基于电力物联网的数据智能检测模型研究

为支撑电力物联网数据共享,发挥电网数据价值,文章针对当前电力物联网数据平台中存在的技术组件多样、应用难度大、检索数据困难、数据应用门槛高和数据模型管控机制不完善等问题,优化电力物联网数据平台整体框架,提出基于孤立森林的量测类实时数据质量异常检测及改进算法,通过抢修故障研判和停电故障研判2个场景仿真验证数据质量检测算法的...     

光伏组件清洁机器人真实地形的路径规划

针对传统环境下路径规划方法已无法满足真实地形方面实际应用的特点,提出基于Unity3D平台的三维虚拟太阳能发电站真实地形下的路径规划方法。首先通过卫星云图进行数据采集和真实环境地形构建,在此基础上结合三维引擎Unity3D平台,采用3ds MAX在地形上建立光伏组件三维模型,生成实际地图。利用加入跳点策略的改进A;算法进行路径寻优,实现了清洁移动机器人在三维可视化实际地图的路径规划和场景漫游。     

光伏组件清洁机器人真实地形的路径规划

针对传统环境下路径规划方法已无法满足真实地形方面实际应用的特点,提出基于Unity3D平台的三维虚拟太阳能发电站真实地形下的路径规划方法。首先通过卫星云图进行数据采集和真实环境地形构建,在此基础上结合三维引擎Unity3D平台,采用3ds MAX在地形上建立光伏组件三维模型,生成实际地图。利用加入跳点策略的改进A;算法进行路径寻优,实现了清洁移动机器人在三维可视化实际地图的路径规划和场景漫游。     

基于WebGL的BIM模型可视化研究

针对水利工程建筑信息模型(BIM)展示需安装专业软件及展示不便、不能远程浏览和远程交互不便等问题,采用基于WebGL技术的Three.js框架,通过坝体三维模型的建立与导入、浏览器中坝体模型的重构、模型环境的渲染等技术手段,实现了大坝三维模型在客户端浏览器Web方式可视化显示、三维漫游及远程实时浏览与交互,避免了模型展示需安装专业软件的繁琐过程,增强了展示效果,提升了用户体验,并可进一步应用于水利信息化可视平台的开发。     

考虑电力数据传输失效的通信路由优化及协调调度

针对电力数据传输过程中存在的延时、丢包和误码等传输失效所导致的电网协调调度偏离实际值的问题,提出了一种基于量化电力数据传输偏差的最优通信路由优化算法,通过得到的数据在考虑预测误差和传输失效后运用模型预测控制进行电网的协调调度。首先,建立电力数据传输的延时、丢包和误码的有效性模型,并量化出在不同负载率、丢包率和误码率情况下的电力数据传输偏差。然后,将量化后的链路传输偏差作为路由算法的权重寻找最优通信路径。进而采用实时得到的电力数据在考虑传输失效以及预测偏差的基础上生成极端场景,运用模型预测控制算法求解分布式电源的出力,从而进行协调调度。最后通过算例验证了所提最小化数据传输偏差算法的有效性,并通过对负载率、丢包率和误码率的灵敏度分析,明确信息传输偏差对电网协调调度的影响。     

启发式快速探索随机树的电力杆塔三维航线规划研究

为了完成对电力杆塔运行状态的有效监测与故障诊断,要求无人机规划最优三维航线。文章基于快速探索随机树(rapidly exploring random trees,RRT)算法,提出一种启发策略的无碰撞三维航线规划方法,该方法集成启发式搜索策略进行代价函数设计,加速算法收敛,确保航线最优。在仿真环境与实际场景下的实验结果表明,同传统的RRT与改进的RRT*算法相比,本方法针对电力杆塔所规划的无碰撞三维航线,具有稳定可靠的最短路径长度,能够满足智能监测的应用需求。     

