Large medium voltage drives — efficiency, energy savings and availability

An overview is given of conventional and modern large adjustable speed drive technologies (MW range). Overall efficiency is evaluated for different adjustable speed drive topologies, motor types, control methods and system configurations. Efficiency improvement opportunities are investigated. It is shown how modern technology can be applied safely with existing/standard petrochemical motors (identified for energy savings). Adjustable speed drives can contribute to remarkable energy savings shown in a case study but system availability can be compromised resulting in potential production losses which can be significantly more than the energy savings. The importance of a holistic evaluation of efficiency, energy savings and system availability is illustrated. Solutions are given to improve system availability and to obtain additional benefits and thereby ultimately improving the feasibility of energy saving projects.