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AC filter differential protection method based on high-voltage side current effective value

A technology of AC filter and current effective value, applied in the field of AC filter differential protection based on high-voltage side current effective value

Active Publication Date: 2015-10-28
EXAMING & EXPERIMENTAL CENT OF ULTRAHIGH VOLTAGE POWER TRANSMISSION COMPANY CHINA SOUTHEN POWER GRID
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Problems solved by technology

[0007] Aiming at the problem of differential protection action caused by freewheeling during the withdrawal process of the AC filter, the present invention provides an AC filter differential protection method using the effective value of the high-voltage side current as an auxiliary criterion, which can reliably operate when a ground fault occurs on the main body , reliable non-action during AC filter exit process

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  • AC filter differential protection method based on high-voltage side current effective value
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  • AC filter differential protection method based on high-voltage side current effective value

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Embodiment Construction

[0027] The content of the present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

[0028] The AC filter differential protection method based on the effective value of the high-voltage side current includes the following steps:

[0029] (1) After performing 50HZ filtering on the high-voltage side current IT1 and the low-voltage side current IT3, Figure 4 The virtual box at the bottom of the center introduces a program logic for calculating the current difference between the high and low voltage sides. Extract the 50HZ components of the high and low voltage side currents, take the absolute value, and then subtract them, and then take the absolute value of the subtraction results. The result is is the differential flow, shown in equation (1).

[0030] (2) Figure 4 The virtual box above introduces a program logic for calculating the effective value of the high-voltage side current IT1. The absolute va...

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Abstract

The invention provides an AC filter differential protection method based on a high-voltage side current effective value. The method comprises the following steps that step one, high-voltage side current and low-voltage side current of an AC filter are sampled; step two, 50HZ filtering is performed on the sampled high-voltage side current and low-voltage side current, differential current of high-voltage side and low-voltage side current is calculated by adopting a 50HZ component and is compared with a differential current fixed value; step three, a high-voltage side current effective value is calculated and compared with an effective value fixed value; and step four, when differential current of high-voltage side and low-voltage side current is greater than the differential current fixed value and the high-voltage side current effective value is greater than the effective value fixed value, actuation of differential protection is outputted without time delay, a high-voltage side switch is tripped off, and differential protection does not actuate under other conditions. Distinguishing is performed by adopting different characteristics of high-voltage side current when the AC filter withdraws and fails to work so that reliable actuation protection in a local grounding fault can be guaranteed and no actuation in the withdrawing process of the AC filter can be reliably guaranteed.

Description

technical field [0001] The invention belongs to the technical field of AC filters, in particular to an AC filter differential protection method based on the effective value of the high-voltage side current. Background technique [0002] The schematic diagram of AC filter structure and differential protection 87ACF in power engineering is as follows figure 1 As shown, the existing AC filter differential protection criterion is ABS(IT1-IT3)﹥△, where IT1 is the high-voltage side current, IT3 is the low-voltage side current, ABS means to take the absolute value, and △ is the fixed value of the differential current. When the differential protection criterion ABS(IT1-IT3)﹥△ is satisfied, the protection action exits and the high-voltage side switch is tripped. [0003] The differential protection shall operate reliably when the AC filter body has a ground fault, and shall not operate reliably under other circumstances. However, incidents of differential protection misoperation oc...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H7/00H02H3/26
Inventor 郑伟陈晓鹏张楠邬乾晋顾保全
Owner EXAMING & EXPERIMENTAL CENT OF ULTRAHIGH VOLTAGE POWER TRANSMISSION COMPANY CHINA SOUTHEN POWER GRID
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