大型电力网络故障数据库快速 数据定位模型仿真

对大型电力网络故障数据进行快速定位,对提高电力网络配电管理及故障诊断方面具有重要意义。传统的定位算法,利用故障数据库慢变包络切片对定位信息进行能量聚集,容易受到的电磁干扰,导致定位准确度不好。提出一种基于时频分析和滑动时间窗口重排的大型电力网络故障数据库的快速数据定位模型。构建大型电力网络故障数据库模型,对故障数据信息进行时频特征提取,对提取的故障数据的时频特征进行滑动时间窗口重排,实现数据的快速定位,通过特征提取和特征分类实现故障诊断。仿真结果表明,采用该模型进行大型电力网络故障数据库的故障数据定位,具有较好的抗干扰能力,实现对故障数据的快速定位,进而实现对电力网络的故障检测,检测概率高于传统算法。     

基于人工鱼群和蛙跳混合算法的光伏阵列多场景参数辨识

光伏阵列模型的准确性对大规模光伏发电系统的并网运行与调度至关重要。在建立光伏阵列机理模型的基础上,采用人工鱼群和蛙跳混合算法对模型中的未知参数进行辨识,并将辨识结果与人工鱼群算法和蛙跳算法单独辨识的结果进行了对比分析,证明了混合算法兼具两种算法的优点,并能有效克服两种算法的不足,验证了其优越性和有效性。为使光伏阵列模型的输出与实际光伏电站任意1 d的实测曲线均能很好拟合,采用混合算法对不同场景下的参数进行了辨识,并采用任意2 d的实测数据对辨识结果进行了适应性验证,证明了辨识结果的准确性,进一步验证了混合算法的有效性和实用性。     

基于Hotbooting Q算法的多微网能量交易博弈模型

文章构建了多个风-光-储微网能量交易博弈模型,每个微网可根据风光等新能源机组的发电水平以及负荷需求,确定自己与其余微网和上级电网的能量交易策略。在对多微网能量交易博弈模型的求解上,提出了一种将热启动Hotbooting技术与Q-学习相结合的Hotbooting Q交易算法,并以电力市场相似场景下的大规模实验数据作为训练数据。通过算例表明,微网间能量交易减少了从上级电网的购电量,采用Hotbooting Q交易算法可加快系统的收敛速度,提高微网的交易学习效果。     

基于大数据的居民用电消费习惯研究与分析

居民用电消费受较多因素的影响,掌握居民用电习惯及其主要影响因素间的规律对电力系统调度具有重要意义。国网浙江省电力公司借助大数据平台,基于线性回归、灰色预测等算法搭建数据挖掘模型,实现了居民用电消费分析和用电负荷预测分析的场景应用。数据挖掘模型的建立一方面了解了居民用电消费行为,有效提高了负荷预测的及时性和准确性;另一方面验证了大数据技术在电力行业应用的可行性,为国网浙江省电力公司大数据应用体系的形成与完善提供了切实可行的实践经验。     

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.     

Performance assessment of some ice TES systems

In this paper, a performance assessment of four main types of ice storage techniques for space cooling purposes, namely ice slurry systems, ice-on-coil systems (both internal and external melt), and encapsulated ice systems is conducted. A detailed analysis, coupled with a case study based on the literature data, follows. The ice making techniques are compared on the basis of energy and exergy performance criteria including charging, discharging and storage efficiencies, which make up the ice storage and retrieval process. Losses due to heat leakage and irreversibilities from entropy generation are included. A vapor-compression refrigeration cycle with R134a as the working fluid provides the cooling load, while the analysis is performed in both a full storage and partial storage process, with comparisons between these two. In the case of full storage, the energy efficiencies associated with the charging and discharging processes are well over 98% in all cases, while the exergy efficiencies ranged from 46% to 76% for the charging cycle and 18% to 24% for the discharging cycle. For the partial storage systems, all energy and exergy efficiencies were slightly less than that for full storage, due to the increasing effect wall heat leakage has on the decreased storage volume and load. The results show that energy analyses alone do not provide much useful insight into system behavior, since the vast majority of losses in all processes are a result of entropy generation which results from system irreversibilities.     

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%.     

