1. A station building power supply device that converts
regenerative power generated by a regenerative brake of a
direct current (DC)-fed train, into alternating current
5 (AC) power, and supplies the AC power to a station load side, the device comprising:
a first circuit breaker to disconnect a connection with the DC-fed train side;
a second circuit breaker to disconnect a connection 10 with the station load side;
a power converter disposed between the first circuit breaker and the second circuit breaker to convert the regenerative power into the AC power;
a housing to house the first circuit breaker, the 15 power converter, and the second circuit breaker;
a charged-state detection unit to detect a charged state of the housing; and
a control unit to control operations of the first circuit breaker, of the power converter, and of the second 20 circuit breaker based on a detection result from the charged-state detection unit.
2. The station building power supply device according to
claim 1, wherein the control unit controls the operations
25 of the first circuit breaker, of the power converter, and
of the second circuit breaker based on the detection result from the charged-state detection unit following a determination that the housing is in a charged state.
30 3. The station building power supply device according to claim 2,
wherein
the charged-state detection unit includes a voltage

sensor to detect a voltage value between the housing and a railway track on which the DC-fed train runs, and
in a case in which the voltage value detected in the charged-state detection unit is greater than a voltage 5 threshold, and a predetermined time period has elapsed since the voltage value has continuously exceeded the voltage threshold, the control unit determines that the housing is in a charged state.
10 4. The station building power supply device according to claim 2,
wherein
the charged-state detection unit includes a current relay to turn on when a current flowing between the housing 15 and a railway track on which the DC-fed train runs exceeds a current threshold, and
in a case in which a predetermined time period has elapsed since the current relay has continuously turned on in the charged-state detection unit, the control unit 20 determines that the housing is in a charged state.
5. The station building power supply device according to claim 2,
wherein
25 the charged-state detection unit includes a current sensor to detect a current value of a current flowing between the housing and a railway track on which the DC-fed train runs, and
in a case in which the current value detected in the
30 charged-state detection unit is greater than a current threshold, and a predetermined time period has elapsed since the current value has continuously exceeded the current threshold, the control unit determines that the

housing is in a charged state.
6. The station building power supply device according to
claim 2, wherein following the determination that the
5 housing is in a charged state, the control unit disconnects the connection with the DC-fed train side by means of the first circuit breaker, disconnects the connection with the station load side by means of the second circuit breaker, and stops an operation of the power converter. 10
7. The station building power supply device according to
claim 2, comprising:
a display unit to display a charge status of the housing, 15 wherein
following the determination that the housing is in a charged state, the control unit causes the display unit to indicate that the housing is in a charged state.
20 8. The station building power supply device according to claim 3, comprising:
a display unit to display a charge status of the housing,
wherein 25 the voltage threshold is used as a first voltage
threshold, and a voltage threshold lower than the first voltage threshold is used as a second voltage threshold, and
in a case in which the voltage value detected in the 30 charged-state detection unit is less than or equal to the first voltage threshold, but is greater than the second voltage threshold, and a predetermined time period has elapsed since the voltage value has continuously exceeded

the second voltage threshold, the control unit determines that the housing may afterward change to a charged state, and causes the display unit to indicate that the housing may afterward change to a charged state. 5
9. The station building power supply device according to claim 5, comprising:
a display unit to display a charge status of the housing,
10 wherein
the current threshold is used as a first current threshold, and a current threshold lower than the first current threshold is used as a second current threshold, and
15 in a case in which the current value detected in the charged-state detection unit is less than or equal to the first current threshold, but is greater than the second current threshold, and at least a predetermined time period has elapsed since the current value has continuously
20 exceeded the second current threshold, the control unit determines that the housing may afterward change to a charged state, and causes the display unit to indicate that the housing may afterward change to a charged state.
25 10. A charged-state detection method in a station building power supply device including a first circuit breaker to disconnect a connection with a direct current (DC)-fed train side, a second circuit breaker to disconnect a connection with a station load side, a power converter
30 disposed between the first circuit breaker and the second circuit breaker to convert regenerative power into alternating current (AC) power, and a housing to house the first circuit breaker, the power converter, and the second

circuit breaker, the method comprising:
a charged-state detection step of detecting a charged state of the housing by a charged-state detection unit; and
a control step, performed by a control unit, of 5 disconnecting the connection with the DC-fed train side by means of the first circuit breaker, disconnecting the connection with the station load side by means of the second circuit breaker, and stopping an operation of the power converter in a case in which the control unit 10 determines that the housing is in a charged state based on a detection result from the charged-state detection unit.