There are a large number of chain power supply networks existing in power system

where the regional automatic input device of backup power supply is widely used due to its advantage of quickly restoring power when the power supply fails. The principle and operation logic differences of regionalautomatic input device of backup power supply are analyzed

and the major risks and the corresponding control measures are pointed out for installation and commissioning

setting calculation and maintenance. Two extra logic criteria are also introduced

that is

the switch position of this side and the voltage of the other side of tie line

which can effectively avoid the possible malfunction behavior in the case of lightload and busbar PT breaking in substation. Finally

combined with the 110 kV Caochi-Shiliba chain power network

the RTDS simulation system is built. The simulation tests are carried out under different cases such as power supply point

tie line failure

switch trip without fault and busbar PT breaking. The results show that the regional automatic input device of backup power supply can locate the fault point accurately

switch to the backup power supply and restore power quickly

and optimize the busbar voltage loss criterion to avoid the malfunction behavior

which will improve the power supply reliability of chain power network.