A wind power generation system (10, 110) comprising: a power generator body that generates first AC power from wind power; an auxiliary device (13, 14) that assists the power generator body; and a power conversion apparatus that converts the first AC power from the power generator body to second AC power, and outputs the second AC power to an electric power grid, wherein the power conversion apparatus includes a first power conversion circuit that converts the first AC power to DC power, and a second power conversion circuit that converts the DC power resulting from conversion at the first power conversion circuit to the second AC power, characterized in that the power conversion apparatus further includes a breaker that is provided between the second power conversion circuit and the electric power grid, and a control unit that controls the second power conversion circuit and the breaker, and the wind power generation system (10, 110) further comprises a power storage element (33, 133) that stores power by receiving the DC power from the first power conversion circuit via a first passing point provided between the first power conversion circuit and the second power conversion circuit, wherein when the power generator body is generating power, the control unit brings the breaker into conduction so as to set a grid-connected operation mode in which the second power conversion circuit cooperates with the electric power grid, and controls the second power conversion circuit to convert the DC power from the first power conversion circuit to the second AC power during the grid-connected operation mode, when the power generator body is in a power generation standby state which is a time period of being on standby for power generation, the control unit shuts off the breaker so as to set a parallel-off mode in which the second power conversion circuit is disconnected from the electric power grid, and controls the second power conversion circuit to convert power of the power storage element (33, 133) received by the second power conversion circuit via the first passing point, to a third AC power having a preset voltage, and the auxiliary device (13, 14) is configured to receive the second AC power or the third AC power outputted from the second power conversion circuit via a second passing point provided between the second power conversion circuit and the breaker. a power generator body that generates first AC power from wind power; an auxiliary device (13, 14) that assists the power generator body; and a power conversion apparatus that converts the first AC power from the power generator body to second AC power, and outputs the second AC power to an electric power grid, wherein the power conversion apparatus includes a first power conversion circuit that converts the first AC power to DC power, and a second power conversion circuit that converts the DC power resulting from conversion at the first power conversion circuit to the second AC power, a first power conversion circuit that converts the first AC power to DC power, and a second power conversion circuit that converts the DC power resulting from conversion at the first power conversion circuit to the second AC power, characterized in that the power conversion apparatus further includes a breaker that is provided between the second power conversion circuit and the electric power grid, and a control unit that controls the second power conversion circuit and the breaker, and a breaker that is provided between the second power conversion circuit and the electric power grid, and a control unit that controls the second power conversion circuit and the breaker, and the wind power generation system (10, 110) further comprises a power storage element (33, 133) that stores power by receiving the DC power from the first power conversion circuit via a first passing point provided between the first power conversion circuit and the second power conversion circuit, wherein when the power generator body is generating power, the control unit brings the breaker into conduction so as to set a grid-connected operation mode in which the second power conversion circuit cooperates with the electric power grid, and controls the second power conversion circuit to convert the DC power from the first power conversion circuit to the second AC power during the grid-connected operation mode, when the power generator body is in a power generation standby state which is a time period of being on standby for power generation, the control unit shuts off the breaker so as to set a parallel-off mode in which the second power conversion circuit is disconnected from the electric power grid, and controls the second power conversion circuit to convert power of the power storage element (33, 133) received by the second power conversion circuit via the first passing point, to a third AC power having a preset voltage, and the auxiliary device (13, 14) is configured to receive the second AC power or the third AC power outputted from the second power conversion circuit via a second passing point provided between the second power conversion circuit and the breaker.