Perspectives of China’s Wind Energy Development

Wind energy is a kind of clean renewable energy, which is also relatively mature in technology, with large-scale development conditions and prospect for the commercialization. Wind energy’s development and utilization is an important measure to increase energy supply, adjust energy structure, ensure energy security, protect the ecological environment, reduce greenhouse gas emission and build a harmonious society. Wind energy is a kind of clean renewable energy, which is also relatively mature in technology, with large-scale development conditions and prospect for the commercialization. The development of wind energy is a systematic project, involving policy, law, technology, economy, society, environment, education and other aspects. The relationship among all the aspects should be well treated and coordinated. This paper has discussed the following relationships which should be well coordinated: relationship between wind resources and wind energy development, relationship between the wind turbine generator system and the components, relationship between wind energy technology and wind energy industry, relationship between off-grid wind power and grid-connected wind power, relationship between wind farm and the power grid, relationship between onshore wind power and offshore wind power, relationship between wind energy and other energies, relationship between technology introduction and self-innovation, relationship among foreign-funded, joint ventured and domestic-funded enterprises and relationship between the government guidance and the market regulation, as well as giving out some suggestions.     

A New Task Scheduling Scheme Based on Genetic Algorithm for Edge Computing

With the continuous evolution of smart grid and global energy interconnection technology, amount of intelligent terminals have been connected to power grid, which can be used for providing resource services as edge nodes. Traditional cloud computing can be used to provide storage services and task computing services in the power grid, but it faces challenges such as resource bottlenecks, time delays, and limited network bandwidth resources. Edge computing is an effective supplement for cloud computing, because it can provide users with local computing services with lower latency. However, because the resources in a single edge node are limited, resource-intensive tasks need to be divided into many subtasks and then assigned to different edge nodes by resource cooperation. Making task scheduling more efficient is an important issue. In this paper, a two-layer resource management scheme is proposed based on the concept of edge computing. In addition, a new task scheduling algorithm named GA-EC(Genetic Algorithm for Edge Computing) is put forth, based on a genetic algorithm, that can dynamically schedule tasks according to different scheduling goals. The simulation shows that the proposed algorithm has a beneficial effect on energy consumption and load balancing, and reduces time delay.     

Local and global properties of the harmonic polynomial cell method: In‐depth analysis in two dimensions

A detailed and systematic analysis is performed on the local and global properties of the recently developed harmonic polynomial cell (HPC) method, a very accurate and efficient field solver for problems governed by the Laplace equation. At the local cell level, a simple rule is identified for the proper choice of harmonic polynomials in the local representation of the velocity potential in cells with symmetry properties. The local solution error, its convergence rate, its dependence on the cell topology, its distribution inside the cell, and its features across cells with different dimensions are carefully examined with relevant findings for HPC numerical implementations. At the global level, the error convergence rate is analytically estimated in terms of error contributions from the boundary conditions and from inside the liquid domain. In most cases, the error associated with boundary conditions dominates the global error. In order to minimize it, Quadtree grid strategies or high‐order local expressions of the velocity potential are proposed for cells near critical boundary portions. To model accurately the boundary conditions on rigid or deformable surfaces with generic geometries, 3 different grid strategies are proposed by adopting concepts of immersed boundary method and overlapping grids. They are comparatively studied for a circular rigid cylinder in infinite fluid and for the propagation of a free‐surface wave. Then, an immersed boundary strategy, using numerical choices suggested in this paper, is successfully compared against a fully nonlinear boundary element method for the case of a surface‐piercing circular cylinder heaving in otherwise calm water.     

Load management as a smart grid concept for sizing and designing of hybrid renewable energy systems

Optimal sizing of hybrid renewable energy systems (HRES) to satisfy load requirements with the highest reliability and lowest cost is a crucial step in building HRESs to supply electricity to remote areas. Applying smart grid concepts such as load management can reduce the size of HRES components and reduce the cost of generated energy considerably. In this article, sizing of HRES is carried out by dividing the load into high- and low-priority parts. The proposed system is formed by a photovoltaic array, wind turbines, batteries, fuel cells and a diesel generator as a back-up energy source. A smart particle swarm optimization (PSO) algorithm using MATLAB is introduced to determine the optimal size of the HRES. The simulation was carried out with and without division of the load to compare these concepts. HOMER software was also used to simulate the proposed system without dividing the loads to verify the results obtained from the proposed PSO algorithm. The results show that the percentage of division of the load is inversely proportional to the cost of the generated energy.     

