The available soil water capacity (ASWC) is important for studying crop production, agro-ecological zoning, irrigation planning, and land cover changes. Laboratory determined data of ASWC are often not available for m...The available soil water capacity (ASWC) is important for studying crop production, agro-ecological zoning, irrigation planning, and land cover changes. Laboratory determined data of ASWC are often not available for most of soil profiles and the nationwide ASWC largely remains lacking in relevant soil data in China. This work was to estimate ASWC based on physical and chemical properties and analyze the spatial distribution of ASWC in China. The pedo-transfer functions (PTFs), derived from 220 survey data of ASWC, and the empirical data of ASWC based on soil texture were applied to quantify the ASWC. GIS technology was used to develop a spatial file of ASWC in China and the spatial distribution of ASWC was also analyzed. The results showed the value of ASWC ranges from 15 × 10-2 cm3·cm-3 to 22 × 10-2 cm3·cm-3 for most soil types, and few soil types are lower than 15 × 10-2 cm3·cm-3 or higher than 22 × 10-2 cm3·cm-3. The ASWC is different according to the complex soil types and their distribution. It is higher in the east than that in the west, and the values reduce from south to north except the northeastern part of China. The "high" values of ASWC appear in southeast, northeastern mountain regions and Northeast China Plain. The relatively "high" values of ASWC appear in Sichuan basin, Huang-Huai-Hai plain and the east of Inner Mongolia. The relatively "low" values are distributed in the west and the Loess Plateau of China. The "very low" value regions are the northern Tibetan Plateau and the desertified areas in northern China. In some regions, the ASWC changes according to the complex topography and different types of soils. Though there remains precision limitation, the spatial data of ASWC derived from this study are improved on current data files of soil water retention properties for Chinese soils. This study presents basic data and analysis methods for estimation and evaluation of ASWC in China.展开更多
Congestion is the prime cause of problems, due to open access of power system. The AC Power Transmission Congestion Distribution factor (PTCDF) is suitable for computing change in any line quantity for a change in MW ...Congestion is the prime cause of problems, due to open access of power system. The AC Power Transmission Congestion Distribution factor (PTCDF) is suitable for computing change in any line quantity for a change in MW bilateral transaction. The proposed PTCDF method is more accurate as compared to the DC power distribution factor. With PTCDF ATC can be calculated. After calculating ATC it is possible to know the valid multiple transaction on power system. With the help of ATC calculations congestion problem can be solved in restructured electrical power network. The paper presents the method for calculating ATC using PTCDF.展开更多
提出了包括传统静态安全性和鞍结分岔稳定性的可用输电能力(Available Transfer Capability,ATC)的新模型.该模型将系统安全性约束的众多不等式转化为一个半光滑等式约束方程组,结合鞍结分岔稳定性的约束条件,构建了一类同时考虑安全性...提出了包括传统静态安全性和鞍结分岔稳定性的可用输电能力(Available Transfer Capability,ATC)的新模型.该模型将系统安全性约束的众多不等式转化为一个半光滑等式约束方程组,结合鞍结分岔稳定性的约束条件,构建了一类同时考虑安全性和稳定性的ATC模型的半光滑方程系统.基于光滑化策略和方法,建立了模型求解的Levenberg-Marquardt计算方法.9节点和30节点系统的计算结果表明该模型和计算方法的可行性和有效性.展开更多
近年来,随着清洁能源占比的持续攀升和跨省跨区交易电量规模的日益扩大,我国电力市场建设亟需充分利用输电通道容量以及避免网络阻塞导致交易效率降低的问题。从北欧与美国PJM电力市场的建设经验来看,可用传输容量(available transfer c...近年来,随着清洁能源占比的持续攀升和跨省跨区交易电量规模的日益扩大,我国电力市场建设亟需充分利用输电通道容量以及避免网络阻塞导致交易效率降低的问题。从北欧与美国PJM电力市场的建设经验来看,可用传输容量(available transfer capability,ATC)作为电网跨区功率交换水平的重要量化指标,对于提高输电通道利用效率或降低网络阻塞风险可以起到关键作用。因此,需要紧密结合国外典型电力市场在ATC应用上的相关做法,形成对我国的借鉴与启示,并对ATC如何应用于我国电力市场进行深入研究。首先介绍了ATC的定义及其计算方法。在此基础上,梳理以北欧与美国PJM为代表的典型电力市场中ATC的相关应用情况并进行对比总结。然后,结合我国电网建设和电力市场发展现状,指出目前我国电力市场考虑ATC的必要性,并凝练ATC应用的关键问题。最后,基于国外典型电力市场ATC应用经验和我国实际情况,探讨我国电力市场环境下ATC应用关键问题的解决思路。展开更多
