基于一主三从博弈的风-水-气区域电力系统调度研究

伴随电力市场开放程度与日俱增,发电企业在调度出力中将拥有更大的决策权。因此,立足于兼顾电网与多种类型发电厂利益构建的调度模型显得极为必要。将电网作为博弈主体,在保证电力供求平衡的基础上,以其购电成本与环境成本最小化为优化目标;将风、水、天然气电厂作为3个参与电力市场博弈的独立从体,在综合考虑各类电厂出力特性的基础上,以3个参与者的收益最大化作为优化目标;将电厂出力策略以及电网优化的上网电价作为决策空间,构建了基于一主三从博弈理论的区域电力系统调度模型,并提出了基于NSGA-II求解该模型Stackelberg-Nash均衡解的算法。算例仿真表明,所建立的一主三从博弈区域电力系统调度模型能够适应不同季节下的区域系统调度,并显著提高了调度控制中各电厂间利益分配的均衡度与稳定程度。

Temporal-Spatial Variances of Holocene Precipitation at the Marginal Area of the East Asian Monsoon Influences from Pollen Evidence

The woodland-steppe ecotone in the. southern Nei Mongol Plateau is located at the northern edge of the east Asian monsoon influences. A marked southeastern - northwestern (SE - NW) precipitation gradient exists in this region. Quantitative reconstruction of palaeo-precipitation of this region is helpful to reveal the development of monsoon climate and to predict die future desertification. Based on modern vegetation and surface pollen studies, a pollen-precipitation transfer function in the study region was established. Pollen data from three sediment sequences within the ecotone were used to reconstruct palaeo-precipitation during the Holocene. The processes of precipitation changes in the three sequences were quite different. There was a tendency of precipitation declined from the onset of the Holocene to 1 100 a BP in Haoluku. But, in Liuzhouwan and Xiaoniuchang, both located south of Haoluku, the annual precipitation reached highest values during 7 800 - 6 200 a BP and 7 200 - 5 000 a BP, respectively. The influences of southwestern (SW) monsoon and the variances of topographical conditions have possibly caused these temporal-spatial variances.

Numerical simulatim of rainwater accumulation and flow characteristics over windshield of high-speed trains

In this paper, a Euler-Lagrangian particle/fluid film/VOF coupled multiphase flow model is presented. Numerical simulations are conducted, and the rainwater accumulation and flow characteristics over two types of windshields are studied based on the presented model. The results show that an uneven water film is formed over the windshield, with rain water accumulation occurring for the concave windshield but not for the convex windshield. At low speeds, the average fluid-film thickness for a concave windshield is larger than that of a convex windshield;however, a minor difference occurs between these two values at high speeds, and a critical velocity is observed for the two types of windshields. When the train velocity is less than the critical velocity, the fluid film at the lower part of the windshield and the train nose flows downward, and beyond the critical velocity, the fluid film over the entire windshield and train nose flows upward.

The climate variability in global land precipitation in FGOALS-f3-L:A comparison between GMMIP and historical simulations

The climate variability in global land precipitation is important for the global hydrological cycle.Based on the Coupled Model Intercomparison Project Phase 6(CMIP6)historical experiments and the Global Monsoons Model Intercomparison Project(GMMIP)Tier-1 experiments,the spatialtemporal characteristics of global and regional land precipitation long-term climate changes in CAS FGOALS-f3-L are evaluated in this study.By comparing these two kinds of experiments,the precipitation biases related to the SSTs are also discussed.The results show that the two experiments could capture the precipitation trend and amplitude to a certain degree compared with observations.The GMMIP simulations show a higher skill than the historical runs verified by correlation coefficients partly because the observed monthly mean SST was prescribed.For the Northern Hemisphere,GMMIP can reproduce the trend and variability in global precipitation,while historical simulations cannot reproduce the trend and variability.However,both experiments fail to simulate the amplitude of the southern hemisphere summer precipitation anomalies.Ensemble empirical mode decomposition(EEMD)was applied to compare the simulated precipitation on different time scales.The sea surface temperature anomaly(SSTA)bias,especially the La Ni?a-type SSTA,is the dominant source of the model bias for simulating interannual precipitation anomalies.The authors also emphasize that the response of precipitation anomalies to the ENSO effect varies regionally.This study highlights the importance of the multiannual variability in SSTAs in global and hemispheric precipitation simulations.The ways to improve the simulation of global precipitation for CAS FGOALS-f3-L are also discussed.

