Method for distinguishing magnetizing inrush current by sample current added with zero-sequence current component

Abstract

The invention provides a method for distinguishing magnetizing inrush current by sample current added with zero-sequence current component. The sample current added with the zero-sequence current component is utilized to sufficiently reserve wave forms of the inrush current and harmonic characteristics. The method has the beneficial effect of more actually reflecting exciting current. The method is used to realize sufficient decoupling of each phase inrush current with slight mutual influences, achieve split-phase inrush current braking, and improve reliability of magnetizing inrush current lockout of transformer differential protection and sensitivity of air-drop fault actions.

Description

technical field [0001] The invention relates to a sample current used for identification of excitation inrush current and fault current in the differential protection of power system transformers. Background technique [0002] In order to ensure the safe operation of the transformer, it must be equipped with differential protection, and the excitation inrush current of the transformer has always been a major hidden danger of the misoperation of the transformer differential protection. According to the different wiring types of transformer windings, there are two main methods of amplitude and phase correction differential current commonly used at home and abroad: one is the differential current synthesis based on the phase-to-phase current; the other is the differential current synthesis based on the subtractive zero-sequence current. And the identification of the inrush current is completed by the synthesized differential current. [0003] Based on the differential current ...

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Problems solved by technology

[0003] Based on the differential current synthesis between phase currents, the differential current of each phase introduces other phase currents, which cannot achieve decoupling, causing the excitation inrush current of this phase to be affected by the excitation inrush current of other phases, and there is a loss of inrush current characteristics during the conversion process. Misoperation is prone to occur during airdrop, and it is not suitable to use phase-separated locking, which will cause the airdrop to fail to open quickly when the airdrop fails

[0004] Based on the differential current synthesis based on the subtractive zero-sequence current, the differential current of each phase introduces other phase currents, and the degree of decoupling is limited, so that the excitation inrush current of this phase is easily affected by the excitation inrush current of other phases, and there is a certain degree of loss of inrush current characteristics during the conversion process. , it is prone to misoperation during airdrop, and it is not suitable to use phase-separated locking, which will cause the airdrop failure to not be opened quickly

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