Abstract: The novel controllable line commutated converter (CLCC) can entirely eliminate commutation failure, which provides a new way for high-voltage direct current to connect to the power grid. This paper reveals the fault response mechanism of high-voltage direct current based on CLCC, and compares the power characteristics differences between CLCC, line commutated converter (LCC) and voltage source converter (VSC). Then, the CLCC optimization control method of increasing maximum triggering angle is proposed, which can improve the fault response characteristics of CLCC and increase the recovery speed of the power grid voltage. Finally, based on the PSD-PSModel simulation software, the hybrid simulation model for the electromechanical transient model of the power grid and the electromagnetic transient model of CLCC is established to verify the accuracy of theoretical analysis and the effectiveness of optimized control proposed in this paper.