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1
Zhao i Wang. "Comprehensive Evaluation of AC/DC Hybrid Microgrid Planning Based on Analytic Hierarchy Process and Entropy Weight Method". Applied Sciences 9, nr 18 (12.09.2019): 3843. http://dx.doi.org/10.3390/app9183843.
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The comprehensive evaluation of AC/DC hybrid microgrid planning can provide reference for the planning of AC/DC hybrid microgrids. This is conducive to the realization of reasonable and effective microgrid planning. Aiming at comprehensive evaluation of AC/DC hybrid microgrids, this paper establishes an evaluation index system for planning of AC/DC hybrid microgrids. This paper combines the subjective evaluation method with the objective evaluation method, and proposes a comprehensive evaluation method of AC/DC hybrid microgrid planning based on analytic hierarchy process and the entropy weight method. Finally, the validity and rationality of the evaluation method are verified by an example.
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Barros, J. Dionísio, Luis Rocha i J. Fernando Silva. "Backstepping Predictive Control of Hybrid Microgrids Interconnected by Neutral Point Clamped Converters". Electronics 10, nr 10 (19.05.2021): 1210. http://dx.doi.org/10.3390/electronics10101210.
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In this work, DC and AC parts of hybrid microgrids are interconnected by a neutral point clamped—NPC converter controlled using a new backstepping predictive (BP) method. The NPC converter is controlled to operate in the DC microgrid voltage control mode or in the AC microgrid power control mode. The novel backstepping predictive controller is designed using the dq state space dynamic model of the NPC converter connected to the hybrid microgrid. The designed BP controller regulates the DC voltage or AC injected power, balances the capacitor voltages, controls the AC currents, and enforces the near unity power factor. Simulation (MATLAB/Simulink) and experimental (laboratory prototype) results show that the converter can regulate the DC voltage in the DC microgrid interconnection point, by adjusting the AC power conversion to compensate variations on the loads or on the distributed renewable energy sources in the DC microgrid. AC currents are sinusoidal with low harmonic distortion. The obtained BP controller is faster at balancing capacitor voltages than PWM (pulse width modulation) control with carrier offset. The fast AC power response allows the converter to be used as a primary frequency regulator of the AC microgrid. This research is appropriate for power and voltage control in hybrid microgrids with renewable energy.
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Jadidi, Saeedreza, Hamed Badihi i Youmin Zhang. "Passive Fault-Tolerant Control Strategies for Power Converter in a Hybrid Microgrid". Energies 13, nr 21 (27.10.2020): 5625. http://dx.doi.org/10.3390/en13215625.
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Control of AC/DC pulse-width modulation (PWM) power electronic converter, referred to as “AC/DC PWM converter”, is vital to the efficient regulation of power flow between AC and DC parts of a hybrid microgrid. Given the importance of such converters in AC/DC microgrids, this paper investigates the design of fault-tolerant control for AC/DC PWM converters in the presence of microgrid faults. In particular, two novel fault-tolerant schemes based on fuzzy logic and model predictive control are proposed and implemented in an advanced hybrid microgrid benchmark in MATLAB/Simulink environment. The considered hybrid microgrid consists of dynamic loads and distributed energy resources including solar photovoltaic arrays, wind turbines, and battery energy storage systems. The proposed schemes especially target the fault effects due to common power-loss malfunctions in solar photovoltaic arrays in the presence of microgrid uncertainties and disturbances. The effectiveness of proposed fault-tolerant control schemes is demonstrated and compared under realistic fault scenarios in the hybrid microgrid benchmark.
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Chang, Fangyuan, John O’Donnell i Wencong Su. "Voltage Stability Assessment of AC/DC Hybrid Microgrid". Energies 16, nr 1 (29.12.2022): 399. http://dx.doi.org/10.3390/en16010399.
