Research on Protection Configuration Method for Low Voltage Flexible DC Interconnection System

Flexible interconnection devices are mostly voltage source converters composed of fully controlled power electronic devices. When a single pole grounding fault or inter pole short circuit fault occurs on the DC side of the interconnection system, the fully controlled devices inside the interconnection device will quickly lock, and the diodes in anti-parallel with the fully controlled devices may burn out due to overcurrent. This article proposes a protection device for flexible interconnection devices, which can quickly block short-circuit current or limit short-circuit interruption within a certain range when a fault occurs on the DC side, thereby protecting the power electronic components inside the device from damage. At the same time, with the line protection and equipment protection of the grid, accurate fault location can be achieved, effectively reducing the range of power outages caused by faults and improving the reliability of system operation.