Transient stability study of the large synchronous motors starting and operating for the isolated integrated steel-making facility

This paper presents the influence of the large motor starting and the large rolling mill operation on the isolated integrated steel cogeneration facility by executing the transient stability analysis. The system configuration of the steel facility is introduced first. Furthermore, the proper mathematical models and the accurate parameters of the cogeneration units, excitation systems, and governor systems are investigated in detail. Both the static and dynamic load models are applied in this paper. To reduce the starting current of large motors, the conventional step-down voltage method by adjusting the suitable tap position of the autotransformer and the constant magnetic flux control method by using the variable-voltage and variable-frequency inverter are considered in the computer simulations. Also, the system voltage and frequency fluctuations due to the operation of the rolling mill are observed and investigated carefully to verify that the isolated cogeneration can be operated well and safely.