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AC/DC hybrid microgrids are becoming potentially more attractive due to the proliferation of renewable energy sources, such as photovoltaic generation, battery energy storage systems, and wind turbines. The collaboration of AC sub-microgrids and DC sub-microgrids improves operational efficiency when multiple types of power generators and loads coexist at the power distribution level. However, the voltage stability analysis and software validation of AC/DC hybrid microgrids is a critical concern, especially with the increasing adoption of power electronic devices and various types of power generation. In this manuscript, we investigate the modeling of AC/DC hybrid microgrids with grid-forming and grid-following power converters. We propose a rapid simulation technique to reduce the simulation runtime with acceptable errors. Moreover, we discuss the stability of hybrid microgrids with different types of faults and power mismatches. In particular, we examine the voltage nadir to evaluate the transient stability of the hybrid microgrid. We also design a droop controller to regulate the power flow and alleviate voltage instability. During our study, we establish a Simulink-based simulation platform for operational analysis of the microgrid.
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Pan, Hao, Ming Ding, Rui Bi i Lei Sun. "Research on Cooperative Planning of Distributed Generation Access to AC/DC Distribution (Micro) Grids Based on Analytical Target Cascading". Energies 12, nr 10 (15.05.2019): 1847. http://dx.doi.org/10.3390/en12101847.
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With the wide application of distributed generation (DG) and the rapid development of alternating current/direct current (AC/DC) hybrid microgrids, the optimal planning of distributed generation connecting to AC/DC distribution networks/microgrids has become an urgent problem to resolve. This paper presents a collaborative planning method for distributed generation access to AC/DC distribution (micro) grids. Based on the grid structure of the AC/DC distribution network, the typical interconnection structure of the AC/DC hybrid microgrid and AC/DC distribution network is designed. The optimal allocation models of distributed power supply for the AC/DC distribution network and microgrid are established based on analytical target cascading. The power interaction between the distribution network and microgrid is used to establish a coupling relationship, and the augmented Lagrangian penalty function is used to solve the collaborative programming problem. The results of distributed power supply allocation are obtained, solving the problem so that distribution generation with different capacity levels is connected to the power grid system in a single form.
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Azeem, Omar, Mujtaba Ali, Ghulam Abbas, Muhammad Uzair, Ayman Qahmash, Abdulmohsen Algarni i Mohammad Rashid Hussain. "A Comprehensive Review on Integration Challenges, Optimization Techniques and Control Strategies of Hybrid AC/DC Microgrid". Applied Sciences 11, nr 14 (6.07.2021): 6242. http://dx.doi.org/10.3390/app11146242.
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The depletion of natural resources and the intermittence of renewable energy resources have pressed the need for a hybrid microgrid, combining the benefits of both AC and DC microgrids, minimizing the overall deficiency shortcomings and increasing the reliability of the system. The hybrid microgrid also supports the decentralized grid control structure, aligning with the current scattered and concentrated load scenarios. Hence, there is an increasing need to explore and reveal the integration, optimization, and control strategies regarding the hybrid microgrid. A comprehensive study of hybrid microgrid’s performance parameters, efficiency, reliability, security, design flexibility, and cost-effectiveness is required. This paper discusses major issues regarding the hybrid microgrids, the integration of AC and DC microgrids, their security and reliability, the optimization of power generation and load management in different scenarios, the efficient management regarding uncertainty for renewable energy resources, the optimal placement of feeders, and the cost-effective control methodologies for the hybrid microgrid. The major research areas are briefly explained, aiming to find the research gap that can further improve the performance of the grid. In light of the recent trends in research, novel strategies are proposed that are found most effective and cost-friendly regarding the hybrid microgrid. This paper will serve as a baseline for future research, comparative analysis, and further development of novel techniques regarding hybrid microgrids.
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Nallolla, Chinna Alluraiah, Vijayapriya P, Dhanamjayulu Chittathuru i Sanjeevikumar Padmanaban. "Multi-Objective Optimization Algorithms for a Hybrid AC/DC Microgrid Using RES: A Comprehensive Review". Electronics 12, nr 4 (20.02.2023): 1062. http://dx.doi.org/10.3390/electronics12041062.
