As you work to save kWh and $, you want an energy optimization solution that automatically and continuously minimizes consumption. That means it requires no manual intervention to optimize your chilled water plant.
Optimization projects usually start with an evaluation of the current plan. The evaluation results in recommended measures to reduce kW/ton and a corresponding energy savings projection.
Under the Model-and-Tweak approach, the optimization plan, or “Model,” uses collected data to create a series of operating “recipes.” These contain the values of key operating parameters for the full range of expected load and ambient conditions. As these conditions change during actual operation, the BAS looks up the corresponding values. It then uses them in its program to control the plant equipment.
Model and Tweak: Practical Limitations
The impact of the Model part of the Model-and-Tweak approach on optimizing kW/ton depends heavily on two unavoidable aspects of developing any model:
- Similarity to the actual system: For example, are there allowances for conditions that cannot be practically modeled, such as piping idiosyncrasies or electrical service limitations? The model can also often miss the all-too-often scenario where the drawings don’t exactly match the “as-built” reality.
- Operating assumptions: Most models assume that the correct control sequence will always be followed during actual operations. We all know that rarely happens. Models also don’t consider common operational issues, such as equipment performance that doesn’t match the specs or maintenance problems that require override.
The Tweak process compensates for the inherent Model limitations. It starts with actual plant efficiency and equipment operating data collected by the BAS. The Model-and-Tweak supplier technicians periodically review the data and then determine revised recipe values to adjust for the Model limits and further reduce the kW/ton.
The BAS uses the revised parameter values, and the collect/analyze/tweak process is repeated. As with the Model, practical limitations hinder the Tweak effectiveness, in large part because there’s no way to predict the frequency, duration or timing of the disruptive events. The frequency of the Tweak and the technician skill level can also play a part.
Adaptive Control: Real-Time Energy Optimization
The adaptive control approach also starts with a model that produces a set of initial values for the key operating parameters. The difference: The system uses the model’s initial value just once. It doesn’t continuously rely on these values with their inherent limitations. Then, the adaptive algorithms continuously analyze the real-time process variables and automatically adjust the parameter values on-line without operator intervention.
Adaptive control based energy optimization ensures a more energy efficient system than a model-and-tweak solution for three major reasons:
- There is no manual intervention
- Using real-time operating data automatically accommodates the piping idiosyncrasies, spec deviations and maintenance events that cannot be modeled
- There is no delay between the Model and the Tweak – the adjustments immediately impact efficiency
For more information
To learn more about how tekWorx can use the adaptive control approach to increase your plant’s KWh efficiency and cost savings, contact us. Then, follow us on LinkedIn for the most up-to-date news and events.