House to grid (H2G) ancillary services supplied by next generation AC/DC household systems

At household level, the development of appliances has recently increased the presence of internal DC links. This, combined with the diffusion of the smart full-electric house concept including embedded generators and storage systems (typically operating in DC), could modify the present AC paradigm towards the partial use of DC distribution schemes. The end-user system architecture based on the solid state transformer seems an interesting solution to suitably supply both future DC appliances and present AC devices. This approach ensures high performances in terms of voltage stability and power quality of household buses, whereas high safety levels are obtained through the galvanic insulation. The paper investigates the active role that this kind of future customers may have in the future ancillary services market. With the proposed architecture, domestic endusers are able to support the frequency stability, as well as contributing in the network voltage regulation and balancing. Additionally, buses supplying household appliances are negligibly affected by public network perturbations and active end-users have the ability of negotiating with the distribution system operator a controlled power profile at the point of delivery. The control schemes developed by the authors to provide a wide spectrum of ancillary services are detailed in the paper. Dynamic simulations confirm the effectiveness of the proposed approach.