Ride-Through Testing: What the Grid Simulator Has to Do, Not Just Reach
Grid & inverters · 4 min read · 24 cited facts
A specification sheet will tell you whether a source can reach 1.20 pu. It will not tell you whether it can drive a ride-through profile, because a profile is not a level — it is a shaped trajectory through voltage and time, executed against a device that is feeding power back the whole way. IEEE 1547-2018's Category III envelope keeps an inverter connected from 0.88 pu down to 0.50 pu in the mandatory region; the simulator's job is to take a live, exporting DUT into that region on a defined edge, hold it there for a defined dwell, and bring it back out without adding events the standard did not ask for.
The conformance framework — which tests exist, and which document the certificate will actually name — is covered elsewhere on this site. This piece is about the instrument.
A trajectory, not a set point
Ride-through and trip requirements are timed at both extremes. The fast end is the 0.16 s window on the OV2 trip at 1.20 pu; the slow end is 300 s dwells in the frequency-trip schedule. One profile can contain both, so the source needs sub-cycle event timing and the patience to hold a depressed operating point for minutes — in the same programmed sequence, with the transitions themselves under control. Drop voltage, recovery voltage, rise time and drop time have to be programme parameters, not side effects of the amplifier.
| Parameter | Value | Clause |
|---|---|---|
| Ride-through Cat III | continuous 0.88–1.10 pu; mandatory 0.50–0.88 pu; cease >1.20 pu | IEEE 1547-2018 |
| Frequency trip | 62.0 Hz/0.16 s; 61.2 Hz/300 s; 58.5 Hz/300 s; 56.5 Hz/0.16 s | IEEE 1547-2018 |
Frequency ride-through adds a rate: 3.0 Hz/s for Category III, per Table 21 of IEEE 1547-2018. A rate is a harder ask than an end point for the same reason a profile is harder than a level — the simulator has to move frequency continuously and accurately while the DUT stays synchronised to it, not merely arrive at the final value and wait.
The DUT is pushing back the whole time
During a low-voltage ride-through the inverter does not politely stop exporting. Current keeps coming, and the simulator must absorb it while holding the sagged voltage stiff — a supply that can only source gets pushed off its own profile by the device it is supposed to be testing. That is what four-quadrant regenerative architecture is for, and it also settles where the energy goes: the PAS-F returns up to 92% of what it absorbs to the facility grid rather than dissipating it, which matters at 200 kVA in a way it never does at bench scale.
The figures that decide it
- Output 0–300.0 V L-N, three-phase, with independent per-phase voltage and phase-angle setting for unbalanced events
- Frequency 45–65 Hz standard, 40–70 Hz as an option — the trip schedule's extremes at 56.5 Hz and 62.0 Hz sit well inside it
- Response time ≤2 ms, voltage resolution 0.1 V with accuracy 0.15% F.S. + 4 counts, frequency accuracy ±0.1% F.S. — the figures that place an envelope boundary rather than approximate it
- Built-in LVRT and HVRT simulation with programmable drop voltage, recovery voltage, rise time and drop time, plus step and gradual sequence memories
- 45 kVA to 1.6 MVA, sourcing and sinking up to 277.8 A RMS per phase at the 200 kVA rating
Where this instrument is the wrong answer: the PAS-F is a 50/60 Hz-class grid simulator. It does not reach 400 Hz aviation buses, and harmonic-immunity synthesis under IEC 61000-4-13 is a different specification conversation entirely. But if the programme is ride-through and trip conformance against a live inverter, a shaped trajectory held by a source that also sinks is the shape of instrument the profile demands.
Scoping a ride-through bench?
Send us the ride-through categories and the inverter's rating. We will size source and sink together, and say plainly if the profile needs more instrument than the budget expected.
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