计及暂态电压约束的负荷恢复能力快速计算

电力系统恢复过程中,需要确定变电站的单次最大负荷恢复量。通常主要考虑系统频率和稳态电压的约束,文中在此基础上加入了暂态电压安全的约束限制,建立了确定变电站最大负荷恢复量的数学模型。基于描述暂态电压安全问题的二元表,构建了分析暂态电压安全的微分代数方程组,对系统中各部分组成进行适当简化,在保证精度的前提下提高了计算速度。提出一种改进的二分法对模型进行求解,该方法考虑了每次迭代的约束裕度,加快了搜索寻优时的收敛速度。IEEE 14节点算例和山东电网仿真结果表明了模型的有效性和方法的快速性。     

电力系统恢复典型案例分析

电网发生部分乃至全部停电事故后，系统恢复目标是在尽可能短的时间内对尽可能多的负荷恢复供电。这就要求各电网制定可行的恢复方案，适时更新并且利用检修时机进行现场实验和仿真。文中给出了几个国外典型恢复案例分析和经验，对其他电力公司制定电力系统恢复方案有一定的借鉴价值。     

基于加权复杂网络模型的恢复路径优化方法

输电网络重构是电力系统大停电或部分停电后进行恢复的第2个阶段,如何确定恢复的目标骨架网络及其恢复路径序列是该阶段的主要任务。文中提出了一种新的基于加权复杂网络模型的输电网络重构优化算法,考虑了节点有功发电出力和有功负荷（特别是重要负荷）的大小以及各节点在网络中的分布情况和重要性程度,并利用了加权复杂网络模型中衡量网络枢纽性的介数指标来优化恢复路径。该算法可以得到最优的恢复路径序列和目标骨架网络,克服了现有方法在确定目标骨架网络和优化恢复路径序列这2个输电网络重构环节严重脱离的缺点,并在一定程度上解决了现有的恢复路径优化方法采用专家经验或分段寻优策略而无法得到最优解的问题。最后,以新英格兰10机39节点系统为例说明了所提出的方法的基本特征。     

高压配电网故障恢复系统推理策略

介绍了高压配电网故障恢复系统的推理策略。以孤岛恢复策略作为常规恢复策略为出发点，根据配电网故障恢复系统的结果、运行方式和要求建立特殊恢复策略，提出了有效的停电恢复策略，从而提高整个恢复系统的恢复效率。     

基于等值的电力系统机电暂态仿真并行异步算法

提出了一种基于等值的机电暂态稳定并行异步仿真新方法。该方法将系统按地理位置分区后的各子系统在每一时步进行相互等值,每个子系统利用其他子系统传递来的等值信息进行独立迭代计算;在每一时步的迭代过程中,各子系统只需1次相邻子系统的预测等值信息和校正等值信息;采用异步并行策略进行子系统间的等值信息传递和迭代,及时更新等值信息,从而加速迭代收敛。多个算例表明,文中的方法具有较快的计算速度和较高的计算效率,并具有工程可接受的仿真精度;对于一些大规模的实际系统,已实现实时或超实时仿真速度。     

电力系统稳定破坏后的系统非同步运行分析(一)

本文叙述电力系统稳定破坏后，进入稳态非同步运行时各运行量的变化规律及其检测和判断 方法。首先由简单的两机系统入手，然后给出复杂电网的计算方法。根据所介绍的方法编制 了程序，对计算机求得的运行量的波形图与实际系统稳定破坏后的波形图进行了比较，结果 表明十分吻合。本文还介绍稳态非同步运行时，电压、电流幅值轨迹图的实用方法。 本文简述电力系统稳态非同步运行时，振荡中心位置和频率变动的限度的估算方法；以及当 主系统失步后，进入非同步运行状态后，另一子系统又发生失步的计算方法。文章最后还推 导了为计算稳定破坏后动态过程的数学模型。     

电力系统稳定破坏后的系统非同步运行分析(一)

本文叙述电力系统稳定破坏后，进入稳态非同步运行时各运行量的变化规律及其检测和判断 方法。首先由简单的两机系统入手，然后给出复杂电网的计算方法。根据所介绍的方法编制 了程序，对计算机求得的运行量的波形图与实际系统稳定破坏后的波形图进行了比较，结果 表明十分吻合。本文还介绍稳态非同步运行时，电压、电流幅值轨迹图的实用方法。 本文简述电力系统稳态非同步运行时，振荡中心位置和频率变动的限度的估算方法；以及当 主系统失步后，进入非同步运行状态后，另一子系统又发生失步的计算方法。文章最后还推 导了为计算稳定破坏后动态过程的数学模型。     

