Method for controlling an installation for converting hydraulic energy into electrical energy comprising a hydraulic machine operated in turbine mode, said hydraulic machine being linked to a generator by a shaft, the installation comprising first connection means connecting a static frequency converter and the generator, second connection means connecting the static frequency converter and the grid, and third connection means connecting the generator and the grid, said method comprising the steps of: detecting partial load operation of the hydraulic machine; and upon detection of partial load operation, switching first connection means and second connection means to a conducting state, switching third connection means to a nonconducting state, commanding the static frequency converter to reduce the rotation speed of the hydraulic machine, wherein it is determined that the hydraulic machine is operating in partial load operation - by measuring a mechanical strain in the hydraulic machine with a measuring device and/or - by measuring a pressure in the gap between the guide vanes and the runner of the hydraulic machine and/or - by detecting that an amplitude of acoustic noise in the hydraulic machine is greater than a predetermined threshold and/or - by detecting that an amplitude of hydraulic couple fluctuations on the output shaft of the hydraulic machine is greater than a predetermined threshold and/or - by detecting that an amplitude of radial hydraulic thrust of the hydraulic machine is greater than a predetermined threshold. detecting partial load operation of the hydraulic machine; and upon detection of partial load operation, switching first connection means and second connection means to a conducting state, switching third connection means to a nonconducting state, commanding the static frequency converter to reduce the rotation speed of the hydraulic machine, wherein it is determined that the hydraulic machine is operating in partial load operation - by measuring a mechanical strain in the hydraulic machine with a measuring device and/or - by measuring a pressure in the gap between the guide vanes and the runner of the hydraulic machine and/or - by detecting that an amplitude of acoustic noise in the hydraulic machine is greater than a predetermined threshold and/or - by detecting that an amplitude of hydraulic couple fluctuations on the output shaft of the hydraulic machine is greater than a predetermined threshold and/or - by detecting that an amplitude of radial hydraulic thrust of the hydraulic machine is greater than a predetermined threshold. - by measuring a mechanical strain in the hydraulic machine with a measuring device and/or - by measuring a pressure in the gap between the guide vanes and the runner of the hydraulic machine and/or - by detecting that an amplitude of acoustic noise in the hydraulic machine is greater than a predetermined threshold and/or - by detecting that an amplitude of hydraulic couple fluctuations on the output shaft of the hydraulic machine is greater than a predetermined threshold and/or - by detecting that an amplitude of radial hydraulic thrust of the hydraulic machine is greater than a predetermined threshold.