Using the hydraulic synchronous machine, various operating modes are available. These modes are valid for both the hydraulic and thermal models since they mainly concern the generic parts (generator- excitation):
| Generating Mode: | This is the most common mode. Positive mechanical torque is applied to the shaft of the machine, thereby inducing its rotation. This mechanical torque originates from a hydraulic or thermal turbine. The generator offers an equivalent electrical torque, but of opposite sign, thereby providing electric power to the network. Any imbalance between the electrical and mechanical couple translates into a speed variation of the turbine generator. The excitation circuit is used to regulate the output voltage of the machine and the speed regulator to control the water or steam input (thermal or hydraulic), thus ensuring a balance between the mechanical and the electrical couple. |
| Synchronous Compensator Mode: | Any turbine generator can be used in the synchronous compensator mode by removing the turbine (hydraulic or thermal) and using the machine with no load. By adjusting the excitation circuit, it is possible to control the network voltage and to provide or absorb the required reactive power. |
| Synchronous Motor Mode: | The same machine can also be used as a motor, in other words with a reverse mechanical couple, allowing, for example, to pump water upstream to the dam. |
| Type 1 Machine Mode: | In some cases, stability programs require a “Type 1" machine or a constant voltage source behind an impedance, but with a frequency varying as a true machine. Such behavior can also be emulated. |