无功控制功能是特高压直流输电工程设计的重要组成部分,目的是满足换流站的直流系统无功需求、滤除交流侧谐波、保持交流侧母线电压稳定的要求。±800 k V普洱换流站是云广Ⅱ回特高压直流输电工程中的整流站,其直流站控系统中无功...无功控制功能是特高压直流输电工程设计的重要组成部分,目的是满足换流站的直流系统无功需求、滤除交流侧谐波、保持交流侧母线电压稳定的要求。±800 k V普洱换流站是云广Ⅱ回特高压直流输电工程中的整流站,其直流站控系统中无功控制功能的电压有效性选择逻辑存在缺陷,文中提出了优化的措施,对特高压直流输电工程的可靠运行有着重要意义。展开更多
分析了传统LCC直流输电系统无功控制(reactor power control,RPC)功能在工程实现中存在的逻辑和电气设计隐患。针对无功控制中缺少交流滤波器投切异常监视、测量参数异常监视等功能,提出了一种无功控制的监视方法。监视方法在起动程序...分析了传统LCC直流输电系统无功控制(reactor power control,RPC)功能在工程实现中存在的逻辑和电气设计隐患。针对无功控制中缺少交流滤波器投切异常监视、测量参数异常监视等功能,提出了一种无功控制的监视方法。监视方法在起动程序内进行逻辑判断,根据结果进入正常运行程序或故障计算程序,实现了交流滤波器投切异常分析判断、交流滤波器投切状态判断、交流电压有效性检查、无功有效性检查、RPC震荡闭锁等功能,其中部分功能已运用于工程中,运行情况良好。展开更多
A new finite element modeling method has been developed using laminate theory in a virtual work principle for active constraining layer damping plate. The frequency dependent modulus of viscoelastic material is descri...A new finite element modeling method has been developed using laminate theory in a virtual work principle for active constraining layer damping plate. The frequency dependent modulus of viscoelastic material is described by introducing a few dissipation coordinates, known as GHM (Golla-Hughes-McTavish) method, a standard linear system with constant coefficient. The effectiveness of this method is validated by experimental model. Compared with conventional methods, this method can reduce a number of degrees of freedom and improve accuracy, provides a good model for analogous configurations.展开更多
The classical Hashin-Shtrikman variational principle was re-generalized to the heterogeneous piezoelectric materials.The auxiliary problem is very much simplified by selecting the reference medium as a linearly isotro...The classical Hashin-Shtrikman variational principle was re-generalized to the heterogeneous piezoelectric materials.The auxiliary problem is very much simplified by selecting the reference medium as a linearly isotropic elastic medium.The electromechanical fields in the inhomogeneous piezoelectrics are simulated by introducing into the homogeneous reference medium certain eigenstresses and eigen electric fields.A closed-form solution can be obtained for the disturbance fields,which is convenient for the manipulation of the energy functional.As an application,a two-phase piezoelectric composite with nonpiezoelectric matrix is considered.Expressions of upper and lower bounds for the overall electromechanical moduli of the composite can be developed.These bounds are shown better than the Voigt-Reuss type ones.展开更多
文摘无功控制功能是特高压直流输电工程设计的重要组成部分,目的是满足换流站的直流系统无功需求、滤除交流侧谐波、保持交流侧母线电压稳定的要求。±800 k V普洱换流站是云广Ⅱ回特高压直流输电工程中的整流站,其直流站控系统中无功控制功能的电压有效性选择逻辑存在缺陷,文中提出了优化的措施,对特高压直流输电工程的可靠运行有着重要意义。
文摘分析了传统LCC直流输电系统无功控制(reactor power control,RPC)功能在工程实现中存在的逻辑和电气设计隐患。针对无功控制中缺少交流滤波器投切异常监视、测量参数异常监视等功能,提出了一种无功控制的监视方法。监视方法在起动程序内进行逻辑判断,根据结果进入正常运行程序或故障计算程序,实现了交流滤波器投切异常分析判断、交流滤波器投切状态判断、交流电压有效性检查、无功有效性检查、RPC震荡闭锁等功能,其中部分功能已运用于工程中,运行情况良好。
文摘A new finite element modeling method has been developed using laminate theory in a virtual work principle for active constraining layer damping plate. The frequency dependent modulus of viscoelastic material is described by introducing a few dissipation coordinates, known as GHM (Golla-Hughes-McTavish) method, a standard linear system with constant coefficient. The effectiveness of this method is validated by experimental model. Compared with conventional methods, this method can reduce a number of degrees of freedom and improve accuracy, provides a good model for analogous configurations.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11072179 and 11090334)Shanghai Leading Academic Discipline Project (Grant No. B302)
文摘The classical Hashin-Shtrikman variational principle was re-generalized to the heterogeneous piezoelectric materials.The auxiliary problem is very much simplified by selecting the reference medium as a linearly isotropic elastic medium.The electromechanical fields in the inhomogeneous piezoelectrics are simulated by introducing into the homogeneous reference medium certain eigenstresses and eigen electric fields.A closed-form solution can be obtained for the disturbance fields,which is convenient for the manipulation of the energy functional.As an application,a two-phase piezoelectric composite with nonpiezoelectric matrix is considered.Expressions of upper and lower bounds for the overall electromechanical moduli of the composite can be developed.These bounds are shown better than the Voigt-Reuss type ones.
