Transcript
Supercapacitor Ride-Through Test Overview
Today, we’re testing the supercapacitor ride-through ability of the BOLT. The supercapacitor provides power to the BOLT when AC voltage is lost. The BOLT normally powers itself on channel one AC voltage, and during an interruption or recloser operations, that voltage can go away.
The supercapacitor provides several minutes of runtime for the BOLT during that period, and it’s important to be able to operate for several minutes to catch those recloser events. We are going to test this with a simulated recloser sequence.
Test Setup
We have a three-phase power supply, and phase A, B, and C of the power supply is connected to three input channels of the BOLT. We have an incandescent bulb on channel one, so that you can visibly see what we’re doing with the voltage.
In this scenario, we are simulating a recloser that will operate immediately four, eight cycles, trying to close during a fault. During that fault, it’s a single-phase fault, so the voltage on phase A drops, but the voltage on the other two phases will increase.
Voltage swells happen with type one sags, where fault current flows on phase A and pulls the neutral away from the other two phases. So, the BOLT will record a deep voltage sag on channel one, and also an interruption when the recloser opens, and a voltage swell on the other two phases. Those swells are important for power quality, and so you want to be able to record those cleanly during the sequence.
Recloser Sequence Timing
This recloser sequence is set to reclose immediately, and then another reclose attempt at five seconds, and then 30 seconds, and finally, a long sequence. The last one is three minutes later, where the reclosure will try to, one last time, clear the fault. Then the fault clears in this simulation and power is restored.
Running the Test
So, we are going to give the BOLT a test here to make sure it captures all those events cleanly. I’ll begin the test. You can see when the recloser tries to close again, you’ll see a very dim amount of light from the bulb during that deep voltage sag. We can see from the LEDs, the BOLT is still recording.
This BOLT is actually still connected through WiFi, and it will send alerts during this period to PQ Canvas, and we can check the PQ Canvas recording as soon as this is done to make sure that everything was recorded correctly.
You can check the supercapacitor voltage on the BOLT. I’m actually connected to the BOLT through WiFi during this time. We still have a good amount of charge, 3.7 volts on the supercapacitors at this point. We’ve gone through the reclose operations that are very quick, the immediate one, the five-second and 15-second. Now we’re waiting for the three-minute attempt.
Final Reclose Attempt and Results
Now the recloser has made one final attempt to close, and this time, it was able to clear the fault. The circuit is back in normal operation, and the BOLT has been running this entire time. The supercapacitor dropped down to 3.4 volts, so we still have a little bit of power left in the supercapacitor.
Reviewing Data in PQ Canvas
Now we can check the data in PQ Canvas to make sure that it recorded each of those reclose attempts cleanly, and it also recorded the swells on the other two phases. To do that, I will jump onto PQ Canvas and take a look.
I’ve logged into PQ Canvas, and we’ll take a look at this BOLT’s recording. We’ll look at the interval data. Zoom into this session, and we can see before the test, we were at 120, 120, and 120 on all three phases.
We can see the recloser sequence here, where during the test, phases B and C go up to about 135 volts, while phase A is down here at about 30, 35 volts while the fault current is flowing. We can see the swells on the other two phases, and then interruptions where there is no voltage while the reclosure was actually open, and then at the end, we can see that the voltage was restored in all three phases cleanly.
Supercapacitor Ride-Through Design
The supercapacitor ride-through is designed to be longer than any reclosure sequence that a utility might have, so that the sequence of close, opens, can be captured cleanly, and we can capture not only the deep voltage sags on one phase, but the voltage swells on the other phases.
Email Notifications
In addition, we can see that the BOLT has generated a slew of emails. I have this BOLT configured in PQ Canvas to generate emails for each waveform capture and for low and high voltage conditions. We have several alarm conditions being generated during this sequence of events, and we are getting the notifications in real time as these are happening, since this BOLT is also networked through WiFi.
The supercapacitor has enough power to allow that to happen also, for those alerts to get through during the event itself. So, the BOLT has passed the supercapacitor ride-through test with flying colors.
