Transcript
Introduction to Merlin and Waveform Capture Analysis
Good afternoon, everyone. Welcome to today’s white paper webinar. Today, we’re gonna be talking about Merlin and waveform capture analysis. Merlin is a new AI component in PQ Canvass that analyzes power quality data, and it does an assortment of power quality functions, including triggered waveform analysis, where Merlin can analyze every waveform for you. Caleb Payne has written a white paper on that, and we’re gonna show you how Merlin works specifically within waveform capture.
Merlin is a comprehensive power quality package that analyzes trip charts and other types of information and gives you an overall top level PQ breakdown. But we’re gonna dive into what it does for waveforms, in particular, so you can understand what it can do, what it doesn’t do, and make better use of Merlin as a partner in your PQ investigation.
How Merlin Classifies Waveforms
Merlin starts with looking at every single waveform. It looks at it graphically and through metrics that are passed to it, and it analyzes the waveform in terms of classifying it. It’ll classify it per IEEE 1159, in terms of transient, either oscillatory or impulsive transient or a voltage sag or a swell, a rapid voltage change, or maybe a no event. If it’s a periodic capture that was just kind of a steady state baseline, the classification may be none.
It will determine the type of event, and that will show up in the Merlin waveform. I’m gonna actually just jump to Merlin so you can see what this looks like. I’m gonna pick an example file in PQ Canvass and go to the Merlin section, and this is the waveform section here in the center.
Oscillatory Transient Example
Click on this, and it’s showing you the waveforms. These are sorted by severity. And Merlin has done the classification. For example, I’m gonna pick this oscillatory transient. This is a waveform that was classified as an oscillatory transient. Here we see a little mini graph of the waveform, and this is Merlin’s analysis of this capture. The oscillatory transient on all three phases, and it gives you the peak voltage, the IEEE classification.
It often tries to determine attribution. It’ll look at the relationship between voltage and current, clues like if it’s a swell on two phases and a sag on the third phase that indicates an upstream fault. It’ll use the power quality knowledge that we’ve baked into it with our white papers and our PQ knowledge inside Merlin to try to determine what that cause was. Here, this is most consistent with an upstream cap bank switch with an induced transit ring. It’s also determining that because the RMS voltage changes slightly afterward.
Verifying Merlin’s Analysis
We can click on this waveform and check Merlin to make sure it got it right. We click on this, and here we see in PQ Canvass the full waveform capture, and yeah, it is an oscillatory transient. You can see the ring. But we can also look at the RMS version of this, and we can see that the voltage just after is a little bit higher than the voltage before.
Before we were running base A, for example, at 284.3 volts. After this ring, we’re now at 286.5 volts. So we’ve gone up a couple of volts on all three phases. That’s consistent with a capacitor switching in, and that is raising the voltage slightly. Those clues are the kinds of things Merlin is looking for for determining, well, what was the root cause of this? A ring followed by a small step change in voltage with a very little change in current indicates a primary side event, and it’s using these clues and heuristics to determine attribution.
Severity Scoring
Merlin does this in parallel for every waveform in the recording. You could have as many as a hundred of these. And it sorts them by severity. It’ll give a severity score from zero being benign, perfect, 60 hertz sine wave. A 10 is very severe. That would indicate almost certain equipment damage if you see a 10. And from one to 10 indicates the level of severity.
That severity score spans multiple types of events, so a sag or a swell or an impulsive transient, and it’s prioritizing equipment damage and then equipment mis-operation. So this is an overall score for each waveform capture here. The swell was the highest at seven. These transients are fairly high for their peak voltage that they go to.
Also, a solitaire transient that has a very high Q that has a lot of ringing that persists for many cycles would also bump that severity score up because it’s more likely than not to cause light flicker or other sorts of mis-operations.
Browsing Waveforms by Severity
We can scroll through the list. These are, again, sorted in order of severity. When we get to the lower severity waveforms, we’ve got things like rapid voltage changes that are pretty benign that are most likely just gonna cause flicker or noticeable light flicker if they’re frequent. And then at the very bottom, we have the zero or ones severity. These are basically clean sine waves that were triggered by periodic captures. So Merlin’s saying, “Well, there’s nothing to see here. This is a perfectly benign waveform.”
When you’re looking at these waveforms, you’re doing your own PQ analysis, you can go to the waveform capture list, and here we have Merlin’s severity score that you can sort by and also Merlin’s kind of one-line summary of each of these captures. This can be very useful too if you’re analyzing data by hand. You can concentrate on the most important waveforms and see what they were. And if you hover over them, it’ll show you Merlin’s full analysis for each waveform. And this can be a very handy time saver.
Overall Waveform Capture Report
Merlin does more with these waveforms than just look at them one at a time. That information goes into Merlin’s overall waveform capture report. And that’s what we talk about next in the paper. This waveform report is an analysis of the waveform capture set as a whole.
Here, Merlin is looking for patterns. It determines any sort of groups or clustered waveform captures. For example, a recloser sequence that’ll have several closely spaced waveform captures will be flagged by Merlin or some sort of periodic trend or daily trend if they’re happening at certain times a day. And this is all determined or all reported in the classification report.
This is a fairly substantial report with different sections. You can see the table of contents here on the left side. And you can click on this to go directly to these sections.
