A Real-Time Digital Simulation of Synchronous Machines: Stability Considerations and Implementation

The study of the transient behavior of a large power system has been difficult and time consuming even on mainframe computers. One way to obtain real-time studies is to configure digital simulation modules in a parallel processing network that corresponds to the physical system. The focus of this work is on the creation of a generator module that is compatible with such a digital simulation network. To approach operation in real time, a fast and accurate state equation integrator is required. Investigation has revealed that the load imposed on the simulated generator plays a major role in the stability of the integration routines. The linearized stability limits of forward difference, modified Euler, fourth-order Runge-Kutta and Adams-Bashforth-Moulton integration methods were calculated for an impedance terminated generator. These were found to agree closely with the corresponding experimentally determined nonlinear limits. The TMS32010 digital signal processor was chosen as the heart of the generator simulator module, and fixed-point arithmetic routines were developed to make it a high-speed state equation integrator. Operation in real time was achieved for an infinite bus-type termination, but an impedance load led to a somewhat slower simulation.