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1.
分布式发电(DG)的接入对配电网的规划和运行产生了深远影响,由于DG的存在,配电网检修负荷转移方案有了更多的选择。文中通过对DG运行方式和负荷转移优化问题的研究,给出了制定含DG的配电网检修负荷转移方案的3条原则,并建立了相应的数学模型。该模型以降低供电企业综合检修成本为目标,包括降低供电企业额外购买的DG电量费用、售电损失和开关操作费用,并在传统负荷转移模型约束条件的基础上增加了其他约束,保证利用可再生能源发电的DG以最大发电能力上网发电和保证利用化石能源发电的DG至少按照正常发电计划发电,以反映DG对负荷转移方案的影响。仿真结果证明了所提出的模型的正确性和有效性。  相似文献   

2.
近年来,分布式发电(DG)作为一种经济、环保的发电技术在世界范围内快速发展,DG的接入系统将对电网带来多方面的严重影响,通过分析DG接入电力系统后,对配电网在电压调节、继电保护及自动装置、供电可靠性、电能质量、电网规划及运行管理等方面造成的影响,提出应对的措施,供电网经营企业参考。  相似文献   

3.
随着IEEE 1547—2003标准的出台,分布式发电(DG)孤岛运行成为关注的热点。针对系统故障后DG与系统解列形成的孤岛运行的特点,结合DG并网运行时配电网保护与控制的现状,根据电力系统相关理论并采用PSCAD仿真方法,研究了短时间断供电及不间断供电2种孤岛运行的模式和DG形成孤岛需要满足的条件,以及不同容量的DG暂态失稳对孤岛运行的影响,提出了实现孤岛运行所要采取的与保护和控制相关的措施,据此得出短时间断供电形成的孤岛运行是目前可行的模式。  相似文献   

4.
为满足实际应用的要求,在随机生产模拟中运用负荷曲线分解技术和动态规划,提出了抽水蓄能电站及其系统的概率模拟与运行优化模型。模型以系统发电运行成本与缺电损失最小为目标,满足电站水库蓄水及库容限制条件,满足日或周的抽水—发电循环电力电量平衡条件,并考虑了抽水蓄能电站在抽水和发电方式下随机停运的影响。可应用于电源规划、发电计划和系统运行优化,可以更准确地模拟、分析和优化抽水蓄能电站及其系统的运行状况。通过算例对模型和应用进行了说明。  相似文献   

5.
传统输电网规划方案由于没有考虑网络中各线路的负载运行水平,得到的最小费用方案会导致部分线路负载率偏高。文中的新规划模型将线路投资费用和网络剩余输电容量作为目标函数,同时考虑优化线路负载率的分布,用以求取最少投资下具有最大网络剩余输电容量的规划方案。结合混沌变量的随机遍历特性,将混沌优化算法应用于输电网非线性混合整数规划模型的优化求解。算例表明方法的正确性和有效性。  相似文献   

6.
在配电网中合理规划分布式发电(DG)对充分发挥DG的效益、抑制DG的负面影响具有重要意义。文中研究了配电系统中DG位置和容量规划问题,建立了考虑经济性和安全性的DG规划多目标模糊优化模型。目标函数由DG投资成本最小、系统网损最小和静态电压稳定裕度最大 3个优化子目标组成,应用模糊理论将多目标规划转化为单目标规划问题。在模型中计及了短路电流约束,对配电网中计及DG影响的故障计算原理进行了分析。考虑到DG出力具有一定的间歇特点,模型中增加了系统的旋转备用约束,保证任意一台DG退出时,系统具有足够的功率来满足负荷要求。在43节点配电系统中进行了测试,表明了文中方法的可行性。  相似文献   

7.
研究了电力市场的发电和输电中期规划模式。根据中国电力市场和电网结构的特点,提出了节点输电电价和建立当地电价系统的建议;推荐采用“统一规划、发电投标决策”和“参考规划、发电自主决策”规划模式协调输电和发电规划。  相似文献   

8.
发电上网分时电价与当时的发电燃料边际成本及供电风险密切相关,随机生产模拟计算可以给出系统的最优发电方式、燃料费用、边际发电成本及系统可靠性指标。在随机生产模拟计算的基础上,提出了3种既考虑电能成本又考虑风险成本(可靠性成本)的分时电价制定方案,并以某实际系统为例计算出典型日运行方式下每种方案的分时电价,同时统计出该运行方式下的峰、腰、谷分时电价比,为电网实现分时电价提供了参考和依据。  相似文献   

9.
分时电价的方法能反映用电负荷的市场化行为,指引用户的用电时段,同时也可促进分布式可再生能源的消纳利用。基于用电负荷三段式分类方法,本文提出了分时电价机制下分布式风-光联合发电系统接入配网系统的功率消纳模型。该模型采用配网系统对内分时电价的方式来提高分布式风-光联合系统的并网消纳功率,并结合模拟退火算法对模型进行优化求解。最后通过仿真算例验证了本方法促进分布式风-光联合发电系统功率消纳、配网系统和用户取得双赢效果的可行性。  相似文献   

