High voltage direct current transmission trigger pulse control method and device

Abstract

The invention discloses a high-voltage direct current transmission trigger pulse control method and device, through real-time monitoring of the commutation voltage of the three-phase valve arm of the high-voltage direct current transmission system; according to the commutation voltage of the three-phase valve arm and the three-phase valve According to the rated voltage of the three-phase valve arm, calculate the commutation voltage amplitude difference of the three-phase valve arm; calculate the commutation voltage phase angle of the three-phase valve arm according to the commutation voltage amplitude difference of the three-phase valve arm offset difference; according to the commutation voltage, rated voltage and commutation voltage phase angle offset difference of each phase valve arm, the initial trigger pulse angle of each phase valve arm in the HVDC transmission system is corrected to obtain a three-phase valve arm The cut-off angle setting value; according to the cut-off angle setting value of the three-phase valve arm, the trigger pulse control of the high-voltage direct current transmission system is carried out; the present invention can correct the trigger pulse in a targeted manner when the system fails, and improve each The control degree of freedom of the phase valve group improves the phase commutation capability of the system and ensures the stability of the system voltage.

Description

technical field [0001] The invention relates to the field of high voltage direct current transmission control, in particular to a high voltage direct current transmission trigger pulse control method and device. Background technique [0002] There are two main trigger pulse mechanisms for HVDC transmission systems: one is individual phase control, and the control circuit forms the required trigger pulses through phase shifting according to the moment when the voltage of each phase crosses zero. However, when the AC voltage is unbalanced or the waveform is distorted, the pulse interval of each phase will be different, which will easily generate non-characteristic harmonics and cause harmonic instability. This method is no longer used in existing DC projects. The second is equal interval pulse control. The PLL (Phase Locked Loop) circuit forms the phase control reference point, and then forms the trigger pulse through phase shifting. The trigger angle of each converter valve i...

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Problems solved by technology

However, when the AC voltage is unbalanced or the waveform is distorted, the pulse interval of each phase will be different, which will easily generate non-characteristic harmonics and cause harmonic instability. This method is no longer used in existing DC projects.

The second is equal interval pulse control. The PLL (Phase Locked Loop) circuit forms the phase control reference point, and then forms the trigger pulse through phase shifting. The trigger angle of each converter valve is uniformly controlled. However, under the equal interval pulse control, when the fault When the DC current rises, the voltage amplitude decreases, and the phase angle shifts during phase locking, the commutation angle that the HVDC transmission system can provide is smaller than the actual demand value, which may easily cause commutation failure and cause high-voltage DC transmission system failure. voltage instability

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