Inrush current suppression system and method based on residual magnetism prediction and circuit breaker discrete improvement

Abstract

The invention discloses an inrush current restraining system and method based on residual magnetism prediction and circuit breaker discreteness improvement. According to the inrush current restraining method, real-time operation conditions of a transformer are monitored on line, the hysteresis loop of an iron core is calculated according to a JA module, the residual magnetism value of the transformer when the transformer is switched off is obtained, the residual magnetism inside the iron core of the transformer and the magnetic bias are opposite in direction through control over the switch-on angle, the no-load excitation inrush current of the transformer is restrained, and a feedback mechanism is introduced into the inrush current restraining process. Compared with the prior art, a hardware system can be universal; in the no-load switching process of the transformer, no-load excitation inrush current can be effectively restrained, and operation of an electric transport system is made stable and reliable; residual magnetism prediction is introduced, calculation of the switch-on angle is more accurate; the feedback mechanism is introduced into the inrush current restraining process, and the system can automatically adapt to aging of a circuit breaker and changes in the external environment, so that the accuracy and reliability of the system are improved, and the inrush current restraining effect is realized.

Description

technical field [0001] The invention belongs to the technical field of transformer excitation inrush suppression in power transmission systems, and in particular relates to a system and method for suppressing inrush current based on residual magnetism prediction and improved discreteness of circuit breakers. Background technique [0002] At present, there are defects in the inrush current suppression technology measures of transformer no-load switching. When the transformer in power transmission is switched on at no-load and put into the power grid, due to the saturation of the magnetic flux of the transformer iron core and the nonlinear characteristics of the iron core material, it will have a similar amplitude. The large excitation inrush current will cause the differential protection of the transformer to malfunction, and at the same time cause the deformation of the winding and reduce the service life of the transformer. Usually the excitation inrush current contains mul...

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Problems solved by technology

[0006] In order to solve the above problems, the present invention proposes a system and method for suppressing inrush current based on residual magnetism prediction and improved discreteness of circuit breakers. This method improves the phase-selection closing technology and improves its inherent disadvantages: the discreteness of circuit breakers is uncertain The disadvantages of unstable closing angle and inaccurate calculation of closing angle caused by inaccurate residual magnetism prediction

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