Surrogate models for parameterized representation of wake‐induced loads in wind farms

A procedure for mapping wake‐induced load predictions computed with the dynamic wake meandering model to a computationally efficient surrogate model approximation is defined and demonstrated. Using the mapping function, the load variation can be efficiently estimated for a wind farm with arbitrary layout. The resulting load assessment procedure provides continuous, differentiable output with known analytical derivatives and can be used for applications such as wind turbine layout optimization, estimation of turbine lifetime, and uncertainty analysis.     

The representation of variable hydro potential in long-range electricity planning models

The long-range planning of electricity supply in countries for which hydro power constitutes a sizeable proportion of total capacity should take into account the effects of variable hydro inflow. Fluctuations occur in the water intake to storage lakes from year to year; reserve generating capacity is required to ensure that demand can still be met in years of low water intake. The least cost choice for reserve capacity must take into account not only the capital costs of generating capacity but also the extra fuel and operating costs, the latter costs being incurred only when water intake is low.This paper describes an LP model of the long-range planning problem in which the effects of both low water inflows and high water inflows are included. The formulation used to represent these variable elements in the model was designed to minimise the number of additional constraints required.     

On representation of temporal variability in electricity capacity planning models

This paper systematically investigates how to represent intra-annual temporal variability in models of optimum electricity capacity investment. Inappropriate aggregation of temporal resolution can introduce substantial error into model outputs and associated economic insight. The mechanisms underlying the introduction of this error are shown. How many representative periods are needed to fully capture the variability is then investigated. For a sample dataset, a scenario-robust aggregation of hourly (8760) resolution is possible in the order of 10 representative hours when electricity demand is the only source of variability.The inclusion of wind and solar supply variability increases the resolution of the robust aggregation to the order of 1000. A similar scale of expansion is shown for representative days and weeks. These concepts can be applied to any such temporal dataset, providing, at the least, a benchmark that any other aggregation method can aim to emulate. How prior information about peak pricing hours can potentially reduce resolution further is also discussed.     

Offshore wind farm wake recovery: Airborne measurements and its representation in engineering models

We present an analysis of wind measurements from a series of airborne campaigns conducted to sample the wakes from two North Sea wind farm clusters, with the aim of determining the dependence of the downstream wind speed recovery on the atmospheric stability. The consequences of the stability dependence of wake length on the expected annual energy yield of wind farms in the North Sea are assessed by an engineering model. Wakes are found to extend for significantly longer downstream distances (>50 km) in stable conditions than in neutral and unstable conditions (  15 km). The parameters of one common engineering model are modified to reproduce the observed wake decay at downstream distances  30 km. More significant effects on the energy yield are expected for wind farms separated by distances  30 km, which is generally the case in the North Sea, but additional data would be required to validate the suggested parameter modifications within the engineering model. A case study is accordingly performed to show reductions in the farm efficiency downstream of a wind farm. These results emphasize not only the importance of understanding the impact of atmospheric stability on offshore wind farms but also the need to update the representation of wakes in current industry models to properly include wake‐induced energy losses, especially in large offshore clusters.     

锅炉故障诊断专家系统的知识表达

针对循环流化床锅炉实际应用对象的特性，采用面向对象的方法对其进行了分析与描述，提出了现阶段可以实际应用于锅炉系统的故障诊断专家系统的知识处理方案，详细叙述了框架、规则、过程的知识表达方法。     

Methodology for tidal turbine representation in ocean circulation model

The present method proposes the use and adaptation of ocean circulation models as an assessment tool framework for tidal current turbine (TCT) array layout optimization. By adapting both momentum and turbulence transport equations of an existing model, the present TCT representation method is proposed to extend the actuator disc concept to 3-D large-scale ocean circulation models. Through the reproduction of experimental flume tests and grid dependency tests, this method has shown its numerical coherence as well as its ability to simulate accurately both momentum and turbulent turbine-induced perturbations in both near and far wakes in a relatively short period of computation time. Consequently the present TCT representation method is a very promising basis for the development of a TCT array layout optimization tool.     

