Operation and Selection of Electric Motor Driven Compressor Systems
Electric motor driven compressors, both reciprocating and centrifugals, have become a more common choice for pipeline operators due to recent technology improvements, versatility for capacity control and lower point source emissions in most cases. In the last ten years, technology advancements for higher horsepower induction and synchronous motors combined with variable frequency/ variable speed drives have enabled the electric drive option for the gas transmission industry. However, in designing a new or retrofit electric motor driven compressor station, the components of an electric motor driven system must be carefully selected to ensure smooth start-up given the electric utility constraints, adequate power and torque over a range of operating conditions, and low life cycle costs. This paper will present options for start-up utilizing different system configurations, rotordynamic and torsional analyses to consider for both centrifugal and reciprocating compressors and operational issues with electric driven compressors. The operational issues will be presented from a pipeline industry perspective based on actual case studies to highlight some of the complex or unique operational issues with electric motor driven systems. The recommendations for design and selection will be based on the GMRC Application Guideline for Electric Motor Drive Systems developed in 2008.