Commutation failure detection method based on commutating current time area index

Abstract

The invention discloses a commutation failure detection method based on a commutating current time area index. The commutation failure detection method is characterized in that a conception of the commutating current time area is provided for a commutation process of an inversion side of a convertor station for a direct current system according to an area defined by commutating current and a timeaxis; the physical significance of the commutation process is disclosed in terms of energy by a commutating current time area method; corresponding criteria are provided according to the magnitude ofthe commutating current time area; and the criteria can be used as a new index for correctly judging whether the inversion side of the convertor station has commutation failure or not.

Description

technical field [0001] The invention relates to a commutation failure detection method based on a commutation current time area index, which belongs to the field of high voltage direct current transmission. Background technique [0002] Commutation failure is one of the most common faults during the inverter operation of the HVDC converter station. The main reason for its occurrence is that the commutation voltage drops due to the failure of the AC system on the inverter side. In some cases, the commutation failure may recover by itself, but continuous commutation failure may cause the DC transmission system to block, and even endanger the stability of the entire system, causing greater harm. In the AC-DC hybrid operation system, the voltage collapse and the control-induced voltage oscillation will cause permanent commutation failure of the inverter. [0003] Commutation failure refers to: when the commutation between the two bridge arms is over, if the valve that has just ...

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Problems solved by technology

[0004] Commutation failure will lead to a drop in DC voltage and an increase in DC current. If improper control measures are taken, subsequent commutation failures will also occur. In severe cases, the DC transmission power will be interrupted, making the entire system unstable and affecting the safe operation of the power grid. significant impact

Compared with the single-infeed DC transmission system, the multi-infeed HVDC system has a larger transmission capacity and a more flexible operation mode, but it also brings some special problems. The phase failure is more sensitive, and the research on the commutation failure problem will be more complicated

A commutation failure of a converter station will not only cause voltage fluctuations in its own DC system, but may also cause commutation failures in multiple nearby converter stations, and even cause the entire system to collapse.

In recent years, the power grid has experienced extraordinary development, and many DC lines have been put into operation one after another. However, the mixed operation mode of AC and DC is generally adopted in the regional networking. The transfer will make the relevant lines overloaded, which will have a direct impact on the stable operation of the AC system. If multiple DC lines have cascading failures, it may even lead to grid instability.

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