Decentralized Output-Feedback-Based Robust LQR V-f Controller for PV-Battery Microgrid Including Generation Uncertainties

Maintaining nominal voltage and frequency (V-f) for an isolated microgrid (MG) with photovoltaic (PV)-battery system needs stringent control arrangement due to generation arbitraries of renewable energy sources. In present article, a robust V-f controller based on decentralized output-feedback optimal linear quadratic regulator principle is proposed. As state-feedback is not involved, it avoids the usage of any estimator or observer, which makes it computationally more efficient. Moreover, its decentralized structure works on local parameter measurements that eliminate expensive communication infrastructure, making it economical. All possible uncertainties from both source and load sides, neighboring bus parameters are considered for V-f regulation using the resistive-droop mechanism that is more accurate for low voltage resistive network. For this purpose, a novel lower-order simplified small-signal MG model including two PV-battery with exclusive parallel RLC loads and LV network is used, which accounts for intermittency as variable dc-bus link dynamics. The whole MG model is segregated into two subsystems with inclusion of interconnection dynamics. The viability of proposed controller is verified by comprehensive tests, viz., variable solar irradiance, voltage set-point tracking under continuous-bounded and large-scale load perturbations, nearby bus parameter disturbances using hardware-in-the-loop simulations with real-time digital simulator and MATLAB via dSPACE controller.