The invention relates to a power grid disturbance device. The power grid disturbance device comprises three bridge arms. Each bridge arm corresponds to one phase of a three-phase alternating current.At least two AC/AC conversion modules are arranged on each bridge arm in a cascaded mode. The first AC/AC conversion module on each bridge arm is used for being in star connection with one end of an external device to form a first port, used for being connected with a three-phase power grid, of the power grid disturbance device. The last AC/AC conversion module on each bridge arm is used for beingin star connection with one end of the external device to form a second port, used for being connected with a distributed-type power generation system, of the power grid disturbance device. All the AC/AC conversion modules on the bridge arms jointly bear voltages of two ends of the bridge arms, so that power devices in the AC/AC conversion modules bear very low voltages, power devices with high voltage levels are not needed, and operation reliability of the power devices are high. Industrial frequency transformers are omitted, and accordingly, the power grid disturbance device has the advantages of small size and high efficiency.