How can renewable energy plants provide frequency support to the grid?

Frequency support options: Fast frequency response (FFR - rapid power change within seconds, using headroom or storage), Synthetic/virtual inertia (emulate rotating machine inertia response, requires derivative of frequency), Primary frequency response (droop-based power change proportional to frequency deviation), and Secondary response (slower, restore frequency to nominal). Implementation: wind uses kinetic energy (briefly increase torque, causes rotor deceleration), solar uses headroom (operate below MPP) or battery, and storage provides symmetric response. Grid-forming inverters inherently provide inertial response. Control must balance grid support with turbine/panel stress and energy harvest.