Variable speed centrifugal chillers perform much moreefficiently at part-load ratio of cooling demand as well aspartial compression ratio of lift head compared to constantspeed centrifugal chillers. Magnetic bearing technologyfurther improves the benefit of variable speed centrifugalchillers. This performance difference requires a reconsiderationof most effective plant operation when magnetic bearingcentrifugal chillers are incorporated. In this paper, a component-based model is developed for a chilled-water plant withoil-free chillers at the Texas A&M University System RELLISCampus. The model, calibrated by on-site measured data fromthe building automation system, is used to evaluate the savingspotential for different operation strategies. An optimal chillerstaging strategy, based on the optimal efficiency curve, is simulatedfor the case study plant under constant water flow andvariable water flow scenarios respectively. The results showthat optimal chiller staging only improves plant performanceby 2.1% for the constant water flow system. Implementing optimalstaging with variable water flow would increase theenergy savings to 13.7% compared to current operation of thecase-study plant.