Dynamic Virtual Power Plant Design for Fast Frequency Reserves: Coordinating Hydro and Wind

To ensure frequency stability in future low-inertia power grids, fast ancillary services, such as fast frequency reserves (FFR), have been proposed. In this work, the coordination of conventional (slow) frequency containment reserves (FCR) with FFR is treated as a decentralized model-matching problem. The design results in a dynamic virtual power plant (DVPP), whose aggregated output fulfills the system operator's (SO's) requirements in all time-scales, while accounting for the capacity and bandwidth limitation of participating devices. This is illustrated in a 5-machine representation of the Nordic synchronous grid. In the Nordic grid, stability issues and bandwidth limitations associated with nonminimum phase zeros of hydropower is a well-known problem. By simulating the disconnection of a 1400 MW importing dc link, it is shown that the proposed DVPP design allows for coordinating fast FFR from wind, with slow FCR from hydro, while respecting dynamic limitations of all participating devices. The SO's requirements are fulfilled in a realistic low-inertia scenario without the need to install battery storage or to waste wind energy by curtailing the wind turbines.