Research activities in the field of DC distribution networks led to the design, sizing and software simulation of a new solid-state circuit breaker model with integrated fault current limiting function for MVDC (Medium Voltage Direct Current) networks. The control and state management logic of the device was successfully verified using real-time control hardware-in-the-loop (CHIL) simulations. The next phase of development led to the inclusion of such a device in simulations of multi-terminal MVDC meshed networks, in order to implement short-circuit current limiting and selective disconnection of the faulty network trunk.

In such a simulated scenario, although the current limiting and interrupting functions were triggered in time, the device was not able to effectively limit the switching overvoltages due to its topological structure; in particular, the overvoltages reached in highly inductive sections of the circuit proved to be incompatible with the correct operation of the MVDC network.

The purpose of this specification is therefore to update and improve the structure and operation of the device to include the surge damper functionality, while trying to keep the number and size of the main components of the assembly unchanged as much as possible, so as not to distort the original structure.

The paper is structured as follows: the structure of the device and its operating principle are briefly recalled, then a version with an integrated surge damper is proposed, its operation is described and its expected performance is analyzed.

The Report is available on the Italian site