A dispersed power supply system, comprising, a power conditioner configured to control an output of a power supply apparatus; a current sensor electrically connected to the power conditioner; another power conditioner configured to control an output of another power supply apparatus; and another current sensor electrically connected to the another power conditioner, wherein the current sensor and the another current sensor are installed on a position of a grid from a branch point to which each power conditioner is connected, and where power from the grid is detected as the same forward power flow; and when a forward power flow threshold for preventing a reverse power flow of the power conditioner is lower than another forward power flow threshold for preventing a reverse power flow of the another power conditioner, the power conditioner being characterized in that it is configured to: control the output of the power supply apparatus to adjust the forward power flow that is higher than the forward power flow threshold to the forward power flow threshold; and increase the forward power flow threshold when the forward power flow is higher than the forward power flow threshold and in response to the power conditioner detecting, based on a periodicity of change of the forward power flow, that the another power conditioner is controlling the output of the another power supply apparatus based on the another forward power flow threshold. a power conditioner configured to control an output of a power supply apparatus; a current sensor electrically connected to the power conditioner; another power conditioner configured to control an output of another power supply apparatus; and another current sensor electrically connected to the another power conditioner, wherein the current sensor and the another current sensor are installed on a position of a grid from a branch point to which each power conditioner is connected, and where power from the grid is detected as the same forward power flow; and when a forward power flow threshold for preventing a reverse power flow of the power conditioner is lower than another forward power flow threshold for preventing a reverse power flow of the another power conditioner, the power conditioner being characterized in that it is configured to: control the output of the power supply apparatus to adjust the forward power flow that is higher than the forward power flow threshold to the forward power flow threshold; and increase the forward power flow threshold when the forward power flow is higher than the forward power flow threshold and in response to the power conditioner detecting, based on a periodicity of change of the forward power flow, that the another power conditioner is controlling the output of the another power supply apparatus based on the another forward power flow threshold. control the output of the power supply apparatus to adjust the forward power flow that is higher than the forward power flow threshold to the forward power flow threshold; and increase the forward power flow threshold when the forward power flow is higher than the forward power flow threshold and in response to the power conditioner detecting, based on a periodicity of change of the forward power flow, that the another power conditioner is controlling the output of the another power supply apparatus based on the another forward power flow threshold.