The requirements imposed on the excitation systems of synchronous generators are determined by NEC (National Electrical Code);  OSHA (Occupational Safety and Health Administration) standards;

GOST 21558-76 and technical specifications (TS) for a specific excitation system.

Below are the main requirements imposed on modern excitation systems.

3.1 General requirements

The excitation system must ensure all possible operating modes of the generators: initial excitation, no-load operation, and load operation, providing the necessary overloads, excitation forcing, and de-excitation. If the generator is disconnected from the grid, the excitation system must ensure, if necessary, the fastest connection of the generator to the grid.

AVR (Automatic Voltage Regulators) must maintain a given voltage level on the busses of the synchronous machine or on the station busses,  damp oscillations of synchronous machines in post-fault modes, and increase the static and dynamic stability of synchronous machines.

AVR of synchronous generators must increase the transfer capacity and operational stability of power transmissions by maintaining constant voltage on the generator busses and varying its reactive power.