Last night, I stayed in the workshop until 2 AM, not because of equipment failure, but while debugging a new energy-saving control algorithm. Watching the numbers on the energy consumption monitoring screen gradually decrease gave me a sense of accomplishment that was more invigorating than three cups of coffee. After so many years in automation, I increasingly feel that energy saving and emission reduction is not only a response to national policies but also a technical conscience for us engineers.

Starting from an “accidental discovery”

Two years ago, while debugging at a chemical plant, I discovered that their circulation pump was running at full load 24 hours a day. I thought to myself, isn’t this just burning money?After carefully analyzing the process flow, I found that the system did not need to run at full flow for 80% of the time. So, we added variable frequency drive control logic in the PLC program to dynamically adjust the pump speed based on the actual needs of downstream equipment.

// Core control logic example
IF Process_Flow_Demand < 60% THEN
    VFD_Speed_Reference := 45%;
ELSIF Process_Flow_Demand < 80% THEN
    VFD_Speed_Reference := 65%;
ELSE
    VFD_Speed_Reference := 85%;
END_IF;

As a result, after three months, this single improvement saved the customer nearly 30% on their electricity bill. The customer was so excited that he treated us to several big meals, saying it was more cost-effective than buying a new piece of equipment.

Practical Energy-Saving Control Strategies

1. Intelligent Start-Stop Control

The simplest and most effective method. I usually set a device idle detection timer in the PLC program, which automatically switches to standby mode when it detects that a device has been running idle for longer than a set time.

I remember once at a printing factory, their compressor kept running continuously. We added a simple pressure detection logic: when the pressure in the air tank reached the upper limit, it would automatically shut down, and restart when the pressure dropped to the lower limit.This “breathing” operation mode saves more than 40% energy compared to continuous operation.

2. Load Balancing Algorithm

When multiple similar devices run in parallel, rotating start-stop is a brilliant strategy. It not only extends the lifespan of the equipment but also optimizes overall energy consumption. I usually set a device running time accumulator in the PLC, prioritizing the device with the least running time each time it starts.

3. Predictive Energy-Saving Control

This is one of my proudest innovations. By analyzing historical data, the PLC learns to predict peak electricity usage periods. For example, in cold storage control, we cool in advance during low electricity price periods and reduce compressor operation during peak periods. This requires a certain algorithmic foundation, but the results are significant.

Pits I Have Fallen Into

Speaking of energy-saving transformations, I have also paid a lot of “tuition”. Once, in pursuit of extreme energy savings, I set the start-stop intervals for all devices too frequently, resulting in the instantaneous current from frequent motor starts actually increasing total energy consumption. I later realized that energy-saving control must find a balance between equipment protection and energy efficiency optimization.

Another time, the customer asked us to add an energy-saving module to the existing system. I excitedly wrote a complex algorithm, only to find during on-site debugging that the old PLC’s processing capability could not keep up, causing the system response to slow down and nearly affecting normal production. This made me deeply understand that: energy-saving transformations must consider hardware limitations.

Sharing Practical Experience

Anti-Interference and Stability

Energy-saving control often involves frequent start-stop operations, which require high system stability. I usually add software filtering and delay confirmation in critical control loops to avoid misoperation caused by interference signals.

The Importance of Human-Machine Interface

No matter how good the energy-saving algorithm is, if the operator cannot use it, it is useless. I always design intuitive energy consumption monitoring interfaces so that frontline employees can see the energy-saving effects in real-time, stimulating their enthusiasm for participation.

Data Recording and Analysis

Establishing a comprehensive energy consumption database is the foundation for continuous optimization. I will add a data collection module in the PLC program to regularly analyze energy consumption curves and look for further optimization opportunities.

In Conclusion

After so many years in automation, I increasingly feel that technology should not only solve production problems but also bear social responsibility. Whenever I see the energy consumption of the systems we have transformed significantly decrease, I always feel an indescribable sense of pride.The road to energy saving and emission reduction in PLC control systems is still long, but every small improvement contributes to green manufacturing.

If you encounter similar projects next time, why not try these methods? Remember, energy saving is not just about simply stopping and starting equipment, but a systematic engineering mindset.