跨音轴流风扇叶片气弹稳定性研究

基于弱耦合的能量法原理,对近失速工况下NASA 67跨音风扇叶片进行了气弹稳定性分析。本文发展的三维线性插值方法为CSD/CFD数据交换提供了基础。采用FLUENT动网格技术,实现了振动叶片绕流计算。数值模拟了NASA 67叶片前三阶模态振型激励下的非定常气动响应。通过分析叶片表面非定常气动力和振动位移之间的相位差发现：该相位差的存在决定了非定常气动力做功的正、负。由叶片表面非定常压力分析结果得出近失速工况下,叶片的气动弹性稳定性受叶片模态振型和激波的影响较为显著。     

大电网运行控制面临的形势、问题与挑战

多项特高压交直流输变电工程的相继建成投产,标志着我国电网建设已处于国际领先水平。同时,我国当前大电网运行与控制也面临着前所未有的问题与挑战。该文介绍了当前大电网运行面临的形势,即具备新能源占比不断增加,电力跨大区大容量远距离输送等特点,分析了电网运行与控制面临的问题与挑战。以东北电网为例,介绍了应对大电网运行的措施。东北电网通过调峰辅助服务市场、高频紧急控制系统等技术手段促进网源协调,提高了新能源消纳水平。     

极端灾害下基于智能楼宇分布式电源的配电系统负荷恢复力评估分析

作为一类重要的负荷侧资源,智能楼宇中广泛存在的各类分布式电源为极端灾害后电力系统的供电快速恢复及负荷转带提供了新的可能性。为此,提出一种针对智能楼宇负荷恢复力的综合评估框架,用于定量分析和计算极端灾害后智能楼宇末端存活分布式电源对配电系统中重要负荷的转带能力。在对智能楼宇内不同类型物理设备进行建模的基础上,重点考虑多能互补及能量耦合特性,首先,提出了电能转移量、热能转移量、冷能转移量3项定量评价指标,用于精确量化极端灾害后智能楼宇电源对系统负荷恢复的贡献。其次,在此基础上,通过综合利用随机混合整数规划方法,进一步提出了针对上述评价指标的具体计算方法。最后,以某一工业园区负荷为例,对所提评估框架进行有效性验证。仿真结果表明,所提方法在保证智能楼宇正常运行前提下可充分发掘智能楼宇的能源供应潜力,有效提升配电系统在极端灾害下的供能可靠性。     

The role of hemodynamics in the development of the outflow tract of the heart

The question whether, and if so to what extent, hemodynamic forces and mechanical stimuli do modulate the morphogenesis of the vascular system is a century-old problem. It is important especially in the outflow tract where a spiraling septum develops in and after a strong bend in the tube. Spiraling patterns of the flow in bends are well known. Of the mechanical stimuli that can potentially exert an effect on morphogenesis, wall shear stress is the most likely candidate; a number of genes that are expressed in the cardiovascular system have shear-stress responsive elements in their regulatory units. Recent investigations have clearly shown that the disturbance of normal hemodynamic conditions results in maldevelopment of the heart. However, an experimental model alone is necessary, but not sufficient to identify the intermediate steps of the interaction between blood flow and tissue remodeling in the developing cardiovascular system, certainly at Reynolds numbers and Dean numbers that are very small. Therefore, a model with a simple geometry has been created, using the ComFlo software: a fully 3D computational fluid-dynamics code that solves the Navier-Stokes equations on a Cartesian grid. A first assessment of the possible influence of a strong curvature, with biological realistic dimensions, was made using steady-flow conditions. Since both the Reynolds number and the Womersley number (indicating the influence of the pulsatility on the velocity profile of the flow) are extremely low, it is likely that these flow patterns do not differ significantly from those under pulsatile conditions. A first assessment of the effects of the strong curvature on the flow under the given circumstances showed only very small secondary velocities and negligible heterogeneity of the wall shear stress, even in the presence of a strong secondary flow pattern in the inlet of the tube.     

Feasibility analysis of an OTEC plant as the bottom cycle of the third nuclear power plant

Abstract

A conceptual design, performance analysis, system optimization and simulation of an OTEC (Ocean Thermal Energy Conversion) power plant was carried out in the present study. The OTEC plant acts as the bottom cycle of the Third Nuclear Power Plant, utilizing the warm water discharged from the nuclear plant as the heat source and the cold deep seawater pumped from the nearby sea bottom as the heat sink. The nominal net power output from the OTEC plant is estimated to be 8.74 MWe. A plant simulation was further carried out to study the OTEC plant performance due to seasonal variation of the warm water temperature, which shows that the OTEC plant is able to deliver an electricity of 5.18×10⁷ kWH per year. The net power output in the winter season will be reduced to about one eighth of that in the summer season. The final discharged warm water temperature was shown to be below 29°C all year around, so that the current thermal pollution problem of the nuclear power plant can be eliminated. Additionally there is the side benefit of 8.74 MWe net power generation from ocean energy resource. This OTEC plant will become economically feasible if the installation cost is considered as a thermal pollution control investment.     

