Wikipedia
EMTP is an acronym for ElectroMagnetic Transients Program. It is usually part of a battery of software tools targeting a slice of the spectrum of design and operation problems presented by Electric Power Systems to the Electrical Engineer, that of the so-called "electromagnetic transients" and associated insulation issues. Originating in the habilition (postdoctoral) thesis of Dr. Hermann Dommel in Germany in the mid sixties, and brought up to its present robust and industry strength status by the cooperation of many professionals of power engineering led by the two champions: Dr. Dommel (currently with the University of British Columbia, in Vancouver, B.C., Canada), and Dr. Scott Meyer (from the Bonneville Power Administration in Portland, Oregon, U.S.A.). Both have been awarded the highest recognition that the Institute of Electric and Electronic Engineers (IEEE) grants to some of its members: they are both FIEEE (Fellows of the IEEE).
There are two basic streams of EMTP programs: "EMTP" as known such originates from the program development at BPA - an agency of the U.S. Department of Energy - and those written from scratch. The EMTP-ATP and MT-EMTP programs, for example, are based on the original BPA and DCG-EMTP versions. The recent EMTP-type programs are using new numerical methods and modeling approaches, and provide significantly improved capabilities and numerical performances.
Examples of EMTP type programs are EMTP-RV, MT-EMTP, EMTP-ATP, eMEGAsim and HYPERsim from Opal-RT Technologies, RTDS Technologies, and PSCAD-EMTDC.