Power system, controller and control method

A power system includes: power converters configured to acquire an electrical characteristic value of input power or power to output, control a power conversion characteristic of an output of power based on a reference function in which an electrical characteristic value of an output of power is defined according to an input value by using the acquired electrical characteristic value as an input value, and update a stored reference function to the acquired reference function; a controller configured to set a reference function and output the set reference function to the power converters; and a DC electric line to which the plurality of power converters is connected. The controller is configured to calculate a voltage drop in the electric line from a power target value of an output and a line impedance of the electric line, and set the reference function based on the calculated voltage drop.