Overcurrent Protection Method

Abstract

The invention relates to a bridge arm overcurrent protection method of a flexible direct current multilevel converter, including a valve base electronic device detecting valve bridge arm overcurrent fault protection configuration method, and a valve base electronic device detecting an overcurrent fault protection method. The bridge arm overcurrent detection is configured in the upper protection control system and the underlying valve base electronic equipment at the same time, and the timing and constant value are coordinated. Through this method, the flexible DC transmission system can be realized in the event of bridge arm overcurrent. Uninterrupted operation of the system It can reduce the influence of fault current and realize the overcurrent protection of the valve when the bridge arm connecting line and the AC bus bar have grounding or phase-to-phase faults. The operation process is simple and reliable, and it is easy to realize.

Description

technical field [0001] The invention belongs to the field of direct current transmission, and in particular relates to an overcurrent protection method for a flexible direct current multilevel converter, a valve control electronic device, a control protection device and a detection system. Background technique [0002] Flexible DC transmission uses voltage source converters, which can independently adjust the transmission of active and reactive power, improve the transmission capacity of the AC system, and easily form a multi-terminal DC transmission system. And other application fields, have obvious competitiveness. [0003] Flexible DC transmission control and protection equipment and valve-controlled electronic equipment are equipment for controlling and protecting multi-level converters. The purpose of control is to meet the operating requirements of flexible DC transmission converter stations. The adjustment of the voltage and reactive power at the point where the mult...

AI Technical Summary

Problems solved by technology

However, this method cannot distinguish between transient faults and permanent faults in the AC bus or valve area. Once a transient fault occurs in the valve area, although the converter valve is protected in this way, it will be permanently blocked and cause the HVDC system to stop operating.

Another method is to detect the secondary overcurrent of the bridge arm and turn it into a permanent blocking mode for protection, but this method also cannot avoid the system shutdown caused by the instantaneous overcurrent of the bridge arm. On the other hand, if the valve control electronic equipment of each bridge arm There is no communication between them, and the six bridge arms need to be locked for a period of time, which cannot be realized in this way

[0005] A common phenomenon in the multi-level flexible DC transmission system is that the bridge arm has an instantaneous short-circuit fault or an instantaneous fault on the AC bus side causes the bridge arm to over-current. Due to the uncertainty of the duration of the over-current, this instantaneous over-current cannot Maintain the operation of the flexible DC transmission system after clearing the fault with secondary overcurrent detection blocking or fixed delay

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