Basic control loop tuning is valuable, and it can be amplified by proven forensics to help users investigate and resolve complex issues and multi-loop interactions.
While evolving technologies typically become more complex, it can be equally true that advancements can improve the accessibility of technology for a wider audience. Over the years, skilled designers and engineers have used and improved PID loop control for many process industry applications. Our article in the Processing May 2023 issue, titled Accessible Loop Tuning Forensics, explains how there are many more opportunities for improvement at these sites by using advanced tuning software with forensic analytics, made accessible for a wide range of workers.
Great gains have been made by tuning individual loops using control loop performance monitoring (CLPM) software. However, there remain plenty of vexing individual- and multi-loop tuning issues in almost every process plant. Because there are many more operators than engineers, it makes sense to develop modern CLPM software to be usable by operators and maintenance personnel, as well as engineers, to improve operations.
Three key forensic tools
Most plant personnel are not data scientists, so Control Station PlantESP CLPM software makes many types of advanced analytics easily usable as part of a virtual tool bag. For example:
Power spectrum
Power spectrum analysis uses fast Fourier transforms (FFTs) to rapidly obtain a “fingerprint” of signals in the plant, and visually matches which loops may share similar root issues. While this analysis does not determine the root cause, it assists with the next analytical step.
Cross correlation
Cross correlation is a mathematical technique using statistics to determine how similar two signals are, and the lead/lag relationship between them. It isn’t always perfect, but it can narrow the search as users try and pinpoint a root cause of issues.
Automatic PID modelling
CLPM software is good for tuning individual loops, but PlantESP incorporates a more “meta” approach by monitoring all loops for changes, then performing model fits to reveal performance and improved tuning under all types of conditions, instead of just at a single point in time.
An optimization workflow
Control Station PlantESP is used across all industries. One semiconductor manufacturing plant used PlantESP CLPM software forensics to discover a mechanical plumbing issue improperly connecting two logically unrelated systems and causing poor loop performance. Once this was corrected, the loops could be tuned traditionally and then the automatic PID modelling function was used moving forward.
Even the most basic process control loop troubleshooting efforts can make an impact by delivering significant production, safety and efficiency improvements. Process manufacturers will find that the latest generation of CLPM software does much more than this, empowering a much wider range of personnel to address plant optimization for individual loops, and also multiple loops with complex interactions.
The team at Control Station is happy to discuss how CLPM and advanced forensic analytics can be applied to help with your applications. Contact us today!
