Primary frequency control and dynamic grid support for vehicle-to-grid in transmission systems

Because of vehicle-to-grid (V2G) growth, the provision of ancillary services by V2Gs is now required in the most recent network codes. A lack of primary frequency control (PFC) and dynamic grid support (DGS) in V2Gs could thus be detrimental to power system stability. This research presents a detailed V2G model with a hybrid energy storage system (HESS). The main contribution of the model is the simultaneous provision of PFC and DGS at its plug-in terminal. PFC includes both droop response (DR) and inertial response (IR). Accordingly, a frequency management system (FMS) determines the command of the V2G converter control for PFC without disturbing the scheduled charging-discharging. Simultaneously, this control enables DGS. The design of a new model for connecting V2Gs at transmission level allows the assessment of power system stability. This research study analysed the stability of an IEEE 39 bus system with 30% V2G penetration after critical contingencies. Various strategies for providing ancillary services in V2Gs (DGS and/or PFC) were compared in two scenarios defined by extreme V2G operating modes (as load or generator) at different locations. An analysis of the impact of each ancillary service as well as their interaction was performed to measure their influence on both system stability and critical operating variables of V2Gs. The results showed that system stability remained almost invariable when the V2Gs included PFC (DR+IR) and DGS.