Stand-alone wind power system with battery/supercapacitor hybrid energy storage

This paper presents a stand-alone wind power system with battery/supercapacitor hybrid energy storage. A stand-alone wind power system mainly consists of a wind turbine, a permanent magnet synchronous generator, hybrid energy storage devices based on a vanadium redox flow battery and a supercapacitor, an AC/DC converter, two bidirectional DC/DC converters, a DC/AC converter and a variable load. Several control strategies for the stand-alone wind power system are involved such as a maximum power point tracking (MPPT) control, a vanadium redox flow battery charge/discharge control and a supercapacitor charge/discharge control. The proposed MPPT control combines a sliding mode control with an extreme search control to capture maximum wind energy. This strategy avoids the necessity of measuring wind velocity, obtaining models or parameters of the wind turbine and calculating the differentials of the power generated from the wind power system and from the speed of the generator. The battery charge/discharge control maintains a constant DC bus voltage. When the battery charging/discharging current reaches the setting threshold, the charge/discharge control of the supercapacitor is triggered to limit the charging/discharging current of the battery. The simulation results show that the proposed method can rapidly respond to variations in wind velocity and load power.     

Effects of pollutant toxicity on the eyes of aquatic life monitored by visual dysfunction in zebrafish: a review

Environmental Chemistry Letters - The eyes of aquatic organisms may be damaged by exposure to pollutants. Zebrafish is a common laboratory model to study ocular toxicity, combining both fish and...     

寿光土壤中多环芳烃的污染特征及风险评估

以山东省寿光市为研究区域,采集了39个土壤样品,分析了26种PAHs的含量.结果表明,26种多环芳烃的浓度范围为120~1486μg/kg,平均值为(415±312)μg/kg.16种优控PAHs的浓度范围为84~1076μg/kg,平均值为(289±211)μg/kg.与我国其他区域非点源污染土壤相比,寿光市土壤中PAHs含量处于中等水平.采用克里格(Kriging)插值方法对寿光市土壤中PAHs的空间分布特征进行预测发现,该市PAHs高污染区位于东部开发区和西部工业园,高环与低环PAHs在空间分布上有明显差异.主成分分析结果显示,该市土壤中PAHs有3个主要来源,分别为液体化石燃料燃烧源、石油源以及煤燃烧源,其对主要来源的贡献率分别为44.7%、31.7%和23.6%.相关性分析表明,低环和高环PAHs与土壤有机质含量均显著相关,但低环PAHs的相关系数明显高于高环PAHs,表明低环PAHs更容易受到土壤中有机质的影响,而高环PAHs则受控于近距离沉降.对照荷兰的土壤管理标准,寿光市土壤中Flt和Phe超标较严重,TEQBaP以及致癌风险计算结果表明,寿光市土壤PAHs处于较低风险水平.