Hydropower plant for controlling grid frequency and method of operating same

A hydropower plant for regulating the frequency of an electric grid, the hydropower plant comprising:

• an upper water reservoir and a lower water reservoir, wherein a water level of the upper water reservoir lies above a water level of the lower water reservoir;
• a waterway connecting the upper water reservoir with the lower water reservoir;
• a turbine arranged in the waterway, the turbine including a runner, a guide vane apparatus and a device for blowing out a runner space;
• an electric double-fed asynchronous machine mechanically connected to the turbine, the double-fed asynchronous machine including a rotor and a stator;
• a frequency converter electrically connected to the rotor of the double-fed asynchronous machine, the frequency converter having a DC intermediate circuit;
• a mains transformer electrically connected to the frequency converter, to the stator of the double-fed asynchronous machine and to the mains grid;
• a resistor arranged in the DC intermediate circuit of the frequency converter and configured to connect line sections of the DC intermediate circuit to one another;
• and
• a device for cooling the resistor.