Virtual inertia Ancillary service 1 Battery energy storage 1 Battery storage 1 Controllers 1 Costs 1 Distributed Energy Resources 1 Electric batteries 1 Electric inverters 1 Energy resources 1 Fast frequency measurement 1 Fast frequency regulation 1 Frequency measurements 1 Frequency regulations 1 Hardware-in-the-loop simulation 1 Legacy resource 1 Microgrid 1 Particle swarm optimization 1 Photovoltaic generator 1 Power hardware in the loops 1 Synthetic apertures 1 System stability 1 Virtual synchronous generator 1 ancillary services 1 distributed energy resources 1 fast frequency measurement 1 fast frequency regulation 1 legacy resources 1 microgrids 1 power hardware-in-the-loop 1