Control method of ferroresonance elimination of electromagnetic voltage transformer

Abstract

The invention discloses a control method of ferroresonance elimination of an electromagnetic voltage transformer. A one-third frequency component, a half frequency component, a triple-frequency harmonic component and a power frequency component included in an open delta winding voltage of the voltage transformer are calculated in real time, when the values thereof exceed setting values of corresponding resonance criteria, corresponding single conduction continuous times, adjacent conduction state interval times and maximum triggering conduction frequencies are respectively set for an electronic switch resonance elimination circuit connected to an open delta winding of the voltage transformer in parallel according to different resonant frequencies, and the validity and the success rate of resonance elimination are improved through a differentiated pulse-type conduction control method.

Description

technical field [0001] The invention relates to the field of power systems, in particular to a method for identifying and eliminating ferromagnetic resonance of an electromagnetic voltage transformer. Background technique [0002] In the neutral point indirect grounding system, some voltage transformers used to measure the insulation to the ground, the neutral point of the primary winding is directly grounded, when the no-load bus closes, the single-phase ground fault disappears or the system load is severe When changing, the excitation inductance of the voltage transformer will have a nonlinear change, which may form a parameter match with the system's ground capacitance, thereby causing ferromagnetic resonance, causing system overvoltage and TV overcurrent, and then causing insulation damage to grounding or phase-to-phase faults , and the TV fuse is blown, burned or exploded, and even the arrester explosion, weak insulation flashover, grounding line selection device misope...

AI Technical Summary

Problems solved by technology

[0006] After the existing microcomputer resonance elimination device recognizes the ferromagnetic resonance, the on-off method of the electronic switching device is relatively simple. For the resonance of different frequencies, the same on-time and on-state interval time (that is, the off-time ), the harmonic elimination effects of these devices are quite different in field application, the harmonic elimination speed is slow, and the overall harmonic elimination success rate is low

Moreover, some devices do not have a preset limit on the maximum number of conduction times. Since ferromagnetic resonance may exist for a long time when the resonance elimination is unsuccessful, it may cause the device to continuously trigger the open triangle circuit according to the preset conduction and shutdown method, and the resonance elimination circuit of the device A large pulsed harmonic elimination short-circuit current flows in the medium, which may cause hardware burnout or component damage of the harmonic elimination circuit under the action of a long time

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