Concise short-circuit current expression for grid-connected doubly fed induction generator

Due to the limited capacity of the power converter, the crowbar is still an important piece of equipment for DFIG to perform low-voltage ride-through. Therefore, understanding the characteristics of the short-circuit current of DFIG under crowbar activation is of great significance for engineers in terms of design protection principles. However, the existing short-circuit current expressions have complex and diverse forms, and their inherent relationships are still unclear. Moreover, they do not specifically consider the impact of interconnected systems. Therefore, this paper analyzes the steady-state and transient components of short-circuit currents separately and derives a concise current expression for DFIG. The proposed current expression takes into account the influence of interconnected systems. Moreover, by proving the potential relationships between different current expressions, this paper provides a universal principle for constructing a short-circuit current expression. Extensive simulation tests under different fault types and operating conditions have verified the practicality of the proposed expression, which can accurately depict the short-circuit characteristics of grid-connected DFIG.