Enhancement of Withstand Capability of Grid-Tied Inverters during transients, utilizing dc-side magnitudes

As the future power systems tend to be more inertialess, several stability and reliability issues have been aroused, provoking desynchronization events, firstly at the grid-tied inverters and then gradually to the entire network. This paper proposes an active power compensation scheme, which is partially untangled from phase locked loops, to enhance system reliability and widen the inverter-based distributed generators withstand capability under large transients. Regarding synchronization schemes inherited vulnerability due to their high non-linearity, a more reliable physical magnitude is utilized such as the dc-side current, to improve the synchronization method response in an indirect manner, providing adequate time to follow the abrupt frequency events. This is made feasible by introducing a dc-dc converter at the dc-side, which provides the unique ability to mitigate dc current deviations, allowing the regulation of dc current trajectories during synchronization phase loss. Thus, active power compensation and dc current retention are achieved. The theoretical analysis is verified through simulations, whereas experimental validation is carried out on a scaled-down test bench.