Basic generator control loops

 

Basic generator control loops

•        In an interconnected power system , LFC (Load frequency control) and AVR (Automatic voltage regulator) equipment's are installed for each generator. ( in fig LFC and AVR loops are shown).

•        Controllers are set for a particular operating condition and take care of small changes in load demand to maintain frequency and voltage within the specified limits.

•        Small change in real power depend on rotar angle delta and thus frequency.

•        The reactive is mainly dependent on voltage magnitude (i.e , on generator excitation).

•        The excitation system time constant is much smaller than the prime mover time constant and its transient decay much faster and does not affect the LFC dynamics. Therefor cross-coupling between LFC loop and AVR loop is negligible. And the load frequency and excitation voltage control are analyzed independently.