Short-circuit limitation thanks to a series connected VSC

Interconnection of medium voltage grids associated to the modulation of the transmission line impedance can improves system operation and power quality. However it also leads to rise of the short circuit power. To cope with this constraint and make this new distribution scheme a viable alternative to radial distribution in the future, investigations on short-circuit limitation with a particular line´s compensator relying on a series connected Voltage Source Converter (VSC) (also called SSSC for Static Synchronized Series Compensator) has been achieved. Short-circuit limitation is also motivated because power systems grow and become more constrained (due to Distributed Generation (DG) widespread). This paper presents a new concept for a combined short-circuits circuit limiter and dynamic series compensator for medium voltage grids. In non-fault use, it is designed to regulate active and reactive power flow in order to optimize grid behavior. Indeed, coordination of several units dispatched thought the grid could lead to more efficient grid exploitation (i.e. grid losses, loop flow, voltage drop reductions). During fault use (short-circuit) it will limit short-circuit currents to protect the grid and itself. Two innovative short-circuit limitation methods have been developed and experimented thanks to a test bench. The significant operation improvement is expected to justify the cost of the new device.