Systemic Analysis of Fault Current Dynamics in DC Distribution Networks

In future distribution networks, the use of direct current (DC) technology is becoming increasingly significant. However, many aspects still need to be investigated in depth. Especially in the field of protection, where DC networks can behave significantly differently from alternating current (AC) networks due to their nature. As a novel contribution in this context, this paper provides a definition of the dynamics of short-circuit current in DC networks, dividing it into three stages. Each stage has its own particularities, which must be considered when planning and operating these networks. The focus of this paper is on the initial stage, known as the sub-transient stage. From there, the appropriate methods for calculating the fault current in this stage are defined. The authors then carry out a systemic simulation on an example of a distribution network accessible through the Power Factory software, in which 474 distribution lines are simulated within the short-circuit context. The results presented are significantly relevant to the development of protection and control philosophies and the design of protection equipment.