Electromagnetic transient studies of large distribution systems using frequency domain modeling methods and network reduction techniques

This paper presents the practical application of frequency domain methods to perform detailed electromagnetic transient analysis on very large multi-phase power distribution networks. The proposed technique demonstrates substantial computational gain offering an attractive complement or alternative to widely available time domain tools. This work provides modeling guidance and procedures to derive the system matrix, perform system reduction using network equivalent techniques, and obtain the time domain response. The basic network elements include lumped and distributed parameter lines, transformers, circuit breakers, sources, and loads. In-depth methodology verification confirms great agreement for steady-state and transient simulations when compared with results from ATP/EMTP for two well-known IEEE test feeders (13-bus and-34 bus). Moreover, substantial testing using two large-scale three phase power systems, the IEEE 123-bus and a synthetic 1188-node system emulating a densely meshed urban distribution network, confirm the accuracy of implementing network reduction to solve large networks. The flexibility and adaptability of the proposed methodology can provide considerable time savings to utility companies and engineering firms assessing system wide transients resulting from symmetrical and unsymmetrical faults, network upgrades, and switching schemes.