In line with Power Grid Safety and Stability, how is it possible that Power Swings affect Distance Relays? If so, what remedies are to be taken?

the impedance measured during the power swing varies and give tripping to distance protection relay, in distance relays to block the tripping due to power swing a delay timer is used.

Power swings are large disturbances in the power system like fluctuations. That if not remedied could cause a wrong operation of a distance relay or impedance relay. Which will have a undesirable tripping in the system that supposed not to have.  One of the remedies is by means of the settings which depends on the ratio of voltage & current. Second is by the use of delay timer with respect to zoning. Third as I know is the use of Power Swing Block Protection which can differentiate between power swings & power faults.

Obviously the power swings affect the distance relays, the impedance measured during the power swings changes and may enter the tripping characteristics of zone 3 , zone 2 or even zone 1 (in case of severe power swing), a feature is added in distance relays to block the tripping when due to power swings, impedance locus passes through zone 3 or zone 2 so that the system may adjust to new rotor angle following the faults in the system.