A Method for Evaluating Commutation Failure Occurrence Based on Harmonic Synthetic Commutation Coefficients

Abstract

The invention relates to a method for assessing occurrence of commutation failure based on the harmonic comprehensive commutation coefficient. The corresponding AC bus voltage of a certain extinctionangle drop moment of operation to the inverter station converter valve is acquired, and the phase offset of the voltage amplitude of each harmonic and the fundamental phase relative to the normal commutation situation and the corresponding leading trigger angle and the extinction angle of the moment under normal operation of the system are obtained after Fourier transform of the AC bus voltage ofthe moment; the harmonic voltage comprehensive influence factor and the harmonic phase comprehensive influence factor are calculated, the two factors are added to obtain the harmonic comprehensive commutation coefficient, and the DC system commutation failure is judged according to the situation of whether the harmonic comprehensive commutation coefficient is greater than the maximum commutation area margin. The calculation method is low in calculation dimension and fast in speed; the method comprehensively considers the harmonic order, the harmonic voltage amplitude and the fundamental offsetcaused by the harmonic waves so that the calculation and judgment result is enabled to be more accurate; and the method is suitable for evaluation of continuous commutation failure.

Description

technical field [0001] The invention relates to a high-voltage direct current transmission technology, in particular to a method for evaluating commutation failure occurrence based on harmonic comprehensive commutation coefficients. Background technique [0002] With the construction and operation of the large-scale direct current transmission project of the State Grid Corporation of China "nine ACs and thirteen direct currents", my country has gradually formed a UHV, multi-point AC-DC hybrid system. High voltage direct current (HVDC) has the characteristics of large capacity, long distance, and asynchronous grid interconnection, and has gradually been widely used. At the same time, the close connection of AC and DC systems brings unique electrical characteristics to the power grid, that is, disturbances in the AC system often affect the normal operation of the DC system. [0003] Commutation failure, the most common fault in DC systems, has been widely concerned. A series ...

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Problems solved by technology

[0004] The present invention aims at the problem of ignoring the influence of fundamental wave voltage zero-crossing point offset on commutation failure in the prior art, and proposes a method for evaluating commutation failure based on harmonic comprehensive commutation coefficient, combined with The calculation method of the harmonic comprehensive commutation influence factor of the shift can be used to calculate and judge the commutation failure of the DC system

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