Low-current line selection device and control method for inhibiting unbalanced current by way of differential filtration

Abstract

The invention relates to a low-current line selection device and a control method for inhibiting unbalanced current by way of differential filtration. The low-current grounding line selection device comprises a multi-channel alternating-current sampled signal input interface, an operational amplifier filter module, an analog/digital conversion module, a central processor module, a power module, a human-computer module and a communication module, wherein the multi-channel alternating-current sampled signal input interface, the operational amplifier filter module and the analog/digital conversion module are sequentially connected, the analog/digital conversion module, the human-computer module and the communication module are respectively bidirectionally connected with the central processor module, and the power module is connected with each part to supply power. The device adopts a zero-sequence current differential filtration algorithm which can effectively extract zero-sequence current fault component, and therefore can effectively extract the zero-sequence current fault component in a high-unbalanced current power supply system during normal operation, and thereby the line selection accuracy of the low-current grounding line selection device can be increased.

Description

technical field [0001] The invention relates to the field of fault detection of a low-voltage distribution network in a power system, in particular to a small current line selection device and a control method for differential filtering to suppress unbalanced current. Background technique [0002] In substations (stations), switching stations and power plants, 66 kV, 35 kV, 10 kV, 6 kV and 3 kV distribution lines are the main components of the power system. In these voltage level systems, most of them adopt the operation mode of small current grounding system, that is, the neutral points of transformers and generators are not grounded or passed through arc suppressing coils and resistance grounding for power transmission and distribution. And there are multiple output or input distribution lines connected to the same voltage level bus, most of which are led out by aluminum or copper bars or high-voltage power cables; the number of lines is generally five or six, a dozen or t...

AI Technical Summary

Problems solved by technology

[0011] In view of the above problems, the present invention provides a small current line selection device and control method for differential filtering to suppress unbalanced currents, which can solve the problem of how to effectively control the current in a power supply system with relatively large unbalanced currents during normal operation in the existing line selection technology. Identify the problem of the fault signal when the system is single-phase grounded, and improve the line selection accuracy of the small current grounding line selection device

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