Executive Summary and IEEE Compliance
The executive summary is kind of an overall picture of what the waveforms are saying in this recording, in terms of the overall PQ picture. And then we can go to the highest severity captures. If you’re gonna do a manual analysis, you’d start with these highest, most important captures.
A summary on IEEE compliance. This is what it can glean on steady state voltage regulation, harmonic distortion, and also transient classifications. Of course, the waveform captures aren’t a complete picture for steady state voltage and unbalance and distortion, but it can tell you a lot. If you have waveforms that span the entire recording session, Merlin will look at the steady state portions of those waveforms and tease out any sort of steady state trends. So is your voltage running high or low? Is your voltage distortion high or low? And give you some useful information, even if you didn’t record harmonics strip charts, the waveform captures still have a lot of information that Merlin will pull out.
Attribution
This attribution section is useful for determining which side of the meter most of these problems were on. These upstream events that are caused on the utility side, on the primary side, or are these mostly customer-caused? And it will show you, or when it’s talking about this, it will call out particular waveforms that are key pieces of evidence. For example, waveform capture 71 is an important one, or 74, where it’s kind of citing its own claim. So it’s showing you the receipts for everything that it’s making a claim for.
Patterns, Steady State Trends, and Investigative Guidance
The pattern and likely origin section is useful for if there are any trends, if there’s something that happens at a certain time of day or a certain day of the week, or clusters, that would usually be noted here in the patterns and likely origins in the closely-spaced multi-trigger events.
The steady state trends is useful if you need more information about what Merlin can glean for steady state voltage regulation, voltage unbalance and distortion. And the more waveforms you have and the more they cover the duration of the recording, the more useful this will be. If you only have one or two waveforms in the recording, you can’t glean a lot from that, but if you have a fair amount of waveforms, you can learn a lot about your steady state voltage in terms of unbalance and especially distortion from these waveforms.
The next two sections are useful if you’re doing a deeper PQ dive. The investigative guidance section will help you do a deeper investigation, suggest things to look at. For example, for SCADA logs, questions to ask your customer, those sort of things, to tie other evidence into these waveforms.
Also, the waveform exam next steps. If you’re gonna look at the waveforms yourself, it will suggest which ones are the most important ones. Sometimes these are the highest severity waveforms. Other times, they may be waveforms that aren’t quite as severe, but have very strong attribution scores, where Merlin is very confident that these are perfect examples of the problem being on the customer side or the utility side. So these aren’t always the most severe waveforms. Sometimes these are the highest confidence waveforms that Merlin’s looking at.
And then finally, the follow-up PQ recording advice. If Merlin has some suggestions for another recording, maybe in different capture settings or other types of data to record, based on what it’s seen here, it’ll suggest that here in the follow-up PQ recording advice section.
Summary of Merlin’s Waveform Analysis Process
So this is a lot of information that Merlin pulls from all these waveforms. Again, starts with an independent analysis of every single capture and each one of these analyses are kind of self-contained with just that one waveform. And then this overall comprehensive report, where Merlin pulls all that information together and determines trends, patterns, and any sort of narrative it can create to get more information from those isolated captures, based on their timing and their relationships.
Merlin Beyond Waveform Captures
This can be very useful on its own, but of course, there’s more to Merlin than waveform captures, not talked about in this paper. But also present are the overall power quality report, the focus areas for flicker, harmonics, sags, and swells, the strip chart Merlin abilities, where Merlin is analyzing strip chart data, for example, for sags and swells and for flicker. All these roll up to the overall power quality report, which gives you a full analysis of everything in that recording.
The waveform capture section is one component of Merlin, but it’s very useful on its own. And in some cases, this may be the key to the whole recording, is a few of these waveforms. In other cases, if you need more, you’d start with the top level power quality report, which will also call out anything that is generated from the waveform captures.
Getting Started with Merlin
Merlin is something that sits inside PV Canvass, so to use Merlin, you would need to get a recording into PQ Canvass, either by having the device stream that directly through a network connection, or a transfer from PMIView or from ProVision into PQ Canvass, and then you can use Merlin credits to run the Merlin analysis.
We show at the bottom of the paper, if you’d like to try that, just give us a call or you can also look at the demo and see what Merlin does with some of the files that I’ve shown. There’s a link in the paper. You can also go right to our website and sign up for the demo registration to see what Merlin can do on these files.
If you have any questions about the white paper or Merlin, feel free to type them here in the questions box now, or again, if you want to sign up, go to the link here in the browser, or give us a call anytime at 1-800-296-4120, or send an email to support@powermonitors.com.
Q&A: Non-PMI Meter Support
Good question. Do we have any support for data from non-PMI meters? We can actually import Schweitzer SEL CEV files, waveform capture files, from an SEL relay, and then if you get these into PQ Canvass, you could use Merlin on those waveforms.
Beyond that, if you have a particular PQ device that you want to put into PV Canvass, let us know and we’d be happy to discuss doing that. We’re open to importing other data into PV Canvass to apply Merlin to that.
Well, that’s all the questions we have now. Again, if you have a question later, give us a call anytime or send us an email and we’d be happy to talk more about Merlin. And thanks for attending, everyone.