风力发电系统发生低压穿越时对电网电能质量的影响分析

介绍了风力发电系统的低压穿越技术,分析了风力发电系统在发生低压穿越时对电网电能质量的影响。提出了使用保护电路单元来改善风力发电系统在发生低压穿越时提高电网电能质量的方法,通过软件仿真,验证了该方法的合理性和正确性。     

基于WAMS的系统自然频率特性系数确定方法

提出一种确定互联电力系统自然频率特性的总体测辨方法。该方法充分利用广域测量系统（WAMS）的高精度、同步测量的优点，利用频率和功率的相关性来确定互联电力系统的自然频率特性。从数学和物理的角度论证了该方法的正确性，同时给出了扰动地点的简单判别方法。以华北电网为例，对WAMS实际记录的扰动数据进行分析计算，所得到的华北电网自然频率特性与华北电网的实际情况十分吻合。     

用于快速评估生水化学物的技术-Journal of Water Supply. Research and Technology-AQUA

在自然产生或人为生产的化学物质对健康危害很大的地方，必须对水质化学物进行监测。一些发展中国家由于人力有限，经费不足，难以进行大量的”化学物监测，因此，在实施监测的过程中需要有一些简单而切实可行的指导原则来指导选择和划分化合物的先后次序。讨论了确定生水中化学污染物的各种筛选措施和快速评估技术。在筛选措施中，     

水生植物水体修复机理及其影响因素

阐述了水生植物的定义、利用水生植物进行水体修复的研究现状、水生植物在水体修复过程中的净化机理及其影响因素,提出了水生植物水体修复技术今后有待进一步研究的问题。水生植物水体修复效果受到多种影响因素的制约,主要包括植物选型和群落配置、温度、透明度、污染物浓度等。必须根据实际情况,选择合适的水生植物,采取必要措施,提高水生植物水体修复效果。     

有关河流生态系统的恢复生态学研究综述

长久以来,人们忽略了河流的生态功能,破坏了河流的各种生态过程,导致河流污染严重、生态作用越来越小。在评述恢复生态学定义及有关认识的基础上,结合分析国内外河流生态恢复的研究现状和特点,提出在河流生态恢复中应注意的几个方面,从而达到人与自然的和谐。     

Vegetation community response to hydrologic and geomorphic changes following dam removal

Dam removal can restore fish passage, natural flow regimes, sediment transport in streams, dispersal of organic matter, and drift of aquatic insects. However, dam removal also impacts the riparian vegetation, with both immediate and delayed responses. In this study, we measure vegetation change at the Merrimack Village Dam site on the Souhegan River in Merrimack, NH, USA. The August 2008 removal caused a ~3‐m drop in water level and rapid erosion of impounded sediment, with ~50% removed in the first 3 months. Terrace, floodplain, and wetland communities were surveyed in summer 2007, 2009, 2014, and 2015. Temporal change was quantified using Analysis of Similarity on the Bray–Curtis dissimilarity matrix. Only herbaceous vegetation closest to the river channel and in the off‐channel wetland changed significantly. The herbaceous plots directly adjacent to the impoundment eroded to bare sand in 2009, but by 2014, the original riparian fringe community had re‐established in the newly developed floodplain. Between 2007 and 2014, the off‐channel wetland area changed from aquatic species to a stable terrestrial community that persisted without significant change in 2015. The vegetation response was greatest in areas with the largest geomorphic and hydrologic change. These included the channel margin where erosion and bank slumping created an unstable scarp. The mid‐channel island and off‐channel wetland were strongly affected by the lowered water table. However, large unvegetated areas never persisted nor did the areal coverage of invasive species expand, which are two frequent concerns of dam removal stakeholders.     

