基于功率逐级切换控制的内河船舶负荷转供策略

针对我国内河流域港口岸电的船舶负荷转供过程的研究,为抑制并网后直接切断船侧柴电系统引起的逆功率与负荷波动问题,提出一种基于船侧负荷由船电转供至岸电的功率逐级切换控制方法。通过分析岸电对船侧负荷转供过程中的功率波动现象,给出基于功率超调和动态响应时间为指标的逐级切换条件,以船侧负荷的电能质量指标为标准,通过对船侧同步电机的输出功率进行逐级调速控制,以降低功率波动以及频率偏移对负荷的负面影响,提高供电质量。通过Simulink平台搭建岸电系统模型进行仿真,这一方法的仿真结果表明了所提出的策略的正确性和有效性,能够实现岸船两侧电力系统的并网后负荷的平稳过渡。

Simulation of energy and water balance in Soil-Vegetation-Atmosphere Transfer system in the mountain area of Heihe River Basin at Hexi Corridor of northwest China

In the mountain area of inland Heihe River Basin at Hexi Corridor of northwest China during the vegetation growing season from May to September, the Simultaneous Heat and Water (SHAW) model of Soil-Vegetation-Atmosphere Transfer (SVAT) system is applied to simulating and studying energy and water balance of the soil-residue-plant canopy layers in the Picea crassifolia forest and the grassland by the forest at the shaded slope and the grassland at the sun-facing slope. The simulation of energy balance indicates that net radiation of the grass- land at the sun-facing slope is more than that of the Picea crassifolia forest and the grassland by the forest at the shaded slope. The energy outgoing components are the first latent heat and next sensible heat from the grassland both at the shaded slope and the sun-facing slope, but those at the former are less. The energy outgoing components are the first sensible heat and next latent heat from the Picea crassifolia forest. The composition and distribution of energy in the soil-residue-plant canopy layers in the Picea crassifolia forest and the grassland by the forest at the shaded slope make the soil layer receive less energy, which therefore, especially the forest possesses the energy conditions for soil water conservation. The simulation of water balance indicates that the water loss of the grassland at the sun-facing slope is mainly caused by soil evaporation, while evapotranspiration of the Picea crassifolia forest and the grassland by the forest at the shaded slope is less than that of the grassland at the sun-facing slope. Half of the evapotranspiration of the Picea crassifolia forest and the grassland by the forest at the shaded slope is consumed by transpiration. After precipitation, the soil water storage is increased much more for the Picea crassifolia forest and also more for the grassland by the forest at the shaded slope. Therefore the shaded slope vegetation, especially the forest is favorable for soil water storage.

上海港内河水-水中转集疏运模式研究

上海港在国家"一带一路"倡议和长江经济带战略背景下面临重大发展机遇,同时也面临缺乏后备土地、集疏运体系结构失衡、受城市可持续发展制约等发展瓶颈和问题,大力开展内河水-水中转集疏运对于上海港解决上述问题有重要意义。建立了Logit流量分配模型,并通过案例数值计算,得出内河水-水中转在整个集疏运体系中的分担率和流量,并揭示了内河水-水中转集疏运模式对降低社会物流总成本、减少交通碳排放量和缓解上海港周边地区公路拥堵的重要作用。