Steady-state control strategy of VSC-HVDC transmission system based on full-order terminal sliding mode control method

摘要

High-voltage direct current (HVDC) techniques play an important role in the power transmission, especially for the distance district. For the HVDC, control system is necessary to the operation of flexible transmission system, so it is significant to research its control strategy. Normally, the traditional control method is proportional integral (PI) control under the dq frame system, but if the grid voltage is unbalanced, the traditional control method cannot reach the required aim. So the article proposed the full-order terminal sliding mode (TSM) control under the $lpha eta $αβ frame system. In the proposed control strategy, the cross-coupled term of current in two-phase stationary reference frame is avoided; thus, the feed-forward decoupling is not needed and the whole control system becomes simple. At last, the proposed control strategy is simulated in PSCAD/EMEDC, and simulation results show that the proposed control strategy is correct and effective.