Transformer secondary side short-circuit fault discrimination method based on short-circuit voltage characteristics

Abstract

The invention relates to a transformer secondary side short-circuit fault judgment method based on short-circuit voltage characteristics, and belongs to the technical field of power electronics. The method comprises the following steps: S1, sampling to obtain a three-phase voltage of multiple secondary sides of the transformer; s2, comparing the three-phase voltage effective difference value with a preset theoretical value by using a comparison unit, if the three-phase voltage effective difference value is gt; if a voltage theoretical value is preset, entering S3; s3, recalculating the three-phase voltage relation by using a mathematical operation unit; s4, judging whether the three-phase voltage relation meets short-circuit fault voltage characteristics or not; and S5, when judging that the three-phase voltage meets the short-circuit voltage condition, prompting a short-circuit fault type and frequency converter fault tripping. Real-time voltage is compared with voltage characteristics in the short-circuit fault, the short-circuit state of the secondary side of the transformer is timely and effectively judged, and the fault type is determined.

Description

technical field [0001] The invention belongs to the technical field of power electronics, and relates to a method for judging a short-circuit fault on a secondary side of a transformer based on short-circuit voltage characteristics. Background technique [0002] At present, unit cascaded high-voltage inverters all use multi-secondary phase-shifting transformers to supply power to the power unit. Once a short circuit occurs on the secondary side of the transformer, the secondary side current increases sharply. According to the magnetic potential balance formula, the secondary side current is the same as the primary side If the current is in reverse phase, the secondary current will demagnetize the main current of the primary current. According to the principle of electromagnetic inertia, to keep the main magnetic unchanged, a large current will inevitably be generated to offset the demagnetization of the secondary short-circuit current. Magnetic action, so that the large curr...

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Problems solved by technology

[0003] Therefore, it is necessary to use necessary methods to judge the state of the secondary side of the transformer, and to judge the short-circuit fault state in time, but the traditional method has the problem that the short-circuit fault of the transformer cannot be detected in time

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