Combined resonance eliminating device suitable for 4PT

Abstract

The invention discloses a combined resonance eliminating device suitable for a 4PT. The combined resonance eliminating device comprises a three-phase voltage transformer, a zero-sequence voltage transformer, a controllable switch KA and a microcomputer resonance eliminating device body. The primary side of the three-phase voltage transformer is in a star shape through connection, and the neutral point of the star shape is grounded through the primary side of the zero-sequence voltage transformer. The secondary side of the three-phase voltage transformer comprises a first winding and a second winding, one end of a triangular opening of the first winding of the secondary side is connected with the end 0 of the controllable switch KA, the other end of the opening is connected with the end 2 of the controllable switch KA, the second winding of the secondary side is in a star shape through connection, and the neutral point of the star shape is grounded through the secondary side of the zero-sequence voltage transformer. The microcomputer resonance eliminating device collects the voltage of the secondary side of the zero-sequence voltage transformer, and the power resistance output end is connected with the end 1 and the end 2 of the controllable switch KA and outputs a control signal of the controllable switch KA at the same time. The combined resonance eliminating device suitable for the 4PT is simple in structure, easy to control and capable of eliminating resonance of an ultra-low-frequency transformer.

Description

technical field [0001] The invention relates to a protection device for secondary power equipment, in particular to a composite harmonic elimination device suitable for 4PT. Background technique [0002] The electromagnetic characteristics of voltage transformers in substations and the grounding capacitance of lines and equipment cause ferromagnetic resonance in the system, causing overvoltage and overcurrent, which seriously threaten the safety of power equipment in the power grid and the stability of system operation. At present, under the premise of not changing the parameters of the system, there are two commonly used methods to eliminate the resonance of the voltage transformer: one is to insert resistance at both ends of the secondary side of the voltage transformer auxiliary open triangle winding to destroy the resonance condition, the most commonly used The device is a microcomputer harmonic elimination device. Its principle is to monitor the voltage of the open ...

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Problems solved by technology

[0004] In order to solve the above-mentioned problems, the present invention aims at the problem that the triangular winding in the existing transformer resonance elimination device is too large to burn the equipment when it resonates at ultra-low frequency, and proposes a compound with simple structure, simple control and the ability to eliminate ultra-low frequency transformer resonance. Harmonic elimination device

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