Electric storage device control method, electric storage device control device, and electric storage device control system

PROBLEM: To provide an electric storage device control method in which a discharge can be performed as an electric power assist by a simple system. MEANS FOR SOLVING: The electric storage device control method for controlling an electric storage device that supplies an electric energy stored in the electric storage device to a driving circuit of a load in addition to an electric power of an AC power system, includes the steps of: measuring a value of electric power supplied from the AC power system to the driving circuit; acquiring a waveform of a supply electric power supplied from the AC power system to the driving circuit; storing a regenerative energy from the driving circuit or a peak assist energy, which assists a peak electric power to the load, from the AC power system in the electric storage device; calculating an electric poweer threshold, at which a peak assist discharge from the electric storage device is started, based on the waveform of the supply electric power and the stored peak assist energy; and starting the peak assist discharge from the electric storage device when the measured electric power is greater than the electric power threshold.