Control method and apparatus for high-voltage, direct current first commutation failure in alternating-current fault

An apparatus for suppressing a first high-voltage direct-current (HVDC) commutation failure under an alternative current (AC) system fault, applied to an HVDC transmission system, and comprising a first acquisition and calculation module, a second acquisition and calculation module, a comparison and selection module, and a control module, wherein

• the first acquisition and calculation module is configured to obtain a three-phase voltage of a converter bus in the HVDC transmission system, and calculate a zero-sequence component amplitude and an αβ component amplitude of the three-phase voltage of the converter bus;
• the second acquisition and calculation module is configured to obtain a setting value of an extinction angle of the HVDC transmission system, a per unit value of a short-circuit reactance of a converter, a per unit value of a DC current, a commutation time and an impedance ratio, and calculate a first trigger-angle command for a single-phase fault and a second trigger-angle command for a three-phase fault according to the zero-sequence component amplitude and the αβ component amplitude;
• the comparison and selection module is configured to select a smaller one of the first trigger angle command and the second trigger angle command as a trigger-angle command for an extinction-angle controller controlling a converter valve in the converter;
• and
• the control module is configured to adjust a trigger angle of the HVDC transmission system by using trigger-angle command for the extinction-angle controller as an upper limit value for an output of the extinction-angle controller of the HVDC transmission system.