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Optimization methods for a hybrid microgrid system that integrated renewable energy sources (RES) and supplies reliable power to remote areas, were considered in order to overcome the intermittent nature of RESs. The hybrid AC/DC microgrid system was constructed with a solar photovoltaic system, wind turbine, battery storage, converter, and diesel generator. There is a steady increase in the utilization of hybrid renewable energy sources with hybrid AC/DC microgrids; consequently, it is necessary to solve optimization techniques. Therefore, the present study proposed utilizing multi-objective optimization methods using evolutionary algorithms. In this context, a few papers were reviewed regarding multi-objective optimization to determine the capacity and optimal design of a hybrid AC/DC microgrid with RESs. Here, the optimal system consisted of the minimum cost of energy, minimum net present cost, low operating cost, low carbon emissions and a high renewable fraction. These were determined by using multi-objective optimization (MOO) algorithms. The sizing optimization of the hybrid AC/DC microgrid was based on the multi-objective grey wolf optimizer (MOGWO) and multi-objective particle swarm optimization (MOPSO). Similarly, multi-objective optimization with different evolutionary algorithms (MOGA, MOGOA etc.) reduces energy cost and net present cost, and increases the reliability of islanded hybrid microgrid systems.
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Lotfi, Hossein, i Amin Khodaei. "Hybrid AC/DC microgrid planning". Energy 118 (styczeń 2017): 37–46. http://dx.doi.org/10.1016/j.energy.2016.12.015.
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Rezaei, Omid, Omid Mirzapour, Mohammad Panahazari i Hassan Gholami. "Hybrid AC/DC Provisional Microgrid Planning Model Considering Converter Aging". Electricity 3, nr 2 (7.06.2022): 236–50. http://dx.doi.org/10.3390/electricity3020014.
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Renewable energy deployment through distributed energy resources is among the central goals of future power systems. Microgrids have proven to be an economically viable solution for distributed energy resources’ integration into the power system and benefits customers with uninterrupted power supply. In this context, provisional microgrids have been introduced with the main goal of rapid renewable energy resource deployment. Since a considerable portion of renewable energy resources, as well as residential loads, are DC, and this portion is expected to grow even further, hybrid AC/DC design of provisional microgrids can improve both efficiency and economic benefit through an optimal arrangement of AC/DC feeders and converters. This paper presents a planning model for hybrid provisional microgrids considering the long-term influence of energy storage and the aging process of converters on economic revenues. Due to several intrinsic uncertainties involved in provisional microgrid operation, robust optimization is applied to the problem to ensure optimality under worst-case conditions. Results show the economic benefits of a hybrid provisional microgrid compared to a provisional microgrid and independent microgrid. Several sensitivity analyses are carried out to identify critical factors in planning.
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Vinothkumar, J., i R. Thamizhselvan. "Efficient Power Management and Control Strategy of Hybrid Renewable Energy System in Microgrid". International Journal on Applied Physics and Engineering 2 (17.07.2023): 106–27. http://dx.doi.org/10.37394/232030.2023.2.11.
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Currently, the use of renewable energy has gradually increased due to the environmental problems present nowadays. The intermittency of distributed renewable generation poses significant challenges for the operation and integration of microgrids. Unlike the main power grid, where load balancing resources, in general, are abundant, the balancing of generation and load in a microgrid must be done by small gas turbines, diesel generators, or energy storage devices with very limited capacity and at much higher costs. Consequently, the proposed methodology seeks a model for minimizing the Energy Cost (EC) and enhancing the power supply for rural areas by designing and analyzing four different hybrid system configurations based on integrating a biomass system with a photovoltaic (PV), wind turbine (WT) and battery system. To ensure the desired power demand with minimum production cost, the research proposed an energy-efficient Hybrid DC/AC microgrid using four renewable energy sources. Lithium-ion batteries were chosen for this study due to their high energy density, long life cycle, and high efficiency. The existence of both AC and DC microgrids has led to a new concept of hybrid AC/DC microgrids which consists of both AC and DC grids tied by an Interlinking Converter (ILC). It comprises a DC grid and AC grid interlinked by a bidirectional DC/AC converter. Such a hybrid AC/DC microgrid has the advantages of both AC and DC with increased efficiency and less cost. To provide higher voltages, the Multi-Input Booster (MIB) DC-DC converters are used as a power converter in between load and source to enforce and increase the PV depending on the voltage output signal. Further extract maximum power from the solar PV system, perturb and observe algorithm-based power point tracking control mechanism is proposed DC link voltage of ILC is regulated usually by DC side control in load sharing among sources in the DC microgrid. In addition, to overcome the load fluctuation problem in a microgrid, the research introduced a Mamdani type 2 PID-fuzzy controller. Performance index parameters of the transient response characteristics are also improved by using the proposed control approach. The time-domain dynamic responses reveal that the proposed type-II fuzzy PID controller can balance the power generation and demand properly and control both system frequency and tie-line power effectively.
