Patent ID: 7075274

Claim:
A reactive power compensator comprising: an electric power converting circuit connected to an alternating-current power system and a direct current power source circuit, converting direct current voltage from the direct current power source circuit to an alternating voltage by switching, and supplying the alternating voltage to the alternating-current power system; alternating voltage detecting means for outputting an alternating voltage detecting signal representing the alternating voltage in the alternating-current power system; alternating electric current detecting means for outputting an alternating electric current detecting signal representing an alternating electric current in the alternating-current power system; control command means for receiving an electric current command signal and outputting an alternating voltage command signal in accordance with the electric current command signal, the alternating voltage detecting signal, and the alternating electric current detecting signal; alternating voltage control means for controlling the switching of said electric power converting circuit in accordance with the alternating voltage command signal; changing amount detecting means for outputting a changing amount representing a change of an alternating current electric amount of one of the alternating voltage and the alternating electric current in the alternating-current power system based on the alternating current electric amount; and limiting means for limiting the electric current command signal, wherein said limiting means limits the electric current command signal based on the changing amount.