Method for estimating effect of suppressing commutation failure of line commutated converter high voltage direct current (LCC-HVDC) system by reactive compensation device

Abstract

The invention discloses a method for estimating effect of suppressing a commutation failure of a line commutated converter high voltage direct current (LCC-HVDC) system by a reactive compensation device. The method comprises the steps of simulating an AC fault by a fault inductor at an AC bus connected with a DC inverter, and setting start moment and continuous time when the fault is input; acquiring commutation failure probability on the premise that the reactive compensation device is not input; acquiring commutation failure probability on the premise that the reactive compensation device isinput; acquiring a curve graph of the commutation failure probability changing with the fault inductance by taking the fault inductance value as transverse coordinate and the commutation failure probability as longitudinal coordinate; acquiring area ratio of the commutation failure probability according to the obtained curve graph; and intuitively estimating an effect of suppressing the commutation failure of the LCC-HVDC system by the reactive compensation device according to the area ratio of the commutation failure probability. By the method, the effect of suppressing the commutation failure of the LCC-HVDC system by the reactive compensation device can be more intuitively estimated, so that the method can be applied to actual engineering experiment.

Description

technical field [0001] The invention relates to the technical field of direct current transmission, in particular to a method for evaluating the effect of a reactive power compensation device on suppressing commutation failure of an LCC-HVDC system. Background technique [0002] The Line Commutated Converter High Voltage Direct Current (LCC-HVDC) system based on grid commutation converters has the advantages of large transmission power, fast and controllable transmission power, and low operating costs. Networking" project has been widely used. However, since the converter of the LCC-HVDC system uses the thyristor without self-shutdown capability as the commutation element, on the one hand, its normal operation requires a certain strength of the AC system to provide the commutation voltage; on the other hand, the thyristor-based converter requires Consumes a large amount of reactive power, and the bus voltage decreases, and static reactive power compensation devices such as ...

AI Technical Summary

Problems solved by technology

However, since the converter of the LCC-HVDC system uses the thyristor without self-shutdown capability as the commutation element, on the one hand, its normal operation requires a certain strength of the AC system to provide the commutation voltage; on the other hand, the thyristor-based converter requires Consumes a large amount of reactive power, and the bus voltage decreases, and static reactive power compensation devices such as capacitors that compensate reactive power on the spot will reduce reactive power output. Therefore, once the AC system is weak or an AC fault occurs, the inverter of the LCC-HVDC system is easy to commutation failure

[0003] At present, the existing indicators for evaluating the immunity of LCC-HVDC system to commutation failure are mainly commutation failure immunity index and commutation failure probability index. Although these two indexes can describe the effect of reactive power compensation device on LCC-HVDC The inhibitory effect of system commutation failure, but it is difficult for operators to understand in actual engineering, and the evaluation process is not intuitive enough

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