Converter transformer phase selection closing excitation inrush current suppression method based on magnetic bias simulation

Abstract

The invention discloses a converter transformer phase selection closing excitation inrush current suppression method based on magnetic bias simulation. The method comprises the following steps: 1, estimating three-phase residual magnetism values of a Y-bridge converter transformer and a D-bridge converter transformer; 2, extracting a result of considering the influence of the series closing resistor of the circuit breaker on the closing magnetic bias amplitude and phase, and constructing a magnetic bias function; and 3, comparing the residual magnetism estimated when the converter transformer is switched off with a magnetic bias function to obtain proper switching-on time of the converter transformer. According to the invention, residual magnetism during switching-off of the converter transformer and magnetic bias during switching-on can be used for counteracting each other, so that the magnetizing inrush current suppression effect of the converter transformer is effectively improved, magnetizing inrush current caused by switching-on charging of the converter transformer during maintenance and operation mode change of a high-voltage direct-current power transmission project can be suppressed, and the problem of commutation failure caused by the excitation surge current of the commutation transformer is solved.

Description

technical field [0001] The invention relates to a method for suppressing excitation inrush current of commutation variable phase selection closing based on bias magnetic simulation, and belongs to the technical field of excitation inrush current suppression of power transformers. Background technique [0002] UHV DC transmission has the characteristics of large transmission capacity and long distance. It is the main transmission technology to realize the power transmission of large energy bases in southwest and northwest my country. Converter transformer refers to the power transformer that connects the converter bridge with the AC system. It is one of the core equipment of DC power transmission. The basic structure of UHV DC power transmission converter usually consists of two 6-pulse converter bridges connected in series to form a 12-pulse converter bridge. , at the same time, among the two sets of converter transformers, one set adopts Y-Y connection, and the other set ad...

AI Technical Summary

Problems solved by technology

The series combination resistance measure is limited by the selection of the closing resistance value and the resistance input time, and sometimes the closing inrush current is relatively high; after adopting the phase-selection closing measure, since the phase-selection closing operation depends on the fixed closing phase, that is, Y The three phases of the bridge converter rheology switch on respectively at their voltage peaks, the first closing phase of the D bridge converter switches on at its voltage peak value, and the other two phases close 1 / 4 cycle behind the first closing phase. When considering the commutation The original closing phase may not meet the closing requirements due to the different residual magnetism values ​​after switching off and the mechanical stability of the circuit breaker, which may cause a large excitation inrush current

Therefore, when considering the maintenance and switching operation mode of the HVDC transmission system, the above-mentioned measures have a limited effect of suppressing the excitation inrush current of the converter transformer, and the suppression measures of the excitation inrush current of the HVDC transmission system converter transformer considering the influence of residual magnetism and closing resistance are still needed. to further improve

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