Comparative Study of Short-Circuit Fault Characteristics for VSC-Based DC Distribution Networks With Different Distributed Generators

Distributed power generation integration can effectively improve the reliability and economy of dc distribution network operation. However, it is difficult to evaluate the fault behaviors caused by the diversification of distributed generation, which might render preexisting protection schemes invalid and even cause damage to power electronic equipment. When different distributed generators access a voltage source converter (VSC)-based dc system, an in-depth study of fault characteristics is of great significance to design relay protection. This paper investigated the short-circuit fault characteristics of VSC-based dc distribution networks containing distributed generation systems. The fault responses of different fault stages for three kinds of distributed generators (photovoltaic power system, supercapacitor energy storage system, and wind power generation system) were investigated to provide an intuitive comparison of fault behaviors. The effects of these distributed generators on the magnitude and peak time of fault current were analyzed. It was found that the dc cable parameters and these distributed power generators' dc-link capacitors have great impacts on the fault behaviors of dc distribution networks. Detailed analyses based on MATLAB calculations are presented, and simulation results based on power systems computer aided design/electromagnetic transients including dc verified the effectiveness of the proposed transient fault models.