Design and Application of Calibration Current Source for UHVDC Current Transformer

摘要

The direct current (DC) current transformers in ultra high-voltage direct current (UHVDC) converter stations have problems such as inconvenient on-site calibration. In order to solve these problems, according to the impedance characteristics of the UHVDC current transformers, the current output scheme for the individual control of multiple current modules is determined. Based on this, a calibration current source is designed, including a DC/DC converter main circuit, a high-frequency transformer, a PWM output control circuit, and a peripheral circuit. The calibration current source has been verified by tests. The results show that the output DC current accuracy is 0.1%, 1 minute stability reaches 0.02%, and accurate regulation can be achieved.