Some advanced process control (APC) projects don’t succeed. Some project fails because the plants are not capable or be aware of maintaining their process equipment. Advanced process control (APC) systems cannot overcome sticky valves or unreliable sensors. If field devices begin to behave erratically, the advanced process control (APC) system attempts to tweak the operation, making the disturbances from minute to minute worse.
With advanced process control (APC) ability to press limits and work against constraints, the system can push a process into areas where operators fear to tread. Advanced process control (APC) systems suffer from operators that simply cannot allow the system to do its job without human intervention and keeping the process in so called “comfort zone”. Advanced process control (APC) systems that aren’t used correctly can get turned off permanently and the company loses its faith in the technology.
Other advanced process control (APC) systems stop to work after some time due to lack of awareness for advanced process control (APC) models upgrades. Most of the advanced process control (APC) systems are designed and commissioned for he existing plant operation when all process equipment worked properly. If valves get sticky or slow, or if plant starts to operate at some different capacity, grade or conditions advanced process control (APC) models could start to deviate from the reality. This could lead to inappropriate and missed behaviour of advanced process control (APC) system. After some time, without proper maintenance and improvement of advanced process control (APC) models the systems could be easily turned and stayed off.
The last, but not the least common reason why advanced process control (APC) systems get failed is too aggressive, too sluggish or not tuning at all of base level PIDs which are the part of advanced process control (APC) system. To sluggish or to aggressive base level PIDs can cause and transfer inappropriate dynamic response to advanced process control (APC) system resulting in poor or oscillatory action. To achieve optimal performance of advanced process control (APC) system all fast and slow base level PIDs needs to be optimally tuned. With process and condition changes some of the base level PIDs needs to be retuned in order to keep the stability and high performance of advanced process control (APC) system.
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