Robust Decentralized Output-Feedback Type LQR Voltage Controller for Inverter-Based Microgrid

Microgrids (MGs) provides an interconnection of energy consuming components like various loads and generation components i.e. microsources (MSs) preferably the renewable energy resources (RESs) viz. solar PV and wind turbines. These RESs are interfaced to the low voltage (LV) distribution system through power electronics inverters. During islanded operation of MG, voltage and frequency control are of utmost importance. This paper presents a voltage regulation strategy based on the principle of robust decentralized output-feedback type controller implemented as linear quadratic regulator (LQR). It considers various uncertainties viz. load variation and deviations in the neighboring bus parameters within the MG to obtain a robust optimal operation. A standard MG model having two inverter based sources with dedicated RLC type loads is taken as the test system. The Matlab/Simulink based simulation of various test cases viz. set-point tracking under bounded load variation, load perturbation and neighboring bus dynamics are performed to verify the effectiveness of the proposed voltage controller.