Analysis and Test Method on Transient Step Response Character of High Voltage DC Electronic Current Transformer

High voltage DC electronic current transformer is the key equipment in HVDC system, and its transient step response is one of the most important indicators for the control and protection, which is significant to power quality and power supply reliability of the power network. This paper introduces the structure of DC electronic current transformer and the corresponding transient step response character and related influence factors. A closed-loop test method on transient step response for DC electronic current transformer is proposed. Polynomial fitting is used to calculate the delay time of the step response, the rise time error of the field testing results and other key indicators. The validity of the test method is proved at a HVDC converter station testing system.