Difference Analysis of Converter AC Side Faults and Converter Protection Action Affected by DC Control

The main task of converter protection is to identify the internal faults in converter. However, the converter AC side faults also cause the converter protection action, and the relationship between faults and the converter protection becomes more complex. Considering the function of DC control, the dynamic characteristics and action of converter protection under various faults on the AC side of the converter are analyzed. Whether there is a fault ground point in the circuit determines the change of the DC side electrical quantity in each converter protection. The relative position between the current transformer and the fault point directly affects the response of DC control system. Affected by DC control system, the dynamic characteristics and action results of each converter protection under the two-phase grounding fault cannot be considered as a simple superposition of that under the single-phase grounding fault and interphase short circuit fault.