In today's tough business environment, many chemical plants view upgrading their process control systems as an important step toward improved competitiveness. After all, a control system can hugely impact performance over the entire lifecycle of a facility. Still, of course, the replacement system must offer a superior business-value proposition.
A well-planned and executed migration to a modern control system not only improves plant availability and reliability but also can provide a more flexible production platform. Many companies now are looking for increased flexibility so they can make the most of business opportunities.
A structured, organized approach to automation upgrades enhances the benefits of new technology, reduces risks and preserves valuable intellectual property.
So, here, we'll provide tips for optimizing migrations. The goal is to help plants accelerate the migration process, minimize potential complications and ensure successful project results. These insights have been gained from experience with migrations at plants of all types and sizes, and with a wide range of operational and business requirements.
Every distributed control system (DCS) at some point requires upgrading to maintain reliable operation and leverage the latest technology. The existing DCS may pose significant maintenance issues, which can be aggravated by problems in obtaining spare parts. It also can be difficult to find personnel qualified to troubleshoot and repair an older system. As plant workers familiar with the current DCS reach retirement age, outside support often becomes necessary.
Excessive failure rates, difficultly in procuring spare parts and lack of qualified maintenance personnel all add up to an increased risk of downtime —a significant expense for any manufacturing facility, but particularly for a process plant.
[Podcasts Worth Listening To: Leadership Focus Podcast: Control System Migration and Podcast: Book Review -- Control System Migrations Handbook]
In addition, process control with an outdated DCS may result in inadequate quality and excessive energy usage. Deviations from set points, particularly for extended periods of time, can directly impair quality. Control performance also can affect throughput. Newer automation platforms allow automating more processes and can enable tighter control of existing ones.
Today, many control system migrations are performed "on-process," using technology that replaces the existing human-machine interfaces (HMIs) and provides modern functions while retaining the original system's controllers, input/output and field devices. With this approach, all or part of the old DCS and the new automation system operate simultaneously, allowing elements as small as one control loop at a time to be migrated from the old DCS to the new automation system. If the user has a redundant control architecture, on-process migration permits an upgrade to the next system release while maintaining view and control of processes.
The first step in preparing for a control system migration is developing a comprehensive project plan. This involves working with all stakeholders —including operations, engineering and plant management — to align on scope, risk assessment and the overall project roadmap. Project participants should evaluate and prioritize what's important from their individual perspectives. This helps to create ownership and a shared vision throughout the organization.
Among key factors to consider at the project planning stage are:
• establishing specific goals for your upgrade;
• developing an organized approach to planning;
• determining how you will build your new system;
• communicating with operations, management and outside support personnel;
• remembering that a migration primarily consists of sequential operations (skipping a step could result in putting yourself in a precarious position); and
• retaining focus on your plan.
In the early stages of a control system migration, the project team should identify the primary objectives for technology upgrades. These may include:
• increased control system reliability;
• reduced risk;
• enhanced alarming functionality;
• improved utilization of historical data;
• expanded access to DCS information from third-party systems;
• heightened overall intercommunications; and
• strengthened security capabilities (often overlooked).
An effective plan identifies migration and support strategies for existing control system nodes, such as controllers, HMIs, supervisory computing nodes, etc. It also includes proposals for consolidating legacy control systems to reduce costs and enhance safety. Additionally, the plan provides recommendations for ensuring the reliability, robustness, security, expandability and ease of diagnosis of process control networks.
In many cases, the success of a migration hinges on initial preparation involving the control system supplier and its migration specialists. The supplier's expertise, combined with extensive data gathering and analysis in the early stages of the project, help reduce the effort and risk involved in migration. Close collaboration with the supplier also can minimize interruptions to process operators, and eliminate loss of control and view of the process (Figure 1).
Plant personnel should approach migration planning by asking: "What existing functionality do we want to maintain, change or improve, and what's the desired outcome of the upgrades?" "What are the steps involved?" "Is the project a clean build or translation?" "Are there third-party software considerations?"
In addition, it's crucial to understand how migration activities will affect the process. Non-redundant controllers likely will be down during software upgrades. Control nodes also may be unavailable during upgrade and cutover (so any associated control will be lost).
Plants should prepare for upgrading software and licenses for each system during the migration — including DCS, server and data historian applications — and determine what's needed from third-party suppliers.
Sites that haven't gone through a migration in many years — and that thus lack their own "proven approach" — should consider adopting a sister plant's approach, to leverage established and successful upgrade methodologies. They also should rely on recommendations from key vendors. Ultimately, there's no substitute for doing homework to come up with the best working strategy.
