A Risk-Based Methodology and Tool Combining Threat Analysis and Power System Security Assessment

A thorough investigation of power system security requires the analysis of the vulnerabilities to natural and man-related threats which potentially trigger multiple contingencies. In particular, extreme weather events are becoming more and more frequent due to climate changes and often cause large load disruptions on the system, thus the support for security enhancement gets tricky. Exploiting data coming from forecasting systems in a security assessment environment can help assess the risk of operating power systems subject to the disturbances provoked by the weather event itself. In this context, the paper proposes a security assessment methodology, based on an updated definition of risk suitable for power system risk evaluations. Big data analytics can be useful to get an accurate model for weather-related threats. The relevant software (SW) platform integrates the security assessment methodology with prediction systems which provide short term forecasts of the threats affecting the system. The application results on a real wet snow threat scenario in the Italian High Voltage grid demonstrate the effectiveness of the proposed approach with respect to conventional security approaches, by complementing the conventional "N - 1" security criterion and exploiting big data to link the security assessment phase to the analysis of incumbent threat

Anisotropic Strain Limiting

Many materials exhibit a highly nonlinear elastic behavior, such as textiles or finger flesh. An efficient way of enforcing the nonlinearity of these materials is through strain-limiting constraints, which is often the model of choice in computer graphics. Strain-limiting allows to model highly non-linear stiff materials by eliminating degrees of freedom from the computations and by enforcing a set of constraints. However, many nonlinear elastic materials, such as composites, wood or flesh, exhibit anisotropic behaviors, with different material responses depending on the deformation direction. This anisotropic behavior has not been addressed in the past in the context of strain limiting, and naïve approaches, such as applying a different constraint on each component of the principal axes of deformation, produce unrealistic results. In this paper, we enable anisotropic behaviors when using strain-limiting constraints to model nonlinear elastic materials. We compute the limits for each principal axis of deformation through the rotation and hyperbolic projection of the deformation limits defined in the global reference frame. The limits are used to formulate the strain-limiting constraints, which are then seamlessly combined with frictional contact constraints in a standard constrained dynamics solver. Categories and Subject Descriptors (according to ACM CCS): modeling