Forced commutation bridge circuit

A technology of forced commutation and bridge arms, which is applied in the field of power transmission and distribution, can solve the problems of high capacitor volume and cost, and achieve the effects of prolonging the service life, realizing capacitor self-charging, and reliable shutdown

Active Publication Date: 2014-05-28
NORTH CHINA ELECTRIC POWER UNIV (BAODING) +3
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The forced commutation circuits in the prior art mainly include series inductive voltage source inverters and series diode current source inverters. Although both inverter topologies can achieve reliable shutdown of thyristors under fault conditions, However, since the capacitors in the forced commutation are always in operation, a large number of harmonics are generated when the converter valve works normally. very high

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Embodiment Construction

[0022] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0023] The invention provides a forced commutation circuit that can significantly reduce the working harmonics of the converter valve and prolong the service life of the capacitor, such as figure 1 As shown, one phase half-bridge arm of the commutation bridge circuit includes two thyristor strings connected in parallel; the thyristor string includes 2N thyristors connected in series, and N is at least 1; the midpoint of the two thyristor strings is connected through a capacitor, and the capacitor The thyristor strings are respectively divided into two symmetrical thyristor strings. The half-bridge arm includes four current flow paths:

[0024] When the converter valve is working normally, the current flow path is a branch formed by a thyristor string after triggering conduc...

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Abstract

The invention provides a forced commutation bridge circuit. A one-phase semi-bridge arm of the commutation bridge circuit comprises two thyristor strings which are connected in parallel, and each thyristor string comprises 2N thyristors which are connected in series, wherein N is at least equal to 1; the midpoints of the two thyristor strings are connected through a capacitor by which each thyristor string is divided into two symmetric segments of thyristor strings. Compared with the prior art, the forced commutation bridge circuit provided by the invention is suitable for traditional high-voltage direct-current power transmission, and not only can be used for realizing the reliable cutoff of the thyristors under a fault condition, but also can ensure that the capacitor is not used when a converter valve is normally used, so that no great number of harmonic waves are generated, and the service life of the capacitor is prolonged; moreover, the capacitor can be self-charged without an external power source.

Description

technical field [0001] The invention relates to the technical field of power transmission and distribution, in particular to a forced commutation bridge. Background technique [0002] The one-phase half-bridge arm of traditional HVDC power transmission is composed of several thyristors connected in series. Under normal circumstances, the series-connected thyristors can be turned on and off at the same time under the action of a trigger signal; If the valve out of conduction fails to recover its blocking ability during the period of time when the reverse voltage is applied, or the commutation process has not been completed during the reverse voltage, it will cause the valve voltage to be switched to positive. All the valves in the same phase will reverse the phase to the valve that was originally scheduled to withdraw from conduction, and a phase commutation failure will occur. [0003] Forced commutation mainly uses the method of charging and discharging the commutation cap...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M7/521H02M1/12
Inventor 赵成勇李春华李路遥郭春义许韦华阳岳希
Owner NORTH CHINA ELECTRIC POWER UNIV (BAODING)
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