Properly planned and implemented, a migration should permit a plant to move from legacy control platforms at its own pace, allowing new controllers to be added at any time and integrated with existing equipment. It also should permit the upgrade of subsystems and function blocks to new controllers whenever the user decides.
Success typically depends upon an optimal migration strategy — this demands a structured, organized approach. Regardless of vendor support, plant personnel should play an integral part in the migration effort, reviewing its progress every step of the way.
As part of good engineering and project management practices, plants should take the following steps when developing a migration strategy:
1. Determine the best time to migrate.
2. Identify the best migration path associated with clearly defined goals.
3. Define the project through front-end engineering.
4. Use a proven approach with comprehensive checklists.
5. Develop detailed cutover plans.
6. Establish intermediate operability and training plans.
While timing a migration for a scheduled turnaround may make sense, keep in mind that a host of other factors could affect the timing. These include:
• production rates;
• holiday schedules;
• availability of support;
• release dates of software and associated functionality; and
• general business outlook.
Perform a front-end-loading (FEL) study to identify potential difficulties with a migration project and provide plans to mitigate risks. The study should analyze all aspects of the project, including mechanical, civil/structural, instrument, electrical and controls. The result is an overall design specification, outlining the strategy and schedule for migration activities.
It's also important to allow plenty of time for system upgrades and dealing with software issues. It even might be a good idea to create a complete system build in advance.
Don't forget to prepare notes and detailed instructions on repetitive processes. Engineers may find it useful to write notes as they go on the first build, completing one station and server, testing and debugging, and then revising the notes for the second build. All stations then can be built using the refined method. This will provide a consistent deployment procedure to minimize potential errors.
Also, maintain close contact with plant operations staff during the on-process migration — the more they know, the better (Figure 2). Keep an eye open for improvements without detouring the migration process, which can be long, slow and tedious. Don't get excited or impatient with laborious upgrade tasks. Keep safety top-of-mind while executing your plan and ensure you have adequate help for each migration function.
Most plants lack sufficient in-house staff and expertise to manage large capital projects internally, particularly for specialized tasks performed infrequently such as a DCS migration. That's why many sites hire outside service providers to manage upgrades.
Plants normally want to update their automation technology without having to "rip and replace" their entire legacy hardware and software system, which would be time consuming and often is impractical. They typically should turn to the control system supplier for knowledgeable assistance, including:
• strategies for migrating and supporting existing control system nodes;
• proposals for consolidating legacy control systems to drive down costs and enhance safety; and
• recommendations for ensuring the reliability, robustness, security and future expandability of process control networks.
Plants will benefit from working with their supplier's migration specialists upfront to plan the migration steps and timeframe. (The supplier's migration team may be booked months in advance, so get on its schedule as soon as possible!) Gathering data often requires different permission sets (e.g., local admin, domain admin and software admin). Pre-work and data collection can be a long process; review the collection procedures and make sure to gather all necessary data.
Routine maintenance and refresh of automation systems minimizes the risk of downtime due to equipment failure and lowers operating and support costs. It also reduces security risks resulting from unsupported operating systems and, at the same time, improves operational and production efficiencies via incremental functionality.
Sites must deal with a number of critical issues when it comes to supporting open control and safety systems utilizing commercial off-the-shelf hardware. With a well-executed hardware refresh, they can achieve significant operational and financial benefits:
• reduced potential for incidents/upsets;
• shortened duration of outage incidents;
• minimized complexity through hardware standardization;
• enhanced capabilities/functionality by using new hardware;
• lowered capital and operating expenses;
• improved visibility into future infrastructure investments; and
• centralized funding of required infrastructure modernization.
Upgrading to new hardware at the same time you're doing an on-process migration simplifies the efforts and allows quicker turnover of servers and stations (Figure 3). When performing a hardware refresh, it's critical to build and check all PC and server boxes before starting the migration.
Plants shouldn't overlook myriad factors related to the upgrade of DCS software and associated applications. To obviate software issues during migration:
• Reconfirm you have correct/complete licenses on all software before you start.
• Double check for approved configurations.
• Make certain to install software patches in the correct order.
• Be sure to update firewalls before starting the controller upgrade.
• Reverify settings during migration.
• Corroborate that host files have been updated on the new hardware to ensure proper functionality.
A successful modernization program can help reduce total cost of ownership, increase production rates, meet regulatory guidelines and manage risks, extend the life and performance of systems, and improve response to changing business demands.
The approach you use to undertake a control system migration can significantly influence whether you actually achieve the value of technology upgrades. The most critical consideration is planning: the more upfront detailed planning you perform, the lower the risks you face in the execution phase of a project.
CHRISTOPHER PETERS is a Richmond, Va.-based consultant for HPS Lifecycle Solutions and Services Americas. E-mail him at email@example.com.