In order to study the influence of frequency difference on switching of the high-voltage auxiliary power supplies

firstly

a reduced-order motor model was established in the stator complex coordinate system using space phasor method

and a single motor was taken as an example to derive the change law of the phase angle difference between switching power supplies. Then

the PSCAD/EMTDC was used to establish a switching system model for simulation research

which demonstrated the feasibility of the high-voltage auxiliary power supply switching technology under large frequency differences and drew a preliminary conclusion on the influence of the frequency difference on the switching mode. Finally

the auxiliary power source system working under isolated network variable frequency operation condition was taken as the test object

a field switching test of auxiliary power with load under large frequency difference was carried out to verify the above conclusions. The results show that

within a certain frequency difference range

the greater the frequency difference

the faster the simultaneous capture and switching

and the more severe the fluctuation of the factory bus voltage during the transition process. Therefore

it is feasible to switch high-voltage auxiliary power under large frequency differences

but the safe frequency difference threshold should be determined through experiments to ensure the safety of auxiliary power.