Abstract
When starting-up or shutting-down a power generator, there is a need to transfer the generator auxiliary load bus, known as motor bus, from the start-up source to the generator or from the generator to the start-up source respectively. In the course of the transfer process, the auxiliary induction and synchronous motors are exposed to electromechanical and electromagnetic forces that could damage them if an improper transfer is performed. There is also a need to avoid paralleling sources that could increase the short circuit levels during faults causing auxiliary equipment damage. Similar but not less important, is the coasting down duration of the motor bus voltage under the open circuit conditions, which is a complex process owing to the fast voltage, frequency and phase angle variations at the motor bus.
During the past twenty years, digital power system simulators have seen very significant technological advances on their numerical algorithms. This has allowed them not only to have more exact and sophisticated power system models, but also to include tools to simulate complex protective relays and control systems interactions with the power system simulation. Until a few years ago, such cases were not only difficult to simulate but also time consuming to carry out.
The main purpose of this thesis is the modeling of a motor bus transfer case with standard transfer methods. This model allows the power plant protection and control engineers to study and analyze the induction motor transient behavior during a motor bus transfer in order to implement or upgrade their current motor bus transfer schemes and strategies.
Secondly to analyze the electromagnetic transient behavior of the induction motor during the motor load transfer process. Simulations were developed and validated to test and analyze the performance of the motor bus transfer model under several power plant’s normal and emergency conditions and the results are discussed.