Abstract: In order to take full advantage of the ability of voltage source converter high voltage direct current (VSC-HVDC) to support the reactive power of the ac system, and suppress commutation failures of line-commutated converter high voltage direct current (LCC-HVDC), this paper proposes a commutation failure suppression strategy based on multi-angle prediction in hybrid dual-infeed HVDC system. Combining two prediction methods, constant extinction area prediction and zero-sequence detection and αβ transform prediction, we obtain the extinction angle reference γref. Then, the required reactive power that is calculated by the difference between the extinction angle reference γref and the setting value γset is fed back to the VSC control loop to adjust the reactive power that VSC generates after fault occurs,and thus to improve the immune ability to commutation failure of LCC. This method doesn’t depend on the mesurement of real extinction angle, so it’s more easier to implement. The simulation result obtained in PSCAD/EMTDC shows that the proposed strategy can improve the ability of suppressing commutation failures of LCC-HVDC.

Key words: hybrid dualinfeed HVDC system, coordination control, commutation failure, constant extinction area prediction, zero-sequence detection, α&beta, transform prediction