A case study of replacing steam turbines with LCI-type variable-speed drives

The problems and experiences associated with the installation, start-up, and operation of 7000 HP 1800 r/min and 3600 HP 6000 r/min synchronous motors using load commutated inverter (LCI) variable-speed controllers are examined. The application of new technology in existing process units can present some unusual and sometimes perplexing challenges. The steep learning curve, and the fact that most projects are time and money driven, all contribute to the hurdles that must be overcome. The described application of LCI variable-speed drives covered all of the factors. Some of the problems and concerns encountered with this project resulted from equipment previously installed, coupled with the dynamics of the electrical, instrumentation, and process systems. When planning the application of variable-speed drives, factors such as electrical system disturbances, impact of harmonics on the existing equipment, training, commissioning, operator acceptance, craft training, and spare parts all need to be taken into consideration