Converter station AC filter phase selection opening and closing state monitoring system and method

The invention discloses a converter station AC filter phase selection opening and closing state monitoring system and method, and relates to the field of power monitoring. The system comprises a firstcollection unit, a second collection unit, a third collection unit, a first monitoring processing unit, a second monitoring processing unit, a third monitoring processing unit, and an alarm output unit. The method conforms to any one or more of the following criteria, an alarm signal is outputted, and the first criterion is that a certain phase differential current in three-phase differential currents of an alternating current filter is greater than a set differential current alarm threshold value; the second criterion is that the time difference between the current starting moment and the voltage zero-crossing moment of the phase-selection switching-off and switching-on device is greater than a set time difference alarm threshold value; and the third criterion is that when the selected reference voltage is diffe