Transcript
Introduction to Getting PQ Data from Your SCADA System
Hello, everyone, and welcome to today’s white paper webinar. Today we’re talking about using your SCADA system to get power quality data from various PMI devices.
SCADA is traditionally used for steady state monitoring, where you’re looking at RMS voltage and current and maybe real power for monitoring DG. But increasingly you need more information than that from devices out in the field and distribution. We’re gonna show you how to get that sort of power quality information into your SCADA system.
The Revised Point Map and Available Measurements
The revised point map that’s supported by the Seeker and the Bolt and the Guardian and the Tensor allow you to get a lot more than steady state RMS voltage. As we see here in the list, we can now extract or supply the basics of real and apparent power, power factor, displacement power factor, but also things like total harmonic distortion, voltage THD, current THD, line frequency, and advanced measurements like PST flicker, IFL flicker, and each individual harmonic for voltage and current for magnitudes and phase angles.
So you could pull certain harmonics if you’re concerned about, for example, a resonance where you have a certain frequency that’s of interest or that could be a problem. Or, looking at 60 Hz fundamental voltage and current magnitudes and phase angles allows you to do a lot more calculations offline if you want to look at, say, three-phase voltage imbalance or phase angle issues from the fundamental.
Back-End Systems and Real-Time Control
A lot of these situations would be where the SCADA system is really the pass through to something on the back end, either going into a PI historian that allows you to look at this data in more detail, or to something like a DERMS or ADMS system, where you’re looking at information in real time, or the software is, and sending commands out in the field.
For example, you may have DG sites, a photovoltaic or a wind turbine site, that you’re monitoring voltage THD or current THD, and you want to send a command to trip that system off if the distortion exceeds a certain level, or if, for example, PST flicker exceeds a certain level.
So this allows the Seeker or the Bolt or the Guardian and the Tensor to be the device out in the field that’ll communicate through a cell modem to then feed power quality information into your SCADA system to allow your back-end system, like a ADMS or DERMS system, to make decisions in real time based on what’s happening out in the field. So you can go beyond the substation certainly, but also beyond traditional RMS voltage and current.
Combining PQ Data with Other SCADA Information
Again, this can be done most frequently if you’re looking at DG sites with flicker or voltage or current THD or individual harmonic magnitudes. If you’re looking at the harmonics in aggregate, you could pull all 50 harmonics through SCADA or just the odds, or again, if you have a resonance in your system, say you have a resonance at 300 Hz, then the fifth harmonic could be one you’d wanna keep track of, and you may wanna keep track of that, for example, as cap bank switching it out, which will change your resonant frequency.
So using your SCADA system to gather this data allows you to combine power quality information from the PMI devices with other devices in your system. You could look at the SCADA information from your cap bank switching or recloser operations or other types of sensors that you may have in the substation to look at all this data in one place in PI or some other back-end system, or again, to use this in real time with a control system that is intelligent enough to make use of these more advanced metrics that you can pull.
Setting Up DNP3 Configuration
So to set this up with a Seeker or a Bolt or Guardian or Tensor, you use the DMU tool that we provide to configure DNP3 parameters. The device, for example, the Seeker operates as a DNP3 slave, and it’s pulled by the master. This can be done with either TCP or UDP, and you would typically program the parameters into the Seeker, for example, what IP address the master uses, so it knows what IP address to expect.
We can whitelist those for security reasons and reject connections from other devices. The port that it should listen to, if it’s TCP or UDP, what port it should reply back on. So these are the parameters to get it set up on your SCADA network. You can also enable unsolicited report by exception. And once this has been configured, then the Seeker or Guardian or Tensor or Bolt are now available for polling through DNP3 by a SCADA master.
Dual Duty: PQ Recording and SCADA Participation
Now, they’re still power quality recorders. This doesn’t interfere with its power quality recording. So you can still go to the field, download it through USB or a local connection or with Wi-Fi to get the full PQ data into ProVision. But you can also still have it stream PQ data to the cloud. You can have it in parallel with the participation in your SCADA system. Use it with PQ Canvas to get power quality information remotely.
