多端柔性直流系统在分布式能源和直流负荷接入、网络柔性互联、电能质量等方面具有显著优势,成为未来电网的重要发展趋势。为了保证多端柔性直流系统安全稳定可靠运行,需要能够在数毫秒内开断故障电流的直流断路器。本文面向张北±5...多端柔性直流系统在分布式能源和直流负荷接入、网络柔性互联、电能质量等方面具有显著优势,成为未来电网的重要发展趋势。为了保证多端柔性直流系统安全稳定可靠运行,需要能够在数毫秒内开断故障电流的直流断路器。本文面向张北±500 k V柔性直流电网示范工程的应用需求,开展了500 k V直流断路器原理研究与样机研制。首先,提出500 k V耦合负压换流型混合式直流断路器系统方案,给出其拓扑结构、工作原理和控制逻辑;进而,设计基于电磁斥力操动机构和电磁缓冲机构的快速机械开关、基于二极管和复合被动保护支路的交叉桥式电力电子开关和基于耦合负压电路的换流装置等;最后,研制500 k V耦合负压换流型混合式直流断路器工程样机进行实验验证。研究结果表明,研制的100 k V混合式直流断路器能够在3 ms开断25 k A短路电流,具有低损耗、低成本、高可靠性等特点,相关成果已经过实验验证。展开更多
Objective To assess the effects of suction drainage versus nondrainage on the post-operative rehabilitation of patients receiving primary bilateral total knee arthroplasties(TKA).Methods A prospective study including ...Objective To assess the effects of suction drainage versus nondrainage on the post-operative rehabilitation of patients receiving primary bilateral total knee arthroplasties(TKA).Methods A prospective study including 40 patients was conducted.These patients were diagnosed with osteoarthritis and underwent primary bilateral TKA between October 2007 and September 2009 with the same operation team.A suction drainage was placed by randomization in only one knee for each patient,while the other knee as self-control.Pain visual analogue scale score,extremity swelling,wound healing,range of motion and incidence of early post-operative complications between the drained and nondrained group were compared statistically.Results Each patient was followed up for 12 months.Placing drainage did not relieve the pain,extremity swelling,ecchymosis,or reduce the incidence of early complications(all P>0.05).Conclusions Suction drainage in TKA does not exhibit substantial advantages in promoting post-operative rehabilitation after unsophisticated TKA,compared with nondrainage.On the other hand,it might complicate the surgical operation,and increase the incidence of post-operative hemorrhage and retrograde infection.Thus we do not recommend suction drainage in unsophisticated TKA.展开更多
文摘多端柔性直流系统在分布式能源和直流负荷接入、网络柔性互联、电能质量等方面具有显著优势,成为未来电网的重要发展趋势。为了保证多端柔性直流系统安全稳定可靠运行,需要能够在数毫秒内开断故障电流的直流断路器。本文面向张北±500 k V柔性直流电网示范工程的应用需求,开展了500 k V直流断路器原理研究与样机研制。首先,提出500 k V耦合负压换流型混合式直流断路器系统方案,给出其拓扑结构、工作原理和控制逻辑;进而,设计基于电磁斥力操动机构和电磁缓冲机构的快速机械开关、基于二极管和复合被动保护支路的交叉桥式电力电子开关和基于耦合负压电路的换流装置等;最后,研制500 k V耦合负压换流型混合式直流断路器工程样机进行实验验证。研究结果表明,研制的100 k V混合式直流断路器能够在3 ms开断25 k A短路电流,具有低损耗、低成本、高可靠性等特点,相关成果已经过实验验证。
文摘Objective To assess the effects of suction drainage versus nondrainage on the post-operative rehabilitation of patients receiving primary bilateral total knee arthroplasties(TKA).Methods A prospective study including 40 patients was conducted.These patients were diagnosed with osteoarthritis and underwent primary bilateral TKA between October 2007 and September 2009 with the same operation team.A suction drainage was placed by randomization in only one knee for each patient,while the other knee as self-control.Pain visual analogue scale score,extremity swelling,wound healing,range of motion and incidence of early post-operative complications between the drained and nondrained group were compared statistically.Results Each patient was followed up for 12 months.Placing drainage did not relieve the pain,extremity swelling,ecchymosis,or reduce the incidence of early complications(all P>0.05).Conclusions Suction drainage in TKA does not exhibit substantial advantages in promoting post-operative rehabilitation after unsophisticated TKA,compared with nondrainage.On the other hand,it might complicate the surgical operation,and increase the incidence of post-operative hemorrhage and retrograde infection.Thus we do not recommend suction drainage in unsophisticated TKA.