基于印刷企业的制造网格研究

分析了印刷企业的生产模式和发展状况,介绍了网格、制造网格的基本原理,剖析了3种网格体系结构,并研究了印刷企业制造网格的体系结构.     

Hybrid Renewable Energy Resources Management for Optimal Energy Operation in Nano-Grid

Renewable energy resources are deemed a potential energy production source due to their cost efficiency and harmless reaction to the environment, unlike non-renewable energy resources. However, they often fail to meet energy requirements in unfavorable weather conditions. The concept of Hybrid renewable energy resources addresses this issue by integrating both renewable and non-renewable energy resources to meet the required energy load. In this paper, an intelligent cost optimization algorithm is proposed to maximize the use of renewable energy resources and minimum utilization of non-renewable energy resources to meet the energy requirement for a nanogrid infrastructure. An actual data set comprising information about the load and demand of utility grids is used to evaluate the performance of the proposed nanogrid energy management system. The objective function is formulated to manage the nanogrid operation and implemented using a variant of Particle Swarm Optimization (PSO) named recurrent PSO (rPSO). Firstly, rPSO algorithm minimizes the installation cost for nanogrid. Thereafter, the proposed NEMS ensures cost efficiency for the post-installation period by providing a daily operational plan and optimizing renewable resources. State-of-the-art optimization models, including Genetic Algorithm (GA), bat and different Mathematical Programming Language (AMPL) solvers, are used to evaluate the model. The study's outcomes suggest that the proposed work significantly reduces the use of diesel generators and fosters the use of renewable energy resources and beneficiates the eco-friendly environment.     

我国能源形势及发展对策

总结了近年来我国能源发展取得的成绩,研究分析了我国能源发展面临的形势和挑战,提出了当前和今后一个时期能源工作的主要任务。特别强调保证能源安全供应是能源战线的一项首要任务、基本任务和长期任务,同时要大力节约能源,调整优化能源结构,加快能源科技自主创新,扩大能源国际合作,推动能源科学发展,为经济社会健康、持续、协调发展提供保障。     

冰灾对江西电网的灾害分析和电网应急平台体系建设

回顾2009年全国大面积雪灾对江西省电网造成的巨大损失,分析了灾害的成因,并重点提出了电网应急管理平台建设的具体技术思路。     

改进自动网格法测量相似材料模型变形

在研究地下采矿引起的岩层移动及变形问题时，通常采用相似材料模型法，一般采用基于图像处理的自动网格法来自动识别变形。目前的自动网格法主要局限于灰度图像，且编码算法繁琐，可靠性低。本文提出一种改进的自动网格法，基于彩色图像，充分利用了颜色信息，并且采用基于网格区域的搜索匹配算法，搜索快速，准确可靠。     

A multilevel tabu search algorithm for balanced partitioning of unstructured grids

This paper presents a multilevel algorithm for balanced partitioning of unstructured grids. The grid is partitioned such that the number of interface elements is minimized and each partition contains an equal number of grid elements. The partition refinement of the proposed multilevel algorithm is based on iterative tabu search procedure. In iterative partition refinement algorithms, tie‐breaking in selection of maximum gain vertices affects the performance considerably. A new tie‐breaking strategy in the iterative tabu search algorithm is proposed that leads to improved partitioning quality. Numerical experiments are carried out on various unstructured grids in order to evaluate the performance of the proposed algorithm. The partition results are compared with those produced by the well‐known partitioning package Metis and k‐means clustering algorithm and shown to be superior in terms of edge cut, partition balance, and partition connectivity. Copyright © 2015 John Wiley & Sons, Ltd.     

常乐电厂筹建的可行性分析与重要作用

常乐电厂由甘肃省电力投资集团公司筹建,规划建设4×1000MW的燃煤发电机组,一期建设2×1000MW机组,拟采用超超临界机组,同步建设脱硫、脱硝装置,采用间接空冷.项目可研工作已完成,目前已上报国家发改委审批.本文对常乐电厂在电网和地域中的优势地位进行了论述.     

美国得州2021轮停事故分析及其对中国电网改革的启示

2月15日—16日,受冬季暴风影响,得州遭遇大规模轮流停电,约450万人口用电受到影响,现货市场电价大幅飙升,经济社会秩序受到严重影响。2月24日得克萨斯州电力可靠性委员会(ERCOT)发布了关于停电事件的首份事故报告。结合该份事故报告,简单介绍了得州电网的基本情况和此次轮停事件的始末,详细分析了导致停电事件的原因,并结合我国电网实际,重点提出了我国电网在实现“碳达峰、碳中和”目标下的发展建议。     

物流网格体系结构的研究

通过介绍物流和网格计算的基础理论,运用物流模式和网格计算的关键技术,提出了物流网格的概念,主要分析了物流网格系统的特点、功能及主要构成要素,在此基础上,构建了物流网格的体系结构,并详细阐述了物流网格系统在物流运作中的具体运用.