A Discrimination Method for Outlet Fault of AC Line

Abstract

The invention discloses an alternating current line outlet fault judgment method comprising the steps of designing a digital filter to simulate transfer characteristics of a capacitor voltage transformer; acquiring a memory voltage via a voltage at a relay protection device; when a protected alternating current line has a short-circuit fault, acquiring a postfault voltage and a postfault current at the relay protection device; reconstructing a virtual fault voltage by using the memory voltage and a fault generation moment; processing the virtual fault voltage and the postfault current via a digital filter; setting an outlet fault protection range via a circuit parameter, and computing a first voltage difference by using the fault current processed by the digital filter; computing a secondvoltage difference by using the postfault voltage and the voltage of a virtual fault point; and judging whether an outlet fault occurs according to the sum of absolute values of the first voltage difference and the second voltage difference within a period of time after the fault. The method provided by the invention is simple to judge and quick in action speed, can overcome the influence of the transient process of the capacitor voltage transformer on the judgment of the outlet fault, and effectively enhances the action speed of the outlet fault of the alternating current line.

Description

technical field [0001] The invention belongs to the field of relay protection of electric power system, and more specifically relates to a method for judging the outlet fault of an AC line. Background technique [0002] With the increase of the AC transmission voltage level and the further expansion of the transmission capacity, higher requirements are placed on the protection action speed of the AC line. As a serious fault type, the near-field exit fault of the AC line is of great significance to quickly and effectively identify the near-field exit fault of the AC line to improve the protection action speed and ensure the safe and stable operation of the system. At present, due to the application of the transient transmission characteristics of the capacitive voltage transformer for the judgment of the fault in the vicinity of the outlet of the AC line, it is impossible to directly judge whether the outlet fault occurs based on the measured voltage. Therefore, it is usually...

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Problems solved by technology

[0003] Aiming at the above defects or improvement needs of the prior art, the present invention provides a method for judging the outlet fault of the AC line, thereby solving the problems in the prior art that the identification speed of the outlet fault of the AC line is slow and the fault removal time is long question

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