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Cendoya, Marcelo G., Juan I. Talpone, Paul F. Puleston, Jose A. Barrado-Rodrigo, Luis Martinez-Salamero i Pedro E. Battaiotto. "Management of a Dual-Bus AC+DC Microgrid Based on a Wind Turbine with Double Stator Induction Generator". WSEAS TRANSACTIONS ON POWER SYSTEMS 16 (22.12.2021): 297–307. http://dx.doi.org/10.37394/232016.2021.16.30.
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The topology and management of a sustainable dual-bus, AC and DC, microgrid designed to operate connected to a weak grid is presented. AC+DC hybrid microgrids are a robust and cost-competitive solution for poorly connected areas, as can be found in rural or island electrification. The versatile microgrid proposed in this work is developed around a wind turbine based on a particular induction generator with double stator winding and squirrel cage rotor (DWIG). This singular generator is especially suitable for a combined AC+DC coupled microgrid application. One of its stator windings is coupled to the DC bus via a controlled AC/DC converter. The other is directly connected to the AC bus, only during the periods of abundant wind resource. The DWIG is complemented with photovoltaic panels and a hybrid energy storage system, comprising flow batteries assisted by supercapacitors, which converge to the DC Bus. The DC bus exchanges power with the AC bus through an interlinking inverter. The article describes the topology and details the operation of its Supervisory Control system, which gives rise to the five operating modes of the proposed AC+DC DWIG based microgrid. Its performance under different generation conditions and load regimes is thoroughly assessed by simulation.
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Wang, Hongjun, Wanfeng Li, Youjun Yue i Hui Zhao. "Distributed Economic Control for AC/DC Hybrid Microgrid". Electronics 11, nr 1 (22.12.2021): 13. http://dx.doi.org/10.3390/electronics11010013.
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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.
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Sheng, Wanxing, Yinqiu Hong, Ming Wu i Yu Ji. "A Cooperative Control Scheme for AC/DC Hybrid Autonomous Microgrids". Processes 8, nr 3 (7.03.2020): 311. http://dx.doi.org/10.3390/pr8030311.
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The AC/DC hybrid microgrid (MG) has been widely promoted due to its high flexibility. The capability to operate in islanding mode is an appealing advantage of the MG, and also sets higher requirements for its control system. A droop control strategy is proposed on account of its distinguishing feature of automatic power sharing between distributed generations (DGs), but it introduces some drawbacks. Therefore, distributed cooperative secondary control is introduced as an improvement. In order to optimize the active power sharing in AC/DC hybrid microgrids, a number of cooperative control strategies have been proposed. However, most studies of AC/DC hybrid microgrids have mainly focused on the control of the bidirectional converter, ignoring the effects of secondary control within subnets, which may make a difference to the droop characteristic. This paper extends the cooperative control to AC/DC hybrid microgrids based on normalizing and synthesizing the droop equations, and proposes a global cooperative control scheme for AC/DC autonomous hybrid microgrids, realizing voltage restoration within AC and DC subnets as well as accurate global power sharing. Ultimately, the simulation results demonstrate that the proposed control scheme has a favorable performance in the test AC/DC hybrid system.
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Gupta, Shruti, Dr Malaya S. Das i Dr Anuprita Mishra. "Modeling and Simulation of Hybrid Wind/Photovoltaic for Improvement of Reliability of The DC Microgrid". SMART MOVES JOURNAL IJOSCIENCE 4, nr 8 (5.08.2018): 1–7. http://dx.doi.org/10.24113/ijoscience.v4i8.154.
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This paper presents modeling and simulation of an autonomous DC microgrid in Matlab Simulink environment. The proposed microgrid system consists of a wind turbine, solar PV array ac grid and DC loads. The wind turbine &Ac grid is interfaced to the microgrid with a rectifier and a buck converter which are controlled to maintain a constant DC bus voltage. While the PV array is connected via a boost converter which extracts maximum power from the circuit. the microgrid system also consists of a Energy Storage System (ESS) which is connected via a bidirectional buck-boost converter. The overall stability of the microgrid is maintained by the control action of the ESS. DC microgid system have been analyzed and simulation done using Matlab.
