Reliability assessment of PV units in primary and secondary frequency control ancillary services

Recent studies have demonstrated how storage-less PV units have the technical capability to contribute to grid frequency control. However, system operators have stringent criteria for the dynamic response as well as the availability of the assets participating in these ancillary services. In this paper, we propose a methodology to assess and certify the impact of storage-less PV units on grid frequency regulation when the primary energy source availability is uncertain. The proposed approach is based on a first-principle dynamic model that is independent of the specific control strategy employed in the PV units, together with a statistical analysis of real data of power forecast error. The resulting methodology can be used to pre-qualify PV participation in the ancillary service market. The proposed approach is illustrated using real data and specifications from the Swiss transmission system operator.