Doctor of Philosophy (PhD)
Electrical and Computer Engineering
The current interruption in dc circuits is more difficult to achieve compared to the ac circuits because, unlike ac systems, dc circuits do not have the natural current zero-crossing. Presently there are three categories of basic dc breaker models namely mechanical, static, and hybrid dc breakers. As current power systems is moving more towards microgrids, DERs, Electric Vehicles (EVs), and with recent advancements in dc circuits, wide verities of dc power sources, and loads, dc breakers are very important in future system protection.
New alternate methods to break dc currents for low-voltage applications are proposed in this work. The proposed mechanisms utilize two separate principles to clear the dc faults. In the first mechanism, I use one switch to generate zero-crossing with an alternate oscillatory circuit and use another switch, which can be a conventional low-cost ac breaker and is used in the main circuit, in series with the first switch. In the second breaker prototype, I use two switches in series along with two anti-parallel diodes, to change the direction of the current flow and clear the fault. It is shown in this dissertation that the proposed methods can break the fault current quickly with minimal arc and reduce the switching voltage stress across the switches and other components. The performances of the proposed breakers were also compared to the available models to show the effectiveness of them over available models. Additionally, I also, modified our prototype and made use of surge arresters as a voltage suppressing device. Lastly, I tested our breaker model at 1000V testbed and it showed promising results.
Sen, Sudipta, "Inductor Free Methods for Breaking DC Currents" (2021). LSU Doctoral Dissertations. 5728.
Available for download on Friday, December 13, 2024