In the current work, to predict and improve the formability of deep drawing process for steel plate cold rolled commercial grade （SPCC） sheets, three parameters including the blanking force, the die and punch comer ...In the current work, to predict and improve the formability of deep drawing process for steel plate cold rolled commercial grade （SPCC） sheets, three parameters including the blanking force, the die and punch comer radius were considered. The experimental plan according to Taguchi＇s orthogonal array was coupled with the finite element method （FEM） simulations. Firstly, the data from the test of stress-strain and forming limit curves were used as input into ABAQUS/Explicit finite element code to predict the failure occurrence of deep drawing process. The three parameters were then validated to establish their effects on the press formability. The optimum case found via simulation was finally confirmed through an experiment. In order to obtain the complex curve profile of cup shape after deep drawing, the anisotropic behavior of earring phenomenon was modeled and implemented into FEM. After such phenomenon was correctly predicted, an error metric compared with design curve was then measured.展开更多
为了满足新型电力系统安全稳定运行的实际需求,研究构网型储能变流器(grid-forming energy storage converter)的控制策略和稳定机理具有重要意义。本研究建立了基于下垂控制的构网型储能并网系统小信号阻抗模型,采用复向量形式的阻抗...为了满足新型电力系统安全稳定运行的实际需求,研究构网型储能变流器(grid-forming energy storage converter)的控制策略和稳定机理具有重要意义。本研究建立了基于下垂控制的构网型储能并网系统小信号阻抗模型,采用复向量形式的阻抗模型表达式以简化建模,重点考虑了构网型储能功率同步环的动态特性,采用扫频法验证了阻抗模型的准确性。然后,基于广义Nyquist稳定性判据分析了构网型储能并网系统在不同控制参数和不同电网强度下的稳定性,理论分析结果与时域仿真分析具有一致性。研究结果表明,随着有功下垂系数或短路比的增大,构网型储能并网系统的稳定性均会变差。最后,在物理实验平台中进行了验证。展开更多
由跟网型变换器(grid-following voltage source converter,GFL-VSC)及构网型变换器(grid-forming voltage source converter,GFM-VSC)构成的混联系统中,复杂的暂态交互作用使系统的安全稳定运行面临挑战,明确变换器间的动态耦合机理及...由跟网型变换器(grid-following voltage source converter,GFL-VSC)及构网型变换器(grid-forming voltage source converter,GFM-VSC)构成的混联系统中,复杂的暂态交互作用使系统的安全稳定运行面临挑战,明确变换器间的动态耦合机理及其对系统暂态稳定性的影响至关重要。GFM-VSC中设置的电流限幅环节会导致其暂态运行方式发生切换,进一步增加了GFM-VSC与GFL-VSC之间的耦合机理的复杂性。为揭示GFM-VSC发生暂态模式切换时与GFL-VSC之间的动态耦合机理及该耦合对GFM-VSC故障恢复过程的作用机制,首先,建立考虑GFM-VSC限幅环节的混联系统暂态耦合模型;基于此模型,分析故障期间及故障切除后,GFL-VSC的参数对GFM-VSC工作模式切换的影响机理;随后,针对不同程度的电网电压跌落故障,分析故障切除后GFM-VSC的工作模式切换过程,得到混联系统中GFM-VSC在故障切除后可切换回正常工作模式的临界条件;最后,构建混联系统的仿真模型,验证理论分析的正确性。展开更多
基金Project(107.02-2013.01)supported by the Vietnam’s National Foundation for Science and Technology Development
文摘In the current work, to predict and improve the formability of deep drawing process for steel plate cold rolled commercial grade （SPCC） sheets, three parameters including the blanking force, the die and punch comer radius were considered. The experimental plan according to Taguchi＇s orthogonal array was coupled with the finite element method （FEM） simulations. Firstly, the data from the test of stress-strain and forming limit curves were used as input into ABAQUS/Explicit finite element code to predict the failure occurrence of deep drawing process. The three parameters were then validated to establish their effects on the press formability. The optimum case found via simulation was finally confirmed through an experiment. In order to obtain the complex curve profile of cup shape after deep drawing, the anisotropic behavior of earring phenomenon was modeled and implemented into FEM. After such phenomenon was correctly predicted, an error metric compared with design curve was then measured.
文摘为了满足新型电力系统安全稳定运行的实际需求,研究构网型储能变流器(grid-forming energy storage converter)的控制策略和稳定机理具有重要意义。本研究建立了基于下垂控制的构网型储能并网系统小信号阻抗模型,采用复向量形式的阻抗模型表达式以简化建模,重点考虑了构网型储能功率同步环的动态特性,采用扫频法验证了阻抗模型的准确性。然后,基于广义Nyquist稳定性判据分析了构网型储能并网系统在不同控制参数和不同电网强度下的稳定性,理论分析结果与时域仿真分析具有一致性。研究结果表明,随着有功下垂系数或短路比的增大,构网型储能并网系统的稳定性均会变差。最后,在物理实验平台中进行了验证。
文摘由跟网型变换器(grid-following voltage source converter,GFL-VSC)及构网型变换器(grid-forming voltage source converter,GFM-VSC)构成的混联系统中,复杂的暂态交互作用使系统的安全稳定运行面临挑战,明确变换器间的动态耦合机理及其对系统暂态稳定性的影响至关重要。GFM-VSC中设置的电流限幅环节会导致其暂态运行方式发生切换,进一步增加了GFM-VSC与GFL-VSC之间的耦合机理的复杂性。为揭示GFM-VSC发生暂态模式切换时与GFL-VSC之间的动态耦合机理及该耦合对GFM-VSC故障恢复过程的作用机制,首先,建立考虑GFM-VSC限幅环节的混联系统暂态耦合模型;基于此模型,分析故障期间及故障切除后,GFL-VSC的参数对GFM-VSC工作模式切换的影响机理;随后,针对不同程度的电网电压跌落故障,分析故障切除后GFM-VSC的工作模式切换过程,得到混联系统中GFM-VSC在故障切除后可切换回正常工作模式的临界条件;最后,构建混联系统的仿真模型,验证理论分析的正确性。
