High-voltage DC fault recovery method based on commutation voltage phase detection

Abstract

The invention discloses a high-voltage DC fault recovery method based on commutation voltage phase detection. According to the method, commutation voltage of each converter valve is calculated throughthree-phase voltage of a converter bus; an orthogonal quantity of each commutation voltage is constructed, amplitudes of a corresponding sine component and a cosine component are calculated by usingthe commutation voltages and the orthogonal quantities, and after filtering processing, the amplitudes of the sine component and the cosine component are divided, and arc tangent transformation is carried out to obtain an initial phase of the commutation voltages; a phase error of the phase-locked loop is calculated by using the synchronous phase outputted by the phase-locked loop and the detectedcommutation voltage initial phase, the minimum phase error amount corresponding to each commutation voltage and a trigger angle instruction value outputted by the controller are added, and a final trigger angle instruction is obtained. According to the method, the deviation between the actual trigger angle and the controller instruction under the fault can be effectively reduced, so that the effectiveness of the controller is improved, and the recovery performance of the system after the fault is improved.

Description

technical field [0001] The invention relates to the technical field of high voltage direct current, in particular to a high voltage direct current fault recovery method based on commutation voltage phase detection. Background technique [0002] In the DC transmission control system, the trigger phase control of the converter realizes the control of the DC transmission system and its converter operating state regulation by changing the trigger phase of the converter valve. In order to avoid the problem of harmonic instability, the current HVDC project generally adopts the equal-interval triggering technology, which generates equal-interval trigger pulse signal sequences according to the synchronous phase of the three-phase phase-locked loop, so as to realize the trigger phase control of the converter. [0003] The three-phase phase-locked loop commonly used in HVDC transmission is the synchronous rotating frame phase-locked loop (SRF-PLL). When the system is running in a stea...

AI Technical Summary

Problems solved by technology

[0003] The three-phase phase-locked loop commonly used in HVDC transmission is the synchronous rotating frame phase-locked loop (SRF-PLL). When the system is running in a steady state, the SRF-PLL can accurately track the phase of the AC voltage. At this time, the actual The firing angle is equal to the firing angle command output by the controller; when the AC system on the inverter side fails, the phase of the AC voltage may change rapidly due to the removal of the fault and the restoration of the transmission power, resulting in the failure of the phase-locked loop to perform phase-locking in time , so that the actual firing angle deviates from its command value

If the actual firing angle exceeds the command value of the controller in a short period of time, the fixed turn-off angle controller will not be able to adjust the turn-off angle in time, and the converter is likely to fail in subsequent commutation at this time

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