Impact of Control Parameters on Short-Circuit Capacity of Inverter Based Sources

The increasing penetration of the Inverter-based Distributed Generators (IDGs) in the power network can significantly affect the performance and reliability of the conventional network protection schemes due to the short-circuit capacity of IDGs. The short-circuit current contribution of IDGs is low compared to the synchronous-based DGs and significantly depends on the parameters of the associated controllers. Thus, the conventional overcurrent-based protection scheme may fail to pick up and negatively hamper the secured operation of the power network in many operating conditions. In this paper, a detailed analysis of the short-circuit behavior of IDGs is discussed. First, an analogy for the short-circuit current characteristic is established as a function of the control parameters of the IDG. Secondly, the proposed analogy is tested for an IDG with a dq controller operating in the grid-connected mode. A numerical simulation is performed on a test system to evaluate the impact of the control parameter on the short-circuit current contributed by the IDG. Further, the analysis is verified on the Real-Time Digital Simulator (RTDS), considering variations in the controller’s parameters.