Operation Control and Analysis of a Hybrid AC/DC Microgrid.

Distributed renewable energy production is making smart microgrid concepts based on AC, DC, and hybrid-MG design more attractive (DRE). In light of the growing population and the pressing need to minimize the load, research into effective control techniques and architectural solutions is a hot topic right now. "However, a comprehensive and coordinated literature assessment of hierarchical control approaches based on diverse configurations of the microgrid (MG) architecture has been explored relatively little in the past.'' Primary, secondary, and tertiary methods to MG system control are outlined in this suggested method. Primary, secondary and third-tier techniques are examined for each MG structure in a short literature review. In addition, the paper offers the best and worst aspects of current control methods. In addition, a simulation research connected to the literature review's future trends in MG control is offered as a further contribution to this subject. Since renewable energy supplies are intermittent in nature, a hybrid microgrid is needed to minimize overall deficit inadequacies and increase system dependability. This is due to the depletion of natural resources and to the intermittent nature of renewable energy resources. Using a hybrid microgrid, the present distributed and concentrated load situations may be accommodated. In order to better understand how the hybrid microgrid may be integrated, optimized and controlled, there is a growing demand for research. It is necessary to do a thorough evaluation of the performance, efficiency, dependability, security, design flexibility, and cost-effectiveness of a hybrid microgrid. Issues such as AC and DC microgrids integrating into a single hybrid microgrid are discussed in this paper, as well as how to manage renewable energy resources in a cost-effective manner and how to place the optimal number of feeders in a microgrid. There is a quick overview of the primary research fields, with the goal of finding the research gap that may further enhance the grid's performance. ''New hybrid microgrid solutions are being offered in light of current study trends that have been determined to be the most effective and most-friendly." Research, comparative analysis, and further development of new methodologies related to hybrid microgrids will be aided by this study as the foundation for future work

Global Sliding-Mode Control with Fractional-Order Terms for the Robust Optimal Operation of a Hybrid Renewable Microgrid with Battery Energy Storage

The efficiency of hybrid microgrid systems is drastically affected by the number of power electronics converters interfacing with its components. Integrating distributed energy sources with microgrids with the optimal number of converters is crucial to minimizing the switching losses and power conversion stages, thereby improving the efficiency of the systems. This paper considers an efficient and economical configuration for a wind/solar photovoltaic (PV) system integrated with a battery energy storage system (BES). The PV system is connected directly to the DC-link, thus lowering the losses and cost by eliminating the PV boost converter. In the literature, only a few publications have investigated this effective microgrid configuration. In addition, none of the publications have developed a nonlinear control approach for the microgrid configuration. Due to the greater flexibility of fractional calculus in speeding up the system response and improving the robustness, this article proposes a global sliding-mode control method with fractional-order terms (GSMCFO) to enhance the transient, steady-state, and robust operation of the hybrid microgrid. This controller provides the maximum power point tracking (MPPT) of both the solar PV and wind power generators, regulates the DC-link voltage, ensures proper power transfer to the grid, and maintains the power balance. In addition, the GSMCFO guarantees the global stability of the hybrid microgrid. Furthermore, considering the simplicity, robustness, few control variables, and fast convergence rate of the differential evolution (DE) optimization method, it is utilized to optimize the performance of the GSMCFO. The proposed hybrid microgrid configuration under the action of the GSMCFO was simulated in MATLAB/SIMULINK. Various scenarios were investigated to illustrate the feasibility of the proposed scheme. The simulation results show that the GSMCFO can achieve superior dynamic performances than the proportional–integral (PI) controller with zero overshoot, a shorter settling time, and stronger robustness, thus improving the power balance of the hybrid microgrid.

Research on Voltage Stabilizing Control Strategy of Critical Load in Unplanned Island Based on Electric Spring

Aiming to solve the problem of voltage fluctuation of critical load caused by lack of control when an unplanned island occurs in a microgrid, a voltage stabilizing control strategy of critical load based on electric spring is proposed in this paper. When unplanned islanding occurs in a microgrid system, the system bus voltage fluctuates dramatically due to instantaneous power imbalance, compromising the power supply safety of important loads on the bus. In this paper, the electric spring control mode is integrated into the voltage stabilizing control strategy of critical loads in an unplanned island for the first time to realize the protection of critical loads. First of all, a model of an optical storage AC/DC hybrid microgrid is built, the overall system architecture is determined, and the microgrid is divided into four working states. Second, the working principle of electric spring is introduced, and a decoupling control strategy based on double closed loop is proposed. Finally, the experimental simulation of the proposed control strategy is experimentally simulated in Matlab/Simulink environment. The simulation findings show that when the bus voltage and current of microgrid change due to an unplanned island, the proposed control strategy based on electric spring may achieve the stability of voltage and current on critical loads.

Distributed Economic Control for AC/DC Hybrid Microgrid

In this paper, a new double-layer droop control mode for island AC/DC microgrids is proposed to realize autonomous and cost-effective operation. The optimal power reference iterative algorithm is used to realize the internal active power distribution in the subnet. On this basis, secondary frequency and voltage adjustments are introduced to realize the economic operation, autonomy and stability of the subnet. At the microgrid level, the local control strategy of cost micro increment deviation is designed to optimize the exchange power between subnets. The cooperation of the two can realize the global economic operation of the microgrid, as well as voltage following and frequency regulation in the subnet. Based on the hybrid AC/DC microgrid simulation model, the effectiveness of the proposed method is verified.