Longitudinal differential protection device and method for series transformer based on joint judgment of dual differential modules

Abstract

The invention discloses a longitudinal differential protection device and method for a series transformer based on joint judgment of dual differential modules. The longitudinal differential protectiondevice comprises a first current transformer, a second current transformer and a third current transformer, wherein the first current transformer and the third current transformer are respectively arranged at two ends of a primary winding of the series transformer; the second current transformer is arranged at one end of a secondary winding of the series transformer; the first current transformerand the second current transformer form a first differential module, and the first differential module performs differential protection calculation based on the head end current of the primary winding of the series transformer and the current of the secondary winding of the series transformer; the third current transformer and the second current transformer form a second differential module, andthe second differential module performs differential protection calculation based on the tail end current of the primary winding of the series transformer and the current of the secondary winding of the series transformer; and the series transformer performs longitudinal differential protection when either the first differential module or the second differential module meets a differential operation condition. The longitudinal differential protection device can effectively improve the sensitivity of longitudinal differential protection of the series transformer.

Description

technical field [0001] The invention belongs to the field of power systems, and in particular relates to a longitudinal differential protection device and method for series transformers based on double differential module joint judgment. Background technique [0002] The primary winding of the series transformer has no neutral point, and the two ends of the winding are directly connected in series to the power grid. Compared with ordinary parallel transformers, series transformers have different working characteristics and different primary wiring forms. [0003] Such as figure 1 As shown, one end of each phase winding on each side of an ordinary parallel transformer is connected to the busbar, and the other end is directly grounded or forms a neutral point. When a common parallel transformer is set with a differential circuit, a current transformer is generally installed at one end of each phase winding on each side, and the longitudinal differential protection collects t...

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Problems solved by technology

[0006] In order to overcome the problem of low sensitivity of some protection areas in the existing longitudinal difference protection method when applied to series transformers, the present invention proposes a series transformer longitudinal difference protection device and method based on double differential module joint judgment. The current at both ends of the primary winding of the series transformer realizes the longitudinal differential protection method of the series transformer with joint judgment of double current transformers, which can effectively improve the sensitivity of the longitudinal differential protection of the series transformer

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