Abstract
To improve the quality or the utilization efficiency of electric power, semiconductor fabrication plants (or fab’s) commonly have their manufacturing process installed with uninterruptible power supplies (UPS’s), and their cooling water pumps and ventilation installed with inverter controlled motors. Both the UPS’s and inverters have caused harmonic problems. Each time, when network changes, no matters in-plant or out-of-plant (e.g. when load transfers due to the outage of in-plant power facilities or, or when the system network expands), fab’s utility engineers have to conduct harmonic analyses to explore the potential problem of harmonics. However, the use of commercial software package, as in the traditional approach to harmonic analysis, is inadequate for the network under constantly temporary change, also difficult for field engineers to clarify and grasp the in-depth character of harmonics.The thesis contents are three folds:(1)To encounter the above inadequacy, a fast computation method is developed for the prediction of harmonic resonance. The prediction of resonant frequency for any pre-specified power system bus can be done by hand calculation. Comparison of the new method with the traditional approach is presented.(2)The harmonic problems which could be caused by the future expansion of UPS’s and UPS’s load growth, for a specific fab, have been investigated. The effects of network variation under both normal and abnormal operation conditions on the harmonic resonant frequency are also evaluated. The complete simulation process for the industrial harmonic analysis, including the implementation procedure for harmonic source measurement and fab’s harmonic characteristics are presented.(3)The transient stability problem for the same fab under island operation is studied, which is the operation powered by the emergency diesel generators after disconnection with the commercial power utility system. The study includes:●Evaluation on the manual operation sequence of diesel generators, and on the design settings for automatic load recovery;●Impact analysis of the diesel generator tripping on system frequency change and thus on the inverter tripping of the inverter-controlled motors. A preliminary result for the analysis is presented.