In order to accurately analyze the high- and low-voltage ride through capacity of variable frequency speed regulation system in thermal power unit, this paper proposes a new design of power electronic voltage disturbance generator, according to the market demand on the voltage ride through capacity testing equipment. It adopts uncontrollable rectifier and booster circuit, which boosts the direct current voltage generated by uncontrollable rectifier circuit to the scheduled voltage, and then controls output analog voltage fault waveform through the inverter. It can simulate single-, bi-, and tri-phase voltage swell and sag, and its duration, depth, start-stop phase and type can all be adjusted smoothly. The experimental results prove that the new designed voltage disturbance generator is safe and reliable, which can correctly reflect the grid fault voltage type, and can be widely used in studying the high- and low-voltage ride through ability of frequency speed regulation system in thermal power unit.