Judging method for current changing saturation based on differential current difference value

A technology of differential current and discrimination method, which is applied in the direction of automatic disconnection emergency protection devices, electrical components, circuit devices, etc., can solve problems such as misjudgment of current mutation criteria, influence on action performance, and influence on protection action speed, etc., to achieve The effect of reducing the amount of calculation and improving security

Active Publication Date: 2008-06-25
BEIJING SIFANG JIBAO AUTOMATION +1
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Problems solved by technology

[0004] In particular, for phase transition faults with different names, the current sudden change criterion may be misjudged and affect the action performance of the protection. When a fault occurs, due to the system impedance, the B-phase current also feels a sudden change at this time. After 10ms, the fault in the area begins, and the B-phase feels the emergence of a differential current. Press figure 1 According to the principle of synchronous identification, there is a sudden change of current first, and then there is a differential current. It is judged that the CT is saturated, and the differential protection is blocked. Although the existing technology can reopen the bus differential, it has seriously affected the operating speed of the protection.

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  • Judging method for current changing saturation based on differential current difference value
  • Judging method for current changing saturation based on differential current difference value
  • Judging method for current changing saturation based on differential current difference value

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Embodiment Construction

[0023] figure 1 It is a schematic diagram of the method of CT saturation discrimination. Such as figure 1 As shown, there are various schemes for judging the time when a fault occurs: some use sudden changes in voltage, some use sudden changes in current, some use impedance changes, etc., but each scheme has the possibility of misjudgment . For example: the voltage criterion is invalid when there is no voltage, and the impedance criterion is of course invalid at this time. The description on this aspect has already been introduced in the background technology section, and will not be repeated here.

[0024] figure 2 It is a simplified schematic diagram of the busbar system. This method analyzes the secondary and tertiary differences of the differential current. The normal differential current has no differential pulse, but the differential current formed by saturation has obvious pulses. Using the differential pulse characteristics of the differential current can correct...

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Abstract

This invention relates to method for judging saturation of current transformation based on difference value of difference current. Said method comprises steps of: sampling phase current according preset sampling rate, storing said sampling results in storage zone, processing said results, calculating difference value of the phase difference current, comparing said calculated difference value with preset valve valve. If said difference value is greater than valve value with an amount, current transformation is judged, if not, there must be fault in the zone. This invention has advantages of: decreased calculation for judging saturation of current transformation, high safety for bus bar protection.

Description

technical field [0001] The invention relates to the field of relay protection of electric power systems, and more particularly relates to a method for judging saturation of a current transformer (CT) based on a differential current differential value. Background technique [0002] In recent years, the voltage level of my country's power system has gradually increased, the power supply capacity has increased rapidly, and long-distance power transmission and large-area grid interconnection are also developing rapidly, so the probability of CT saturation caused by power system failures is increasing, and the depth of CT saturation It is also increasing, and the 750kV system to be built in the Northwest Power Grid of my country also puts forward higher requirements for CT saturation discrimination. Power CT saturation may cause misoperation of bus differential protection. If it cannot be judged quickly and appropriate measures are taken, it will cause large-scale power outages an...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02H3/26
Inventor 宋小舟操丰梅
Owner BEIJING SIFANG JIBAO AUTOMATION
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