高压直流断路器是多端柔性直流输电工程换流站内重要的电气设备,直接关系到柔直系统运行的可靠性。根据±200 k V高压直流断路器在系统操作合闸过程中,出现的位置信号未及时返回控制系统,断路器后序无法进行分闸操作的故障现象,经...高压直流断路器是多端柔性直流输电工程换流站内重要的电气设备,直接关系到柔直系统运行的可靠性。根据±200 k V高压直流断路器在系统操作合闸过程中,出现的位置信号未及时返回控制系统,断路器后序无法进行分闸操作的故障现象,经报文分析判断和现场故障检测,得出故障原因是断路器开关内极柱分位传感器位置偏移,造成分位信号响应延迟、断路器拒动。最后通过将分位传感器调整至正常工作位置的方法解决了该问题,并提出了需要制定高压直流断路器检修规程及监控后台增加断路器操作次数统计功能的建议。展开更多
Petermann Glacier is a marine-terminating outlet glacier that had a 70 km-long floating ice tongue prior to a ～ 270 km2 calving event that was observed from satellite sensors in August 2010,shortening the ice tongue ...Petermann Glacier is a marine-terminating outlet glacier that had a 70 km-long floating ice tongue prior to a ～ 270 km2 calving event that was observed from satellite sensors in August 2010,shortening the ice tongue by ～ 27 km.Further,in July 2012,another 10 km was lost through calving.In order to understand these events in perspective,here the authors perform a long-term data analysis of Petermann Glacier calving-front variability and ice velocity for each year in the 1990s-2000s,supplemented by available observations from the previous three decades.Five major （on the order of 100 krm2） calving events are identified,with ～ 153 km2 calved from 1959 to 1961,～ 168 km2 in 1991,～ 71 km2 in 2001,～ 270 km2 in 2010,and ～ 130 km2 in 2012-as well as ～ 31 k m2 calved in 2008.The increased frequency of major calving events in recent years has left the front terminus position retreated nearly 25 km beyond the range of observed in previous decades.In contrast,stable ice-dynamics are suggested from ice-velocity measurements made each year between 1993-2012,which are on average 1063 m yr-1,with limited interannual variability and no significant trend; moreover,there is no apparent relationship between ice-velocity variability and calving events.The degree to which the massive calving events in 2010 and 2012 represent natural episodic variability or a response to atmospheric and/or oceanic changes remains speculative; however,melt-induced weakening of the floating ice tongue in recent years is strongly suggested.展开更多
文摘高压直流断路器是多端柔性直流输电工程换流站内重要的电气设备,直接关系到柔直系统运行的可靠性。根据±200 k V高压直流断路器在系统操作合闸过程中,出现的位置信号未及时返回控制系统,断路器后序无法进行分闸操作的故障现象,经报文分析判断和现场故障检测,得出故障原因是断路器开关内极柱分位传感器位置偏移,造成分位信号响应延迟、断路器拒动。最后通过将分位传感器调整至正常工作位置的方法解决了该问题,并提出了需要制定高压直流断路器检修规程及监控后台增加断路器操作次数统计功能的建议。
基金supported by the Trond Mohn Donation to the Mohn-Sverdrup Center at the Nansen Center,the Research Council of Norway’s UK/Netherlands/Norway RAPID programthe project AWAKE under the Polish-Norwegian Research Fund(2009–2011)
文摘Petermann Glacier is a marine-terminating outlet glacier that had a 70 km-long floating ice tongue prior to a ～ 270 km2 calving event that was observed from satellite sensors in August 2010,shortening the ice tongue by ～ 27 km.Further,in July 2012,another 10 km was lost through calving.In order to understand these events in perspective,here the authors perform a long-term data analysis of Petermann Glacier calving-front variability and ice velocity for each year in the 1990s-2000s,supplemented by available observations from the previous three decades.Five major （on the order of 100 krm2） calving events are identified,with ～ 153 km2 calved from 1959 to 1961,～ 168 km2 in 1991,～ 71 km2 in 2001,～ 270 km2 in 2010,and ～ 130 km2 in 2012-as well as ～ 31 k m2 calved in 2008.The increased frequency of major calving events in recent years has left the front terminus position retreated nearly 25 km beyond the range of observed in previous decades.In contrast,stable ice-dynamics are suggested from ice-velocity measurements made each year between 1993-2012,which are on average 1063 m yr-1,with limited interannual variability and no significant trend; moreover,there is no apparent relationship between ice-velocity variability and calving events.The degree to which the massive calving events in 2010 and 2012 represent natural episodic variability or a response to atmospheric and/or oceanic changes remains speculative; however,melt-induced weakening of the floating ice tongue in recent years is strongly suggested.
