为准确获得淮南—上海1 000 k V同塔双回交流输电线路的工频序参数,采用基于全球定位系统的异频双端同步测量方法测量试验中各相导线首、末端电压与电流;提出了将所测电压与电流代入长线方程来求解异频下的工频序参数的计算方法,并与单...为准确获得淮南—上海1 000 k V同塔双回交流输电线路的工频序参数,采用基于全球定位系统的异频双端同步测量方法测量试验中各相导线首、末端电压与电流;提出了将所测电压与电流代入长线方程来求解异频下的工频序参数的计算方法,并与单端测量所得结果进行比较。结果表明,采用所提出的双端测量计算法能够获得准确的工频序参数,与采用分布参数模型的单端测量计算结果相比,其差异百分比≤1.52%;而与采用常规集中参数算法的单端测量法相比相差较大,其中零序电阻差异百分比可达16.48%,这是因为单端测量法不适用于长距离线路的参数计算。将上述双端测量计算法用于测量特高压同塔双回交流输电线路淮芜Ⅰ线与Ⅱ线的工频序参数,获得了准确的结果,为继电保护及短路电流计算等提供了数据基础。展开更多
Flow distribution in branch piping system is affected by flow characteristics and different geometric variations. Most of the flow distribution studies are performed with one-dimensional analysis to yield overall info...Flow distribution in branch piping system is affected by flow characteristics and different geometric variations. Most of the flow distribution studies are performed with one-dimensional analysis to yield overall information only. However, detailed analysis is required to find effects of design parameters on the flow distribution. For this aspect, three-dimensional turbulent flow analysis was performed to assess turbulence model performance and effects of upstream pressure and branch pipe geometry. Three different turbulence models of standard k-e model, realizable k-e model and standard k-co yield similar results, indicating small effects of turbulence models on flow characteristics analysis. Geometric variations include area ratio of main and branch pipes, branch pipe diameter, and connection shape of main and branch pipes. Among these parameters, area ratio and branch diameter and shape show strong effect on flow distribution due to high friction and minor loss. Uniform flow distribution is one of common requirements in the branch piping system and this can be achieved with rather high total loss design.展开更多
文摘为准确获得淮南—上海1 000 k V同塔双回交流输电线路的工频序参数,采用基于全球定位系统的异频双端同步测量方法测量试验中各相导线首、末端电压与电流;提出了将所测电压与电流代入长线方程来求解异频下的工频序参数的计算方法,并与单端测量所得结果进行比较。结果表明,采用所提出的双端测量计算法能够获得准确的工频序参数,与采用分布参数模型的单端测量计算结果相比,其差异百分比≤1.52%;而与采用常规集中参数算法的单端测量法相比相差较大,其中零序电阻差异百分比可达16.48%,这是因为单端测量法不适用于长距离线路的参数计算。将上述双端测量计算法用于测量特高压同塔双回交流输电线路淮芜Ⅰ线与Ⅱ线的工频序参数,获得了准确的结果,为继电保护及短路电流计算等提供了数据基础。
基金Project supported by Changwon National University in 2010
文摘Flow distribution in branch piping system is affected by flow characteristics and different geometric variations. Most of the flow distribution studies are performed with one-dimensional analysis to yield overall information only. However, detailed analysis is required to find effects of design parameters on the flow distribution. For this aspect, three-dimensional turbulent flow analysis was performed to assess turbulence model performance and effects of upstream pressure and branch pipe geometry. Three different turbulence models of standard k-e model, realizable k-e model and standard k-co yield similar results, indicating small effects of turbulence models on flow characteristics analysis. Geometric variations include area ratio of main and branch pipes, branch pipe diameter, and connection shape of main and branch pipes. Among these parameters, area ratio and branch diameter and shape show strong effect on flow distribution due to high friction and minor loss. Uniform flow distribution is one of common requirements in the branch piping system and this can be achieved with rather high total loss design.
