Static synchronous power generator reactive support control method for power grid asymmetric short circuit fault

The invention relates to a static synchronous power generator reactive support control method for a power grid asymmetric short circuit fault. Unbalance degree of voltage of a grid-connected point is calculated in real time, negative sequence reactive current is dynamically outputted, and reactive support is performed on one phase or two phases with the short circuit fault; and an instruction current amplitude limiting strategy is adopted, and negative sequence reactive current is ensured to be outputted to the maximum limit along with increasing of degree of asymmetry so that negative sequence current support control at the maximum degree is realized. Problems of overcompensation and overvoltage caused by injection of three-phase symmetric reactive current of an original control strategy can be effectively avoided by the control strategy so that a new solution idea is provided for the asymmetric short circuit fault.