Study of centralized and distributed coordination of power injection in multi-TSO HVDC grid with large off-shore wind integration

This paper studies centralized and distributed schemes for the coordination of power injection in an HVDC grid connected to large wind generation. This coordination of power injection aims to keep the power balanced within the HVDC grid especially during large wind disturbances. Furthermore, the coordination tries to follow the converters' schedules set by the connecting AC-TSOs every 15-min. This schedule comes from an overall combined AC/DC economic dispatch calculation with lower resolution compared to this coordination. In this paper, the coordination of power injection has been formulated as a non-linear constrained optimization problem for the centralized architecture. Next, the centralized optimization problem is decomposed to sub-problems using the Auxiliary Problem Principle (APP) method for the distributed architecture. This distributed optimization problem is solved by exchanging the required information between the AC TSOs. These two different approaches have been evaluated for a 5-terminal HVDC grid. Furthermore, a sensitivity analysis has been carried out to find the optimal updating rate of power injection set-points. The result shows that the more frequent updating of power injection coordination in the centralized architecture improves the generation reserves in each AC area. (C) 2016 Elsevier B.V. All rights reserved.