Supplementary Frequency Control for Low Inertia Power Systems

The energy matrix is rapidly changing in recent years mainly due to concerns with the environment. The participation of renewable resources connected to the power system via frequency inverters is increasing, adding new challenges to the power systems operation and control. The system inertia reduction as a result of the conventional synchronous generators replacement makes the system more susceptible to frequency variations, leading to the deterioration of the system dynamic response. In this paper, a control scheme is proposed, aiming to improve the system frequency response after disturbances. The control scheme is based on the online identification of a system model. Changes in system inertia, resulting from changes in the dispatch of renewable sources and disconnection of conventional sources, are taken into account by the periodic update of the identified model. A design method is applied to update the control in order to limit frequency excursions and improve dynamic response. The impact of PMUs and transmission latency on the control performance are also evaluated. Simulations are performed in order to validate the proposed approach.