BH curve characteristic CT state recognition and unsaturation degree computing method based on reconstruction

A technology of state recognition and calculation method, which is applied in the direction of measuring devices, instruments, and measuring electrical variables, etc., can solve problems such as complex recognition principles, only qualitative judgments, and inability to reflect the changing process of CT iron cores, so as to improve reliability and reduce Effect of Differential Malfunction Probability

Active Publication Date: 2014-01-15
卢庆港
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Problems solved by technology

The above-mentioned various identification methods are proposed based on one or more characteristics of the saturation current after the occurrence of CT saturation. The identification principle is relatively complicated and cannot reflect the change process of the CT iron core. It can only be judged qualitatively and cannot provide a quantitative iron core. Saturation information

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  • BH curve characteristic CT state recognition and unsaturation degree computing method based on reconstruction
  • BH curve characteristic CT state recognition and unsaturation degree computing method based on reconstruction
  • BH curve characteristic CT state recognition and unsaturation degree computing method based on reconstruction

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Embodiment Construction

[0030] In the differential protection CT circuit, when there is an external fault in the differential protection area, a huge current passes through the differential protection area to form a penetrating current, and due to the differences in the characteristics of the CTs on both sides, there are often differences in the degree of saturation, forming a differential current It leads to the wrong judgment of the differential protection device, and the wrong trip when the fault is not in the protection area reduces the reliability of the differential protection.

[0031] According to the working principle of CT, the primary current generates alternating magnetic flux, which is coupled to the secondary coil through the iron core to form an induced potential and generate a secondary current to balance the influence of the flux change of the primary current. However, due to magnetic flux leakage, core loss, External circuit impedance voltage drop and other factors, the magnetic flux...

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Abstract

The invention provides a BH curve characteristic CT state recognition and unsaturation degree computing method based on reconstruction. The BH curve characteristic CT state recognition and unsaturation degree computing method is used for recognizing CT working conditions on the two sides through power system differential motion protection. Particularly, key characteristics of effective information carried through two side differential motion currents are extracted and recognized, and on the condition that any hardware is not additionally arranged, sample data of the currents on the two side differential motion currents are used for calculating to obtain the variation trends of the magnetic field strength H and the magnetic induction intensity B to construct a BH curve for reflecting an iron core interior flux changing process and provide quantized CT iron core state information. According to the characteristics of the BH curve under different states, a recognition threshold is automatically adjusted, CT saturation caused by external through currents is effectively recognized, saturation caused by a CT open circuit, internal faults and external faults can be effectively distinguished, the differential motion malfunction probability caused by CT saturation degree differences is reduced, and the reliability of a differential motion protection motion is improved.

Description

technical field [0001] The invention relates to a method for identifying the working state of CTs on both sides of the differential protection of a power system. Specifically, through the extraction and identification of the key features of the effective information attached to the currents on both sides, the quantified CT core state information is provided to provide judgment for the differential protection. It belongs to the technical field of power system automation control. Background technique [0002] The differential protection in the power system calculates the differential current and braking current in real time through continuous AC sampling of the current on both sides of the protected area, effectively identifying faults inside and outside the area, and protecting the reliable operation of equipment. For the differential protection CT, due to factors such as residual magnetism, secondary circuit impedance, and non-periodic components in the primary current, the ...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R35/02
Inventor 卢庆港
Owner 卢庆港
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