Direct-current fault current limiter suitable for self-cleaning MMC type direct-current distribution network and control method

Abstract

The invention discloses a direct-current fault current limiter suitable for a self-cleaning MMC type direct-current distribution network and a control method. The direct-current fault current limiter comprises an H-bridge circuit, a direct-current reactor, a current-limiting resistor, a main circuit breaker and a direct-current line. According to the direct-current fault current limiter working in the normal operation state, when a direct-current fault is detected, an IGBT in a main circuit breaker is immediately conducted, a conduction signal is applied to a rapid mechanical switch, an IGBT in a load branch is locked, fault current is converted from the load branch to the main circuit breaker, and preparation is made for dissipating fault energy; after entering a fault point isolated state, the recovery current limiter supplies power to the whole DC power distribution network. Compared with the prior art, the direct current fault development speed can be delayed, effective cooperation among fault current limiting, protection and current cutoff is achieved, and reliable fault ride-through of the residual network is ensured; and a self-adaptive DC fault current-limiting control strategy is realized.

Description

technical field [0001] The invention relates to the field of direct current transmission / distribution / microgrid, in particular to an adaptive direct current fault current limiter and its control strategy suitable for self-clearing MMC type direct current distribution network. Background technique [0002] When a DC fault occurs in the DC power distribution system, the capacitors of each sub-module release electric energy to the fault point, causing the bridge arm current and the DC line current to rise rapidly, which poses a serious threat to the safety and reliability of normal operation. In this case the faulty cable should be quickly isolated. Typical fault isolation methods include AC circuit breaker (ACCB), DC circuit breaker, and self-clearing converter topologies for fault isolation. [0003] Although using ACCB for fault isolation is simple and convenient, it is easy to implement in engineering practice; however, the tripping time of ACCB is generally 2 to 3 AC cycl...

AI Technical Summary

Problems solved by technology

[0007] Aiming at the problems that current flexible DC system protection and circuit breaker action speed cannot guarantee reliable fault ride-through of the remaining network after a DC fault, the existing current limiting technology will adversely affect the system and cannot achieve matching and coordination with the current interruption function, etc., the present invention proposes A DC fault current limiter and control method suitable for self-clearing MMC type DC distribution network, realizing an adaptive DC fault recovery control strategy

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