An Improved Droop Control Method to Enhance Dynamic Performance of AC Microgrid

The sources, interfaced with the microgrid using power electronic converters have inherently low physical inertia. With step variation in load demand, voltage and frequency difference are created among the sources during transient and the low frequency oscillations appear in the power supplied through the interconnecting lines. This may even lead to false triggering of fault protection system. To suppress these transient in powers and to improve dynamic response of microgrid in islanded mode, a modified droop controller which uses dynamic variation in droop gains of active power frequency ( P-ω) characteristics is proposed. The variation of droop gains is based on the rate of change of active power supplied by the corresponding source. Key advantages offered by the modified droop controller are improved dynamic response with reduced peaks in power supplied by the sources during step change in load power demand. The effectiveness of the proposed technique is demonstrated using linearized model derived for microgrid taking into account the dynamics of proposed controller, loads and distribution network. The root loci plots are used to study the behavior of the AC microgrid with respect to variation in parameters of proposed controller. The effectiveness of the controller is validated using simulation study in Simulink/Matlab for a microgrid test model.