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Shan, Yinghao, Liqian Ma i Xiangkai Yu. "Hierarchical Control and Economic Optimization of Microgrids Considering the Randomness of Power Generation and Load Demand". Energies 16, nr 14 (20.07.2023): 5503. http://dx.doi.org/10.3390/en16145503.
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Hierarchical control has emerged as the main method for controlling hybrid microgrids. This paper presents a model of a hybrid microgrid that comprises both AC and DC subgrids, followed by the design of a three-layered control method. An economic objective function is then constructed to account for the uncertainty of power generation and load demand, and the optimal power guidance value is determined using the particle swarm optimization algorithm. The optimized power output is subsequently used to guide the tertiary control in the microgrid, mitigating potential safety and stability issues. Finally, the performance of each control layer is compared under dynamic changes in AC and DC loads, as well as stochastic variations in power generation and load consumption. Simulation results demonstrate that the hybrid microgrid can function stably, ensuring reliable and cost-effective AC and DC bus voltage supply despite the randomness of power generation and load demand.
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Liu, Hanmin, Zhenyu Wang, Shouxiang Wang, Qi Liu, Guozhong Zhang, Yunfeng Tian, Yu Shen i Qianyu Zhao. "Two Level Control Strategy for Independent AC/DC Hybrid Microgrid Based on Integrated Control". E3S Web of Conferences 256 (2021): 02039. http://dx.doi.org/10.1051/e3sconf/202125602039.
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Aiming at the independent AC/DC microgrid, a simple and effective multi time scale control strategy is proposed by adopting the combination of day ahead scheduling and real-time control. The day ahead scheduling strategy takes the minimum operation cost of AC/DC microgrid as the goal, and schedules the controllable loads in the AC/DC microgrid with particle swarm optimization, which makes full use of renewable energy. The real-time control strategy controls the output of the distributed generation, the load reduction and the switching of the diesel generator according to the real-time energy storage state of charge (SOC), which keep the power balance of the AC/DC microgrid. The effectiveness of the proposed two-level control strategy is verified by a practical AC/DC hybrid microgrid. The results show that the proposed method can make full use of renewable energy and ensure the economic and reliable operation of AC/DC hybrid microgrid.
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Gai, Xinnan, Yali Wang, Renliang Chen i Liang Zou. "Research on Hybrid Microgrid Based on Simultaneous AC and DC Distribution Network and Its Power Router". Energies 12, nr 6 (20.03.2019): 1077. http://dx.doi.org/10.3390/en12061077.
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Under the dual pressure of environmental pollution and energy crisis, the global energy consumption structure reform deepens unceasingly and the concept of energy internet has developed rapidly. The widespread volatility, randomness, and uncertainty of distributed new energy generation impose new requirements on distribution systems. The zigzag transformer is used as the coupling and isolating device for simultaneous AC–DC transmission. The basic principle and structure of simultaneous AC–DC power distribution network is analyzed. The topology structure of the simultaneous AC–DC hybrid microgrid and basic operating principle of the microgrid under different operating modes are proposed for the distributed power grid technology. Combined with power electronic technology, a modular multi-interface structure of power routers applied to AC–DC hybrid microgrid and its control strategy are proposed to realize the power routing control of microgrid and ensure reliable operation control of the microgrid. By building the model of simultaneous AC–DC hybrid microgrid and its power router, the rationality and effectiveness of the power router for microgrid routing control are verified.
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Wang, Zonghao, i Liying Sun. "Design of voltage stabilizing control for a hybrid microgrid with state constraints based on the switching system". Journal of Physics: Conference Series 2474, nr 1 (1.04.2023): 012067. http://dx.doi.org/10.1088/1742-6596/2474/1/012067.
