Valeriu Savcenco

A Multirate Approach for Time Domain Simulation of Very Large Power Systems

The time evolution of power systems is modeled by systems of differential and algebraic equations (DAEs) [8]. The variables involved in these DAEs may exhibit different time scales. Some of the variables can be highly active while other variables can stay constant during the entire time integration period. In standard numerical time integration methods for DAEs the most active variables impose the time step for the whole system. We present a strategy, which allows the use of different, local time steps over the variables. The partitioning of the components of the system in different classes of activity is performed automatically based on the topology of the power system. The performance of the multirate approach for two case studies is presented.

Multirate Integration of a European Power System Network Model

An efficient approach for the numerical integration of a European power system network model is described. The time evolution of the power system is modeled by a system of differential and algebraic equations. In standard numerical time integration methods the most active variables impose the time step for the whole system. We describe an approach, which allows the use of different, local time steps over the variables. The partitioning of the components of the system in different classes of activity is based on the topology of the power system.

Multirate time stepping for stiff ODEs

Multirate time stepping is a numerical technique for efficiently solving large‐scale ordinary differential equations (ODEs) with widely different time scales localized over the components. This technique enables one to use large time steps for slowly time‐varying components, and small steps for rapidly varying ones. In this paper we describe a self‐adjusting multirate time stepping strategy, in which the step size for a particular component is determined by its own local temporal variation, instead of using a single step size for the whole system. We primarily consider Rosenbrock methods, suitable for stiff or mildly stiff ODEs.