This paper presents a robust H∞ control technique for an islanded microgrid in the presence of sudden changes in load conditions. The proposed microgrid scheme consists of a parallel connected inverter with distributed generations. When the load is suddenly changed the frequency deviates from its nominal value. The objective is to design a robust frequency droop controller in order to achieve the frequency at nominal values without using any secondary controller and communication systems while improving power sharing accuracy. Small signal modeling of the power system is designed for the formulation of the problem and the H∞ optimal linear matrix inequality technique is applied in order to achieve the objectives. The proposed controller has been tested with the MATLAB/ SimPowerSytem toolbox.

The future of power systems depends on the microgrid (MG) which includes distribution generators utilizing Renewable Energy Resources (RERs) and storage facilities. Decentralized control techniques are more reliable and stable in comparison with centralized controlled techniques. In this paper, a decentralized control strategy is presented for an islanded AC MG system. The control strategy includes improved droop control and virtual impedance. Control strategy with PI controllers to control the voltage and current is implemented to two Voltage Source Inverter (VSI) distribution generation units connected in parallel through a Point of Common Coupling (PCC). Circulating current and power-sharing deviations caused by the mismatched line impedance were taken into account. The proposed control scheme was tested in MATLAB/Simulink. Power-sharing accuracy and circulating current suppression were obtained by implementing the proposed virtual impedance-based decentralized control strategy.

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This paper presents the design of a Multi-Input Multi-Output (MIMO) PID controller for a twin-rotor MIMO system. A multivariable control system consisting of two loops is designed for a non-linear system with two inputs and two outputs. The designed controllers have been tested on a simulated model with different possibilities and real-time results were taken. The designed PID controller efficiently controls the loops of the system and does not suffer from any process interactions. The results indicate that the performance of the PID controllers is excellent and both the transient and the steady-state enactment are adequate. The yaw and pitch rotor’s real-time responses are almost the same as the desired ones.

Microgrids (MGs) are the emergent solution to overcome the current electricity demand. The MGs provide the facility to operate in both isolated and grid-connected modes. For both operating modes, Distributed Generation (DG) inverters are operating under grid forming or grid following control modes. During mode switching, the MG experiences enormous fluctuations, which occur due to the unidirectional islanding event. This paper presents a control strategy by using the modified power control scheme, current controller, and DC linked voltage controller scheme to ensure the operational mode transfer smoothly from the grid-connected to the islanded mode and vice versa. The proposed control scheme is applied to a three-phase distributed energy resource-based MG system with fixed loads. The simulation results validate the effectiveness of the control technique while tested at the point of common coupling and also at the time of mode transfer.