Testing a grid-tied inverter properly means more than supplying clean DC to its input — it means recreating the grid disturbances the inverter has to survive once it's installed: voltage sags, frequency excursions, and the ride-through events that compliance standards specifically test for. A standard AC source can simulate steady-state grid conditions, but it can't absorb the power an inverter pushes back onto it during a ride-through test. That's what Preen's PAS/PFV regenerative grid simulator series is built to do.
What a Regenerative Grid Simulator Does Differently
Both series operate as four-quadrant systems with energy feedback, meaning they don't just source power to a DUT — they can absorb power the DUT pushes back, at greater than 90% efficiency, rather than dumping it as heat through a resistive load bank. That capability is what makes them suitable as the grid-side element in inverter test setups: a PV inverter under test pushes real power onto the simulated grid exactly as it would onto a real one, and the simulator recovers that energy rather than wasting it.
Output covers 0-300V (line-to-neutral) at a standard frequency range of 45-65Hz, with an optional 40-70Hz range for wider-margin compliance testing. Built-in low-voltage and high-voltage ride-through (LVRT/HVRT) capability is standard, following IEEE-1547 and BDEW ride-through profiles — the specific test curves inverter compliance programs are built around.
PAS vs PFV: Choosing the Right Series
The two series share the same regenerative four-quadrant architecture but differ on scale and ride-through capability, which is the detail that decides which one a given test program actually needs.
| Attribute | PAS Series | PFV Series |
|---|---|---|
| Power Range | Up to 2000kVA | Up to 400kVA |
| Source and Sink | Both (regenerative) | Source only |
| Voltage Ride-Through (LVRT/HVRT) | Yes | No |
| Efficiency | >90% | >90% |
In short: PAS is the series to specify whenever ride-through compliance testing or very high power inverter testing (up to 2000kVA) is on the requirement list. PFV covers applications where a source-only regenerative grid simulator at a more moderate power level (up to 400kVA) meets the need without the added cost of ride-through capability the test program doesn't require.
LVRT/HVRT and Grid Compliance Testing
Ride-through testing exists because grid codes in most markets now require inverters to stay connected and ride through brief voltage sags or swells rather than tripping offline at the first sign of disturbance — a single nuisance trip across many distributed inverters can itself destabilise the grid it's meant to support. IEEE-1547 and BDEW define the specific voltage-vs-time profiles an inverter has to survive without disconnecting, and PAS series units generate those profiles directly, on demand, as part of a repeatable compliance test sequence rather than relying on live grid events that can't be scheduled or reproduced.
A Typical PV Inverter Test Configuration
In a standard test bench configuration, a Preen ADG+ series programmable DC supply emulates the PV array on the inverter's DC input side, while the PAS or PFV series takes the AC output side, standing in for the grid. The inverter under test operates exactly as it would in the field — converting DC to AC and pushing power onto what it treats as a live grid connection — while the PAS/PFV simulator holds that "grid" at whatever steady-state or ride-through condition the test program specifies, and recovers the energy the inverter feeds back rather than dissipating it.