Fault handling device and method for hybrid DC transmission system with fault restart function

Abstract

The invention discloses a fault handling device for a hybrid DC transmission system with a fault restart function, which comprises an acquisition unit, a fault identification unit and a fault handlingunit. The invention also discloses a fault handling method. The DC voltage and the DC of the hybrid DC transmission system and the AC voltage and the AC of an AC power grid connected with a rectifierconverter station and an inverter converter station are acquired; whether the hybrid DC transmission system fails is identified according to the acquired analog; and if fault happens, a thyristor converter is controlled to switch a trigger angle instruction value, and a current source-type converter based on a fully-controlled power electronic device is controlled to switch a DC instruction valueand / or a DC voltage instruction value. the above technical scheme can effectively handle the DC transmission line fault of the hybrid DC transmission system, reliable fault ride through can be realized, fast DC power recovery after the fault disappears can be realized, the stability of the AC / DC transmission system can be better maintained, and the safety of the AC / DC transmission system is protected.

Description

technical field [0001] The invention belongs to the field of hybrid direct current transmission, and in particular relates to a fault processing device and a fault processing method of a hybrid direct current transmission system with a fault restart function. Background technique [0002] HVDC systems can be divided into two types: conventional DC transmission systems (LCC-HVDC) based on thyristor technology and flexible HVDC systems based on fully controlled power electronic device technology (Flexible-HVDC). Among them, the conventional direct current transmission system (LCC-HVDC) has low cost, low loss, and mature operation technology. The inverter side is prone to commutation failure, strong dependence on the AC system, absorbing a large amount of reactive power, and large area occupied by the converter station. The new generation of flexible direct current transmission system (Flexible-HVDC) can realize the decoupling control of active power and reactive power, can su...

AI Technical Summary

Problems solved by technology

After the DC line fault disappears, the converters on the rectification and inverter sides will first close the DC side switch, then re-close the AC side circuit breaker for pre-charging, and finally restore the power of the DC system, so that the entire system can be restarted and restored The time is long, usually at the second level, which is not conducive to the transient stability of the AC-DC transmission system

Since at least one end of the hybrid HVDC system uses a flexible HVDC converter and the other end uses a conventional HVDC converter, when the HVDC line fails, one end of the HVDC system generally adopts a conventional HVDC converter. The processing method of the system adopts the processing method of the flexible DC transmission system at one end of the flexible DC transmission converter, so the restart and recovery time of the entire hybrid DC transmission system is also relatively long, usually on the order of seconds, which is not conducive to the temporary maintenance of the AC-DC transmission system. State stable

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