Patent ID: 7514813

Claim:
A power supply system for supplying power to a load, comprising: a plurality of power supply units, the outputs of which are parallelly connected to power transmission lines to the load, each of the power supply units comprising: a generator; an inverter for converting a voltage generated by the generator into an AC voltage and outputting the AC voltage; an inverter control unit for controlling the inverter, comprising a first synchronization controller operable in a linkage operation with an external AC power supply, for detecting a voltage of the external AC power supply to control the inverter so that the AC voltage outputted from the inverter is in phase with the voltage of the external AC power supply; a connection apparatus for connecting the AC voltage outputted from the inverter to power transmission lines; means for generating an autonomous operation detection synchronizing signal; and an autonomous operation detector for detecting, during a predetermined time period from the output timing of the autonomous operation detection synchronizing signal, whether the power supply system is in the autonomous operation in which the system is disconnected from the external AC power supply, whereby all the power supply units in operation can conduct the autonomous operation detection at the same timing; and a multiple power unit controller for controlling the plurality of power supply units to individually start and stop and for controlling output power of the respective power supply units.