IEEE PES 2006年度学术会议和国际大电网会议(CIGRE)2006基本上代表了当今电力技术的最高水平和最新研究方向,其论文集对我国电力系统运行和科研工作有较高的参考价值。本文对上述2个会议的论文集进行了综述,主要内容包括动态安全评估...IEEE PES 2006年度学术会议和国际大电网会议(CIGRE)2006基本上代表了当今电力技术的最高水平和最新研究方向,其论文集对我国电力系统运行和科研工作有较高的参考价值。本文对上述2个会议的论文集进行了综述,主要内容包括动态安全评估、广域量测系统、广域控制系统、系统恢复等方面的研究现状介绍与经验总结。最后结合我国电力系统调度自动化方面的实际情况提出了一些建议。展开更多
Wideband IMT-Advanced mobile communication systems tend to operate in the high frequency bands due to a relatively large capacity available. Thus, Measurement and modelling methods of radio propaga- tion eharaeteristi...Wideband IMT-Advanced mobile communication systems tend to operate in the high frequency bands due to a relatively large capacity available. Thus, Measurement and modelling methods of radio propaga- tion eharaeteristics are proposed for the field test of Chinese 4th generation （4G） trial system. The mea- surement system is established for 3.5GHz based on the sophistieated measurement instruments and the virtual instrument teehnology. The characteristic parameters of radio propagation sueh as path loss （PL） exponent and shadow fading standard deviation are extracted from measurement data, which result in the path loss model finally. The comparisons with other existing international models results validate our mea- surement in terms of path loss model. Based on the analysis of the existing extension model assumed for the microwave frequency at 3.5GHz, we find that the Stanford University Interim （SUI） model fits very well with the measurement result in the hotspot scenario, while the COST 231 model is closer to the mea- surement result in the suburban scenario. This result provides a measurement-based channel referenee for the development of the future IMT-Advanced systems in China.展开更多
Investigation of seismic performance of buildings with STRP （scrap tire rubber pad） seismic isolators by means of pseudo-dynamic tests and numerical simulation is presented. The isolated building is numerically mode...Investigation of seismic performance of buildings with STRP （scrap tire rubber pad） seismic isolators by means of pseudo-dynamic tests and numerical simulation is presented. The isolated building is numerically modeled, while the base isolation layer is considered as the experimental substructure in the pseudo-dynamic tests. The test result verifies that the STRP isolator shows acceptable shear deformation performance predicted by the design methods, and demonstrated that seismic isolation using STRP works as a protective measure to provide enhanced seismic performance of the building indicated by the reduction of top floor absolute acceleration, drift and base shear as designated.展开更多
One of the most interesting outcomes from the recent collaboration between natural and social scientists is the concept of resilience, which imported from engineering to ecology. The problem with that concept is that ...One of the most interesting outcomes from the recent collaboration between natural and social scientists is the concept of resilience, which imported from engineering to ecology. The problem with that concept is that it is hard if not impossible to get simple measures for resilience as far as social-ecological systems are complex ones. Using a system dynamics model, the author shows that, for assessing resilience of systems like irrigation systems, it probably helps to see the process of resilience loss as a systemic one, in which dynamics is given by positive self-reinforcing loops, like the one we have labeled in this paper--the death spiral. The author also presents a list of symptoms of collapse in irrigation systems, in order to assess the resilience of those systems, and suggest some future avenues of research on the subject.展开更多
Two-level system model based probabilistic steady-state and dynamic security assessment model is introduced in this paper.Uncertainties of nodal power injection caused by wind power and load demand,steady-state and dy...Two-level system model based probabilistic steady-state and dynamic security assessment model is introduced in this paper.Uncertainties of nodal power injection caused by wind power and load demand,steady-state and dynamic security constraints and transitions between system configurations in terms of failure rate and repair rate are considered in the model.Time to insecurity is used as security index.The probability distribution of time to insecurity can be obtained by solving a linear vector differential equation.The coefficients of the differential equation are expressed in terms of configuration transition rates and security transition probabilities.The model is implemented in complex system successfully for the first time by using the following effective measures:firstly,calculating configuration transition rates effectively based on component state transition rate matrix and system configuration array;secondly,calculating the probability of random nodal power injection belonging to security region effectively according to practical parts of critical boundaries of security region represented by hyper-planes;thirdly,locating non-zero elements of coefficient matrix and then implementing sparse storage of coefficient matrix effectively;finally,calculating security region off-line for on-line use.Results of probabilistic security assessment can be used to conduct operators to analyze system security effectively and take preventive control.Test results on New England 10-generators and 39-buses power system verify the reasonableness and effectiveness of the method.展开更多
