Short-Circuit Current Computation Method for Electric Elements with Converter

In view of the protective relay based on fundamental frequency, a novel short-circuit current computation method for electric elements with converter during transient fault process is proposed, where the basic functions, controlling peculiarity and complex transient process of the converter are simplified. The response characteristic of the element with converter in AC side fault is revealed by qualitative and quantitative analysis on the output variation rules, thus the approximately analytic expression of transient response is obtained. The simulation shows that the novel short-circuit current calculation method has a high accuracy, the converter is regarded as an equivalent controlled component with AC-DC power conversion function, and the transient response of the converter depends on the control strategy and control parameters. The control characteristic plays an important role in the fault response of the converter.