Coordination control method for direct current control for increasing quiescent voltage stability of alternating current/direct current system

Abstract

The invention discloses a coordination control method for direct current control for increasing the quiescent voltage stability of an alternating current / direct current system. The method comprises the following steps: when the voltage of an alternating current bus on an inversion side of the alternating current / direct current system is boosted, matching an angle control module of a converter transformer with an inverter constant voltage control module, thereby restraining the increasing of reactive absorption of the direct current system; when the voltage of the alternating current bus on the inversion side of the alternating current / direct current system is reduced, increasing a power factor of the inverter by the inverter constant voltage control module by reducing an advanced triggering angle gamma; and when the advanced triggering angle gamma of the inverter is less than a preset value under the constant voltage control, switching the constant voltage control to the minimum extinction angle Gamma min control, thereby maintaining the power factor of the inverter within a preset scope. According to the invention, the angle control of the converter transformer is blocked by the constant voltage control on the inversion side, so that the capacity of the constant voltage control to increase the direct current power factor by adjusting the triggering angle when the voltage of the alternating current system is reduced is fully exerted.

Description

technical field [0001] The invention relates to the technical field of power grids, in particular to a DC control coordinated control method for improving the static voltage stability of an AC-DC system. Background technique [0002] HVDC transmission has the advantages of long-distance large-capacity transmission, connection to asynchronous grids, and fast power modulation. DC transmission lines and AC lines are mixed to form an AC-DC hybrid system. However, while the DC system provides active power transmission for the AC system at the receiving end, it also needs the AC system to provide reactive power support. Insufficient reactive power is often one of the main reasons for the voltage instability of the AC-DC system. [0003] The direct current transmission system has a high degree of controllability. Through the cooperation of the converter transformer control and the converter control mode, the direct current voltage and the firing angle of the converter can be contro...

AI Technical Summary

Problems solved by technology

[0005] (1) The coordinated control strategy between the traditional converter transformer control method and the converter control method is relatively fixed, and the angle control of the converter transformer is in phase with the converter with constant current (or constant power) on the rectifier side or constant voltage on the inverter side. Coordination, the voltage control of the converter transformer is coordinated with the converter with a fixed arc-extinguishing angle on the inverter side. This coordinated control strategy is mainly to ensure the stable operation margin of the DC system, and does not consider the impact on the static voltage stability of the AC-DC system.

[0006] (2) When the angle control of the converter transformer is coordinated with the constant voltage control on the inverter side, it limits the ability of the constant voltage control to improve the DC power factor by adjusting the trigger angle when the AC system voltage drops

[0007] To sum up, in the prior art, there is still no effective solution to the problem that the coordinated control of the converter transformer control mode and the converter control mode cannot guarantee the stability of the static voltage of the AC-DC system

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