Voltage sags improvement for the high-tech industrial customers by using cogeneration system

This paper presents the improvement of the voltage sags for the semiconductor fabrication facility by the installation of cogeneration systems. The critical equipment is evaluated against the SEMI F47 and ITIC power quality documents. The cogeneration system is installed to mitigate the voltage sags due to external system faults. Also, the under voltage relays to disconnect the cogeneration system from the utility are designed by considering the critical clearing times at the point of common coupling and voltage sags ride-through curves. The dynamic responses of different fault conditions are executed by using the transient stability analysis to calculate and define the voltage sags ride-through curves with and without considering the disconnection of the cogeneration system. It is concluded that the voltage sags ride-through capability can be improved greatly if the cogeneration systems are performed to trip accurately according to the under voltage relays design proposed by the paper.