Siemens - SCADA System
Individual Project
Project Mentor: Dr. Thomas Groegler, Siemens
Summer 2015
This shows the simulation running. I modeled the complete cooling plant, down to the piping networks. Green outlines show running equipment. Yellow outlines shows standby equipment and Red shows fault/failure. Warnings & Alerts are shown in the top center. Blue and Red pipes show cold and hot water respectively.
Within the simulation, clicking on the Cooling Towers or Chiller Trains opened their respective Face-plates (pop-up window). In this case, the plate shows all components are functioning (green) on Chiller Train 2. Colors of pipes change based on the temperature of the flowing fluid
This shows the simulation running. I modeled the complete cooling plant, down to the piping networks. Green outlines show running equipment. Yellow outlines shows standby equipment and Red shows fault/failure. Warnings & Alerts are shown in the top center. Blue and Red pipes show cold and hot water respectively.
As a summer intern (2015) at Siemens' office at the Qatar Science and Technology Park, I worked on simulating a Supervisory Control and Data Acquisition system (SCADA) that Siemens was creating for a central cooling plant in Qatar Foundation. My simulation was designed to be run on any computer with WinCC software, without requiring additional hardware but could also be linked to external hardware for inputs/outputs. This simulation implemented sample functionality of the full product, to showcase to potential customers and give them a 'feel' of the SCADA system.
I handled both the back-end and front-end aspects in this individual project. The programming was done using Ladder Logic on Siemens STEP7 and the GUI (screenshots above) was created using Siemens WinCC proprietary software.
Background
The industrial facility in question is a water cooling plant. Input water is cooled using Chiller trains (consisting of two pumps and two heat exchangers) and Cooling towers (think: fans blowing air to cool water). The cooled water (which is around 6°C) is taken from the plant as output and circulated throughout Qatar Foundation. Various Air Handling Units (AHUs) take this chilled water, and use it for air conditioning in various buildings. The warmer water is circulated back to the plant as input.
To oversee all the complex equipment in such an industrial plant, a central operator room ('Mission Control', if you like) is present. A SCADA system acquires data from all the equipment and shows the status of each to the operator in a user-friendly form. The scope of the SCADA system is typically the entire plant, including power supplies, valves, vents etc.
To showcase such a product to potential buyers would require tours to an existing operator room in a functioning plant, which is not always feasible. Hence, my assignment was to simulate the SCADA system on a PC, with mock inputs that can be toggled to simulate various operating conditions without requiring any industrial hardware.
Ladder Logic (LAD)
After first understanding the functioning of the plant through site visits, the majority of the work on the back-end was done using Ladder logic (LAD). Coming from a text based programming background (C, MATLAB...) this was confusing for me at first, but I soon got the hold of it.
To get an idea of what LAD is, take a look at Item 3b. Essentially, all operations are reduced to a network of logical (bit-wise) operations that are then compiled and run on Programmable Logic Controllers (PLC). The reason for using such a low-level language is that PLC processors, while being highly reliable, have low clock speeds and aren't very fast. Using a higher level language would be tough on these processors. In fact, to test this, I created two iterative functions - one to be run on MATLAB on my laptop, and one on a low end Siemens PLC (S7-300 series). While both returned the same outputs, the PLC just took half the time, even though it had barely a fourth of the computing power of my laptop!!
If you want to learn more about LAD programming, I highly recommend this introductory PDF from Siemens
Item 3b: Sample Ladder Logic code. Source: https://goo.gl/DA6cbL
Since this work was done at Siemens WLL, I am not able to post my ladder logic codes on the website. Given the scale of this project (simulating an entire cooling plant), the complete code, when put in PDF form, runs over 140 pages, and took me 3 months to create and test.