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Renewable energy-based energy conversion technologies have become more relevant due to environmental considerations even though they are intermittent in nature. As a result, the concept of microgrid and microgrid control techniques have been evolved as major areas of power system research. Among different inverter control methods, the droop-based control method is more popular in microgrid systems due to its simplicity and non-requirement of expensive communication systems. The transient performance, power-sharing accuracy and decoupling between real and reactive power are improved by modifying the natural droop control method. In this study, the selected microgrid system consists of two inverters operating in parallel, two interconnecting lines and three loads. A state-space model of the microgrid is created based on the small-signal stability and the transient response is improved by introducing virtual impedance and dynamic droop gains. The different controller parameters are optimised using particle swarm optimisation ensuring stability. Eigenvalue analysis is done to analyse stability. The analysis of the response of the system for various disturbances validates the effectiveness of the proposed controller. The strategy developed ensures improved power-sharing capability with high values of natural droop gains without compromising stability by using optimised dynamic droop gains.

Droop control is widely used for inverter dominated microgrid due to its simplicity and lack of expensive communication interfaces. It mimics the governor action of alternator by controlling frequency and magnitude of voltage to regulate active and reactive power flow respectively. A reduced order small signal model is developed for a microgrid system with two inverters, two interconnecting lines and three loads. The stability of the system is improved by the optimal setting of droop gains using particle swarm optimization after defining suitable objective function. The eigenvalues which are present near imaginary axis are shifted towards left using state feedback control for improving stability. Hence a new control scheme is proposed in this paper by combining state feedback control with droop control to improve the transient performance. The response of the system for change in load current verifies the effectiveness of the proposed control method.

The concept of microgrid has become more relevant due to the increase in the use of distributed energy resources. However, the important factors which are to be considered are their ability to control the power flow and stability of the system. Droop control strategy requires no communication system and realizes the “plug and play” function between source and load. In this paper a state space model of such a system is developed based on small signal disturbances. Eigenvalue analysis of the system is also done and the parameters which determine the stability of the system are identified. The optimum values of these parameters are found out by increasing the stability of the system using particle swarm optimization (PSO) technique. The simulation is done by MATLAB coding and the results show that the values of the optimized parameters will improve the stability of the system by shifting the eigenvalues away from the imaginary axis as far as possible on the left half of s plane.