Alternating-current side short-circuit current suppression method and system for hybrid direct-current flexible direct-current converter valve

Abstract

The invention relates to a hybrid DC flexible DC converter valve AC side short-circuit current suppression method and system, and the method comprises the steps: carrying out the primary suppression of a short-circuit current fed into an AC system in a flexible DC manner through a two-stage current limiting method of total current limiting and reactive current low-voltage current limiting; dividing the short-circuit current after primary suppression into a first-stage short-circuit current and a second-stage short-circuit current according to the action process of the alternating-current circuit breaker; performing secondary suppression on the first-stage short-circuit current by increasing a proportion parameter of a dq decoupling inner loop controller and accelerating the judgment speed of an alternating current system fault; and performing secondary suppression on the second-stage short-circuit current by increasing the proportion parameter of a dq decoupling inner loop controller, increasing the proportion parameter of a phase-locked loop, reducing a reactive current limiting value and/or accelerating the judgment speed of an alternating current system fault. The overall short-circuit current level of the alternating-current system can be effectively reduced, and the short-circuit current of the system is prevented from exceeding the standard. The method can be applied to the field of direct-current power transmission.

Description

technical field [0001] The invention relates to the field of DC power transmission, in particular to a method and system for suppressing short-circuit current at the AC side of a hybrid DC flexible DC converter valve. Background technique [0002] In some load centers in China, such as East China, the demand for DC infeed is increasing, but the dense infeed of DC outside the area will reduce the electrical distance between converter stations, reduce the short-circuit ratio of multiple feeds, and fail to commutate multiple DCs at the same time. The risk is gradually increasing, making the power grid face serious security and stability problems. In order to realize long-distance large-capacity power transmission and multi-drop power supply, and solve the problem of reducing the short-circuit ratio of multiple feeds at the receiving end, the hybrid cascaded UHV DC transmission technology can be used, that is, conventional DC converters and multiple flexible DC converters. The ...

AI Technical Summary

Problems solved by technology

[0004] However, none of the current existing technologies involves the control method and setting method for suppressing the flexible DC short-circuit current according to the different stages of fault development

Images