Power grid voltage phase lock method for zero voltage ride through of photovoltaic grid-connected inverter

The invention discloses a power grid voltage phase lock method for zero voltage ride through of a photovoltaic grid-connected inverter, and discloses a zero voltage ride through control method for the photovoltaic grid-connected inverter. The method comprises a power grid voltage phase lock method, an active current control method and a reactive current control method in a zero voltage ride through process of the photovoltaic grid-connected inverter. The phase lock method is used for supplying a phase to current control in the zero voltage ride through process. According to the power grid voltage phase lock method disclosed by the invention, the inverter can perform automatic amplitude limitation on active current conveyed to a power grid in a power grid voltage falling process and also quickly recover the amplitude after the power grid voltage is recovered; meanwhile, the inverter has the capability of sending reactive current to the power grid according to the reduction degree of the amplitude of the power grid voltage.