Reference condition approach to restoration planning

Ecosystem restoration planning requires quantitative rigor to evaluate alternatives, define end states, report progress and perform environmental benefits analysis (EBA). Unfortunately, existing planning frameworks are, at best, semi‐quantitative. In this paper, we: (1) describe a quantitative restoration planning approach based on a comprehensive, but simple mathematical framework that can be used to effectively apply knowledge and evaluate alternatives, (2) use the approach to derive a simple but precisely defined lexicon based on the reference condition concept and allied terms and (3) illustrate the approach with an example from the Upper Mississippi River System (UMRS) using hydrologic indicators. The approach supports the development of a scaleable restoration strategy that, in theory, can be expanded to ecosystem characteristics such as hydraulics, geomorphology, habitat and biodiversity. We identify three reference condition types, best achievable condition (A _BAC), measured magnitude (MM_i which can be determined at one or many times and places) and desired future condition (A_DFC) that, when used with the mathematical framework, provide a complete system of accounts useful for goal‐oriented system‐level management and restoration. Published in 2010 by John Wiley & Sons, Ltd.     

Effects of process-based floodplain restoration on aquatic macroinvertebrate production and community structure

Recent stream restoration approaches, such as Stage 0 restoration, aim to restore natural processes to regain lost ecosystem functions, but project implementation can also represent a reach-scale disturbance. Assumed outcomes of these restoration actions, like greater biological productivity, are rarely evaluated. In this study, we examined the short-term effects of Stage 0 floodplain restoration on the secondary production of aquatic macroinvertebrate communities in the South Fork McKenzie River, Oregon, 1–2 years following project implementation. We seasonally sampled macroinvertebrates from benthic and submerged wood surfaces in the restored reach, and two unrestored reference reaches located upstream, to estimate annual secondary production. Macroinvertebrate production estimates were 3× lower on a per-meter-squared basis in the restored reach than in the upstream unrestored reference reaches (9764 vs. 29,636 mg DM/m²/yr). However, because there was 4.5-times greater wetted area available in the restored reach, overall macroinvertebrate production per unit of valley length was 3.4× higher in the restored reach than in unrestored reference reaches (2744 vs. 802 kg DM/km). Additionally, the mosaic of aquatic habitats created via restoration (main-channel, side-channel, and wetted forest habitats) supported a diversity of macroinvertebrate assemblages both within and among reaches. Our findings suggest Stage 0 project implementation, which can include dewatering and filling incised channels, may reduce aquatic macroinvertebrate production on a per-unit-area basis for at least 1 or 2 years following restoration. However, this short-term disturbance effect may be offset by channel aggradation and widening, which can provide a more wetted area for macroinvertebrate production and may support greater macroinvertebrate community diversity. Future studies are needed to examine the longer term (2–10 years) aquatic macroinvertebrate response to Stage 0 restoration, and the impacts of shifting resource availability on stream fishes.     

面向对象的变电站故障定位及恢复处理智能系统

提出用邻接矩阵表示变电站的网络拓扑，利用广度搜索方法隔离故障点，根据Floyd算法寻找最短可供电路径，迅速恢复非故障停电区域供电的主要原理。     

刘树坤访日报告:自然环境的保护和修复(一)

由于人类的大规模开发建设活动,自然环境遭受到严重的破坏。考虑到现有的环境影响评价制度不足以保护生物多样性,开展自然环境的保护和修复工作已经被提到重要日程。目前,世界上一些国家特别是日本都把生态系统保护的重点放在湿地保护上,并提出了一些生物生息地的保护和恢复对策并付诸实施,取得了一定成效,值得借鉴。     

刘树坤访日报告:湿地生态系统的修复(三)

湿地被称为“地球之肾”,与生态环境关系非常密切。一般来讲,湿地分为自然湿地和人工湿地。在日本,农村的湿地包括水田、弃耕水田和池塘,在农村景观中占有重要的地位。为了保护农村湿地,必须全面考虑自然社会因素,加强湿地整体管理。     

衡水湖湿地生态系统恢复原理与方法

由于衡水湖流域上游建设了大量水利工程,使衡水湖入湖水量逐年减少,最终导致干涸。自2000年河北省政府批准建立衡水湖省级自然保护区,由外流域调水与本地水资源联合调度水资源,开始实施对衡水湖湿地的恢复。通过对衡水湖湿地生态系统恢复的原则、原理和方法进行分析,衡水湖湿地生态恢复方法采用外流域调水补充水源、利用水生植物控制湿地营养物质的措施、利用种子库、植物繁殖体等途径恢复植被等措施。确定恢复目标为恢复湿地功能、保护野生动物、恢复传统景观等,并对恢复后的衡水湖生物多样性进行评价,探讨湿地恢复过程中的具体问题,为北方干旱地区湿地生态恢复提供参考依据。