DC CONVERTER VALVE STATE DETECTION METHOD BASED ON PORT CURRENT SEQUENCE CHARACTERISTICS

摘要

Provided is a DC converter valve state detection method based on port current sequence characteristics, comprising the following steps: collecting the three-phase AC current on the valve side of a converter of a DC transmission system; taking as a reference value the equal current when two converter valves commutate, a value greater than the reference value being defined as a valve conduction state, a value less than the reference value being defined as a valve closed state; according to the relative relationship between the amplitudes of the three-phase AC current, calculating the time width of each valve conduction state; comparing the time width of the conduction state of the six valves with the time width of the conduction state of the normal operation valve, and according to the result of comparison, determining whether the six valves are in a normal state and locating all abnormal valves. The detection method can reliably detect valve status and locate abnormal valves by means of sequential detection, can be used in actual fault phase discrimination and commutation failure discrimination, and provides good support for accurate discrimination in DC control protection.