In recent years, in a DC feeding system, regenerative power generated by a regenerative brake of a train is used as power-running electric power for other trains via an overhead wire. In such a DC feeding system, surplus regenerative power is intermittently generated in a same power transformation zone when the regenerative power exceeds the power-running electric power and it is effectively re-used by a power regenerative inverter installed in a substation.
Meanwhile, such a technique is disclosed in which if supply of commercial frequency power to an AC bus bar of the substation for electric railways is shut off, the operation of the power regenerative inverter is stopped and the power regenerative inverter is operated as a self-exciting inverter; and power supplied from an adjacent DC substation via the DC feeding system is converted to AC power. Accordingly, the emergency power is supplied to station building facilities of a station building via a high-voltage or extra high-voltage distribution system (Patent Literature 1, for example).