Advanced Numerical Methods for Simulating Nonlinear Multirate Lumped Parameter Models

Abstract : Naval shipboard electric power systems are transitioning from the relatively simple distribution of ship service electric power to extremely complex integrated electric drive (IED) systems. The optimal design of warships employing IED is presently hampered by the lack of existing simulation computer tools for analyzing the highly coupled and controlled electro-mechanical systems characteristic of IED. As a first step in the development of a viable computer simulation tool, the numerical algorithm testing program WAVESM was created. The key contributions of WAVESM are the systematic treatment of waveforms as an abstract data type, the development of the terminal description of devices, and the use of structural jacobians in system reduction. WAVESIM represents variables by waveforms consisting of a vector of coefficients and a waveform type code indicating how the coefficients should be interpreted. The principal advantage of using waveforms over conventional discrete point methods is the avoidance of unstable integration techniques since for most waveform types, integration and differentiation are linear matrix operations.