A cogeneration scheme with biogas and improvement of frequency stability using inertia based control in AC microgrid

Abstract

Abstract Currently, penetration of the renewable energy sources (RES) like solar photovoltaic (PV) panels, wind turbine-based plants is increasing in the conventional power grid to combat pollution, global warming, and to enhance energy sustainability. Fast power electronic converters are necessary to extract power from these sources which do not have any inertia. When more renewable sources are connected to the power grid, it reduces the effective system inertia which results in unacceptable grid frequency changes for any transient. This leads to frequent tripping, cascading fault, and instability of the overall system which can create large-scale blackouts. This work is related to the generation of physical inertia through the biogas plant and emulates inertia from the dc-link capacitor to control the rate of change of frequency (RoCoF) under abrupt load change. The stored energy in a biogas plant and dc-link capacitor in an AC microgrid (MG) can support momentary power requirement which improves the transient performance of grid frequency under unavailability of PV power. A storage system can help to compensate for abrupt frequency change during transient but due to its higher cost and relatively lesser lifetime, these systems can’t be relied upon in the long run. The proposed scheme of cogeneration and frequency control can provide better performance which is simulated in MATLAB 2013 (b). The control system is implemented in hardware using NI-cRiO 9082 in 500 W AC MG which shows 53.57% improvement in RoCoF which complies with the requirement of IEEE/IEC 60255-118-1.