巨型风电并网系统的协同自律控制

巨型风电场并网发电的调度和控制是我国电力系统发展亟需解决的关键难题之一.本文提出了风-水-气协同自律控制的理念和理论,给出了消纳巨型风电的两种基本调度和控制策略,即基于智能调度自动化系统(smartenergy manage system,SEMS)的集中式控制和基于协同自律控制的调度策略.本文对比分析了上述两种控制策略的适用情景,指出后者更加合理和高效.进一步,本文探讨了发展基于协同自律控制的风-水-气联合调度系统所需关键技术,试图为解决我国巨型风电并网发电调度难题给出一种方略.

State Modeling Based Prediction of Torsional Resonances for Horizontal-Axis Drive Train Wind Turbine

This paper focuses on the state space modeling approach and output torques prediction of torsional vibrations for variable speed wind turbines. The multi-body system model under study is mainly comprised of a wind turbine, a three stage planetary gear box and an induction generator. The masses-springs approach of shaft system differential equations is developed from Newton＇s law and Lagrange formulas. For an easy comprehension for electrical engineers and tutorial purpose, an electrical equivalent circuit of the system is proposed by using mechanical and electrical components similarities. Extensive numerical simulations are performed to investigate system mechanical resonances and impacts of damping factors on the system dynamic and stability.

Climate Change Risk Research: A Case Study on Flood Disaster Risk in China

This paper discusses theories and methods of climate change risk studies for the research expansion in China. Climate change risks consist of three basic components including sensitivity, exposure, and possibility. Uncertainty, future events, damages, and relativity are the major features of climate change risk. Climate change risk research includes two key steps: risk assessment and risk management, the former is the process, and the latter is the ultimate goal which is the basis for actions to address climate change. We present the main framework and methods for climate change risk research. A case study on China's floods risk is taken as an example of climate change risk study. Finally, we point out main aspects of climate change risk research, including ensemble-based probabilistic projection, quantitative risk assessment, risk zoning and mapping, and risk management.

Relationship over southern China between the summer rainfall induced by tropical cyclones and that by monsoon

This study investigates the relationship between tropical cyclone-induced precipitation（P_（TC）） and summer monsoon-induced precipitation（P_（SM）） in southern China（SC） during June-August.The spatial patterns of the first interannual mode are uniform in sign over SC,with positive anomalies for P_（TC） and negative anomalies for P_（SM）.The background of an increase in cyclonic vorticity,an increase in RH,and a decrease in vertical wind shear over the South China Sea（SCS）-western north Pacific（WNP） provides favorable conditions for more TC genesis.The positive equatorial central Pacific SST anomaly and negative North Indian Ocean SST anomaly contribute to the anomalous cyclone over the SCS-WNP,which causes decreasing P_（SM） in SC together with an anomalous anticyclone over eastern China-Japan.By contrast,whilst the spatial patterns of the first interdecadal mode are also uniform in sign over SC,there are positive anomalies for both P_（TC） and P_（SM）.The first interdecadal principal component features significant positive correlation with the number of TCs forming in the SCS.There is a significant increase in P_（TC） and P_（SM） after early 1990 s.A positive tropical Indian Ocean（TIO） SST anomaly persists from the preceding winter to summer.During the preceding winter and spring after the early 1990 s,a positive western Pacific SST anomaly can result in TIO SST warming through vertical circulation.Then,the positive TIO SST anomaly triggers an anomalous WNP anticyclone and contributes to the interdecadal increase in SC P_（SM） in the succeeding summer.The persistent heating source over SC from May to summer related to an earlier onset of the SCS monsoon may strengthen the East Asian subtropical summer monsoon.

FEATURES OF WATER VAPOR TRANSPORT OF TYPHOON DAN (9914)

The 2.5×2.5 gridded ECMWF reanalysis data are used to diagnose the genesis, developmentand dissipation of typhoon Dan by calculated stream function, velocity potential and vapor budget. It is shown inthe result that when typhoon Dan moved westwards, water vapor mainly came from the eastern and westernboundaries, with most of it was transferred by the easterly flow south of the western North Pacific subtropicalhigh; after Dan swerved northwards, water vapor mainly came from western boundary of the typhoon, and thevapor came from the South China Sea and the Indian Ocean. The transfer of water vapor was mainlyconcentrated on the mid-lower troposphere, especially the level of 925hPa, at which the most intensive transferbelt was located. During the different period of typhoon Dan, there was great water vapor change as indicated bystream function, velocity potential and vapor budget, which suggest the importance of water vapor in thedevelopment of typhoon Dan.