As fossil fuel stocks are being depleted,alternative sources of energy must be explored.Consequently,traditional thermal power plants must coexist with renewable resources,such as wind,solar,and hydro units,and all-da...As fossil fuel stocks are being depleted,alternative sources of energy must be explored.Consequently,traditional thermal power plants must coexist with renewable resources,such as wind,solar,and hydro units,and all-day planning and operation techniques are necessary to safeguard nature while meeting the current demand.The fundamental components of contemporary power systems are the simultaneous decrease in generation costs and increase in the available transfer capacity(ATC)of current systems.Thermal units are linked to sources of renewable energy such as hydro,wind,and solar power,and are set up to run for 24 h.By contrast,new research reports that various chaotic maps are merged with various existing optimization methodologies to obtain better results than those without the inclusion of chaos.Chaos seems to increase the performance and convergence properties of existing optimization approaches.In this study,selfish animal tendencies,mathematically represented as selfish herd optimizers,were hybridized with chaotic phenomena and used to improve ATC and/or reduce generation costs,creating a multi-objective optimization problem.To evaluate the performance of the proposed hybridized optimization technique,an optimal power flow-based ATC was enforced under various hydro-thermal-solar-wind conditions,that is,the renewable energy source-thermal scheduling concept,on IEEE 9-bus,IEEE 39-bus,and Indian Northern Region Power Grid 246-bus test systems.The findings show that the proposed technique outperforms existing well-established optimization strategies.展开更多
20世纪70年代,电力工作者开始对系统区域间的可用输电能力(Available Transfer Capability,ATC)进行研究。在联邦能源管理委员会(Federal Energy Regulatory Commission,FERC)下达要求输电网的运行单位需计算ATC的命令之后,ATC的研究受...20世纪70年代,电力工作者开始对系统区域间的可用输电能力(Available Transfer Capability,ATC)进行研究。在联邦能源管理委员会(Federal Energy Regulatory Commission,FERC)下达要求输电网的运行单位需计算ATC的命令之后,ATC的研究受到了广泛的关注。快速、可靠地评估ATC对系统的输电可靠性和电力市场交易顺利进行有着重要的作用。基于预测校正内点法计算速度快、鲁棒性好、快速收敛等优点,将预测校正内点法(Predictor-corrector Primal-dual Interior-point Method,PCPDIPM)应用于电力系统ATC计算;通过对模型进行仿真分析,与传统原对偶内点法(Primal-dual Interior-point Method,PDIPM)计算ATC进行比较,验证模型的实用性和算法的有效性及快速收敛性。展开更多
基金National Natural Science Foundation of China No.43071093
文摘The available soil water capacity (ASWC) is important for studying crop production, agro-ecological zoning, irrigation planning, and land cover changes. Laboratory determined data of ASWC are often not available for most of soil profiles and the nationwide ASWC largely remains lacking in relevant soil data in China. This work was to estimate ASWC based on physical and chemical properties and analyze the spatial distribution of ASWC in China. The pedo-transfer functions (PTFs), derived from 220 survey data of ASWC, and the empirical data of ASWC based on soil texture were applied to quantify the ASWC. GIS technology was used to develop a spatial file of ASWC in China and the spatial distribution of ASWC was also analyzed. The results showed the value of ASWC ranges from 15 × 10-2 cm3·cm-3 to 22 × 10-2 cm3·cm-3 for most soil types, and few soil types are lower than 15 × 10-2 cm3·cm-3 or higher than 22 × 10-2 cm3·cm-3. The ASWC is different according to the complex soil types and their distribution. It is higher in the east than that in the west, and the values reduce from south to north except the northeastern part of China. The "high" values of ASWC appear in southeast, northeastern mountain regions and Northeast China Plain. The relatively "high" values of ASWC appear in Sichuan basin, Huang-Huai-Hai plain and the east of Inner Mongolia. The relatively "low" values are distributed in the west and the Loess Plateau of China. The "very low" value regions are the northern Tibetan Plateau and the desertified areas in northern China. In some regions, the ASWC changes according to the complex topography and different types of soils. Though there remains precision limitation, the spatial data of ASWC derived from this study are improved on current data files of soil water retention properties for Chinese soils. This study presents basic data and analysis methods for estimation and evaluation of ASWC in China.
