Examining the Capability of a Large-Scale Solar PV Plant for Providing Frequency Support Service

Maintaining power system stability and reliability using traditional techniques is getting outdated with a perpetual increase in renewables and retiring synchronous generators. Disconnecting renewable plants, including solar PV, is still a common practice in case of significant system disturbances. However, in a 100% renewable scenario, these plants must provide continuous voltage and frequency support. With changing system strength conditions, evaluating whether solar plants can provide frequency support in different system strength conditions is essential. This paper examines the capability of large-scale solar PV to provide frequency support in weak, strong, and very strong system strength conditions. A droop mechanism is used to control the solar PV plant in a single-machine infinite bus (SMIB) system under various contingency events like transmission line faults and sudden load increase and decrease to create over and under-frequency events. The system was modelled and simulated in the PSCAD analytical software tool. It is concluded that the large-scale solar PV plant can provide frequency support after all disturbances not only in strong and very strong grid conditions but also in weak grid conditions.