A power conversion device comprising: - a voltage source power converter which is connectable to an electric generation grid and which is configured to convert AC power received from the electric generation grid to DC power and transmit the DC power via DC bus; and - a control device configured to control the power converter, wherein the control device includes - a detection unit configured to detect DC current of the DC bus, - an AC voltage control unit configured to cause AC voltage at a power reception end of the power converter to follow an AC voltage command, - a DC current control unit configured to cause the DC current to follow a DC current command, and - a DC voltage control unit configured to cause the DC voltage at the DC-side terminals of the power converter to be constant; and - a protection control unit configured to perform protection control for suppressing an amount of power received from the electric generation grid, by continuing operation of the power converter while decreasing an amplitude of the AC voltage command, and wherein the protection control unit is configured to detect, on the basis of whether the DC current (Idc) varies beyond a range in which the DC current varies in normal operation, an abnormality in another grid to which power is supplied from the power converter via the DC bus, and configured to perform the protection control when the abnormality is detected, and the control device is configured to generate an output voltage command for the power converter on the basis of output of the AC voltage control unit, output of the DC voltage control unit, and output of the DC current control unit. - a voltage source power converter which is connectable to an electric generation grid and which is configured to convert AC power received from the electric generation grid to DC power and transmit the DC power via DC bus; and - a control device configured to control the power converter, wherein the control device includes - a detection unit configured to detect DC current of the DC bus, - an AC voltage control unit configured to cause AC voltage at a power reception end of the power converter to follow an AC voltage command, - a DC current control unit configured to cause the DC current to follow a DC current command, and - a DC voltage control unit configured to cause the DC voltage at the DC-side terminals of the power converter to be constant; and - a protection control unit configured to perform protection control for suppressing an amount of power received from the electric generation grid, by continuing operation of the power converter while decreasing an amplitude of the AC voltage command, and wherein the protection control unit is configured to detect, on the basis of whether the DC current (Idc) varies beyond a range in which the DC current varies in normal operation, an abnormality in another grid to which power is supplied from the power converter via the DC bus, and configured to perform the protection control when the abnormality is detected, and the control device is configured to generate an output voltage command for the power converter on the basis of output of the AC voltage control unit, output of the DC voltage control unit, and output of the DC current control unit.