EU and international policies for hydrometeorological risks:Operational aspects and link to climate action

Changes in hydrometeorological characteristics and risks have been observed and are projected to increase under climate change. These considerations are scientifically well studied and led to the development of a complex policy framework for adaptation and mitigation for hydrometeorological risks. Awareness for policy actions is growing worldwide but no legal framework is in place to tackle climate change impacts on water at a global scale. With the example of international frameworks and the legislation on EU-level, this article elaborates that hydrometeorological risks are not considered in the framework of one single policy. However, various policy instruments are directly or indirectly considering these risks at different operational levels. It is discussed that a tailor-made framework for hydrometeorological risks would improve coordination at international or national level. A major drawback for a single operational framework is that hydrometeorological risks are scientifically tackled in two large communities: the disaster risk reduction community and the climate change adaptation community, both of which are bound to different research and operational funding budgets. In future, disaster risk reduction and climate change adaptation will need been seen as a complementary set of actions that requires collaboration.

A High Resolution Forecast Model of Storm Surge Inundation

In order to forecast storm surge inundation, a two-dimensional model is established. In the model, an alternating computation sequence method is used to solve the governing equations, and the dry and wet method is introduced to treat the moving boundary. This model is easy to use. It has a friendly input interface and Arcview GIS is used as the output interface. The model is applied to the Shantou area to simulate the storm surge elevations and inundations caused by Typhoons 6903 ane 0104 using the same relevant parameters. The calculated results agree well with the observations.

ANALYSIS OF EXTRATROPICAL TRANSITION OF TROPICAL CYCLONE OVER China's Mainland

Typhoon Winnie (1997) experienced three stages after landfall on China: weakening, transition, and re-intensification. The transition is similar to the "complex transition" model proposed by Matano and Sekioka. During the re-intensification stage, the transformed cyclone developed into a pattern of Shapiro-Keyser Cyclone model. From the diagnosis we can find that the cause of Winnie’s transition is the intrusion of cold air from the mid- and upper- troposphere and the warm temperature advection in the lower. Winnie redeveloped after transition, which is the result of three vital factors: the warm temperature advection in the lower troposphere, the divergence on the right side of the upper jet entry and the cyclonic vorticity advection in the upper.

Recent Climatic Effects on Seasonal Rice Yields in Bangladesh： A Statistical Overview

Expecting that agricultural yield is highly dependent on climatic conditions, particularly water availability and suitable temperature, an agroclimatic study was carried out on rice crops during three different seasons in four regions of Bangladesh. Data on climate （surface air temperature and precipitation） and seasonal rice production were examined for the period 1986-2006 from 18 rice growth observatories. The relationship between climate and rice production was statistically analyzed by removing long-term trends so that the effects of improved irrigation, which results in a general increase in crop production, may be removed. The analysis involved both single and multiple regressions. The results suggested that, during monsoon and summer, higher temperatures had negative effects on rice production, especially in the northwestern （NW） region. In winter, positive effects were observed throughout Bangladesh. Since the annual mean temperature was positively correlated with those in the three seasons individually, the annual temperature had negative effects on the annual rice production only in the NW region, while it had positive effects in the central and southern regions. With the exception of the NW region, it was basically dry, excessive rainfall both in summer and monsoon yielded floods and reduced rice yield. In winter, more rainfall showed positive effects on crop production only in the central region, which was least irrigated. These findings suggested that accelerated atmospheric warming would result in serious damage to crops during summer and monsoon. Reliable prediction of future crop production will rely on the temperature and rainfall trends in individual seasons.

