| Powerformer, which is a new kind of power equipment and can be connected to power network directly, is introduced in this paper. It broke the old conventions of a century by replacing the conventional generator, the generator surge arresters, the medium-voltage generator breaker and bus-bars, and the step-up transformer with just a single generating unit. As a new type of energy converting device, Powerformer is different from the conventional generator in stator structure. The advantages of low cost, high efficiency and low maintenance make Powerformer a prospecting future.Sudden short-circuit of synchronous machine is the most serious fault in electric power system. Though the time of short-circuit process is very short, the calculation of armature short-circuit current and rotor current is significant. The calculation of short-circuit current has developed from analysis to numerical method; the latter can be utilized to calculate the fault current easily and precisely.The principle, character and prospective development of Powerformer are introduced firstly in this paper. The mathematical model considering concrete damper end connection and finite entity model is established according to actual structure of a Powerformer. The parameters concerned with the short-circuit state of Powerformer are calculated with the aid of ANSYS, a finite element analysis software.Analysis and numerical method are used together in conventional synchronous generator to research all external short-circuit state in this paper, then this two methods is used to research all external short-circuit state (three phase short-circuit,line-to-line short-circuit,single-phase grounding fault,two-phase grounding fault) of Powerformer, and after that the variable curve of stator current,rotor current and electromagnetic torque are derived. Finally, results derived by analysis and numerical method were compared and analyzed; meanwhile some valuable conclusion has been obtained. |
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