Solar + BESS on a VFD-heavy plant: interlock it or chase alarms

We dropped 2 MW of PV and a 3 MWh BESS onto a solvents plant. Week one the HMI lit up like a pinball machine: VFD DC-bus overvoltage, air compressor trips, tap-changer hunting, relays chattering. Variable sun plus an overzealous peak-shave controller swinging MWs in seconds. Well, there’s your problem.

Lesson learned: if your inverter plant can move faster than your process, you’ll ping-pong. Interlock it. Set PV/BESS ramp limits tied to process states, not just grid signals. Deadbands big enough to beat sensor noise and cloud flicker. Freeze peak-shave during batch transitions and compressor load/unload cycles. Hysteresis on charge/discharge so you don’t see-saw. Coordinate protection assuming low, short-lived inverter fault current. Keep THD in check or your touchy VFDs will prove a point at 2 a.m.

Also, test black start for real. Grid-following PV is a passenger until something forms the bus. Sequence: genset forms, BESS follows, PV last. Verify IEEE 1547 ride-through, log PQ at 10 ms, and stop trusting vendor defaults.

What ramp rates, deadbands, and permissives are you using to keep PV/BESS from whipsawing VFD-heavy plants? Any grid-forming stacks you actually trust?