Three-phase fault current characteristics of permanent magnet synchronous generator

To analyze the permanent magnet synchronous generator (PMSG) fault characteristics, a simplified model of grid-side converter and external characteristics model of controller with chopper are proposed. Grid-side converter is an electric energy balance system under controlling action, its complex structure is ignored and the function and external characteristics are retained only. To reveal the PMSG short-circuit current is to analyze the three-phase current response under the action of turbine terminal voltage sag. A comparison with detailed model indicates that when chopper circuit does not operate, the value of PMSG current is determined by its output power and the degree of voltage sag; besides 50 Hz component, there are components whose frequencies are related to the control parameters; the fault current firstly increases gradually and then decreases to a steady value; with the increasing voltage sag degree, the maximum fault current gets greater and the corresponding period and transient decay time become longer; when chopper circuit operates, the fault current is just the maximum converter current.