PQM (Power Quality Meter)
A meter that continuously measures voltage and current quality parameters — harmonics, flicker, THD, voltage unbalance, and transients — at the point of connection. Grid codes typically require IEC 61000-4-30 Class A certified PQMs to verify that a BESS plant does not degrade supply quality on the connected network.
In energy storage
PQMs are typically installed at or near the point of connection and run continuously, logging power quality data that the TSO or DSO can request at any time. If harmonic distortion or flicker levels exceed grid code limits — often caused by PCS switching — the operator must identify and resolve the issue or face curtailment or disconnection.