A high-voltage DC circuit harmonic impedance analytical equivalent model and frequency analysis method

Abstract

An embodiment of the invention discloses a high-voltage direct-current circuit harmonic impedance analysis equivalent model and a high-voltage direct-current circuit harmonic impedance frequency analysis method, aiming to solve the problems that a harmonic current path in a typical converter model is limited between a converter transformer and a valve bridge, stray capacitance to ground of converter transformer sleeves is ignored, and a large difference exists between a design result and an actual measurement result of the model based on a direct-current-side harmonic current theory. The high-voltage direct-current circuit harmonic impedance analysis equivalent model comprises a current converter adopting a three-pulse converter model, and the three-pulse converter model comprises a leakage current path and a converter bridge. The high-voltage direct-current circuit harmonic impedance analysis equivalent model is more accurate by taking the nature that harmonic waves are reflected by 3n times under the effect of commutation induction of the leakage current path and the converter bridge into consideration; the influences of an alternating-current system and an alternating-current filter on high-voltage direct-current circuit resonance characteristics are taken into account, so that an analysis process of the high-voltage direct-current circuit resonance characteristics is more accurate and rigorous, and results are more reliable.

Description

technical field [0001] The invention relates to the field of equivalent model simulation, in particular to a high-voltage direct current circuit harmonic impedance analysis equivalent model and a frequency analysis method. Background technique [0002] HVDC power transmission has played an important role in my country's strategy of "power transmission from west to east, mutual supply between north and south, and national networking". In the DC transmission system, the DC filter on the DC side is connected in parallel with the DC line and then connected in series with the smoothing reactor, and then connected in series with the converter transformer, AC filter, and AC system on the AC side when the converter valve is on. In the main circuit, there are multiple natural resonant frequencies determined by various equipment parameters and wiring methods, which may cause the DC circuit to resonate near the fundamental frequency and the second harmonic frequency, showing low impeda...

AI Technical Summary

Problems solved by technology

[0003] Due to the nonlinear characteristics of the converter components of the DC transmission system, the resonance characteristics of the DC circuit cannot be calculated by the conventional frequency sweep method

The classic converter model is an internal inductance model, in which the harmonic current path is limited between the converter transformer and the valve bridge, ignoring the stray capacitance of the converter transformer bushing to the ground, using this model based on the DC There is a large difference between the theoretical design results and the actual measurement results of side harmonic currents

At the same time, the influence of the AC system and the AC filter on the resonance characteristics of the DC circuit is rarely considered in the study of DC resonance, which makes the accuracy of the converter model insufficient in the application of resonance analysis

[0004] Therefore, the harmonic current path in the classic converter model is limited between the converter transformer and the valve bridge, ignoring the stray capacitance of the converter transformer bushing to the ground, using this model based on the DC side harmonic current theory to design The large difference between the results and the measured results is a technical problem that those skilled in the art need to solve

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