Operation of a PTG plant under power scheduling

This paper presents a dynamic simulation study of the operation of a Power-to-Gas process. The process consists of three parallel 3MW alkaline electrolyzers driven by real-life national grid frequency data. These feed H2- and O2- compressor trains and storages processes followed by a methanation reactor. The process is controlled on two levels, where on the lower level stabilizing controllers are utilized to control e.g. flows and pressures by manipulation of e.g. valves and compressors. On the higher level, an operational scheduling of the electrolyzer operation is used. On this level the process can be operated as a primary grid frequency control reserve. To meet the local grid balancing needs, scheduling when to operate in frequency control could be determined beforehand from cost-efficient bidding in the local Electricity Spot and Regulation Power Markets. We assess a 24 hour period, in which the process operates to and from frequency control, from the point of view of how well the process can dampen variations. More precisely the effect of this operational scheduling on the electrolyzers, H2-storage system and CO2-methanation reactor is studied. Modelling of the process is done with a commercial, dynamic process simulator, Apros[...].