Synchronous Machine and Torsional Dynamics Simulation in the Computation of Electromagnetic Transients

This paper presents the development of a new time domain simulation program for the computation of machine and network transients over a wide frequency spectrum. The program uses the extensive capability for the detailed representation of, and the computation of electromagnetic transients on, the power system network available in the BPA Electromagnetic Transients Program (EMTP). The model of the synchronous generator, in which both the electrical and the mechanical shaft torsional dynamics are represented, possesses a large degree of generality. The model is interfaced with the EMTP network and a newly developed and computationally efficient numerical integration scheme is used to compute the machine transients. The option for representing arbitrary excitation systems has been implemented. The program´s capability to simulate a three-phase network with an arbitrary number of synchronous machines ¿generators or motors ¿and their auxiliary control equipment, allows the evaluation of network ¿machine ¿control systems interactions. The application of the program to investigate the subsynchronous resonance phenomenon in a realistic-sized system is given. Other typical applications include transmission line reclosure, independent pole switching, load rejection or unit tripping, loss of synchronism and multi-machine interaction problems. The program, in use for some time by a number of utilities, has been incorporated as a standard feature of the EMTP.