光伏发电并网规模持续增长,改变了电力系统大扰动后的动态特性。文章建立了计及低电压穿越(Low Voltage Ride Through,LVRT)功能的光伏发电系统机电暂态仿真模型。针对故障后联系阻抗显著增大的光伏弱交流并网系统,分析了光伏低电压穿...光伏发电并网规模持续增长,改变了电力系统大扰动后的动态特性。文章建立了计及低电压穿越(Low Voltage Ride Through,LVRT)功能的光伏发电系统机电暂态仿真模型。针对故障后联系阻抗显著增大的光伏弱交流并网系统,分析了光伏低电压穿越的恢复过程对系统行为特性的影响,揭示了因光伏频繁进入LVRT引起系统电压周期性振荡的机制,分析了相关影响因素,并提出了缓解应对措施。最后,面向西藏中部光伏高渗透实际电网,仿真复现了大扰动后系统振荡现象,验证了应对措施的有效性。展开更多
Runoff series of the Yangtze River presents an intricate variation tendency under the reinforced influence of human activities.The Morlet Wavelet Transform method has been applied to analyze the annual runoff data fro...Runoff series of the Yangtze River presents an intricate variation tendency under the reinforced influence of human activities.The Morlet Wavelet Transform method has been applied to analyze the annual runoff data from 1950 to 2011 at the Yangtze River Estuary.It can clearly reveal the multi-time scales structure,break point,change and distribution of periodic variation in the different time scales of the runoff series.The main conclusions are that:1) Repeated periodic oscillations accompanied by an extremely large fluctuation are presented in the runoff series with an obvious difference between wet and dry years,and the major periods of the time series are about 3,8,16 and 23 years respectively.Among them,the presented maximum periodic oscillation is 23 years scale.2) In the 23-year time scale,the wet periods are 1950-1958,1969-1980 and 1992-2003,and the dry periods are 1959-1968,1981-1991 and 2004-2011.3) It can be predicted from the view of long time scales that the low annual runoff will likely occur in the near future.展开更多
文摘光伏发电并网规模持续增长,改变了电力系统大扰动后的动态特性。文章建立了计及低电压穿越(Low Voltage Ride Through,LVRT)功能的光伏发电系统机电暂态仿真模型。针对故障后联系阻抗显著增大的光伏弱交流并网系统,分析了光伏低电压穿越的恢复过程对系统行为特性的影响,揭示了因光伏频繁进入LVRT引起系统电压周期性振荡的机制,分析了相关影响因素,并提出了缓解应对措施。最后,面向西藏中部光伏高渗透实际电网,仿真复现了大扰动后系统振荡现象,验证了应对措施的有效性。
基金supported by the National Key Basic Research Program of China (Grant No. 2012CB957704) Marine Public Welfare Program of China (Grant No. 201305003)
文摘Runoff series of the Yangtze River presents an intricate variation tendency under the reinforced influence of human activities.The Morlet Wavelet Transform method has been applied to analyze the annual runoff data from 1950 to 2011 at the Yangtze River Estuary.It can clearly reveal the multi-time scales structure,break point,change and distribution of periodic variation in the different time scales of the runoff series.The main conclusions are that:1) Repeated periodic oscillations accompanied by an extremely large fluctuation are presented in the runoff series with an obvious difference between wet and dry years,and the major periods of the time series are about 3,8,16 and 23 years respectively.Among them,the presented maximum periodic oscillation is 23 years scale.2) In the 23-year time scale,the wet periods are 1950-1958,1969-1980 and 1992-2003,and the dry periods are 1959-1968,1981-1991 and 2004-2011.3) It can be predicted from the view of long time scales that the low annual runoff will likely occur in the near future.
