电力系统静态电压稳定边界(static voltage stability boundary,SVSB)对于判断电压稳定性、评估电压稳定裕度具有重要的指示作用,因此,快速准确地计算SVSB对于电网安全稳定运行具有重要意义。电力系统作为一个超高维多变量的复杂非线性...电力系统静态电压稳定边界(static voltage stability boundary,SVSB)对于判断电压稳定性、评估电压稳定裕度具有重要的指示作用,因此,快速准确地计算SVSB对于电网安全稳定运行具有重要意义。电力系统作为一个超高维多变量的复杂非线性系统,其电压稳定边界本质上是某一拓扑结构下所能维持电源和负荷功率平衡的极限电压所构成的非线性高维边界。因此,将SVSB考虑为高维场景下的电压稳定超曲面,提出计算电压稳定边界的新方法。首先,利用多维全纯嵌入法(multidimensional holomorphic embedding method,MDHEM)求得节点电压的多变量幂级数(multivariate power series,MPS)表达式;然后,基于柯西-阿达马定理,推导并证明电压稳定边界与节点电压幂级数前后项系数之间的解析关系,并通过理论证明将所提出的方法从单维推广到高维场景;接着,基于推导的SVSB解析表达式,提出高维电压稳定边界计算与电压稳定性快速评估方法;最后,在IEEE 14节点、新英格兰39节点和IEEE 118节点系统中验证所提方法的有效性。展开更多
针对电力系统静态电压稳定域边界(staticvoltage stability region boundary,SVSRB)近似解析表达式的构建问题,该文提出一种SVSRB近似的空间切向量法。首先采用SVSRB搜索的预测–校正算法搜索静态电压稳定域(static voltagestabilityreg...针对电力系统静态电压稳定域边界(staticvoltage stability region boundary,SVSRB)近似解析表达式的构建问题,该文提出一种SVSRB近似的空间切向量法。首先采用SVSRB搜索的预测–校正算法搜索静态电压稳定域(static voltagestabilityregion,SVSR)临界点,然后基于该临界点处空间切向量的空间角与最大空间角阈值的关系,对SVSRB进行初始分段近似,以SVSR临界点到初始近似边界的距离与最大距离误差阈值的关系为依据,对初始近似边界进行二次近似,计及SVSRB曲率的变化,得到更为精确的SVSR分段超平面近似边界,实现SVSRB近似解析表达式的构建,该方法可有效提高SVSRB近似精度,增强电力系统电压稳定的态势感知能力。最后,将所提方法应用于WECC3机9节点测试系统和欧洲电网13659节点测试系统,结果表明,所提方法可有效实现SVSRB精确近似解析表达和准确构建。展开更多
The dynamic responses of a multilayer piezoelectric infinite hollow cylinder under electric potential excitation were obtained. The method of superposition was used to divide the solution into two parts, the part sati...The dynamic responses of a multilayer piezoelectric infinite hollow cylinder under electric potential excitation were obtained. The method of superposition was used to divide the solution into two parts, the part satisfying the mechanical boundary conditions and continuity conditions was first obtained by solving a system of linear equations; the other part was obtained by the separation of variables method. The present method is suitable for a multilayer piezoelectric infinite hollow cylinder consisting of arbitrary layers and subjected to arbitrary axisymmetric electric excitation. Dynamic responses of stress and electric potential are finally presented and analyzed.展开更多
A bi-harmonic stress function is constructed in this work. Ariy stress function methodology is used to obtain a set of analytical solutions for both ends fixed beams subjected to uniform load. The treatment for fixed-...A bi-harmonic stress function is constructed in this work. Ariy stress function methodology is used to obtain a set of analytical solutions for both ends fixed beams subjected to uniform load. The treatment for fixed-end boundary conditions is the same as that presented by Timoshenko and Goodier (1970). The solutions for propped cantilever beams and cantilever beams are also presented. All of the analytical plane-stress solutions can be obtained for a uniformly loaded isotropic beam with rectangular cross section under different types of classical boundary conditions.展开更多
Based on the theories of three-dimensional elasticity and piezoelectricity, and by assuming appropriate boundary functions, we established a state equation of piezoelectric cylindrical shells. By using the transfer ma...Based on the theories of three-dimensional elasticity and piezoelectricity, and by assuming appropriate boundary functions, we established a state equation of piezoelectric cylindrical shells. By using the transfer matrix method, we presented an analytical solution that satisfies all the arbitrary boundary conditions at boundary edges, as well as on upper and bottom surfaces. Our solution takes into account all the independent elastic and piezoelectric constants for a piezoelectric orthotropy, and satisfies continuity conditions between plies of the laminates. The principle of the present method and corresponding results can be widely used in many engineering fields and be applied to assess the effectiveness of various approximate and numerical models.展开更多
文摘针对电力系统静态电压稳定域边界(staticvoltage stability region boundary,SVSRB)近似解析表达式的构建问题,该文提出一种SVSRB近似的空间切向量法。首先采用SVSRB搜索的预测–校正算法搜索静态电压稳定域(static voltagestabilityregion,SVSR)临界点,然后基于该临界点处空间切向量的空间角与最大空间角阈值的关系,对SVSRB进行初始分段近似,以SVSR临界点到初始近似边界的距离与最大距离误差阈值的关系为依据,对初始近似边界进行二次近似,计及SVSRB曲率的变化,得到更为精确的SVSR分段超平面近似边界,实现SVSRB近似解析表达式的构建,该方法可有效提高SVSRB近似精度,增强电力系统电压稳定的态势感知能力。最后,将所提方法应用于WECC3机9节点测试系统和欧洲电网13659节点测试系统,结果表明,所提方法可有效实现SVSRB精确近似解析表达和准确构建。
基金Project supported by the National Natural Science Foundation of China (Nos. 10472102 and 10432030) and Postdoctoral Foundation of China (No. 20040350712)
文摘The dynamic responses of a multilayer piezoelectric infinite hollow cylinder under electric potential excitation were obtained. The method of superposition was used to divide the solution into two parts, the part satisfying the mechanical boundary conditions and continuity conditions was first obtained by solving a system of linear equations; the other part was obtained by the separation of variables method. The present method is suitable for a multilayer piezoelectric infinite hollow cylinder consisting of arbitrary layers and subjected to arbitrary axisymmetric electric excitation. Dynamic responses of stress and electric potential are finally presented and analyzed.
基金Project (No. 10472102) supported by the National Natural ScienceFoundation of China
文摘A bi-harmonic stress function is constructed in this work. Ariy stress function methodology is used to obtain a set of analytical solutions for both ends fixed beams subjected to uniform load. The treatment for fixed-end boundary conditions is the same as that presented by Timoshenko and Goodier (1970). The solutions for propped cantilever beams and cantilever beams are also presented. All of the analytical plane-stress solutions can be obtained for a uniformly loaded isotropic beam with rectangular cross section under different types of classical boundary conditions.
基金Funded by the Natural Science Foundation of Anhui Province (No. 070414190)
文摘Based on the theories of three-dimensional elasticity and piezoelectricity, and by assuming appropriate boundary functions, we established a state equation of piezoelectric cylindrical shells. By using the transfer matrix method, we presented an analytical solution that satisfies all the arbitrary boundary conditions at boundary edges, as well as on upper and bottom surfaces. Our solution takes into account all the independent elastic and piezoelectric constants for a piezoelectric orthotropy, and satisfies continuity conditions between plies of the laminates. The principle of the present method and corresponding results can be widely used in many engineering fields and be applied to assess the effectiveness of various approximate and numerical models.
