Impact of domestic frequency responsive demand on the Shetland Islands network frequency stability

This paper evaluates the impact of domestic frequency responsive demand (FRD) on the frequency stability of the Shetland Islands network and investigates the potential increase in wind generation that FRD may enable. To conduct this study, a dynamic model of the Shetland network, including an FRD dynamic user-defined model that reflects the physical characteristics of installed FRD, is implemented in dynamic simulation software. A number of scenarios derived by varying system demand levels, generator status, and the available FRD are considered. A performance assessment of network frequency stability has been conducted by observing the frequency nadir under different disturbances and operational conditions. The results of the preliminary studies suggest that installation of FRD benefits the Shetland system in terms of improving the frequency stability and that this may potentially allow additional wind generation to be accommodated, hence reducing reliance on fossil fuel consumption at the islands' main generation sources.