Model representation of claw-pole stepping motors

The performance of claw-pole stepping motors is significantly influenced by stator iron losses due to the flux-carrying nonlaminated construction. To obtain a suitable model of the magnetic circuit, the stator iron is modeled as a conducting slab of simple geometry; the analytical solution of the skin problem can be approximated by a half-order transfer function. The magnetic circuit consists of the conducting slab in series with the air gap; its dual electric circuit is a complex main field inductance, with its inductive and resistive components depending on frequency. This allows one to use a revised version of the conventional synchronous machine model circuit, the parameters of which are determined from tests. The model is used to simulate steady-state operation of the stepping motor when fed by symmetrical currents. Examples are presented of constant current and constant voltage operation. Attention is drawn to the torque curve in continuous operation. Simulations are shown of the current waveforms when the motor is supplied by rectangular voltage. The results are in acceptable agreement with measured values.     

钢锭优化加热计算机控制系统

以钢锭热过程一维无限长圆筒控制数学模型为基础，开发了均热炉群钢锭优化计算机控制系统，并采用美国爱克新公司生产的ＣＩＭ－ＰＡＣ分布式控制系统在马鞍山钢铁公司初轧厂实现了均热炉群钢锭生产过程的在线优化控制和管理。     

Blowing models for cooling surfaces

To study the cooling of surfaces exposed to high temperature stress and heat flux, the blowing, or transpiration, technique is numerically investigated in the case of a porous circular cylinder. Two models are developed to simulate the blowing impact on the outer flow and an experimental set-up available allows for direct comparison and validation of the numerical simulations. The heat exchange occuring within the porous wall itself between the coolant and the solid part of the wall is accounted. The results show an excellent effectiveness of the blowing in terms of surface temperature reduction, even for low blowing ratii. The incident heat flux exhibits a maximum for medium blowing rates due to a decreasing heat transfer coefficient and a growing temperature difference between the surface and the main flow with the injection rate. Finally, the blowing is demonstrated to be very effective in cooling heavily thermally stressed parts in terms of homogeneity and coolant rate required.     

车用汽油机消声器计算机模拟的应用研究

作者应用不稳定流动计算机模拟方法,不仅能估算排气消声器特性,还能模拟不同消声器结构对发动机性能的影响。本文从工程应用角度出发,以开发的消声器特性模拟软件为分析工具,探求优化设计排气消声器的方法。结合软件分析,提出了消声器性能分析的简易判断准则并予以实际应用。作者设计了性能良好的消声器,使发动机的动力性和消声性能均优于原产品,取得实际效果。     

气门产品计算机工艺管理系统

0　前言在气门生产中 ,编制加工工艺、计算下料定额 ,绘制专用工、模、检具图是气门行业技术部门司空见惯的日常工作。每开发一个产品 ,技术部门都要超前为其设计一套文件 ,用来指导试制和批量生产。而每一套文件 ,都要包含成百上千个工艺数据 ,其计算、绘制、填写工作量很大 ,     

Real-world market representation with agents

As power markets are relatively new and still continue to evolve, there is a growing need for advanced modeling approaches that simulate the behavior of electricity markets over time and how market participants may act and react to the changing economic, financial and regulatory environments in which they operate. A new and rather promising approach is to model the electricity market as a complex adaptive system using an agent-based modeling and simulation (ABMS) approach. The purpose of an ABMS model is not necessarily to predict the outcome of a system but to reveal and understand the complex and aggregate system behaviors that emerge from the interactions of the heterogeneous individual entities. Emergent behavior is a key feature of ABMS and is not easily inferred from the simple sum of the behavior of its components. By relying on both established engineering modeling techniques as well as advanced quantitative economic market principles, the ABMS approach is uniquely suited to addressing the strategic issues of interest to different market participants as well as those of market monitors and regulators.     

