(44f) APC KPI Aggregation

KPIs can be an important facet of the maintenance of any system, as long as the KPIs are properly conceived, well defined, and understood. Similar to a process control feedback loop, KPI values are a measurement of the health of the system. The targets for the KPIs are similar to set points, and the system will drive towards the KPI targets, if not beyond. Think of the old adage, ?You get what you measure.? If you use the wrong KPI, you will tend to drive the system to that KPI anyway.

Typical performance KPIs measure the performance of a controller or subcontroller at a given time. To measure the performance of a controller over a period of time, all the controllers in an area, or all the controllers in an area over a period of time; special care must be given to make sure the aggregated KPI reflects the true performance of the system.

This paper outlines methods we have used to aggregate individual controller KPIs so as to monitor plant-wide APC performance, allocate resources and focus attention in olefins plants.