Now, of course, if it’s in your SCADA system, there may be some cybersecurity issues with having it go to two different places, so we can set that up if you want these in your private network. And you also want PQ data to stream to the cloud, that may involve a tunnel that restricts ports. But you may just want the device in your SCADA system in your private network, in which case you can still locally download the PQ information through USB, so you can use it for dual duty if you’re sending data through DNP3, but also making a full PQ quality recording while it’s doing that.
So, for example, if you have a DG site that you trip offline because of high THD, or it takes itself offline, you’ll get notice of that through SCADA, but you can also download the device locally to get waveform captures and very detailed power quality information that’ll give you even more data. Because it’s not really practical to send waveform captures through the SCADA network. So it’s helpful that it’s a power quality recorder in parallel with its operation as a remote PQ RTU.
The DNP3 Point Map Details
Getting into the specifics of the point map, here we have separate points for each channel of voltage and for current, and you can see that each reading has a certain point available. We also have a spreadsheet that you can download to refer to for help in programming. And we also have analog points that are thresholds. This can be used to trigger counters or trigger exception reports in the SCADA system. So you can set highs and lows for voltage, for current, for power, to make sure that you have exception reporting available.
Now, the Seeker actually has a latching relay that you can use. It has two relays that are form C outputs to use the SeekR as part of a control system. Do you wanna send a command through SCADA to have the SeekR switch something off or on, or operate a contactor? The SeekR has that ability through DNP3, so there are points for that also.
And then we have detail points for every measurement type. And for the PQ information, we also have one-second average values for RMS voltage and current phase angle. And we also, from a power quality standpoint, have one cycle of min and maximum values for power quality parameters. So you can also not only get one-second averages, but get one cycle resolution for looking at voltage sags or swells.
Changing Current Range and Circuit Type
You can change the current range and the circuit type through DNP3. You can also do this through the DMU or ProVision, but the Seeker and the Bolt support various current ranges depending on the probe type you use and circuit type, whether it’s a Y or a delta or a two-element Y, that can also be set through the SCADA system.
Again, there is a link in the white paper to download this information as a spreadsheet to make this a bit easier to program. And if you click on that, here is the spreadsheet that you would get. That has the same information in a way that makes it a bit easier to digest rather than that PDF.
TCP vs. UDP for Cell Connections
Now, when you’re using DNP3 through a cell device, we recommend using UDP. The SeekR and the Bolt and the Guardian all support both TCP and UDP. And TCP is the best method for wired connections. If you’re using Ethernet, that’s a great choice for SCADA polling. But if you’re using a cell connection, in our experience, we found that UDP is more reliable than TCP.
We have a white paper on that choice that goes into a lot more detail. But in our experience, the retry strategy that’s required by DNP3 steps on the retry strategy that TCP uses. And so if you have any sort of dropped packets through a cell connection, the TCP algorithm doesn’t mix well with DNP3, and so they kinda step on each other. So UDP is a better protocol choice if you’re using cell connections or wireless connections in general with your SCADA devices.
But the Seeker, the Guardian, the Bolt all support both mechanisms, so you could choose either one. And the Seeker does have an Ethernet port. You can use a hardwired Ethernet with the Seeker if you have local Ethernet available, so you don’t need to use wireless if you don’t wish to.
Wrap-Up and Contact Information
That wraps up the white paper. If you have any questions about using SCADA with any of these devices, just give us a call anytime, 1-800-296-4120, or send an email to support@powermonitors.com, and we’d be happy to walk you through in more detail how to get a device set up or talk through how the Seeker, the Bolt, or the Guardian may be useful for adding power quality information to your SCADA system, especially if you’re gonna have that feed into something upstream of SCADA, either a PI or an ADMS or a DERMS system. Everyone, thanks for attending. Have a great day.