为获得雷电流冲击下110 k V变压器不接地中性点上的过电压,采用线饼模型对110 k V变压器绕组进行建模,并用PSCAD仿真软件对该模型进行仿真计算。利用该模型对广州地区110 k V变压器中性点击穿事故进行仿真分析,结果表明对变压器中性点...为获得雷电流冲击下110 k V变压器不接地中性点上的过电压,采用线饼模型对110 k V变压器绕组进行建模,并用PSCAD仿真软件对该模型进行仿真计算。利用该模型对广州地区110 k V变压器中性点击穿事故进行仿真分析,结果表明对变压器中性点仅加装放电间隙不足以防止雷电侵害,并且雷电波入侵变压器时中性点故障率高达到0.686次/年,说明需要结合其他防护措施对这一地区变压器中性点进行保护。根据仿真结果提出采用130 mm的间隙并联Y1.5W-72/186避雷器实施改造措施。展开更多
The neutral hydrogen 21 cm line is potentially a very powerful probe of the observable universe, and a number of on-going experiments are trying to detect it at cosmological distances. However, the presence of strong ...The neutral hydrogen 21 cm line is potentially a very powerful probe of the observable universe, and a number of on-going experiments are trying to detect it at cosmological distances. However, the presence of strong foreground radiations such as the galactic synchrotron radiation, galactic free-free emission and extragalactic radio sources make it a very challenging task.For the design of 21 cm experiments and analysis of their data, simulation is an essential tool, and good sky foreground model is needed. With existing data the whole sky maps are available only in low angular resolutions or for limited patches of sky,which is inadequate in the simulation of these new 21 cm experiments. In this paper, we present the method of constructing a high resolution self-consistent sky model at low frequencies, which incorporates both diffuse foreground and point sources.Our diffuse map is constructed by generating physical foreground components including the galactic synchrotron emission and galactic free-free emission. The point source sample is generated using the actual data from the NRAO VLA Sky Survey(NVSS)and the Sydney University Molonglo Sky Survey(SUMSS) where they are available and complete in flux limit, and mock point sources according to statistical distributions. The entire model is made self-consistent by removing the integrated flux of the point sources from the diffuse map so that this part of radiation is not double counted. We show that with the point sources added, a significant angular power is introduced in the mock sky map, which may be important for foreground subtraction simulations.Our sky maps and point source catalogues are available to download.展开更多
文摘为获得雷电流冲击下110 k V变压器不接地中性点上的过电压,采用线饼模型对110 k V变压器绕组进行建模,并用PSCAD仿真软件对该模型进行仿真计算。利用该模型对广州地区110 k V变压器中性点击穿事故进行仿真分析,结果表明对变压器中性点仅加装放电间隙不足以防止雷电侵害,并且雷电波入侵变压器时中性点故障率高达到0.686次/年,说明需要结合其他防护措施对这一地区变压器中性点进行保护。根据仿真结果提出采用130 mm的间隙并联Y1.5W-72/186避雷器实施改造措施。
基金supported by the National Natural Science Foundation of Guangdong (Grant No. U1501501)the Ministry of Science and Technology (Grant No. 2016YFE0100300)+2 种基金the National Natural Science Foundation of China (Grant Nos. 11473044, 11761141012, 11633004, and 11653003)the Chinese Academy of Sciences (Grant No. QYZDJ-SSWSLH017)the support by the China Scholarship Council Cai Yuanpei Grant
文摘The neutral hydrogen 21 cm line is potentially a very powerful probe of the observable universe, and a number of on-going experiments are trying to detect it at cosmological distances. However, the presence of strong foreground radiations such as the galactic synchrotron radiation, galactic free-free emission and extragalactic radio sources make it a very challenging task.For the design of 21 cm experiments and analysis of their data, simulation is an essential tool, and good sky foreground model is needed. With existing data the whole sky maps are available only in low angular resolutions or for limited patches of sky,which is inadequate in the simulation of these new 21 cm experiments. In this paper, we present the method of constructing a high resolution self-consistent sky model at low frequencies, which incorporates both diffuse foreground and point sources.Our diffuse map is constructed by generating physical foreground components including the galactic synchrotron emission and galactic free-free emission. The point source sample is generated using the actual data from the NRAO VLA Sky Survey(NVSS)and the Sydney University Molonglo Sky Survey(SUMSS) where they are available and complete in flux limit, and mock point sources according to statistical distributions. The entire model is made self-consistent by removing the integrated flux of the point sources from the diffuse map so that this part of radiation is not double counted. We show that with the point sources added, a significant angular power is introduced in the mock sky map, which may be important for foreground subtraction simulations.Our sky maps and point source catalogues are available to download.
