三相并网逆变器在新能源发电系统和电动汽车等领域起着重要的作用,为确保系统安全稳定运行,孤岛检测是十分必要的。对基于空间矢量控制的三相并网逆变器,传统的主动频移法(active frequency drift,AFD)不能直接应用,存在检测盲区的问题...三相并网逆变器在新能源发电系统和电动汽车等领域起着重要的作用,为确保系统安全稳定运行,孤岛检测是十分必要的。对基于空间矢量控制的三相并网逆变器,传统的主动频移法(active frequency drift,AFD)不能直接应用,存在检测盲区的问题,且施加的频率扰动量会对三相进网电流波形质量造成一定的影响。提出一种基于空间矢量脉宽调制(space vector pulse width modulation,SVPWM)控制三相并网逆变器的AFD孤岛检测方法,其对锁相环(phase-locked loop,PLL)计算出的相角施加扰动,但不属于主动移相法。分析孤岛检测盲区的成因以及消除盲区的可能性,并对施加扰动后的三相电流进行谐波分析,提出抑制谐波的改进半解耦控制算法,最后给出仿真和实验结果。展开更多
孤岛检测的方法很多,尤其是主动式孤岛检测方法。如何在众多的主动孤岛检测法中选择最合适的方法是应用中的难点。针对主动法中的应用较多的滑模频率偏移法和有源频率偏移法,分别对其检测盲区、检测速度、对电能质量影响进行机理分析。...孤岛检测的方法很多,尤其是主动式孤岛检测方法。如何在众多的主动孤岛检测法中选择最合适的方法是应用中的难点。针对主动法中的应用较多的滑模频率偏移法和有源频率偏移法,分别对其检测盲区、检测速度、对电能质量影响进行机理分析。理论分析结果表明在盲区相同时,SMS(Slip-Mode Frequency Shift)法造成的逆变电流总谐波含量更小,但SMS法的检测速度在不同参数条件下存在较大区别。在Matlab/Simulink中对孤岛检测方法进行建模,实验结果证明了理论分析的正确性。展开更多
Here we investigated the possible roles of oxidative stress in the formation of decreased thermotaxis to cultivation temperature in lead(Pb)-exposed nematodes Caenorhabditis elagans.Exposure to Pb at the examined conc...Here we investigated the possible roles of oxidative stress in the formation of decreased thermotaxis to cultivation temperature in lead(Pb)-exposed nematodes Caenorhabditis elagans.Exposure to Pb at the examined concentrations decreased thermotaxis behaviors,and induced severe deficits in the structural properties of AFD sensory neurons.Meanwhile,Pb exposure caused the induction of severe oxidative damage,reactive oxygen species(ROS)production,and mitochondrial dysfunction in young adults.Moreover,pre-treatment with the antioxidants dimethyl sulfoxide(DMSO),ascorbate and N-acetyl-L-cysteine(NAC),used to inhibit both the ROS elevation and the mitochondrial dysfunction caused by Pb exposure,at the L2-1arval stage prevented the induction of oxidative damage and the formation of severe deficits in thermotaxis and structural properties of AFD sensory neurons in Pb-exposed young adults.Therefore,the formation of oxidative stress caused by Pb exposure may be due to both the induction of ROS elevation and damage to mitochondrial function,and oxidative stress may play a key role in inducing the neurotoxic effects on the structures and function of AFD sensory neurons in Pb-exposed nematodes.展开更多
文摘孤岛检测的方法很多,尤其是主动式孤岛检测方法。如何在众多的主动孤岛检测法中选择最合适的方法是应用中的难点。针对主动法中的应用较多的滑模频率偏移法和有源频率偏移法,分别对其检测盲区、检测速度、对电能质量影响进行机理分析。理论分析结果表明在盲区相同时,SMS(Slip-Mode Frequency Shift)法造成的逆变电流总谐波含量更小,但SMS法的检测速度在不同参数条件下存在较大区别。在Matlab/Simulink中对孤岛检测方法进行建模,实验结果证明了理论分析的正确性。
基金supported by the National Basic Research Program(973)of China(No.2011CB933404)the National Natural Science Foundation of China(No.30870810,81172698)Some strains used were provided by Caenorhabditis Genetics Center(funded by the NIH National Center for Research Resource,USA)
文摘Here we investigated the possible roles of oxidative stress in the formation of decreased thermotaxis to cultivation temperature in lead(Pb)-exposed nematodes Caenorhabditis elagans.Exposure to Pb at the examined concentrations decreased thermotaxis behaviors,and induced severe deficits in the structural properties of AFD sensory neurons.Meanwhile,Pb exposure caused the induction of severe oxidative damage,reactive oxygen species(ROS)production,and mitochondrial dysfunction in young adults.Moreover,pre-treatment with the antioxidants dimethyl sulfoxide(DMSO),ascorbate and N-acetyl-L-cysteine(NAC),used to inhibit both the ROS elevation and the mitochondrial dysfunction caused by Pb exposure,at the L2-1arval stage prevented the induction of oxidative damage and the formation of severe deficits in thermotaxis and structural properties of AFD sensory neurons in Pb-exposed young adults.Therefore,the formation of oxidative stress caused by Pb exposure may be due to both the induction of ROS elevation and damage to mitochondrial function,and oxidative stress may play a key role in inducing the neurotoxic effects on the structures and function of AFD sensory neurons in Pb-exposed nematodes.
