This paper applies a new state feedback control to a Distributed secondary voltage and frequency control in an islanded microgrid. The problem is focused on the output consensus of the multi-agent systems, which is converted to a first-order dynamic system. The inverter-based Distributed generations play as agents in the proposed control strategy. It is assumed that the Distributed generators communicate through a communication network modeled by a directed graph (digraph). The Distributed output consensus is used to design the secondary controllers. Such innovative controllers synchronize Distributed generators' output voltages and frequencies to their reference values by a novel state feedback approach. Compared to the existing consensus protocols, the proposed method provides a different innovative solution to the secondary voltage and frequency control of microgrids, which has a better response in case of communication failures. Finally, extensive and comparative simulations have been presented to verify the validity of the proposed control strategy and the system performance.

Due to the widespread adoption of DC source-based Distributed energy resources (DERs) and loads, alongside advancements in power electronics technology, DC microgrids (DC MGs) have recently gained significant attention. To effectively implement DC MGs, it is crucial to employ a suitable control strategy that maintains the bus voltage at the desired level and ensures appropriate power sharing among the integrated DERs. To address these objectives, a two-layer control scheme is proposed in this paper. In the primary layer, a customized droop control scheme is introduced, which applies lower voltage drop in comparison to the conventional droop strategies. Simultaneously, in the secondary layer, a modified voltage controller  which is supplemented by a term to enhance power sharing in a Distributed manner is employed,. The proposed control strategies are characterized by their simplicity and low communication infrastructure requirements. To assess the efficacy of the proposed control architecture, several case studies, including plug and play integration, load variations, and communication challenges, including link disconnection and noise effects, are conducted. Additionally, the performance of the proposed strategies is benchmarked against an architecture featuring conventional primary droop control and cooperative Distributed secondary control approaches. The simulation studies conducted in MATLAB/SIMULINK software demonstrate that the proposed control methods outperform the alternative approaches, confirming their effectiveness in maintaining voltage regulation and power sharing objectives.

The steady state error in voltage amplitude and frequency and improper reactive power sharing are main disadvantages of droop control in primary level of control of Distributed resources (DERs) in microgrid. secondary control can compensate these problems. In contrary to centralize control, Distributed secondary control may bring merits such as reliability, flexibility and scalability improvement. The Distributed secondary control is usually implemented using consensus algorithm whose communication network is very important. Communication network is usually modeled continuously with a constant transfer rate. In this paper, the consensus algorithm with communication network are implemented in discrete domain because of discrete nature of them. Two aperiodic data transfer strategies state dependent and state independent are also proposed for releasing communication network burden where data rate is not fixed. Time delay as a non-desirable effect is evaluated. The proposed method applied on an islanded microgrid, and simulation results show the effectiveness of the proposed method.

Today, in many control methods, neighboring system information is used for better control and synchronization between different units, and therefore, in the access and transmission of information through communication links, problems such as disruption, uncertainty, noise, delay, and cyber-attacks occur. In this paper, the effect of the Denial of Service (DoS) cyber-attack on the microgrid in island mode is investigated and a cooperative Distributed hierarchical controller is designed with the presence of this cyber-attack. Distributed Generations (DGs) have been analyzed with the help of multi-agent systems and the communication network between them using graph theory. The effects of the DoS cyber-attack on the model of DGs are mathematically formulated and in proving the stability and synchronization of frequency and voltage, the suitable Lyapunov function is presented and the stability analysis of DGs against these cyber-attacks is performed and the stability and synchronization conditions of DGs are proved. To confirm the proposed theoretical issues, a case study model is simulated despite the DoS attack on the communicative links in Matlab Simulink, and the results show the performance of the designed controller in different conditions.

Dedicating more attention to renewable energies and power electronic improvements results in increased direct current microgrids (DC MGs) application. However, DC MGs have some challenges with voltage adjustment and power sharing. To do so, a two-layer hierarchical control structure, including a new fully Distributed secondary control strategy and conventional primary droop control method, is proposed and employed in this paper to share power and swiftly adjust the voltage accurately. Indeed, a Distributed-averaging proportional-integral (DAPI) secondary control strategy is introduced. Another problem in DC MGs is the existence of constant power loads (CPLs), which may result in instability. To overcome the problems caused by CPLs, a term based on the output voltage of CPL is added to the proposed DAPI to prevent instability. The required control inputs are obtained using localized data of the DC bus and their neighbor’s secondary control inputs inspired by cooperative control. Besides, this strategy needs no knowledge of the microgrid topology, which enhances flexibility. For validating the proposed DAPI strategy in DC MGs, an islanded DC MG is simulated in the MATLAB/SIMULINK software. Comparing the results with those obtained from another existing method proves the performance of the proposed DAPI controller under different scenarios of plug-and-play, communication failure, and load changes.

DC Microgrid is turning out to be more popular due to its appealing features such as high efficiency, excellent power quality, low cost and controllability. As the control strategies plays a key role in achieving the desired objectives such as power quality, power sharing, voltage regulation and efficiency. It is necessary to understand the classification and operation of control strategies in DC microgrids. From the control point of view, the traditional droop control methods are commonly employed for regulating proportional load sharing. However, depending on the primary control makes it challenging to maintain stable and coordinated operation in terms of maintaining both the voltage regulation and load sharing accuracy simultaneously in DC microgrids. So to avoid the trade-off in voltage regulation and power sharing accuracy, secondary control layers need to be introduced in the control structure. In this paper a review of primary control and secondary control methods (centralized, decentralized and Distributed control) were discussed in detail with the classification along with the advantages and shortcomings of the control methods.

This paper proposes a novel Distributed adaptive secondary controller for microgrids (MGs) in islanded operation. To enhance the dynamic behaviour of a microgrid considering uncertainties and disturbances, the proposed controller uses a consensus-based adaptive control structure. A novel consensus protocol is proposed to restore the frequency and voltage (f &V) of a microgrid to their rated values. A Lyapunov function is presented to assure the asymptotic stability of the controller and the ultimate boundedness of the global neighborhood consensus error. The nonlinear nature of MGs has been also considered in the algorithm. Unlike other methods in this field that require complete information of Distributed generators (DGs), the proposed controller requires only power droop coefficients and is independent of DGs parameters. Different simulations are conducted in MATLAB/SimPower Toolbox on a typical microgrid and under various disturbances to judge the performance of the adaptive controller. The simulation results show the effect of the proposed controller on increasing the resilience of an MG.

The operation of Fuel Cell Distributed Generation (FCDG) systems in distribution systems is introduced by modeling, controller design, and simulation study of a Solid Oxide Fuel Cell (SaFe) Distributed generation (DG) system. The physical model of the fuel cell stack and dynamic models of power conditioning units are described. Then, suitable control architecture based on fuzzy logic control for the overall system is presented in order to active power control and power quality improvement. A MATLAB/Simulink simulation model is developed for the SOFC DG system by combining the individual component models and the controllers designed for the power conditioning units.Simulation results are given to show the overall system performance including active power control and voltage regulation capability of the distribution system.