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Abstract With the application and development of new energy generation technology and distributed power supply system, AC-DC hybrid microgrid has the comprehensive advantages of AC microgrid and DC microgrid, and it is significant to study the voltage stability of hybrid microgrid. Based on the switching system theory, the voltage stability control of the ac-dc hybrid micro-grid in grid-connected and the off-grid operation mode are studied in this paper. Considering that the AC and DC bus voltages of the microgrid are constrained in practical engineering applications, the Backstepping controller is designed by using the barrier Lyapunov function and Backstepping method. Considering that the equivalent resistance in the system can not be accurately measured and combined with adaptive control, it is more practical for practical engineering applications.
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Pan, Hao, Ming Ding, Anwei Chen, Rui Bi, Lei Sun i Shengliang Shi. "Research on Distributed Power Capacity and Site Optimization Planning of AC/DC Hybrid Micrograms Considering Line Factors". Energies 11, nr 8 (24.07.2018): 1930. http://dx.doi.org/10.3390/en11081930.
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With the rapid development of AC/DC hybrid microgrids and the widespread use of distributed power resources, planning strategies for microgrids with high-density distributed power generation have become an urgent problem. Because current research on microgrid planning has not considered line factors, this paper analyses the planning of an AC/DC hybrid microgrid based on an AC microgrid. The capacity and siting of the distributed power resources are optimized, taking into account the influence of the line investment cost and the interactive power upper limit on the planning results. In the proposed model, the objective is aimed at minimizing the sum of investment cost, load-loss economic cost, and system losses, taking into consideration power balance constraints and feeder number constraints. The commercial solver CPLEX is applied to attain the optimal distributed power capacity and site. The theoretical results are verified by an actual system.
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Pan, Xuewei, Fan Yang, Peiwen Ma, Yijin Xing, Jinye Zhang i Lingling Cao. "A Game-Theoretic Approach of Optimized Operation of AC/DC Hybrid Microgrid Clusters". Energies 15, nr 15 (30.07.2022): 5537. http://dx.doi.org/10.3390/en15155537.
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To maximize the benefits of microgrid clusters, a general model and analysis method for studying the optimized operation of AC/DC microgrid clusters using non-cooperative games is proposed. This paper first establishes the optimized objective function of an AC/DC microgrid for economic operations. Based on the supply and demand theory, the dynamic adjustment mechanism of electricity price is introduced into microgrid clusters, and a game model for the optimal operation of multiple microgrids is established. The Nash equilibrium solution of the established model is obtained by iterative search algorithm, and the convergence of the Nash equilibrium solution is also proven. Finally, the validity and economy of the proposed model are verified by the actual case.
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Qachchachi, Nabil, Hassane Mahmoudi i Abdennebi El Hassnaoui. "Control Strategy of Hybrid AC/DC Microgrid in Standalone Mode". International Journal of Renewable Energy Development 9, nr 2 (30.04.2020): 295–301. http://dx.doi.org/10.14710/ijred.9.2.295-301.
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The fluctuation of production of renewable energy resources (RESs) is a big problem for its installation and integration in isolated residential buildings. A hybrid AC/DC microgrid facilitates the good operation of RESs with a storage system in standalone mode and the possibilities of smart energy management. In this paper optimization research of the hybrid ac/dc microgrid in isolated mode of operation is presented. The power system is supplied by various Renewable Energy Resources (RESs), Photovoltaic arrays (PVA), a Wind Turbine Generator (WTG), Diesel Generator (DG) and supported by Batteries Storage System (BSS) for short term storage. The main objective of this study is to optimize power flow within a hybrid ac/dc microgrid with regards to reliability in islanded mode. First a mathematical model optimized by mixed integer linear programming and solved by CPLEX solver with JAVA language is developed for an islanded RES system and then, based on the developed model, the power system control is simulated for different cases of off-grid mode. Simulation results have shown that the management strategy can maintain power balancing while performing optimized control and give a controllable loads and batteries charging/discharging powers, even with unpredictability of RESs powers outputs and arbitrary energy tariffs. Finally, the proposed algorithm respects the optimization in real-time operation under various constraints.%.©2020. CBIORE-IJRED. All rights reserved
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Dehnavi, Saeed Daneshvar, Mahdi Shahparasti, Mohsen Simab i Seyed Mohammad Bagher Mortazavi. "Employing Interface Compensators to Enhance the Power Quality In Hybrid AC/DC Microgrids". Ciência e Natura 37 (19.12.2015): 357. http://dx.doi.org/10.5902/2179460x20796.
