In order to realize further stability of a stack-type thermoelectric power generating module (i.e. no electrical connections inside), flexible materials of metal springs and/or rods having restoring forces were instal...In order to realize further stability of a stack-type thermoelectric power generating module (i.e. no electrical connections inside), flexible materials of metal springs and/or rods having restoring forces were installed between lower-temperature-sides of thermoelectric elements. These flexible materials were expected to play three important roles of interpolating different thermal expansions of the module components, enlarging heat removal area and penetration of any media through themselves. Then, a low-boiling-point medium (i.e. NOVEC manufactured by 3M Japan Ltd.) was also applied for a high-speed direct heat removal via its phase change from the lower-temperature-sides of the thermoelectric elements in the proposing stack-type thermoelectric power generating module. No electrical disconnections inside the module were confirmed for more than 9 years of use, indicating further module stability. The power generating density was improved to about 120 mW·m-2 with SUS304 springs having 0.7 mm diameter. Increasing power generating density can be expected in terms of suitable selection of flexible metal with high Vickers hardness, cavities control on the spring surface, more vigorous multiphase flow with adding powders to the medium and optimization of the module configurations according to numerical simulations.展开更多
电力系统中的潮流转移会引起线路事故过负荷及其距离Ⅲ段保护误动作,这是导致连锁跳闸,最终发生大停电事故的重要因素之一。为此,利用广域测量系统(wide area measurement system,WAMS)的优势,提出一种潮流转移识别方案。根据三相电流...电力系统中的潮流转移会引起线路事故过负荷及其距离Ⅲ段保护误动作,这是导致连锁跳闸,最终发生大停电事故的重要因素之一。为此,利用广域测量系统(wide area measurement system,WAMS)的优势,提出一种潮流转移识别方案。根据三相电流增量及零序电流的大小来区分线路过负荷和不对称短路故障,根据电压幅值的大小来区分线路过负荷和对称短路故障,并提出了相应的识别判据。考虑到系统振荡对判据判断的影响和故障切除后过负荷发生的情况,提出了具体的潮流转移识别策略,并给出了实现流程,该策略可有效防止距离Ⅲ段元件在事故过负荷时误动,并能保证在故障时可靠开放距离Ⅲ段保护。通过对新英格兰10机39节点系统进行仿真,验证了该方法的有效性。展开更多
可用输电能力(available transfer capability,ATC)的大小不仅能够衡量电力系统安全和可靠性,同时在一定程度上能够反映电力市场交易双方获得利润的多少。随着分布式发电(distributed generation,DG)的广泛开展,其对ATC的影响不容忽视...可用输电能力(available transfer capability,ATC)的大小不仅能够衡量电力系统安全和可靠性,同时在一定程度上能够反映电力市场交易双方获得利润的多少。随着分布式发电(distributed generation,DG)的广泛开展,其对ATC的影响不容忽视。为此,首先基于ATC的定义,阐述了DG对ATC的影响机理;提出了考量DG对ATC影响的分析方法,利用交流潮流法建立了DG输出功率对线路潮流和节点电压影响的数学模型。采用MAT-LAB6.5编写相关的计算程序,通过6节点和30节点测试系统的算例分析,证明了分析方法和数学模型能够有效考量DG对ATC产生的影响。且方法可应用于含有DG设备的配电网规划及电力市场的交易决策中。展开更多
文摘In order to realize further stability of a stack-type thermoelectric power generating module (i.e. no electrical connections inside), flexible materials of metal springs and/or rods having restoring forces were installed between lower-temperature-sides of thermoelectric elements. These flexible materials were expected to play three important roles of interpolating different thermal expansions of the module components, enlarging heat removal area and penetration of any media through themselves. Then, a low-boiling-point medium (i.e. NOVEC manufactured by 3M Japan Ltd.) was also applied for a high-speed direct heat removal via its phase change from the lower-temperature-sides of the thermoelectric elements in the proposing stack-type thermoelectric power generating module. No electrical disconnections inside the module were confirmed for more than 9 years of use, indicating further module stability. The power generating density was improved to about 120 mW·m-2 with SUS304 springs having 0.7 mm diameter. Increasing power generating density can be expected in terms of suitable selection of flexible metal with high Vickers hardness, cavities control on the spring surface, more vigorous multiphase flow with adding powders to the medium and optimization of the module configurations according to numerical simulations.
文摘电力系统中的潮流转移会引起线路事故过负荷及其距离Ⅲ段保护误动作,这是导致连锁跳闸,最终发生大停电事故的重要因素之一。为此,利用广域测量系统(wide area measurement system,WAMS)的优势,提出一种潮流转移识别方案。根据三相电流增量及零序电流的大小来区分线路过负荷和不对称短路故障,根据电压幅值的大小来区分线路过负荷和对称短路故障,并提出了相应的识别判据。考虑到系统振荡对判据判断的影响和故障切除后过负荷发生的情况,提出了具体的潮流转移识别策略,并给出了实现流程,该策略可有效防止距离Ⅲ段元件在事故过负荷时误动,并能保证在故障时可靠开放距离Ⅲ段保护。通过对新英格兰10机39节点系统进行仿真,验证了该方法的有效性。
文摘可用输电能力(available transfer capability,ATC)的大小不仅能够衡量电力系统安全和可靠性,同时在一定程度上能够反映电力市场交易双方获得利润的多少。随着分布式发电(distributed generation,DG)的广泛开展,其对ATC的影响不容忽视。为此,首先基于ATC的定义,阐述了DG对ATC的影响机理;提出了考量DG对ATC影响的分析方法,利用交流潮流法建立了DG输出功率对线路潮流和节点电压影响的数学模型。采用MAT-LAB6.5编写相关的计算程序,通过6节点和30节点测试系统的算例分析,证明了分析方法和数学模型能够有效考量DG对ATC产生的影响。且方法可应用于含有DG设备的配电网规划及电力市场的交易决策中。
