This paper describes the implementation of on-line transient stability as part of the EMS at Northern States Power Company (NSP). The main focus of this project is the implementation of the results of previous EPRI DSA projects in the on-line environment of the EMS at Northern States Power Company (NSP). Previous related EPRI projects focused on improving the performance of transient stability assessment with the eventual goal of implementation in on-line EMS system environment. In this project, EPRI transient stability assessment software is integrated with a Siemens proprietary SINAUT Spectrum EMS in the on-line environment at NSP. The purpose of the on-line transient stability assessment function is to monitor the state of the power system periodically, on demand, and upon occurrence of significant changes in the state of power system and to ensure power system security against occurrence of contingencies.

This paper studies the rheological properties of ultrathin aminomethacrylate membranes that are synthesized at the interface between oil and water. We have measured the kinetics of the cross-linking reactions, the zero shear modulus, and the nonlinear rheological properties of those two-dimensional networks. The measurements were performed at a planar interface using a special surface rheometer. Once stabilized, the membranes exhibit rubber-elastic properties. In addition, we have formed small emulsion droplets using the same type of interfacial polymerization. In order to get more information on the mechanical properties of the resulting microcapsules, we have developed a new experimental technique that consists in measuring the deformation of a capsule in a spinning drop apparatus. A theoretical analysis of the deformation process allows an interface apparent elastic Young modulus to be calculated. From a comparison of the surface shear modulus with the Young modulus, it is then possible to estimate the surface Poisson ratio, which is here approximately zero. These results point to the existence of area compressible anisotropic membranes.

This paper presents the features and implementation of an on-line Dynamic Security Assessment (DSA) function which consists of contingency screening, time-domain simulation and calculation of stability limits. An energy based approach, including an early termination scheme to reduce the computational effort and stability index to calculate the power transfer limit, and automatically determine the degree of stability has been developed and incorporated in the simulation engine. A client server implementation of the simulation engine and concurrent execution of contingencies on multiple workstations is also described. A sample test result is presented.

System stability analysis results have been part of electric utilities' operating guidelines for move than a decade. Today, these guidelines are compiled from offline stability studies conducted jointly with other utilities and independently by each utility. The offline study results are adjusted for actual generation patterns and network conditions, based on sensitivity analysis, and presented to...

This paper presents the features and implementation of a security monitor for an on-line dynamic security assessment (DSA) function. The key features of the security monitor are: time-domain simulation with early termination and calculation of stability limits. An energy based approach is employed to develop an early termination scheme in order to reduce the computational effort as well as to determine the degree of stability/instability. Test and performance results on practical power system models are presented

The radical polymerization of surface-active aminomethacrylates can be used to synthesize ultrathin crosslinked membranes at the interface between oil and water. We have systematically measured the kinetics of the surface gelation and the rheological properties of the stabilized films. The membranes, thus prepared, exhibit striking rubber-elastic properties. These are ideal conditions for the formation of a new type of microcapsule. In a series of experiments we have investigated the influence of the membrane elasticity on the shear-induced deformation of these artificial cells.

AbstractDas im Titel genannte reziproke Salzpaar wird röntgenographisch und durch DTA untersucht.

The reciprocal salt pair Sr2SiO4-Sr2GeO4-Ba2GeO4-Ba2SiO4 was investigated using X-ray powder diffraction and DTA. Unlimited solubility in the low-K2SO4 structure type (α′) occurs throughout the system above 85°C. The nonlinear changes of some lattice constants of the solid solutions are discussed. A stable monoclinic low-temperature (β) form of Sr2SiO4 was found which converts reversibly to the high-temperature α′-modification at 85°C. The enthalpy of the β-α’ transition is 51 cal/mol. In the reciprocal salt pair the β-form solid solutions occur in a very narrow region below 85°C.