DC grid bidirectional current blocking circuit based on series switch

Abstract

The invention relates to a DC grid bidirectional current blocking circuit based on a series switch. The circuit comprises two switching transistors S1 and S2, two diodes D1 and D2, two thyristors Q1 and Q2, a bidirectional thyristor Q3, a capacitor C, a resistor R, and a voltage dependent resistor MOV. The circuit of the invention is connected in series to a DC grid. When no short-circuit fault occurs, the switching transistor S1 is turned on and the switching transistor S2 is turned off in order to turn on the current from P1 to P2; and the switching transistor S2 is turned on and the switching transistor S1 is turned off to turn on the current from P2 to P1, wherein the switching transistors S1 and S2 basically do not generate voltage drops. When a short-circuit fault occurs, by turningoff the switching transistor S1 or S2, the short-circuit current from P1 to P2 or from P2 to P1 can be quickly blocked by the capacitor. Compared with a conventional power electronic fault current limiter, the circuit of the invention is not only low in cost, but also is easy to control, fast in response speed, and can completely block the short-circuit current in both directions, and can be usedas a circuit breaker.

Description

technical field [0001] The invention belongs to the technical field of power electronics, and in particular relates to a DC grid bidirectional current blocking circuit based on a series switch. Background technique [0002] With the continuous development of DC transmission technology and high-power power electronic devices, DC transmission projects are increasing day by day. However, the impedance of DC lines is low. When a short-circuit fault occurs, the circuit current increases rapidly and reaches the level that the grid cannot bear in a short period of time. At this point, DC circuit breakers, as the key equipment of DC transmission, can quickly isolate faults, and are increasingly concerned by people. [0003] The grid-connected structure in the power grid needs to be applied to DC circuit breakers. Here, traditional fuses and circuit breakers are used to block the short-circuit current. If the fuse is blown, it needs to be replaced. The circuit breaker cannot act in ...

AI Technical Summary

Problems solved by technology

In order to overcome these shortcomings, a variety of new power electronic devices are applied to this occasion. However, the existing DC short-circuit fault current limiter can only limit the short-circuit current and needs to be used with a circuit breaker, which cannot fully meet the needs of rapid detection of power grid faults. The need to block bidirectional short-circuit current

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