Wide area measurements based centralized controller to stabilize an inverter fed islanded microgrid

In this paper, a wide area measurements based multi-input multi-output (MIMO) centralized controller has been proposed to stabilize an inverter fed islanded microgrid. The centralized controller utilizes synchronized measurements supplied by phasor measurement units (PMUs) through the wide area measurement system (WAMS). In order to reduce the costs associated with the installation of the PMUs, reduced set of input/output signals have been obtained using geometric measures approach. The design of the controller is based on a linear quadratic Gaussian (LQG) control, which targets the modes of interest directly. The islanded AC microgrid comprises of four low inertial inverter interfaced DGs having unequal power ratings and is supplying both active as well as passive loads. To demonstrate this, a full dynamical linearized small signal state space model of the islanded AC microgrid represented in synchronous (DQ) reference frame has been considered. However, reduced order model of the islanded AC microgrid has been obtained using schur balanced model order reduction method to reduce the complexity in the design of the proposed centralized controller. The performance of the proposed centralized controller has been assessed through eigenvalue analysis and time domain simulations. The robustness of the proposed centralized controller has been verified by assessing its performance under different load disturbances.