February 7, 2018 Andrew Roscoe has joined the BSI committee GEL/8 ‘Systems Aspects for Electrical Energy Supply’ and the mirror committee CENELEC TC8X committee ‘System aspects of electrical energy supply’. In particular, he has joined the new working group WG7 ‘Power frequency measurement for DER management’. This WG 7 is expected to prepare a TS on ‘Requirements for power frequency measurement for distributed energy resources (DER) to be connected to electrical energy supply systems’. A big challenge initially is simply to produce a suitable definition of frequency in single-phase and three phase power systems, since no existing definitions seem to be robust enough, or suitable for power networks with highly dynamic conditions. This challenge has been taken up by the EMPIR ROCOF project team.