I was reading through some past Power magazines over the weekend, and came across a couple that dealt with Plant Data Networks (PDN).
I’ve noticed how, over the years, the amount of data collected and archived at power plants, especially combined cycle plants, has grown significantly. Ten years ago, a 1×1 combined cycle plant might have 800 points archived in their historian. Today that number is easily doubled, and in some cases quintupled. The ease of adding points to the historian, and the low cost of digital storage media have allowed plants to add just about every data point entering the control system to their archives. And, for people like me who love data, this is a great thing! But, not everyone has this luxury.
Historians can be expensive, from $50k for a base model, to millions for a fully configured system at a multiple train site. These historians often offer all sorts of add-ons, too. OSI-PI is famous for some of the wonderful modules that they have available, from the ProcessBook graphics display and trending package to the DataLink add-in for Excel.
But, as I see it, this all has a single purpose:
Get the right data to the right person at the right time.
OK, that sounds more like more than just one purpose. And, its not such a simple thing to do, either.
First, you have to know what you want the data to do (improve predictive maintenance, alert operators to hourly generation overruns, improve annual fuel burn forecasts, etc.), then which data is needed for that purpose, who needs to see it, and who needs to act on it – and then you need to configure the system to get that data to those people ON TIME. If your plant data network is completely connected, things are a little easier. Files, alerts and reports can all be placed in a central location. Pop-ups can be sent electronically to stations when immediate action is needed, or information can be made available for month-end and year-end reporting on an as-needed basis.
But, what about when you don’t have a connected network? Can you still benefit from the data you do have?
The comment on my previous post points out that some facilities do not have historians, let alone complete data networks. But even if you have limited digital access, you can still benefit from what you have available – it just might take more personnel time. For peaking units with limited data connectivity, operators can maintain hourly data logs by manually noting the current load, pressures, temperatures, levels, valve positions, etc. These logs can then be entered, manually, into digital form as a spreadsheet or database, where it would then be available for later use in trends, reports, and potentially, post-event root-cause analysis. When operators find themselves too busy for manual log-taking, you might be able to setup printers to log certain events to hard copy; then, as time allows, the values can be typed into a data archive (spreadsheet or database). Yes, it’s a lot more work than just pulling up a trend from the online historian, but for sites without that sophisticated option, it’s at least a start. And, when that data is finally recognized as indispensible by the people who hold the purse strings, when they become addicted (like me) to more and more data… they just might be able to find a way to install a plant data network at sites where it was previously thought not to make ‘financial sense’.
If you have a site which is trying to justify a new historian, or other plant data network component, let me know (send an email, or post a comment here), and I’ll see if I can’t come up with some numbers to help you make that justification. It doesn’t take much of an upset for heat rate and fuel costs to increase and easily surpass that $50k entry-level data archive value.