In recent years,several failures of double circuit transmission line on the same tower due to lightning were happened in Beijing power grid.Although it can be reclosed successful,the lightning strike caused a grave th...In recent years,several failures of double circuit transmission line on the same tower due to lightning were happened in Beijing power grid.Although it can be reclosed successful,the lightning strike caused a grave threat to the power grid security.The cause of the accident and the accident process were studied for the sake of further understanding of the impact of lightning on power grid.As an example,110 kV double circuit transmission line(Xilong-line) was analyzed.At first,the system topology was given.Through the analysis on relay protection actions and the fault recorder data,over voltage on the insulator strings was calculated.Based on the analysis and the calculation,accident cause and the process were presented respectively.Secondly,it comes to the conclusion that the lightning failure was caused by counterattack.The wave of the lightning over voltage would spread to the not grounded neutral point of the transformers,and make the neutral protective gap breakdown,then cause freewheeling with the frequency of 50 Hz.As results of the relay protection,the double circuit transmission line all tripped out.Finally,the causes of the accident were proposed that included terrain features,large corner towers,strong thunderstorm weather and poor grounded contact of the tower.展开更多
At present, as capital well-known office building, the SCITECHTOWER & PLACE achieved authenticated certificates of ISO 14001both international and China environmental management system fromUKAS and CACEB. It’s th...At present, as capital well-known office building, the SCITECHTOWER & PLACE achieved authenticated certificates of ISO 14001both international and China environmental management system fromUKAS and CACEB. It’s the first time for an office building gained thedouble authentication in mainland. Ms. Zhang Keping, general managerof the SCITECH TOWER & PLACE claimed that, it’s the展开更多
Climate change continues to affect the lives of individuals across the world, creating a rise in demand for new technologies that can slow down the impacts of climate change. Shanghai, one of the largest cities in the...Climate change continues to affect the lives of individuals across the world, creating a rise in demand for new technologies that can slow down the impacts of climate change. Shanghai, one of the largest cities in the world, has one of the highest carbon emission levels. In recent years, the research and development of energy-efficient technologies have gained more and more attention. The Shanghai Tower is a pioneer in green building design and a prominent example of Shanghai’s efforts towards low-carbon city development. In this paper, two technologies within the Shanghai Tower<span style="font-family:Verdana;">—</span><span style="font-family:Verdana;">ground source heat pumps (GSHP) and double skin facades (DSF)</span><span style="font-family:Verdana;">—</span><span style="font-family:Verdana;">will be analyzed. The paper will consist of firstly an investigation of the principles of the technologies, and then analysis, evaluation, and comparison of their respective characteristics. While both GSHP and DSF are used for sustainable purposes, the effectiveness of technologies depends on what environment the technology is used in and what purpose they serve. The evaluation of GSHP and DSF will be based on their performances under Shanghai’s climate and whether they contribute to the purposes of the Shanghai Tower.</span>展开更多
In order to improve the reliability of fault identification of the double-circuit transmission lines on the same tower, a new algorithm for fast protection of double-circuit transmission lines on the same tower based ...In order to improve the reliability of fault identification of the double-circuit transmission lines on the same tower, a new algorithm for fast protection of double-circuit transmission lines on the same tower based on the reactive powers of traveling wave is proposed. With the implementation of S-transform, the initial traveling wave reactive powers are calculated and the change characteristics of reactive power under different fault conditions are studied. The protection criterion is constructed by analyzing the ratio of the reactive powers of the same end on double-circuit transmission lines and the ratio of the reactive powers at both ends on the same line. According to the ratio of reactive power on the same side of the line and both ends of the same line, it is possible to identify whether the faults of the double-circuit line of the same tower occurred in or out of the protection zone. A large number of simulation results show that the protection performance is sensitive and reliable, and quick to respond. The criterion is simple and is basically not affected by fault initial angles, fault types, and transitional resistances.展开更多
文摘In recent years,several failures of double circuit transmission line on the same tower due to lightning were happened in Beijing power grid.Although it can be reclosed successful,the lightning strike caused a grave threat to the power grid security.The cause of the accident and the accident process were studied for the sake of further understanding of the impact of lightning on power grid.As an example,110 kV double circuit transmission line(Xilong-line) was analyzed.At first,the system topology was given.Through the analysis on relay protection actions and the fault recorder data,over voltage on the insulator strings was calculated.Based on the analysis and the calculation,accident cause and the process were presented respectively.Secondly,it comes to the conclusion that the lightning failure was caused by counterattack.The wave of the lightning over voltage would spread to the not grounded neutral point of the transformers,and make the neutral protective gap breakdown,then cause freewheeling with the frequency of 50 Hz.As results of the relay protection,the double circuit transmission line all tripped out.Finally,the causes of the accident were proposed that included terrain features,large corner towers,strong thunderstorm weather and poor grounded contact of the tower.
文摘At present, as capital well-known office building, the SCITECHTOWER & PLACE achieved authenticated certificates of ISO 14001both international and China environmental management system fromUKAS and CACEB. It’s the first time for an office building gained thedouble authentication in mainland. Ms. Zhang Keping, general managerof the SCITECH TOWER & PLACE claimed that, it’s the
文摘Climate change continues to affect the lives of individuals across the world, creating a rise in demand for new technologies that can slow down the impacts of climate change. Shanghai, one of the largest cities in the world, has one of the highest carbon emission levels. In recent years, the research and development of energy-efficient technologies have gained more and more attention. The Shanghai Tower is a pioneer in green building design and a prominent example of Shanghai’s efforts towards low-carbon city development. In this paper, two technologies within the Shanghai Tower<span style="font-family:Verdana;">—</span><span style="font-family:Verdana;">ground source heat pumps (GSHP) and double skin facades (DSF)</span><span style="font-family:Verdana;">—</span><span style="font-family:Verdana;">will be analyzed. The paper will consist of firstly an investigation of the principles of the technologies, and then analysis, evaluation, and comparison of their respective characteristics. While both GSHP and DSF are used for sustainable purposes, the effectiveness of technologies depends on what environment the technology is used in and what purpose they serve. The evaluation of GSHP and DSF will be based on their performances under Shanghai’s climate and whether they contribute to the purposes of the Shanghai Tower.</span>
文摘In order to improve the reliability of fault identification of the double-circuit transmission lines on the same tower, a new algorithm for fast protection of double-circuit transmission lines on the same tower based on the reactive powers of traveling wave is proposed. With the implementation of S-transform, the initial traveling wave reactive powers are calculated and the change characteristics of reactive power under different fault conditions are studied. The protection criterion is constructed by analyzing the ratio of the reactive powers of the same end on double-circuit transmission lines and the ratio of the reactive powers at both ends on the same line. According to the ratio of reactive power on the same side of the line and both ends of the same line, it is possible to identify whether the faults of the double-circuit line of the same tower occurred in or out of the protection zone. A large number of simulation results show that the protection performance is sensitive and reliable, and quick to respond. The criterion is simple and is basically not affected by fault initial angles, fault types, and transitional resistances.