文摘Congestion is the prime cause of problems, due to open access of power system. The AC Power Transmission Congestion Distribution factor (PTCDF) is suitable for computing change in any line quantity for a change in MW bilateral transaction. The proposed PTCDF method is more accurate as compared to the DC power distribution factor. With PTCDF ATC can be calculated. After calculating ATC it is possible to know the valid multiple transaction on power system. With the help of ATC calculations congestion problem can be solved in restructured electrical power network. The paper presents the method for calculating ATC using PTCDF.
文摘提出了包括传统静态安全性和鞍结分岔稳定性的可用输电能力(Available Transfer Capability,ATC)的新模型.该模型将系统安全性约束的众多不等式转化为一个半光滑等式约束方程组,结合鞍结分岔稳定性的约束条件,构建了一类同时考虑安全性和稳定性的ATC模型的半光滑方程系统.基于光滑化策略和方法,建立了模型求解的Levenberg-Marquardt计算方法.9节点和30节点系统的计算结果表明该模型和计算方法的可行性和有效性.
文摘近年来,随着清洁能源占比的持续攀升和跨省跨区交易电量规模的日益扩大,我国电力市场建设亟需充分利用输电通道容量以及避免网络阻塞导致交易效率降低的问题。从北欧与美国PJM电力市场的建设经验来看,可用传输容量(available transfer capability,ATC)作为电网跨区功率交换水平的重要量化指标,对于提高输电通道利用效率或降低网络阻塞风险可以起到关键作用。因此,需要紧密结合国外典型电力市场在ATC应用上的相关做法,形成对我国的借鉴与启示,并对ATC如何应用于我国电力市场进行深入研究。首先介绍了ATC的定义及其计算方法。在此基础上,梳理以北欧与美国PJM为代表的典型电力市场中ATC的相关应用情况并进行对比总结。然后,结合我国电网建设和电力市场发展现状,指出目前我国电力市场考虑ATC的必要性,并凝练ATC应用的关键问题。最后,基于国外典型电力市场ATC应用经验和我国实际情况,探讨我国电力市场环境下ATC应用关键问题的解决思路。
文摘As fossil fuel stocks are being depleted,alternative sources of energy must be explored.Consequently,traditional thermal power plants must coexist with renewable resources,such as wind,solar,and hydro units,and all-day planning and operation techniques are necessary to safeguard nature while meeting the current demand.The fundamental components of contemporary power systems are the simultaneous decrease in generation costs and increase in the available transfer capacity(ATC)of current systems.Thermal units are linked to sources of renewable energy such as hydro,wind,and solar power,and are set up to run for 24 h.By contrast,new research reports that various chaotic maps are merged with various existing optimization methodologies to obtain better results than those without the inclusion of chaos.Chaos seems to increase the performance and convergence properties of existing optimization approaches.In this study,selfish animal tendencies,mathematically represented as selfish herd optimizers,were hybridized with chaotic phenomena and used to improve ATC and/or reduce generation costs,creating a multi-objective optimization problem.To evaluate the performance of the proposed hybridized optimization technique,an optimal power flow-based ATC was enforced under various hydro-thermal-solar-wind conditions,that is,the renewable energy source-thermal scheduling concept,on IEEE 9-bus,IEEE 39-bus,and Indian Northern Region Power Grid 246-bus test systems.The findings show that the proposed technique outperforms existing well-established optimization strategies.
基金This research is supported by the National Natural Science Foundation of China under Grant Nos. 10871031, 10926189, the Natural Science United Foundation of Hunan-Hengyang under Grant No. 10JJS008, and the Educational Department of Hunan under Grant No. 10A015
