Specific Catchment Area （SCA） is defined as the upstream catchment area of a unit contour. As one of the key terrain parameters, it is widely used in the modeling of hydrology, soil erosion and ecological environmen...Specific Catchment Area （SCA） is defined as the upstream catchment area of a unit contour. As one of the key terrain parameters, it is widely used in the modeling of hydrology, soil erosion and ecological environment. However, SCA value changes significantly at different DEM resolutions, which inevitably affect terrain analysis results. SCA can be described as the ratio of Catchment Area （CA） and DEM grid length. In this paper, the scale effect of CA is firstly investigated. With Jiuyuangou Gully, a watershed about 70 km2 in northern Shaanxi Province of China, as the test area, it is found that the impacts of DEM scale on CA are different in spatial distribution. CA value in upslope location becomes bigger with the decrease of the DEM resolution. When the location is close to downstream areas the impact of DEM scale on CA is gradually weakening. The scale effect of CA can be concluded as a mathematic trend of exponential decline. Then, a downscaling model of SCA is put forward by introducing the scale factor and the location factor. The scaling model can realize the conversion of SCA value from a coarse DEM resolution to a finer one at pixel level. Experiment results show that the downscaled SCA was well revised, and consistent with SCA at the target resolution with respect to the statistical indexes, histogram and spatial distribution. With the advantages of no empirical parameters, the scaling model could be considered as a simple and objective model for SCA scaling in a rugged drainage area.展开更多
研究了同群光伏系统等值建模的原理和特点,针对倍乘等值方法的不足,提出一种基于变流器输入阻抗不变的聚合等值方法。以某典型光伏系统为例,在实时数字仿真系统(real time digital simulation system, RTDS)中分别搭建了30台参数相同的1...研究了同群光伏系统等值建模的原理和特点,针对倍乘等值方法的不足,提出一种基于变流器输入阻抗不变的聚合等值方法。以某典型光伏系统为例,在实时数字仿真系统(real time digital simulation system, RTDS)中分别搭建了30台参数相同的1 MW光伏多机参考模型、1台30 MW光伏倍乘模型和1台30 MW光伏聚合模型。通过仿真试验,比对这3个模型在光伏系统公共并网点(point of common coupling, PCC)的故障穿越、有功阶跃、频率偏移等暂态特性及阻抗频率特性。结果表明,3个模型的暂态特性基本相同,倍乘模型与参考模型的阻抗频率特性有明显差异,而聚合模型与参考模型的阻抗频率特性高度一致。展开更多
基金Key Project of National Natural Science Foundation of China No.40930531 National Youth Science Foun-dation of China No.40901185 Specialized Research Fund for the Doctoral Program of Higher Education No.20093207120008
文摘Specific Catchment Area （SCA） is defined as the upstream catchment area of a unit contour. As one of the key terrain parameters, it is widely used in the modeling of hydrology, soil erosion and ecological environment. However, SCA value changes significantly at different DEM resolutions, which inevitably affect terrain analysis results. SCA can be described as the ratio of Catchment Area （CA） and DEM grid length. In this paper, the scale effect of CA is firstly investigated. With Jiuyuangou Gully, a watershed about 70 km2 in northern Shaanxi Province of China, as the test area, it is found that the impacts of DEM scale on CA are different in spatial distribution. CA value in upslope location becomes bigger with the decrease of the DEM resolution. When the location is close to downstream areas the impact of DEM scale on CA is gradually weakening. The scale effect of CA can be concluded as a mathematic trend of exponential decline. Then, a downscaling model of SCA is put forward by introducing the scale factor and the location factor. The scaling model can realize the conversion of SCA value from a coarse DEM resolution to a finer one at pixel level. Experiment results show that the downscaled SCA was well revised, and consistent with SCA at the target resolution with respect to the statistical indexes, histogram and spatial distribution. With the advantages of no empirical parameters, the scaling model could be considered as a simple and objective model for SCA scaling in a rugged drainage area.
文摘研究了同群光伏系统等值建模的原理和特点,针对倍乘等值方法的不足,提出一种基于变流器输入阻抗不变的聚合等值方法。以某典型光伏系统为例,在实时数字仿真系统(real time digital simulation system, RTDS)中分别搭建了30台参数相同的1 MW光伏多机参考模型、1台30 MW光伏倍乘模型和1台30 MW光伏聚合模型。通过仿真试验,比对这3个模型在光伏系统公共并网点(point of common coupling, PCC)的故障穿越、有功阶跃、频率偏移等暂态特性及阻抗频率特性。结果表明,3个模型的暂态特性基本相同,倍乘模型与参考模型的阻抗频率特性有明显差异,而聚合模型与参考模型的阻抗频率特性高度一致。
