A hydroelectric power generation system (20) generates electrical power for an electrical utilization system (72). A controller (42) obtains a requested output electrical power level from a hydro-turbine unit (70) by using a signal indicative of water head (hmeas) to control speed of an asynchrcnous rotary converter (50) coupled to the hydro-turbine unit and to control gate position of the hydro-turbine unit. The requested output electrical power level is applied from the hydro-turbine unit via the rotary converter to the electrical utilization system. In one embodiment, the controller (42B) accesses an updatable memory wherein Hydraulic Hill Chart intormation is stored.; In another embodiment, the controller (42C) also includes a real-time automatic governor which uses a signal indicative of ac transmission frequency to the electrical utilization system to control the output electrical power level of the rotary converter.