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After the introduction of distributed generators, regarding the challenges these networks face, employing AC/DC Hybrid microgrids would be an undeniable issue due to its many advantages and it will certainly find a significant position. Thus, discussing the power quality in this type of microgrids and clean power for feeding the load via this microgrid is a drastic challenge. This paper proposing a hybrid microgrid with 2 interface converters, one placed in series and the other placed in parallel, tries to accomplish these control objectives in an AC microgrid in order to improve power quality: input sine current with Cosϕ=1 and output sine voltage with normal value when source voltage is abnormal and non-sinusoidal, besides, non-linear loads’ presence. Simulation results verify the favorable performance of converters and effective functionality of control systems.
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Timo, Paul N., Tamer F. Megahed, Masahito Shoyama i Sobhy M. Abdelkader. "Operation and Control of a Quasi Z-source Converter in a Renewable Hybrid Microgrid". Renewable Energy and Power Quality Journal 20 (wrzesień 2022): 602–7. http://dx.doi.org/10.24084/repqj20.379.
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The power sharing need and operational reliability of a renewable hybrid microgrid are addressed in this study. A hybrid microgrid allows for the flexible incorporation of renewable energy sources, overcoming the limitations of AC and DC microgrids in terms of conversion losses and efficiency. To ensure optimal system performance, an interlinking converter (IC) is necessary for the seamless transmission of electric power between the two subgrids while keeping a stable DC bus voltage and appropriate AC sub-grid frequency. In this study, a Quasi Zsource converter (qZSC) with integrated boost capability is introduced as an IC in a PV-Wind based hybrid microgrid. Also, an adaptive dual loop based-PI (ADL-PI) control is proposed which maintains a constant peak DC-link voltage and supports maximum power point tracking while improving the system's overall stability. The proposed system and control approach are assessed using MATLAB/Simulink, and the results indicate its efficacy under various scenarios.
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Jiang, Ke, Feng Wu, Linjun Shi i Keman Lin. "Distributed Hierarchical Consensus-Based Economic Dispatch for Isolated AC/DC Hybrid Microgrid". Energies 13, nr 12 (20.06.2020): 3209. http://dx.doi.org/10.3390/en13123209.
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In this paper, a distributed hierarchical consensus algorithm is proposed to solve the economic dispatch (ED) problem for the isolated AC/DC hybrid microgrid. At first, the whole nodes of the AC/DC hybrid microgrid are divided into two parts, that is, the leadership layer nodes and the tracking layer nodes. The leadership layer nodes update the data through their own feedback elements, while the tracking layer nodes receive the information from the leadership layer nodes and update the data. After several iterations, the two different layer nodes obtain the same state, which realizes the dynamic active power balance of the whole AC/DC microgrid. Besides, the AC sub-grid and DC sub-grid can also realize the power balance by the proposed algorithm, and the energy storage units will absorb or release active power to meet the power demand in the respective section. In addition, the constraints of the nodes are also taken into account to guarantee that the power nodes in the AC/DC hybrid microgrid should operate within their own limitations, which is necessary to realize the ED for the considered hybrid microgrid. Finally, case study and simulation results are provided to illustrate the effectiveness of the proposed hierarchal method.
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Estabragh, Mohsen Rezaie, Ali Dastfan i Morteza Rahimiyan. "Grid-Tied Hybrid AC-DC Microgrid: Finding Optimal Number of Parallel-Connected AC-DC Bidirectional Interfacing Converters". International Transactions on Electrical Energy Systems 2022 (2.06.2022): 1–14. http://dx.doi.org/10.1155/2022/1932818.
