MAIN ELECTRO-MECHANICHAL DESIGN AND TESTS CHALLENGES FOR LARGE E-LNG LCI SYSTEM

Abstract

The full electric drive solution for Liquefaction Natural Gas application (e-LNG) is an alternative to the traditional train driven by heavy duty gas turbine especially when it is necessary to contain dimension and weight at site and to reduce environmental impacts [1]. In addition, the LNG train driven by VSDS allows regulating the operating speed in a wider range giving more flexibility in term of compressor operating points. The e-LNG project described in this lecture is composed by three trains with a nominal capacity of 4.64 MTPA each. Each train is composted by three motor driven refrigerant compression lines with 75 MW shaft power. The main engineering challenges presented in this paper in term of system integration are:–The electrical integration studies to evaluate the impacts in the electrical network to predict behaviors and ensure that these large VSDS systems when in operation will be able to accommodate any grid contingency scenarios and sustain grid transient disturbances.–The mechanical integration studies of the large synchronous motors and the full system shaft line to predict the vibrational behavior in different installation scenarios as FAT, string tests and final site conditions.–The improvement of the reliability of the motor exciter rectifier by soft commutations of the diodes.