Frequency Provision with Low-Inertia Hybrid Power Plants: Identifying Gaps in the Standards

Dramatic inertia reduction suffered in worldwide grids caused by the transition towards renewable and distributed generation, raises the risk of disturbances and blackouts due to frequency related issues. Subsequently, ENTSO-E has recently published several documents stating rules and recommendations regarding frequency support; such documents highlight the importance of developing new techniques in a grid dominated by generators with a power electronic-based interface. In fact, they are considered the first guidelines of an up-coming frequency control standard, which contemplates the possibility of having renewable and hybrid plants providing frequency stability as an ancillary service; but also proposes a new terminology and establishes the path to be followed in the following years. Therefore, the main goal of this paper is to assess the suitability of requirements provided in current standards.
The paper critically reviews the last releases of ENTSO-E regarding frequency regulation and ancillary services provided by renewable and HyPP, identifies issues and points out gaps that have not been considered so far. Thereafter, a new approach aiming to avoid second and subsequent frequency dips after a large excursion is proposed.