The future power system integrated a large share of distributed generation (DG) may causes a reduction of the system rotational inertia, resulting in high frequency variations with any disturbances. An additional rotational inertia will be provided to the system if many DG units combined with relative small storage systems operate like virtual synchronous generators (VSG). This paper presents the demonstration approach for the VSGs in order to bring the VSG models developed in the laboratory into practice at two distribution test sites for both single- and three-phase applications. The results show promising results where changes in frequency and voltage are clearly counteracted by power flows from the VSG. In addition, VSG may provide a solution for hosting a large share of DG in future grids while maintaining system stability.@en

Fault current limiters (FCLs) are expected to play an important role in protection of future power systems. Saturated-core FCLs are particularly interesting because of their supreme operational advantages: inherent reaction on a fault, inherent post-fault recovery and unrestricted duration of a limiting period. The testing of a lab-scale FCL prototype proved the principle of operation. The full-scale 10 kV/400 A FCL prototype is built in co-operation with industry partners. The initial low-voltage 400 V testing has been successful. Full-voltage 10 kV testing will be performed later this year.@en

Fault current limiters (FCLs) are expected to play an important role in the protection of future power grids. Inductive FCLs are particularly interesting due to their inherent reaction to a fault, but are not commercialized because of a too large amount of magnetic material and an induced overvoltage across dc windings. This paper introduces a new three-phase FCL with a common core and trifilar windings. With the new FCL topology, the phase windings are placed on a single core, resulting in significant reduction of the amount of required magnetic material. Furthermore, the phase windings are wound simultaneously, so that the flux coupling between the phases is increased considerably. It cancels out the magnetic field and reduces the FCL normal impedance significantly. The dc windings are used only to compensate for possible asymmetry in the system currents. Consequently, the number of dc turns and the induced overvoltage are considerably decreased. Testing of a scaled-down FCL lab prototype made it possible to verify the FE simulation results and demonstrated the principle of operation of the new topology. Experimental and simulation results matched very well.@en