In AC-DC hybrid power systems consisting of converters, renewable sources, loads and possible storages, transient disturbances are inevitable. Grid fault is one of the typical transient disturbances unpredictably occurred in the system. It has many types, suc h as ope n-circuit a nd s hort-circuit faults. From the grid pint of view, it can be single-phase, phase-to-phase or three-phase and may last for a short ti me or long d uration. Co mpared with the conve ntio nal sync hrono us ge nerator, the power-converter responds very differe ntl y to grid faults. In a practical AC-DC hybrid power system, the grid faults will affect the grid-connected converters in various ways, depending on the fault positions, the configuration of the transmission lines, the depth of voltage sags, etc.

The disturbance changes the operating condition of the grid-connected converter dramatically. Therefore, the characteristics of the power converter and its devices should be thoroughly considered in order to understand the safety and reliability of the power electronics based system. This special session will present the state-of-the-art research outcomes in the area of power converter safety under grid faults.