Study on the transient characteristic measurement system of current transformer

Abstract

Nowadays, thirteen ultra-high voltage direct current (UHVDC) transmission projects have commissioned in China, including Jinping-Sunan, Fulong-Fengxian, Yibin-Jinhua project, and so forth. Meanwhile, another two UHVDC transmission projects are under construction. The highest UHVDC voltage level is ±1100kV. The HVDC transmission is superior in high capacity and long transmission distance, and its control response put forward higher requirements for the transient characteristics of DC current transformer. At present, there is no test method and equipment for testing the transient characteristics of the DC current transformer. Therefore, mastering the transient response characteristics of operating DC current transformer remains to be a challenge. In this paper, a transient test system of DC current transformer is developed, which includes a step current output unit, a high precision acquisition unit and a calibrator algorithm. The system was used to test the rising time, maximum overshoot and transient delay of the DC current transformers installed on the pole line and valve outlet. This study can clarify the influence factors of the transient characteristics of DC transformer on the control and protection system of UHVDC, and can define the principle of selecting the transformer parameters to meet the requirements of the control and protection system of UHVDC. The results of this study have great significance to improve the performance of UHVDC control and protection system.