By definition, a digital twin is a digital representation of a physical object or system. While the idea of a digital twin was first introduced by NASA to simulate how space conditions would impact their equipment, the digital twin is a relatively new concept for manufacturers that is quickly permeating the industry. There are quite a few benefits manufacturers can experience with a digital twin, but at a high level, a digital twin helps reduce risk. This is because a digital twin can be used for a variety of functions, from enhancing equipment training to digitally testing system changes prior to live deployments, which are both especially important for manufacturers that have processes that cannot be taken offline for extended periods of time.
Sound interesting? Let’s look more in-depth at four potential benefits you could experience by developing a digital twin for your control system, especially if you are considering embarking on a control system modernization in the near future.
Benefit 1: Testing Your Control System Against Real-World Situations
A digital twin provides a nearly risk-free opportunity to test how your control system will react to various real-world conditions. However, it is important to note that the degree of accuracy for this type of testing starts with the fidelity to which your digital twin is designed. While an overview of fidelity could fill an entire discussion itself, in general, there are a few important things to know. First, a low-fidelity system is not truly a digital twin. Functionality in these systems is typically limited to simulation of basic tasks such as opening and closing limit switches and valves or changing flow rates. This is instead a simulation environment where basic tests of logic can be performed, but it is not a true digital twin.
On the opposite end, a high-fidelity system is designed to precisely model all processes and reactions with data derived from a process model or historical data from the system itself. This usually includes information such as mass and energy balances, reaction profiles, or vapor-liquid interactions. Most digital twins fall somewhere in between high and low fidelity and are based on some level of process data.
For example, for a digital twin we developed for one of the world’s largest PVC manufacturers as part of a DCS modernization, we used Emerson’s Mimic Simulation Software to create dynamic real-time process models to characterize the plant. Our customer chose to simulate a variety of components, such as valves and motors, and inputs and outputs such as discrete inputs, flowrates, and reaction temperatures creating a medium fidelity system. The code was developed and tested within this virtual environment, up to and including the factory acceptance test (FAT). The digital twin provided realistic system conditions for robust testing, leading to a decrease in the amount of time to commission the system.
Benefit 2: Provide Better Training
Whether you are releasing new features, performing a major upgrade, or hiring new operators, a digital twin can provide a realistic and safe training environment for operators. Using a digital training environment not only accelerates operator training, but it also provides a training environment that helps protect your people, processes, and equipment.
With many experienced operators reaching retirement age, manufacturers need a realistic training program that quickly transfers the learned experiences to new operators. With a digital twin, new operators can not only learn the basic functionality of their control system, they can also be trained for real-world scenarios based on input from senior operators prior to stepping onto the plant floor. During this training period, the digital twin can be used to create a progressive training program in a controlled manner. This means that once a trainee is familiar with standard operations, trainers can add in problem scenarios, typically starting with basic issues such as a temperature sensor breaking in a reactor and progressing up to larger issues that may cause equipment failures.
This scenario-based training has two benefits. First, it lets the company evaluate how long it takes operators to identify issues. If operators consistently take a long time to identify certain problems, improvements to the HMI may be needed to show the issue more clearly. Second, once problems are identified, trainers can ensure operators are reacting timely and accordingly. If they are not, trainees have a safe environment where they can see the consequences of inaction. This digital training environment can also be used to train current operators on new processes or procedures before deployment to the plant floor, which will result in minimal downtime and help protect both employees and equipment.
Benefit 3: Decreased Downtime for Upgrades
Without a digital twin it is difficult to familiarize operators with a new system prior to go-live. PowerPoint presentations and training manuals can only go so far. If an operator can gain hands-on experience with process changes before implementation, the transition to the upgraded process can be smoother. In our PVC manufacturer example, the digital twin was launched onsite three months prior to installation. This gave operators time to become familiar with the new system and identify any issues or bottlenecks. As a result, the time to full production following commissioning was dramatically decreased.
Benefit 4: Simulating Process Improvements and Changes Prior to Deployment
Once a digital twin is in place, the system can be used as a test bed for all future changes. In general, this means process control improvements can be developed, tested, and demonstrated without affecting the production of the actual plant. However, there are some additional benefits to simulating process improvements and changes first, including:
- Site engineers and systems integrators can perform design reviews in the simulated environment to demonstrate how programming will be implemented
- Production issues can be investigated on the digital twin using data from the real-world system
- Console operators can gain hands-on experience early in the design phase and suggest improvements to the HMI interface
- SOP documentation can be developed and tested on the digital twin
Whether you are testing small or experimental process improvements or a major upgrade, the digital twin can be used to simulate changes across your DCS to eliminate potential issues with the live system. And, tying back to the benefits already discussed, by using the digital twin as a test bench for change, you can easily train operators prior to a go-live since the simulator is already programmed with these changes.
It Is Never Too Late to Plan for Your Digital Twin
While a digital twin can be developed at any time, it is ideal to plan for this development as part of a control system modernization or initial system development. If done at one of these times, you can benefit from the ability to test and train on the modernized system using the digital twin as opposed to doing it all on the live system after an installation. In the end, no matter when you develop your digital twin you gain the benefits of a more robust training environment as well as a digital sand box to test and demonstrate changes to your process, leading to a more effective operations team and an increase in uptime.
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