Fault ride-through control method and system for load short circuit of direct current transformer

Abstract

The invention discloses a fault ride-through control method and system for load short circuit of a direct-current transformer, and belongs to the technical field of control of direct-current converters. The method comprises the following steps: when a fault does not occur, the DAB direct current converter is modulated under a rated working condition; when a fault occurs, after the time of a switching period of driving signals of internal switching tubes of a primary full bridge and a secondary full bridge is blocked, a modulation method of the DAB direct current converter is set to be extended phase shift modulation, and meanwhile, the driving signals of the internal switching tubes of the primary full bridge and the secondary full bridge are recovered to enter a current limiting state; at the moment, the output current of the circuit which breaks down is larger than the operating value of the circuit breaker, and the circuit breaker completes breaking. According to the control method provided by the invention, the transient overcurrent phenomenon of the fault is inhibited, and the fault branch can trigger the action of the circuit breaker of the short-circuit branch in the current limiting state through the matching of the current limiting value and the action value of the circuit breaker, so that the automatic fault breaking and circuit recovery without a current sensor are realized, and the fault ride-through of the direct-current transformer is realized.

Description

technical field [0001] The invention belongs to the technical field of DC converter control, and more specifically relates to a fault ride-through control method and system for a load short circuit of a DC transformer. Background technique [0002] As a new type of transformer, solid-state DC transformer has become a research hotspot because of its advantages of realizing DC voltage conversion, small size and numerous topological structures. The core unit of the DC transformer is a high-efficiency DC converter. Among them, the dual active bridge DC converter has many advantages: 1) bidirectional flow of energy; 2) high-frequency electrical isolation; 3) high efficiency and power density; 4) rapid regulation . Therefore, it is one of the preferred circuits for building DC transformers. [0003] The discharge process of the short-circuit fault of the DC grid is very short, which makes the traditional mechanical circuit breaker unable to act in time, and the value of the shor...

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Problems solved by technology

[0004] In view of the defects of the prior art, the purpose of the present invention is to provide a fault ride-through control method and system for DC transformer load short circuit, aiming at solving the problem that traditional mechanical circuit breakers cannot act in time when a short circuit fault occurs in the DC power grid and the fault judgment insensitive question

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