Hydromechanics of variable speed turbines

The increased use of wind-driven generators in the last few years has resulted in special generator designs which ope):ate at varying speed and frequency, utilising static inverters for conversion of direct to alternating current. The potential application of this emerging technology to hydropower production schemes has recently received considerable attention, as witnessed, for example,by the recent DOE-EPRI (1983) workshop on applications of variable-speed generators in hydropower. Typically, a variable speed hydroelectric scheme would consist essentially of the turbine, a synchronous generator (variable speed and frequency), a rectifier for the generator output, an inverter at the powerhouse and alternating current transmission, or direct current transmission, and an inverter at the substation.. Regardless of the speed variations, the inverters have the ability to maintain virtually constant frequency and voltage for any given load.