为减少电力系统网侧电流谐波并提高电网电能质量,本文采用状态误差端口受控哈密顿控制方法,实现对三相三线制有源电力滤波器的补偿电流实时控制和直流侧电压恒定控制。在dq旋转坐标系下,建立有源电力滤波器的PCH状态平均数学模型,构建...为减少电力系统网侧电流谐波并提高电网电能质量,本文采用状态误差端口受控哈密顿控制方法,实现对三相三线制有源电力滤波器的补偿电流实时控制和直流侧电压恒定控制。在dq旋转坐标系下,建立有源电力滤波器的PCH状态平均数学模型,构建了期望的闭环状态误差PCH系统,并根据系统的设计目标确定了系统期望平衡点;根据能量成形原理求出期望的闭环哈密顿PCH函数,并依据阻尼和互联配置设计了APF控制器。同时,运用比例积分控制(proportional integral control,PI)方法设计控制器,确保直流侧母线电压恒定。为了验证该控制策略的合理性,采用Matlab/Simulink软件进行仿真分析。仿真结果表明,基于状态误差PCH控制方法的有源电力滤波器对谐波起到了很好的抑制作用;在APF直流侧母线电压趋于恒定情况下,经过APF补偿的电力系统网侧电流中的谐波含量大大降低,达到控制目标,具有良好的稳态和动态控制性能。该研究具有一定的应用价值。展开更多
Electromagnetic forming tests were done at room temperature to reveal the influence of hydrogen content on the compressive properties of Ti-6Al-4V alloy at high strain rate. Microstructure was observed to reveal the m...Electromagnetic forming tests were done at room temperature to reveal the influence of hydrogen content on the compressive properties of Ti-6Al-4V alloy at high strain rate. Microstructure was observed to reveal the mechanism of hydrogen-enhanced compressive properties. The experimental results indicate that hydrogen has favorable effects on the compressive properties of Ti-6Al-4V alloy at high strain rate. Compression of Ti-6Al-4V alloy first increases up to a maximum and then decreases with the increase of hydrogen content at the same discharge energy under EMF tests. The compression increases by 47.0% when 0.2% (mass fraction) hydrogen is introduced into Ti-6Al-4V alloy. The optimal hydrogen content for cold formation of Ti–6Al–4V alloy under EMF was determined. The reasons for the hydrogen-induced compressive properties were discussed.展开更多
Waveforms generated by the 50t explosion of project Brightlight （ I ） were recorded by HILR array. Using array techniques, the author performed identification, f-k analysis, velocity spectrum analysis, etc. of the w...Waveforms generated by the 50t explosion of project Brightlight （ I ） were recorded by HILR array. Using array techniques, the author performed identification, f-k analysis, velocity spectrum analysis, etc. of the weak signals. The analysis results show that the signal-to-noise ratio after beamforming was obviously enhanced, and the signal could be clearly shown. The energy from this explosion was mainly concentrated in the 1 -8Hz range from f-k analysis. The velocity spectrum gave clear positions of event phases, which could not be seen in the original weak signals. The maximum energy distribution obtained by the Beaman method is close to the theoretical value in the azimuth-slowness domain.展开更多
文摘为减少电力系统网侧电流谐波并提高电网电能质量,本文采用状态误差端口受控哈密顿控制方法,实现对三相三线制有源电力滤波器的补偿电流实时控制和直流侧电压恒定控制。在dq旋转坐标系下,建立有源电力滤波器的PCH状态平均数学模型,构建了期望的闭环状态误差PCH系统,并根据系统的设计目标确定了系统期望平衡点;根据能量成形原理求出期望的闭环哈密顿PCH函数,并依据阻尼和互联配置设计了APF控制器。同时,运用比例积分控制(proportional integral control,PI)方法设计控制器,确保直流侧母线电压恒定。为了验证该控制策略的合理性,采用Matlab/Simulink软件进行仿真分析。仿真结果表明,基于状态误差PCH控制方法的有源电力滤波器对谐波起到了很好的抑制作用;在APF直流侧母线电压趋于恒定情况下,经过APF补偿的电力系统网侧电流中的谐波含量大大降低,达到控制目标,具有良好的稳态和动态控制性能。该研究具有一定的应用价值。
基金Project (51205102) supported by the National Natural Science Foundation of ChinaProject (2012M511401) supported by the China Postdoctoral Science FoundationProject (gf201101001) supported by the National Defense Key Disciplines Laboratory of Light Alloy Processing Science and Technology, Nanchang Hangkong University, China
文摘Electromagnetic forming tests were done at room temperature to reveal the influence of hydrogen content on the compressive properties of Ti-6Al-4V alloy at high strain rate. Microstructure was observed to reveal the mechanism of hydrogen-enhanced compressive properties. The experimental results indicate that hydrogen has favorable effects on the compressive properties of Ti-6Al-4V alloy at high strain rate. Compression of Ti-6Al-4V alloy first increases up to a maximum and then decreases with the increase of hydrogen content at the same discharge energy under EMF tests. The compression increases by 47.0% when 0.2% (mass fraction) hydrogen is introduced into Ti-6Al-4V alloy. The optimal hydrogen content for cold formation of Ti–6Al–4V alloy under EMF was determined. The reasons for the hydrogen-induced compressive properties were discussed.
基金The Basic Science Research Project of Commonweal of Nation Level (DQJB06A02 ),ChinaThe Brightlight (Ⅰ) Project from Institute of Geophysics,CEA
文摘Waveforms generated by the 50t explosion of project Brightlight （ I ） were recorded by HILR array. Using array techniques, the author performed identification, f-k analysis, velocity spectrum analysis, etc. of the weak signals. The analysis results show that the signal-to-noise ratio after beamforming was obviously enhanced, and the signal could be clearly shown. The energy from this explosion was mainly concentrated in the 1 -8Hz range from f-k analysis. The velocity spectrum gave clear positions of event phases, which could not be seen in the original weak signals. The maximum energy distribution obtained by the Beaman method is close to the theoretical value in the azimuth-slowness domain.