The Relationship between Precipitation and Airflow over the Tibetan Plateau in Boreal Summer

Based on the observation data and the reanalysis datasets, the variability and the circulation features influencing precipitation in the Tibetan Plateau (TP) are investigated. Taking into account the effects of topography, surface winds are deconstructed into flow-around and flow-over components relative to the TP. Climatologically, the flow-around component mainly represents cyclonic circulation in the TP during the summer. The transition zone of total precipitation in the summer parallels the convergence belt between the southerlies and the northerlies of the flow-over component. The leading mode of rainfall anomalies in the TP has a meridional dipole structure, and the first principal component (PC1) mainly depicts the variation of rainfall in the southern TP. The wet southern TP experiences strengthened flow-over, which in turn mechanistically favors intensified ascent forced by the flow-over component. In addition, variations in the Indian summer monsoon (ISM) have an important role in influencing the flow over the southern TP, and the ISM ultimately impacts the precipitation over southern TP.

Recognition of two dominant modes of EASM and its thermal driving factors based on 25 monsoon indexes

Based on three reanalysis datasets—ERA-Interim,NCAR–NCEP and JRA-55—the classification of25 commonly used indexes of the East Asian summer monsoon(EASM)was investigated.The physical nature of two categories of monsoon index,together with their circulation pattern,climate anomalies,and driving factors,were investigated.Results suggest that the selected 25 monsoon indexes can be classified into two typical categories(CategoryⅠandⅡ),which are dominated by interannual and decadal variabilities of the EASM,respectively.The anomalous circulation patterns and summer rainfall patterns related to the two categories of index also exhibit evident differences.CategoryⅠis closely linked to the low-latitude circulation system and the anomalous circulation pattern is a typical East Asia–Pacific teleconnection pattern.The summer rainfall anomaly exhibits a typical tripole pattern.However,CategoryⅡmainly reflects the impacts of the middle–high latitude circulation system on the summer monsoon and is closely linked to a typical Eurasian teleconnection pattern,which corresponds to a dipole of summer rainfall anomalies.Further analysis suggests that the underlying thermal driving factors of the two categories of monsoon are distinct.The main driving factors of CategoryⅠare the tropical sea surface temperature anomalies(SSTAs),especially ENSO-related SSTAs in the preceding winter and summer SSTAs in the tropical Indian Ocean.The winter signal of Category II summer monsoon anomalous activity mainly originates from the polar region and the middle and high latitudes of the Eurasian continent.CategoryⅡmonsoon activity is also associated with summer SSTAs in the equatorial central Pacific.

Performance Analysis of the Aeration Valves and Its Protections at the Generating Units in ITAIPU Hydroelectric Power Plant

With the growing energetic need present in the world, it is increasingly necessary for the researches and facilities to seek a better use of renewable natural resources. This paper is applied in the study of the performance of the aeration system of the Francis turbines present in Itaipu Hydroelectric Power Plant. When a Francis turbine operates off its optimal conditions, a vortex is formed inside the draft tube that, besides produces cavitation and pressure fluctuations, can pulse at frequencies with risk of resonance with hydraulic system, producing efforts and vibrations that may cause structural failures in the turbines, generators and civil parts of the power house. These damaging effects can be reduced using atmospheric aeration of the turbines. Because of this, the availability and effectively of the aeration system is fundamental to smooth the behavior of the turbines, helping preserve the health of the power plant. An analysis of the performance of the aeration system will be done using maintenance records and disturbances analysis reports （RAP）, allowing verification of the operating conditions of the turbine and fatality of water inlet in air pipes. Through the improvements detected, it is possible to reduce machine stoppages by tripping, thus increasing the availability of the turbines.

Test Calibration of the Paleoclimatic Proxy Data with Chinese Historical Records

The calibration of paleoclimate proxies is one of the key problems in the study of paleoclimate at present. Historical documentary records of climate are suitable for calibration on dating and the climatic implication of the proxy data in a climatological sense. A test calibration on correcting the Delingha tree ring precipitation series using Chinese historical documentary records shows that among the 44 extreme dry cases in 1401 1950 AD, 42 cases （or 95.5%） are believable. Thus the long series of Delingha rings-denoted precipitation is highly reliable. Another test to validate the monsoon intensity proxy data based on the Zhanjiang Huguangyan sediments using historical records indicates that the years of Lake Maar Ti content series-designated winter monsoon intensities are entirely opposite to historical documents- depicted years of harsh winters in 800-900 AD. As a result, serious doubt is raised about the climatic implication of this paleo-monsoon proxy series.