Effect of co-cultivation of Chlamydomonas reinhardtii with Azotobacter chroococcum on hydrogen production

Chlamydomonas reinhardtii cc124 and Azotobacter chroococcum bacteria were co-cultured with a series of volume ratios and under a variety of light densities to determine the optimal culture conditions and to investigate the mechanism by which co-cultivation improves H₂ yield. The results demonstrated that the optimal culture conditions for the highest H₂ production of the combined system were a 1:40 vol ratio of bacterial cultures to algal cultures under 200 μE m^?2 s^?1. Under these conditions, the maximal H₂ yield was 255 μmol mg^?1 Chl, which was approximately 15.9-fold of the control. The reasons for the improvement in H₂ yield included decreased O₂ content, enhanced algal growth, and increased H₂ase activity and starch content of the combined system.     

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.     

Natural-gas fueled spark-ignition (SI) and compression-ignition (CI) engine performance and emissions

Natural gas is a fossil fuel that has been used and investigated extensively for use in spark-ignition (SI) and compression-ignition (CI) engines. Compared with conventional gasoline engines, SI engines using natural gas can run at higher compression ratios, thus producing higher thermal efficiencies but also increased nitrogen oxide (NO_x) emissions, while producing lower emissions of carbon dioxide (CO₂), unburned hydrocarbons (HC) and carbon monoxide (CO). These engines also produce relatively less power than gasoline-fueled engines because of the convergence of one or more of three factors: a reduction in volumetric efficiency due to natural-gas injection in the intake manifold; the lower stoichiometric fuel/air ratio of natural gas compared to gasoline; and the lower equivalence ratio at which these engines may be run in order to reduce NO_x emissions. High NO_x emissions, especially at high loads, reduce with exhaust gas recirculation (EGR). However, EGR rates above a maximum value result in misfire and erratic engine operation. Hydrogen gas addition increases this EGR threshold significantly. In addition, hydrogen increases the flame speed of the natural gas-hydrogen mixture. Power levels can be increased with supercharging or turbocharging and intercooling. Natural gas is used to power CI engines via the dual-fuel mode, where a high-cetane fuel is injected along with the natural gas in order to provide a source of ignition for the charge. Thermal efficiency levels compared with normal diesel-fueled CI-engine operation are generally maintained with dual-fuel operation, and smoke levels are reduced significantly. At the same time, lower NO_x and CO₂ emissions, as well as higher HC and CO emissions compared with normal CI-engine operation at low and intermediate loads are recorded. These trends are caused by the low charge temperature and increased ignition delay, resulting in low combustion temperatures. Another factor is insufficient penetration and distribution of the pilot fuel in the charge, resulting in a lack of ignition centers. EGR admission at low and intermediate loads increases combustion temperatures, lowering unburned HC and CO emissions. Larger pilot fuel quantities at these load levels and hydrogen gas addition can also help increase combustion efficiency. Power output is lower at certain conditions than diesel-fueled engines, for reasons similar to those affecting power output of SI engines. In both cases the power output can be maintained with direct injection. Overall, natural gas can be used in both engine types; however further refinement and optimization of engines and fuel-injection systems is needed.     

Exergetic evaluation of 5 biowastes-to-biofuels routes via gasification

This paper presents the exergy analysis results for the production of several biofuels, i.e., SNG (synthetic natural gas), methanol, Fischer–Tropsch fuels, hydrogen, as well as heat and electricity, from several biowastes generated in the Dutch province of Friesland, selected as one of the typical European regions. Biowastes have been classified in 5 virtual streams according to their ultimate and proximate analysis. All production chains have been modeled in Aspen Plus in order to analyze their technical performance. The common steps for all the production chains are: pre-treatment, gasification, gas cleaning, water–gas-shift reactions, catalytic reactors, final gas separation and upgrading. Optionally a gas turbine and steam turbines are used to produce heat and electricity from unconverted gas and heat removal, respectively. The results show that, in terms of mass conversion, methanol production seems to be the most efficient process for all the biowastes. SNG synthesis is preferred when exergetic efficiency is the objective parameter, but hydrogen process is more efficient when the performance is analyzed by means of the 1st Law of Thermodynamics. The main exergy losses account for the gasification section, except in the electricity and heat production chain, where the combined cycle is less efficient.     

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.     

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.