Thesis (Ph.D., Electrical and Computer Engineering) -- University of Idaho, December 2014 | To increase the robustness of the electrical power supply to an industrial facility, two independent power supplies are typically routed to the facility. A power supply typically consists of a power source and a power line used to transmit the power from the source to the facility. Each power supply terminates in an independent power distribution node know as a bus. If for some reason one of the two power supplies become unavailable either due to a fault on the power line or unavailability of the source, it is possible to parallel the two buses together and keep the facility fully operational.
Induction motors comprise the bulk of the load on the buses, requiring that before the two buses are connected together the voltages of the buses be in synchronism. The process by which the two buses are connected to one another is known in the electrical power industry as an “in-phase motor bus transfer.” In this dissertation the requirements for a successful inphase motor bus transfer are examined and a new method which does not require extensive studies or testing is proposed. The method’s robustness is tested under extreme power system conditions by first subjecting the motor bus to various external fault conditions. Once the motor bus is isolated the ability of the new method to synchronously and successfully transfer the isolated bus to an alternative power source is tested under a variety of different operating conditions. This dissertation shows that the new proposed method successfully performs an in-phase
motor bus transfer and synchronously connects the motor bus to the alternative power source, without first having to conduct any advanced system studies or tests. The new method requires the user to have very little knowledge of the power system or the motor loads on the individual buses.