A high resolution simulation of climate change over China

Multi-decadal high resolution climate change simulations over East Asia were performed by using The Abdus Salam International Centre for Theoretical Physics (ICTP) Regional Climate Model (RegCM3), nested within the NASA/NCAR global model FvGCM/CCM3. Two sets of simulations were conducted at 20-km grid spacings, one for present day (1961-1990) and one for the future climate (2071-2100, IPCC A2 scenario). Simulations of present climate conditions over China by RegCM3 and FvGCM were compared against observations to assess the model performance. Results showed that both models repro- duced the observed spatial structure of 500 hPa height, surface air temperature and precipitation. Compared with FvGCM, RegCM3 provided increasing spatial detail of surface variables. Furthermore, RegCM3 improved the simulation of monsoon precipitation over the region. Changes in the mean temperature and precipitation were analyzed and compared between the two models. Significant warming in the end of the 21st century was simulated by both models in December-January-February (DJF), June-July-August (JJA), and the annual mean. In DJF, greater warming was simulated by FvGCM over Northeast and Northwest China, as well as the Tibetan Plateau, compared with RegCM. In JJA, RegCM3 simulated greater warming over northern China, Inner Mongolia, Northwest China, and the Tibetan Plateau. Simulated changes in DJF precipitation showed similar spatial patterns between the two models. In JJA, while FvGCM projected a prevailing increase of monsoon precipitation over China, which is in agreement with other global models, RegCM3 projected extended areas of decreased precipitation. Changes in the variability for annual mean temperature and precipitation also are presented.

Influence of water flow on gas hydrate accumulation at cold vents

A cold vent is an area where methane-rich fluid seepage occurs. This seepage may alter the local temperature, salinity, and subsequent accumulation of the gas hydrate. Using a kinetic gas hydrate formation model and in situ measurement of tempera- ture, salinity and fluid flux at the southern summit of Hydrate Ridge, we simuIate the gas hydrate accumulation at three distinct fluid sites： clam, bacterial mat, and gas discharge sites. At the clam sites （pore water flux 〈 20 kg m-2 yr-1）, pore water advec- tion has little influence on temperature and salinity. However, the salinity and temperature are increased （peak salinity 〉 0.8 tool kg-1） by the formation of gas hydrate causing the base of the hydrate stability zone to move gradually from -115 to -70 meters below seafloor （mbsf）. The gas hydrate saturation at the clam sites is relatively high. The water flux at the bacterial mat sites ranges from 100 to 2500 kg m-2 yr-1. The water flow suppresses the increase in salinity resulting in a salinity close to or slightly higher than that of seawater （〈 0.65 mol kg-l）. Heat advection by water flow increases temperature significantly, shifting the base of the hydrate stability zone to above 50 or even 3 mbsf. The gas hydrate saturation is relatively low at the bacterial mat site. At the gas discharge sites, the pore water flux could reach 10^10 kg m-2 yr-1, and the temperature could reach that of the source area in 9 min. There is no gas hydrate formation at the gas discharge sites. Our simulative analysis therefore reveals that a lower pore water flux would result in lower salinity, higher temperature, and a shallower base of the hydrate sta- bility zone. This in turn induces a lower gas hydrate formation rate, lower hydrate saturation, and eventually less gas hydrate resources.

Additional risk in extreme precipitation in China from 1.5℃to 2.0℃global warming levels

To avoid dangerous climate change impact, the Paris Agreement sets out two ambitious goals: to limit the global warming to be well below 2 ℃ and to pursue effort for the global warming to be below 1.5 ℃ above the pre-industrial level. As climate change risks may be region-dependent, changes in magnitude and probability of extreme precipitation over China are investigated under those two global warming levels based on simulations from the Coupled Model Inter-Comparison Projects Phase 5. The focus is on the added changes due to the additional half a degree warming from 1.5 ℃ to 2 ℃ . Results show that regional average changes in the magnitude do not depend on the return periods with a relative increase around 7% and 11% at the 1.5 ℃ and 2 ℃ global warming levels, respectively. The additional half a degree global warming adds an additional increase in the magnitude by nearly 4%. The regional average changes in term of occurrence probabilities show dependence on the return periods, with rarer events(longer return periods) having larger increase of risk. For the 100-year historical event, the probability is projected to increase by a factor of 1.6 and 2.4 at the 1.5 ℃ and 2 ℃ global warming levels, respectively.The projected changes in extreme precipitation are independent of the RCP scenarios.