Research on the control strategy of the tap in the back to back converter station of Heihe

In view of the frequent over polarity of on load tap in Heihe, Russian converter station. This paper studies the control strategy of reducing over polarity of tap. Firstly, the cause of over polarity of tap changer is obtained through statistical analysis, and then an improved Udi0 control strategy is proposed for the cause, which can greatly reduce the probability of over polarity of ta. Finally, the effectiveness of the control strategy is verified by simulation, and the influence on the DC control and protection function is analyzed. The research conclusions have a great significance in engineering that reducing the risk about converter faults for back-to-back DC project.