Converting Control Systems: Don’t Forget Strategy Improvements

Jun 8, 2016 11:30:00 PM | Posted by Mayann Stroup

strategy.jpgConsider investing the time to write a scope that includes control strategy improvement and open the door to taking advantage of the functionality provided by a new control system.

One of the most frustrating specifications I see in scope documents is, “Convert the existing control system as-is. We will leave control strategy improvements for later.” It’s painful because if I’ve learned anything during 24 years in systems integration, later never comes.It’s easy to understand why clients take a convert-it-as-it-is approach. First, we know the existing system is working, at least most of it, and where it isn’t, everybody’s already used to the workarounds. Second, it’s an easy scope to sell to management. As mentioned, the existing system is working (mostly) and the new system will be working the same way after the migration. Third, it’s easier to write the scope without doing any research. Lazy, yes, but cheap and expedient.

The frustration and pain is because this kind of project is a huge missed opportunity. A convert-it-as-it-is scope robs a migration project of much of its value. There are major operational improvements possible during a migration, which can be implemented for minimal cost during the project, but many companies simply don’t make the effort.

When a plant has worked with an obsolete system for many years, it’s hard to imagine what these improvements might look like. Finding out what they should ask for takes time to do the homework, but making the investment to write a scope so it includes control strategy improvements opens the door to taking advantage of those new functionalities. When a process can be controlled more stably using better control strategies, the next step is optimization. Operators can run closer to limits without causing trips. Operation with less variation leads to increased production, consistently on-spec products, and probably both.

Developing a plan for process improvement takes pre-project work, often described as front-end loading (FEL). FEL efforts include process studies to identify problem areas, such as the control loop running in manual for the last 10 years, or the distillation column that goes out of whack every time it rains. Field surveys determine the state of existing instrumentation so deficiencies can be addressed and remedied before they hamper the new system. FEL work also provides an improved estimate of project cost.

FEL does add cost to a project, but it is money well spent. Preliminary engineering and design work done during this stage can be rolled into the project immediately. Fleshing out the scope, including instrumentation upgrades, leads to lower risk of project overruns and unpleasant mid-project surprises.

A control system migration is a rare opportunity, and one which should not to be wasted. It is the best time to review and improve your HMIs, go over all your alarm strategies and tighten up cyber security. A control system migration project provides money, resources and support from the business in ways not available during ordinary operation.

Working on a project team allows people from operations, engineering and maintenance to work together on solving problems in ways not usually possible. Planning early in the project allows everyone’s views to be brought into the discussion, ensuring a higher degree of engagement later on. Once the project is over, the team will disperse. The only people left to make control strategy improvements will be the ones also responsible for day-to-day operations. Guess which responsibilities will take priority?

Don’t rely on making control strategy improvements later. Later never comes.

This post was written by Mayann Stroup. Mayann is a senior engineer at MAVERICK Technologies, a leading automation solutions provider offering industrial automation, strategic manufacturing, and enterprise integration services for the process industries. MAVERICK delivers expertise and consulting in a wide variety of areas including industrial automation controls, distributed control systems, manufacturing execution systems, operational strategy, business process optimization and more.

Topics: DCS Migration , DCS