Multirate Integration Research Articles

Dynamic Nuclear Power Plant Simulations Using Single-Board Peripheral Array Processors

The application of a host/ coprocessor system, consisting of an IBM PC/AT and a Marinco peripheral array proc essor, to the simulation of nuclear power plant transients is described. The simulation algorithm employs a multistep, multirate integration method. Rapidly varying transients were implemented on the array processor, while the slow components of the system dynamics were handled by the host computer. The generation of nonlinear functions of dependent variables using table lookup techniques was also implemented on the array processor. A simplified model of a pressurized water reactor was employed as a benchmark. Flow rate and power transients using a variety of integration formulas are presented along with data showing the speed up achieved through the use of the peripheral processor.

Multitime-scale approach to real-time simulation of stiff dynamic systems

Abstract Real-time simulation of stiff dynamic systems plays an important role in many areas of chemical process engineering. Notwithstanding the capabilities of well-known available methods, their implementations in a real-time environment do not seem very promising. To cope with these issues, we use a time-scale decomposition based on the singular perturbation method. On this basis, we elaborate on a class of multirate integration algorithms for approximate simulation of stiff-IVPs. The most attractive aspect of the new procedure is that explicit numerical methods can be used for integrating each one of the subsystems created by time-scale modeling. This is a very appealing feature in real-time programming, where excessive computing time would endanger the validity of the simulation. Implementational details on a real-time training simulator are also discussed.

The exploitation of latency and multirate behavior using nonlinear relaxation for circuit simulation

The speedups derived from the exploitation of the waveform properties are discussed and simple procedures are provided to compute empirical upper bounds on the speed improvement when these properties are exploited. These upper bounds are used to explain the reasons for the variations in the speedups and to evaluate the performance of two circuit simulation algorithms based on nonlinear relaxation that are implemented in the SPLICE3 program. The first algorithm is an advanced version of the iterated timing analysis (ITA) algorithm that exploits the latency property. The second algorithm is a new event-driven multirate integration scheme, based on ITA, that exploits multirate behavior of circuits. It also uses a novel event-driven approach to handle step rejections called selective-backup.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Applications of a Parallel Processing Modular Simulation System for Dynamic Simulation of Nuclear Power Plants

A new approach for high-speed simulation is applied to the analysis of nuclear power system dynamics. The proposed approach is to first identify inherent parallelism and then to develop suitable parallel computation algorithms. The latter includes numerical integration and table lookup techniques that can be used for achieving high-speed simulation. A performance evaluation of the proposed methodology has been completed, which is based on benchmark simulation for pressurized water reactor plant dynamics. The multirate integration algorithm and an innovative table lookup technique running on a parallel processing computer system have proved to be the most advantageous in computational speed.