A general design scheme of voltage sag generators（VSGs）is proposed for low voltage ride-through（LVRT）test of photovoltaic（PV）systems.The VSG can also be adapted to a variety of power grid voltage levels.Based on the requirements of LVRT curve specified in the national standard GB/T 19964—2012，the working principle of the typical impedance-type VSG is expounded.A design method is then proposed for the topology structure and electrical parameters of current limiting reactor and grounding reactor of a VSG.Furthermore，a design example of VSG at 10 kV voltage rating is given.The VSG has 20 different sag depths ranging from 0% to 100% of rated voltage with the step of 5%.Finally，for a grid-connected 500 kW PV inverter，the single-phase and three-phase voltage sag tests with several sag depths，especially 0%，are conducted and the test results prove the effectiveness of the design scheme.