锅炉热力计算的计算机算法

文章介绍了锅炉热力计算中建立的数学模型，并分别给出了与其相适应的计算机算法，通过多年的实际应用，获得了良好的技术经济效益。     

马达保护器的计算机自动测试系统

介绍了马达保护器的测试工作原理、技术指标,提出了马达保护器的计算机自动测试系统的组成结构。该测试系统主要测试在不同的电流和温度条件下,马达保护器的动作时间以及在升温过程中的断开温度和降温过程中的闭合温度,并用VC++设计测试软件实现自动检测。     

Consequence models for vented hydrogen deflagrations: CFD vs. engineering models

This paper compares two approaches for predicting the consequences of vented hydrogen deflagrations: empirical engineering models (EMs) and computational fluid dynamics (CFD) simulations. The study is part of the project ‘Improving hydrogen safety for energy applications through pre-normative research on vented deflagrations’ (HySEA), funded by the Fuel Cells and Hydrogen 2 Joint Undertaking (FCH JU) under grant agreement No 671461. The HySEA project focuses on vented hydrogen deflagrations in containers and smaller enclosures with internal congestion representative of industrial applications. Data from experiments conducted as part of the HySEA project are used to evaluate predictions from a selection of EMs and the CFD tool FLACS. The experiments involve various obstacle and venting configurations, and initially quiescent homogeneous hydrogen-air mixtures with hydrogen concentrations in the range 15–24 vol%. There is a significant scatter in the maximum reduced overpressures predicted by the different EMs in the present study. For certain configurations, there is an order of magnitude difference between the different EM predictions. Two versions of the CFD tool FLACS are used in the present study: i) the standard commercial release FLACS v10.7r2, and ii) an in-house development version termed FLACS-beta. The commercial release generally over-predicts the maximum overpressures measured in the experiments, while the development version of FLACS gives improved results for several configurations.     

A novel formulation representation of the equilibrium constant for water gas shift reaction

In order to meet prominent disagreement for the water gas shift reaction (WGSR) equilibrium constant values obtained from various conventional empirical correlations and mitigate the strong dependence on plenty of experimental data points, here, we report a novel WGSR equilibrium constant formulation representation approach with direct algebraic operation, which only involves experimental data of 3–6 molecular constants for each reactants and products and does not contain the fitting of any experimental equilibrium constant data. The reliability of the developed approach is demonstrated by comparing the predicted values with experimentally measured data and the calculated results with other previous WGSR equilibrium constant correlations. The average absolute deviations between the theoretical values predicted from the developed technique and the directly measured data reported in the literature are 3.993%, 5.970%, 2.418%, 2.083%, 8.659%, 3.733%, and 3.755% for 7 experimental data sets, respectively.     

Strategic appraisal of energy models for Mozambique

The needs that an energy supply system must meet are constantly changing, due to technological, social and political reasons. Effective energy planning is a dynamic process that is repeated periodically and adjusts to changing conditions. Energy decision makers and planners are no longer able to rely on inductive decision making since they have to investigate the effect of various decision parameters and possible future changes. To help in this process, models have been developed where estimates of future load growth, candidate power plants, fuels and other key factors can be introduced, from which the planners can evaluate decision parameters and the available alternatives. The paper presents the different methodologies and practices that are used by 11 energy models for energy demand forecasting, supply side management and generation expansion planning, demand side management and integrated resource planning. The paper concludes to the presentation of a strategic appraisal of the examined energy models appropriate for energy planning in Mozambique. Three models are proposed for conducting demand forecasting, generation expansion planning and demand side management. Copyright © 2002 John Wiley & Sons, Ltd.     

集成化锅炉CAD系统

本文详细地阐述了锅炉计算机辅助设计（ＣＡＤ）系统在开发研制过程中所采用的方法及具体内容。本系统把图形系统、工程数据库、计算分析软件有机地结合起来,是一个集成化程度较高的ＣＡＤ软件包。