Performance evaluation of high power semiconductor devices employed in solid-state circuit breakers for MVDC grids Andreas Giannakis NORWEGIAN UNIVERSITY OF SCIENCE AND TECHNOLOGY, NTNU Department of Electric Power Engineering O.S. Bragstads plass 2E Trondheim, Norway Email: andreas.giannakis@ntnu.no Dimosthenis Peftitsis NORWEGIAN UNIVERSITY OF SCIENCE AND TECHNOLOGY, NTNU Department of Electric Power Engineering O.S. Bragstads plass 2E Trondheim, Norway Email: dimosthenis.peftitsis@ntnu.no Keywords ≪protection device≫, ≪faults≫, ≪power semiconductor device≫, ≪IGBT≫, ≪IGCT≫ Abstract This paper presents a performance evaluation of power losses of three high-power and high-voltage power semiconductor devices, namely, IGBTs, BIGTs, and IGCTs operating in solid-state DC circuit breakers for medium voltage Direct Current grids. The performance of each breaker is evaluated for a wide range of DC voltages and load conditions under steady-state operation, whereas the criteria are the conduction losses associated with the switches and the corresponding junction temperature. The IGCT-based solid-state breaker achieved the lowest power losses, while the IGBT-based performed the highest losses under all the investigated cases. Last but not least, a comparative study regarding the transient responses of the three devices when a short-circuit occurs is also examined and presented. The superiority of BIGT-based breaker in terms of minimizing the short-circuit current is revealed. Introduction Today, electric power transmission over long distances using high voltage Direct Current (HVDC) has gained momentum over the Alternating Current (AC) counterpart. Several reasons have led to this paradigm shift towards HVDC power grids, such as higher efficiency, no need for reactive power com- pensation and no need for synchronization. On the other hand, for electric power distribution medium voltage AC grids are currently utilized. Nevertheless, a clear trend to shift towards medium voltage DC (MVDC) grids is foreseen [1]. Similar to HVDC power systems, the MVDC grid technology will de- crease the transmitted power losses. Furthermore, the ever-increasing renewable energy sources (RES) installations will also lead to the development of MVDC power grids, since they enable easier grid inte- gration. Even if the advantages of the potential MVDC power distribution grids over the existing MVAC coun- terparts are significant, there are still few barriers that impede their further development [2]. Firstly, the higher cost of power electronic converters, which are expected to be the key component of the potential MVDC systems, compared to the low frequency transformers utilized in AC grids. However, this cost seems to decrease due to the massive production of power converters by relevant industries. Furthermore, the lack of zero crossing for the fault current in DC grids along with the low DC line inductance cause excessively high short-circuit current peaks within a short time period. Therefore, the development of fast acting DC circuit breakers is mandatory. Three basic topologies of DC CBs have been identified in literature, namely, mechanical DC CB (along with active or passive resonant circuit), solid-state DC CB and hybrid DC CB. It has shown that the