A DC transmission commutation failure defense method based on current limitation method

Abstract

The invention provides a defense method for commutation failures of direct-current transmission based on a current limiting method. The method comprises the following steps: I, according to an output signal of failure detection, detecting the failure type of a commutation bus of a direct-current transmission system; II, by using the current limiting method, reducing a direct-current instruction and continuing for 60-100 ms; III, judging whether a failure is eliminated and a turn-off angle of the direct-current transmission system is restored; and IV, determining the direct-current instruction according to a judgment result until the failure is eliminated, and restoring the direct-current instruction. According to the method, adverse effects such as increasing a direct-current, increasing a power factor angle of the direct-current transmission system, and the like caused by advanced triggering are avoided, and a timely and effective response is made to an alternating-current system failure, so that the required commutation area of a thyristor is reduced, thereby facilitating that the direct-current transmission system is prevented from having commutation failures.

Description

technical field The invention relates to a method in the technical field of power transmission and distribution, in particular to a method for preventing commutation failure of direct current transmission based on fast current limitation. Background technique Since the 1950s, the traditional line-commutated-converter high-voltage direct current (LCC-HVDC) has gained rapid popularity worldwide due to its large-capacity long-distance power transmission and fast controllable active power. development of. However, since LCC-HVDC uses ordinary thyristors without self-shutoff capability as commutation components, the LCC-HVDC system requires a certain strength of the AC system to achieve commutation, and the commutation voltage needs to be provided by the AC grid. When the power grid fails or the three-phase is seriously asymmetrical, the AC bus voltage will drop, the line voltage zero crossing point may be advanced, the commutation overlap angle of the LCC-HVDC valve arm will ...

AI Technical Summary

Problems solved by technology

To sum up, the existing defense methods have a certain effect on DC transmission system against commutation failure, but they will increase the DC current during the AC fault process and reduce the power factor of the DC transmission system, which may sometimes lead to negative results

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