Frequency-dependent power-system static-load characteristics

The importance of power-system load characteristics under transient conditions has been stressed in the literature, but little information is available, particularly regarding frequency dependence. General conditions regarding the behaviour of active- and reactive-load components with frequency are investigated in relation to their effects in producing positive and negative damping in a system. The importance of reactive-power variation with series and shunt compensation by capacitors and reactors is discussed. Frequency-dependent response of various passive loads usually met in practice is presented along with an illustrative 4-machine example involving such loads. The information can serve as a guide in determining the behaviour of loads under transient conditions, and subsequently can assist in giving more accurate assessment of power-system behaviour.