A topology of hvdc current limiter

Abstract

The invention provides an HVDC DC limiter topology. The DC limiter includes IGBT strings connected in parallel. The middles of the IGBI strings are connected with reactor and diode sets connected in parallel in the reverse direction to form bridge type structures. The bridge type structures are connected with a by-pass switch in parallel. The DC limiter is installed at an inverter station DC outlet; the DC limiter is in a bypassing state when a system normally works, and the DC limiter is put into operation when the system fails. Through continuous switching between two current flow paths according to a certain frequency, the DC rise is limited, the time that the current flowing through a shut-off valve becomes zero can be effectively shortened, and the probability of commutation failures for traditional DC transmission is lowered.

Description

technical field [0001] The invention relates to a device in the technical field of power transmission and distribution, in particular to a topology of an HVDC current limiter. Background technique [0002] Due to its unique technical and economic advantages, HVDC transmission has been widely used in long-distance and large-capacity power transmission. However, the existing high-voltage direct current transmission uses thyristors without self-shutoff capability as commutation components, and requires a certain strength of the alternating current system to achieve commutation. Commutation failed. [0003] Factors affecting commutation failure include: DC current I dL , Echizen firing angle β, commutation bus voltage U L , Converter transformer transformation ratio k and commutation reactance X C etc., the above factors will affect the turn-off angle of the inverter, thereby affecting the commutation. For example, when a certain fault occurs in the system or the transmissi...

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Problems solved by technology

[0003] Factors affecting commutation failure include: DC current I dL , Echizen firing angle β, commutation bus voltage U L , Converter transformer transformation ratio k and commutation reactance X C etc., the above factors will affect the turn-off angle of the inverter, thereby affecting the commutation

For example, when a certain fault occurs in the system or the transmission power increases and the DC current I dL When it increases, the current flowing through the converter valve will increase, which will prolong the time for the current flowing through the shut-off valve to become zero, so that the commutation angle μ increases, the shut-off angle γ decreases, and the system is prone to commutation. phase failure

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