跃,且比普通型一次调频始终大Ef,使调节初期的反调峰值更大,反调峰值时间更短,一次调频调节量更大;在动态响应指标不受太大影响的情况下,使机组调节幅度增大,理论积分电量更多,机组更容易满足一次调频积分电量考核的要求。但因其速动性和幅度的增加,在一次调频频繁动作的情况下,会导致调速系统的加速磨损,也会引起机组功率的大幅波动和漂移。因此,在选择使用增强型一次调频算法时,需对机组安全性及对电网的影响进行评估。 相似文献
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乌溪江水力发电厂一次调频 总被引:1,自引:0,他引:1
阐述了一次调频功能的具体实现方法.通过在调速器程序中设定一次调频专用参数,实现机组自动转入一次调频运行,加快响应时间、增强调节能力,并采用机组接收二次调频信号时将一次调频功能迅速退出,在新的工作起点稳定运行的方法,协调了一次调频和二次调频相互辅助、相互制约的关系.实际运行表明,水电厂一次调频功能的投入对保持电网频率稳定、确保供电质量有着至关重要的作用. 相似文献
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水电机组一次调频动态调节品质与机组型式、调速器控制模式及引水流道、水轮机的水力特性密切相关。比较了水轮机调速器的频率模式、开度模式、有功模式3种控制逻辑原理,分别计算了某水电机组在开度模式、功率模式控制下的一次调频动态响应试验数据,通过与考核指标进行比较,发现调整幅度偏差、调频响应指数等一次调频动态响应指标不能完全满足电网调度的要求,进而分析了部分动态响应指标不合格的原因和一次调频目前存在的问题,并提出了优化建议,为在保证水电机组安全稳定运行的条件下更好地发挥其一次调频作用提供了参考。 相似文献
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汽机一次调频转差与调频负荷关系的探讨 总被引:1,自引:0,他引:1
介绍了目前电调型带基本负荷汽轮机的一次调频转差与调频负荷关系曲线的设置情况.通过对汽轮机几种工况的分析,提出其关系曲线设置的要求,需要考虑对汽机低负荷工况的稳定,也要考虑在机组带基本负荷时受各种因素影响后实际的一次调频能力.分析表明,为满足这些要求,仅设置一组调频曲线是不够的.本文以HNHM电厂为例,对此提出设置方法及解决措施. 相似文献
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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. 相似文献
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《热能动力工程》2014,(5)
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%. 相似文献
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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. 相似文献
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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. 相似文献
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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. σred = σ1 β + (1 − β)σi, where: σ1-maximal principal stress, σi-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. 相似文献
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Jaime Massanet-Nicolau Alan Guwy Richard Dinsdale Giuliano Premier Sandra Esteves 《International Journal of Hydrogen Energy》2010
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. 相似文献
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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. 相似文献