Q8Power System 2

Automatic voltage control in a power system refers to the closed-loop control system, most centrally implemented through the Automatic Voltage Regulator (AVR) fitted to each synchronous generator's excitation system, which continuously senses the generator's terminal voltage, compares it against a desired reference setpoint, and automatically adjusts the field (excitation) current supplied to the generator's rotor winding to correct any detected voltage error, thereby maintaining terminal voltage close to its scheduled value despite ongoing variations in load demand and reactive power flow. Automatic voltage control operates on a much faster timescale than economic dispatch or automatic generation control (which govern real power/frequency), and is essential for maintaining acceptable voltage profiles throughout the network, supporting reactive power balance, and improving both steady-state and transient stability margins of the overall power system.