You can create virtual inertia for any renewable energy source.  With a wind generator this can be achieved with a double fed induction generator configuration.  For a PV source virtual inertia can be programmed into the inverter control logic.,(reply>), @Michael Harrison If you have a PV power plant with a grid-tie inverter without energy storage that is operating at maximum possible power at that moment, you don't have any reserve power to emulate inertia from. Energy storage is needed to provide additional power when it is needed or the power plant has to operate in a deloading mode by varying virtual resistance, like you said. <br><br>My point is that it really is easy to emulate inertia with additional control for the inverter but you need some reserve power to emulate inertia with this inverter. I hope we understand each other now.,(reply>), @đeri662 <br><br>The part I disagree with is that it is impossible to emulate inertia in a PV inverter or other renewable resource.  There are currently legislative issues surrounding the use of such ancillary functions, but legislation is something that can be and is being changed.  Technically it is quite simple to emulate inertia in the inverter control.  Inertia just looks like a resistance for the inverter frequency to be varied.,(reply>), @Michael Harrison Which part of my comment do you disagree with? I'm doing research work on frequency stability support options with asynchronously (via converter) connected renewables.,(reply>), @đeri662 <br><br>I care to disagree.  I have significant experience designing this type of control system.,(reply>), It is impossible for a PV source to emulate inertia on its own, it needs some kind of an energy storage. Synthetic inertia from wind turbines also depends greatly on the current wind speeds (rotational speed according to the MPPT) , there is also a problem with the so-called second frequency dip (because of lower output from wind turbines after the frequency support period due to being off the MPP curve). Maybe deloading can be a better choice but off course, we are wasting clean energy this way. I believe deloading is required by various TSOs and synthetic inertia is required by the Hydro-Québec TSO.