文摘IEEE PES 2006年度学术会议和国际大电网会议(CIGRE)2006基本上代表了当今电力技术的最高水平和最新研究方向,其论文集对我国电力系统运行和科研工作有较高的参考价值。本文对上述2个会议的论文集进行了综述,主要内容包括动态安全评估、广域量测系统、广域控制系统、系统恢复等方面的研究现状介绍与经验总结。最后结合我国电力系统调度自动化方面的实际情况提出了一些建议。
基金supported by the High Technology Research and Development Programme of China(2007AA01Z278)
文摘Wideband IMT-Advanced mobile communication systems tend to operate in the high frequency bands due to a relatively large capacity available. Thus, Measurement and modelling methods of radio propaga- tion eharaeteristics are proposed for the field test of Chinese 4th generation （4G） trial system. The mea- surement system is established for 3.5GHz based on the sophistieated measurement instruments and the virtual instrument teehnology. The characteristic parameters of radio propagation sueh as path loss （PL） exponent and shadow fading standard deviation are extracted from measurement data, which result in the path loss model finally. The comparisons with other existing international models results validate our mea- surement in terms of path loss model. Based on the analysis of the existing extension model assumed for the microwave frequency at 3.5GHz, we find that the Stanford University Interim （SUI） model fits very well with the measurement result in the hotspot scenario, while the COST 231 model is closer to the mea- surement result in the suburban scenario. This result provides a measurement-based channel referenee for the development of the future IMT-Advanced systems in China.
文摘Investigation of seismic performance of buildings with STRP （scrap tire rubber pad） seismic isolators by means of pseudo-dynamic tests and numerical simulation is presented. The isolated building is numerically modeled, while the base isolation layer is considered as the experimental substructure in the pseudo-dynamic tests. The test result verifies that the STRP isolator shows acceptable shear deformation performance predicted by the design methods, and demonstrated that seismic isolation using STRP works as a protective measure to provide enhanced seismic performance of the building indicated by the reduction of top floor absolute acceleration, drift and base shear as designated.
文摘One of the most interesting outcomes from the recent collaboration between natural and social scientists is the concept of resilience, which imported from engineering to ecology. The problem with that concept is that it is hard if not impossible to get simple measures for resilience as far as social-ecological systems are complex ones. Using a system dynamics model, the author shows that, for assessing resilience of systems like irrigation systems, it probably helps to see the process of resilience loss as a systemic one, in which dynamics is given by positive self-reinforcing loops, like the one we have labeled in this paper--the death spiral. The author also presents a list of symptoms of collapse in irrigation systems, in order to assess the resilience of those systems, and suggest some future avenues of research on the subject.
文摘Two-level system model based probabilistic steady-state and dynamic security assessment model is introduced in this paper.Uncertainties of nodal power injection caused by wind power and load demand,steady-state and dynamic security constraints and transitions between system configurations in terms of failure rate and repair rate are considered in the model.Time to insecurity is used as security index.The probability distribution of time to insecurity can be obtained by solving a linear vector differential equation.The coefficients of the differential equation are expressed in terms of configuration transition rates and security transition probabilities.The model is implemented in complex system successfully for the first time by using the following effective measures:firstly,calculating configuration transition rates effectively based on component state transition rate matrix and system configuration array;secondly,calculating the probability of random nodal power injection belonging to security region effectively according to practical parts of critical boundaries of security region represented by hyper-planes;thirdly,locating non-zero elements of coefficient matrix and then implementing sparse storage of coefficient matrix effectively;finally,calculating security region off-line for on-line use.Results of probabilistic security assessment can be used to conduct operators to analyze system security effectively and take preventive control.Test results on New England 10-generators and 39-buses power system verify the reasonableness and effectiveness of the method.