10.
在分布式发电参与的电力市场中,提出了一种考虑可中断负荷及其费用的配电公司最小总费用模型。在对传统运行模式、孤岛运行模式,以及非故障馈线支援模式进行比较的基础上,重点分析了不同负荷水平下分布式发电孤岛运行模式对配电系统的有功网损、配电网络的节点边际电价和配电公司购电费用的影响。数值计算和算例仿真表明,当配电网出现故障时,利用分布式发电形成的安全孤岛可以减少整个系统的失电负荷量、降低配电公司的购电总费用。同时,可以根据非故障馈线的容量裕度,实施最佳的支援方式。  相似文献   

11.
The floodplains of lowland rivers contain diverse aquatic habitats that provide valuable ecosystem services but are perturbed when intensively cultivated. Hydrologic, water chemistry and biological (fish) conditions in five aquatic habitats along the Coldwater River, Mississippi, were measured for more than 4 years: the river, two severed meanders that functioned as backwaters, a managed wetland and an ephemeral channel draining cultivated fields. Off‐channel habitats were connected to downstream regions 0.10% to 32% of the dry season and 24% to 67% of the wet season. The median temperatures for the five monitored sites ranged from 18°C to 23°C, the median total solids concentration for all sites was 135 mg L?1, the median total phosphorus was 0.29 mg L?1 and the median total nitrogen was 1.56 mg L?1. Chemical and physical water quality displayed strong seasonal differences between the wet winter/spring and the dry summer/fall periods so that temporal variation consisted of gradual seasonal trends superimposed on strong diurnal variations. All off‐channel habitats exhibited periods of hypoxia and temperatures >30°C during the dry season. Between‐site gradients of water and habitat quality were strongly coupled to water depth and runoff loading. The rehabilitation of one backwater by increasing water depth and diverting agricultural runoff was associated with improved water quality and fish species richness relative to an adjacent untreated backwater. The diversion of polluted runoff and the use of water control structures to maintain greater water depth were observed to be effective management tools, but the former reduces the water supply to habitats that tend to dry up and the latter reduces connectivity. Published in 2011 by John Wiley & Sons, Ltd.  相似文献   

12.
根据冗各电站地下厂房开挖支护的施工顺序,以隐式杆单元模拟锚杆,以壳单元模拟混凝土喷层,采用三维非线性有限元技术,对洞室群的开挖支护动态过程进行了模拟计算。通过三维非线性有限元计算分析得到:洞室群动态开挖过程中围岩应力变形的分布规律,围岩塑性区的发展规律,锚杆受力变化情况。计算结果表明:整个开挖过程中,洞周围岩位移变化规律正常,量值较小,塑性区主要分布在洞室周边,围岩稳定性较好;但在洞室交叉口处围岩的变形较大,出现较大范围的塑性区,在此基础上提出了支护措施优化方案,并对优化方案的效果进行了评价。  相似文献   

13.
Call for Papers     
正As the eldest and most distributed professional journal of water industry,Water Wastewater Engineering(W WE)gained very wide acceptance from the colleagues working in this field in this country since start publication in 1964.Now it is administrated by the Ministry of Construction of the People’s Republic of China and sponsored by the China Civil Engineering Society etc.  相似文献   

14.
Carbon dioxide (CO2) and methane (CH4) diffusive emissions were measured during two field surveys in Queensland and Tasmania, Australia, using the floating chamber method. Bubbling and degassing emissions in 2010 were estimated in Koombooloomba Dam reservoir using only inverted funnels and gas concentrations, respectively. A total of 14 reservoirs and 16 rivers and lakes were sampled from 2006 to 2010. Spatial variation was substantial within each water body, as well as between them. The main drivers of diffusive emission variation were physiographic region and climate, with a clear demarcation being observed between diffusive emissions from tropical Queensland and temperate Tasmania, and between the humid West Coast Range (Tasmania) and dry Central Plateau (Tasmania). Higher CO2 and CH4 diffusive emissions were observed during the dry season, when long water residence times would promote organic matter degradation. Estimated total gross emissions, including diffusive, bubbling and degassing emissions, for Koombooloomba Dam reservoir were about 1.5 × 106 t CO2eq km2 per year, or 24 × 106 t CO2eq per year. This corresponds to a plant emission factor of 3.18 kg CO2eq MWh?1. Using an estimate of terrestrial emissions derived from literature data for the Tully River catchment area, rough estimated net emissions from the catchment area are about 44 kt CO2eq per year, or 5.83 kg CO2eq MWh?1, which is in the lower range of the studied reservoirs.  相似文献   

