A method and a control system adapted to control a power conversion system connected to an AC power grid, wherein the control system is adapted to receive an externally provided reactive power reference and the control system includes a controller adapted to control the reactive power fed to the AC grid by the power conversion system and to produce a reactive current reference, an active current reference, a total current limiter for producing limited active and reactive current references. The total current limiter operates in reactive current priority limiting the active current reference. Further including means adapted to produce a capacity signal indicating the current capacity of the power conversion system. The control system further includes a minimum reactive power reference tracker adapted to generate an internally generated reactive power reference which is adapted to be fed to the controller adapted to control the reactive power fed by the power conversion system to the AC grid, where the minimum reactive power reference tracker is adapted to control the internally generated reactive power reference to a value with which the active current reference is not limited.