统一潮流控制器(unified power flow controller,UPFC)是最全面的柔性交流输电(flexible alternating⁃current transmission system,FACTS)控制装置,可以独立并快速地调节输电线路中的有功功率和无功功率。随着电网规模及互联水平的不...统一潮流控制器(unified power flow controller,UPFC)是最全面的柔性交流输电(flexible alternating⁃current transmission system,FACTS)控制装置,可以独立并快速地调节输电线路中的有功功率和无功功率。随着电网规模及互联水平的不断提高,厂/站之间的电气距离明显缩短,系统阻抗下降,系统中的短路电流水平显著提升,给电力系统安全、稳定运行以及电力系统中各种电气设备提出了更为苛刻的要求。尤其以浙江、江苏等型态日益复杂的受端电网,潮流分布不均、短路电流控制困难等难题已成为制约电力建设和进一步发展的瓶颈。考虑到故障限流器(fault current limiter,FCL)在系统严重故障时能够有效地控制短路电流,本文在UPFC现有拓扑结构的基础上,将FCL通过快速旁路开关与其相结合,既充分发挥UPFC在稳态情况下的优化潮流和系统故障后的紧急功率控制;同时,在系统严重故障时,FCL投入运行降低系统的短路电流。针对本文提出的优化拓扑结构在浙江电网中的规划应用进行了研究,验证了该优化拓扑结构在短路电流控制和潮流柔性调节的有效性。展开更多
Bundle adjustment （BA） is a crucial but time consuming step in 3D reconstruction. In this paper, we intend to tackle a special class of BA problems where the reconstructed 3D points are much more numerous than the c...Bundle adjustment （BA） is a crucial but time consuming step in 3D reconstruction. In this paper, we intend to tackle a special class of BA problems where the reconstructed 3D points are much more numerous than the camera parameters, called Massive-Points BA （MPBA） problems. This is often the case when high-resolution images are used. We present a design and implementation of a new bundle adjustment algorithm for efficiently solving the MPBA problems. The use of hardware parallelism, the multi-core CPUs as well as GPUs, is explored. By careful memory-usage design, the graphic-memory limitation is effectively alleviated. Several modern acceleration strategies for bundle adjustment, such as the mixed-precision arithmetics, the embedded point iteration, and the preconditioned conjugate gradients, are explored and compared. By using several high-resolution image datasets, we generate a variety of MFBA problems, with which the performance of five bundle adjustment algorithms are evaluated. The experimental results show that our algorithm is up to 40 times faster than classical Sparse Bundle Adjustment, while maintaining comparable precision.展开更多
文摘统一潮流控制器(unified power flow controller,UPFC)是最全面的柔性交流输电(flexible alternating⁃current transmission system,FACTS)控制装置,可以独立并快速地调节输电线路中的有功功率和无功功率。随着电网规模及互联水平的不断提高,厂/站之间的电气距离明显缩短,系统阻抗下降,系统中的短路电流水平显著提升,给电力系统安全、稳定运行以及电力系统中各种电气设备提出了更为苛刻的要求。尤其以浙江、江苏等型态日益复杂的受端电网,潮流分布不均、短路电流控制困难等难题已成为制约电力建设和进一步发展的瓶颈。考虑到故障限流器(fault current limiter,FCL)在系统严重故障时能够有效地控制短路电流,本文在UPFC现有拓扑结构的基础上,将FCL通过快速旁路开关与其相结合,既充分发挥UPFC在稳态情况下的优化潮流和系统故障后的紧急功率控制;同时,在系统严重故障时,FCL投入运行降低系统的短路电流。针对本文提出的优化拓扑结构在浙江电网中的规划应用进行了研究,验证了该优化拓扑结构在短路电流控制和潮流柔性调节的有效性。
基金supported by the National Natural Science Foundation of China under Grant No.60835003the Strategic Priority Research Program of the Chinese Academy of Sciences under Grant No.XDA06030300
文摘Bundle adjustment （BA） is a crucial but time consuming step in 3D reconstruction. In this paper, we intend to tackle a special class of BA problems where the reconstructed 3D points are much more numerous than the camera parameters, called Massive-Points BA （MPBA） problems. This is often the case when high-resolution images are used. We present a design and implementation of a new bundle adjustment algorithm for efficiently solving the MPBA problems. The use of hardware parallelism, the multi-core CPUs as well as GPUs, is explored. By careful memory-usage design, the graphic-memory limitation is effectively alleviated. Several modern acceleration strategies for bundle adjustment, such as the mixed-precision arithmetics, the embedded point iteration, and the preconditioned conjugate gradients, are explored and compared. By using several high-resolution image datasets, we generate a variety of MFBA problems, with which the performance of five bundle adjustment algorithms are evaluated. The experimental results show that our algorithm is up to 40 times faster than classical Sparse Bundle Adjustment, while maintaining comparable precision.
