The embodiment of the present application provides a power control method, device, controller, and system for a photovoltaic power plant, and a medium. The method comprises: obtaining the real-time frequency of a power grid; determining the virtual inertia value and the virtual damping control characteristic value of the photovoltaic power station when the fluctuation of the real-time frequency ofthe power grid reaches a preset condition; determining the active power instruction value of the primary frequency modulation the photovoltaic power plant according to the virtual inertia value and the virtual damping control characteristic value; according to the active power instruction value of the primary frequency modulation and a preset individual active power allocation strategy, allocating and issuing an individual active power instruction value to each individual power controller of the photovoltaic power plant. The method can realize the power coordinated control of the whole fieldso as to provide consistency for the operation of photovoltaic inverters in the whole field, thereby greatly improving the permeability of a wind turbine in the power grid, improving system stability,and improving the grid-connected adaptability of photovoltaic power generation.