15.
The relocation of unionacean mussels is commonly used as a conservation and management tool in large rivers and streams. Relocation has been used to recolonize areas where mussel populations have been eliminated by prior pollution events, to remove mussels from construction zones and to re-establish populations of endangered species. More recently, relocation has been used to protect native freshwater mussels from colonization by the exotic zebra mussel Dreissena polymorpha. We conducted a literature review of mussel relocations and evaluated their relative success as a conservation and management strategy. We found that 43% of all relocations were conducted because of construction projects that were forced to comply with the Endangered Species Act 1973 and that only 16% were monitored for five or more consecutive years. Most (43%) relocation projects were conducted from July to September, presumably a period when reproductive stress is relatively low for most species and the metabolic rate is sufficient for reburrowing in the substrate. The mortality of relocated mussels was unreported in 27% of projects; reported mortality varied widely among projects and species and was difficult to assess. The mean mortality of relocated mussels was 49% based on an average recovery rate of 43%. There is little guidance on the methods for relocation or for monitoring the subsequent long-term status of relocated mussels. Based on this evaluation, research is needed to develop criteria for selecting a suitable relocation site and to establish appropriate methods and guidelines for conducting relocation projects.  相似文献   

16.
Samples were taken year-round at eleven sites along the altitudinal profile (2900-1400 m a.s.l.) of the Gunnison River, a 329 km tributary of the Colorado River, to document the distribution of the Plecoptera and to evaluate responses to hypolimnial-release dams in the headwaters and middle reaches. Twenty-two species were present, with the greatest species richness occurring in an unregulated segment upstream of the middle reach dams; average nymphal biomass over the study period (175 organisms, 395 mg dry mass m?2) was also greatest in this segment. Only four species (58 organisms, 48 mg m?2) were present in the tailwaters of the headwater dam and values were greatly reduced (nine species; 35 organisms, 180 mg m?2) below the middle reach dams. The stonefly community recovered ca. 80 km downstream from the last dam (15 species; 244 organisms, 250 mg m?2), apparently in response to natural resetting of environmental conditions corresponding to those above the middle reach dams. At the most downstream site (11) only four species (four organisms, 16 mg m?2) were present. The observed distributional pattern is a classic serial discontinuity in response to hypolimnial stream regulation in a temperate latitude river.  相似文献   

17.
为了经济可靠地确定深厚覆盖层的基本特性参数,以大渡河双江口水电站坝基河床砂砾石层基本特性研究为工程背景,进行大尺寸模型试验,研究河床砂砾石层的旁压模量和动探击数随密度、级配以及上覆压力的变化规律。根据室内模型试验结果,结合现场旁压试验及钻孔试验成果,推断出坝址区河床砂砾石相关层位的密度,并依此进行砂砾石室内力学试验,获得设计所需力学参数。研究成果可为深厚覆盖层基本特性测试提供新的方法。  相似文献   

18.
A system for removal and pneumatic transport of fly ash is examined, in which air pulses act on batches (pistons) of ash formed in a duct. Studies are made of the effect of several physical parameters on the force required to displace a piston of ash and these serve as a basis for choosing a system for removal and pneumatic transport of ash simultaneously from several hoppers of an electric precipitator. This makes it possible to separate the ash particles according to size without introducing additional components. Formulas are given for calculating the structural and dynamic parameters of this system and measurements of indirect dynamic parameters are used to calculate the input-output characteristics of the system. In order to optimize the system, configurations for summing several ducts into a single transport duct for pneumatic ash transport are proposed. Some variants of dry ash utilization and the advantages of producing of size-separated particles are considered. __________ Translated from élektricheskie Stantsii, No. 2, pp. 26–30 (2008).  相似文献   

19.
The ‘flood pulse advantage’ is the amount by which fish yield per unit mean water area is increased by a natural, predictable flood pulse. Evidence for this increase is presented from tropical and temperate fisheries. It is argued that increasing multispecies fish yield by restoring the natural hydrological regime is consistent with increasing production of other trophic levels and with restoration from ecological and aesthetic viewpoints. When applied to a river-floodplain system, this restoration would provide a large, self-sustaining potential for recreation, commercial exploitation, and flood control. An interim ‘natural flood pulse’ restoration approach is proposed for systems modified for navigation. This approach approximates the natural hydrological regime in a river reach and is intended as a first step in the long process of restoring the watershed.  相似文献   

20.
River regulation in the headwaters and middle reaches of the Gunnison River, Colorado, significantly altered distributions and abundances of Trichoptera fauna. Twenty-five species were collected from mainstream samples, with the greatest species richness occurring at an unregulated, rhithron segment above the central reach dams. At sites immediately below the three hypolimnial-release dams and a reregulation dam, species richness was reduced 35–90 per cent and abundance > 95 per cent. Net-spinning caddisflies were the dominant trichopterans at unregulated sites; Arctopsyche grandis in the upper reaches (218 organisms, 586 mg dry mass m?2) and Hydropsyche cockerelli, H. occidentalis and Cheumatopsyche pettiti in the lower river (9041 total organisms, 6621 mg m?2), downstream from the last dam. The observed distributional pattern of low trichopteran densities in dam tailwaters and high hydropsychid densities at sites 60–80 km below the central reach dams is a classic expression of continuum resets and adjustments in response to stream regulation as predicted by the Serial Discontinuity Concept.  相似文献   

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