Current Transverse Protection Method of Double-branch AC Filter

Abstract

The invention discloses a current transverse difference protection method of a double-branch type AC filter, which comprises the following steps: the AC filter has two branches, which are respectively a first branch and a second branch; real-time detection of the end of the first branch of the AC filter Current and two-branch tail-end current; according to the difference between the first-branch tail-end current and the two-branch tail-end current deviation from the normal value, a transverse differential current alarm signal or a tripping command is issued respectively. When the differential current of any phase of the differential current of the transverse difference protection is greater than the threshold value of the transverse difference overcurrent detection action, the criterion of the transverse difference overcurrent detection will act; None of the CT abnormality detections at the terminals are activated, and when the delay of the transverse differential current tripping is reached, the transverse differential current tripping action is activated. The invention can not only improve the sensitivity and quick action of the AC filter when a grounding fault or a high-end capacitor breakdown fault occurs, but also prevent malfunctions under various external short-circuit faults and various abnormal operating conditions.

Description

technical field [0001] The invention relates to the electrical quantity protection technology of a double-branch type AC filter used in a high-voltage direct current transmission project in the field of electric power system, in particular to a current transverse difference protection method of a double-branch type AC filter. Background technique [0002] Wiring mode of double-branch AC filter, such as figure 1 As shown, the high-side capacitor ( figure 1 shown in C1. The same below) breakdown is the most common internal fault of the AC filter. For this reason, high-end capacitors often use H-type or π-type wiring to facilitate the installation of special capacitor unbalance protection to deal with high-end capacitor breakdown faults and prevent accidents from expanding. If the high-end capacitors do not use the above wiring method, there is no special protection against capacitor breakdown faults. Because the differential current protection cannot reflect the high-end c...

AI Technical Summary

Problems solved by technology

Because the differential current protection cannot reflect the high-end capacitor breakdown fault in principle; moreover, when a non-metallic grounding short circuit fault occurs at the end of the AC filter, the sensitivity of the differential current protection is often insufficient

In addition, whether it is a high-end capacitor breakdown fault or a ground fault, the overcurrent protection or zero-sequence overcurrent protection in the backup protection of the AC filter has shortcomings such as low sensitivity and poor quick action, which cannot meet the needs of the internal fault of the AC filter. , Reliable failure removal requirements

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