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Linking AC and DC microgrids via a bidirectional AC-DC interfacing converter has emerged the hybrid AC-DC microgrid. The DC bus is connected to the grid by a series converter to mitigate the grid voltage’s power quality problems. To enhance the reliability and to increase transferring active and nonactive powers between DC and AC main buses, the AC-DC bidirectional interfacing converters are connected in parallel. In this paper, the optimal number (n) of parallel-connected bidirectional interfacing converters is obtained to minimize the annual cost of investment and the reliability cost. A two-step deciding algorithm is proposed to find n. First, active and nonactive powers between DC and AC buses are obtained with power quality and power flow considerations. Based on two types of powers, two reliability indices are calculated, including the expected energy shortage (EES) based on active power and the expected Volt-Amps shortage (EVAS) based on nonactive power. The sum of two reliability index costs is considered as the reliability cost. Next, a decision-making strategy is executed to determine the optimal n by making a trade-off between minimization of two objectives: the annual cost of investment and the reliability cost. The simulations of a grid-tied hybrid AC-DC microgrid are done with the experimental measurement data of DC and AC loads and distributed generations. Simulation results verify the performance of the represented approach.
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Jiao, Deqiang, Che Liu, Dinghao Wang i Zerui Li. "Harmonic analysis of AC/DC hybrid microgrid". IOP Conference Series: Earth and Environmental Science 651 (10.02.2021): 022087. http://dx.doi.org/10.1088/1755-1315/651/2/022087.
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Liang, Beiming, Li Kang, Jianzong He, Fenglei Zheng, Yunfeng Xia, Zhaoyun Zhang, Zhi Zhang, Guozhong Liu i Yang Zhao. "Coordination control of hybrid AC/DC microgrid". Journal of Engineering 2019, nr 16 (1.03.2019): 3264–69. http://dx.doi.org/10.1049/joe.2018.8505.
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Awais, Muhammad, Laiq Khan, Said Ghani Khan, Qasim Awais i Mohsin Jamil. "Adaptive Neural Network Q-Learning-Based Full Recurrent Adaptive NeuroFuzzy Nonlinear Control Paradigms for Bidirectional-Interlinking Converter in a Grid-Connected Hybrid AC-DC Microgrid". Energies 16, nr 4 (14.02.2023): 1902. http://dx.doi.org/10.3390/en16041902.
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The stability of a hybrid AC-DC microgrid depends mainly upon the bidirectional interlinking converter (BIC), which is responsible for power transfer, power balance, voltage solidity, frequency and transients sanity. The varying generation from renewable resources, fluctuating loads, and bidirectional power flow from the utility grid, charging station, super-capacitor, and batteries produce various stability issues on hybrid microgrids, like net active-reactive power flow on the AC-bus, frequency oscillations, total harmonic distortion (THD), and voltage variations. Therefore, the control of BIC between AC and DC buses in grid-connected hybrid microgrid power systems is of great importance for the quality/smooth operation of power flow, power sharing and stability of the whole power system. In literature, various control schemes are suggested, like conventional droop control, communication-based control, model predictive control, etc., each addressing different stability issues of hybrid AC-DC microgrids. However, model dependence, single-point-failure (SPF), communication vulnerability, complex computations, and complicated multilayer structures motivated the authors to develop online adaptive neural network (NN) Q-learning-based full recurrent adaptive neurofuzzy nonlinear control paradigms for BIC in a grid-connected hybrid AC-DC microgrid. The proposed strategies successfully ensure the following: (i) frequency stabilization, (ii) THD reduction, (iii) voltage normalization and (iv) negligible net active-reactive power flow on the AC-bus. Three novel adaptive NN Q-learning-based full recurrent adaptive neurofuzzy nonlinear control paradigms are proposed for PQ-control of BIC in a grid-connected hybrid AC-DC microgrid. The control schemes are based on NN Q-learning and full recurrent adaptive neurofuzzy identifiers. Hybrid adaptive full recurrent Legendre wavelet-based Neural Network Q-learning-based full recurrent adaptive NeuroFuzzy control, Hybrid adaptive full recurrent Mexican hat wavelet-based Neural Network Q-learning-based full recurrent adaptive NeuroFuzzy control, and Hybrid adaptive full recurrent Morlet wavelet-based Neural Network Q-learning-based full recurrent adaptive NeuroFuzzy control are modeled and tested for the control of BIC. The controllers differ from each other, based on variants used in the antecedent part (Gaussian membership function and B-Spline membership function), and consequent part (Legendre wavelet, Mexican hat wavelet, and Morlet wavelet) of the full recurrent adaptive neurofuzzy identifiers. The performance of the proposed control schemes was validated for various quality and stability parameters, using a simulation testbench in MATLAB/Simulink. The simulation results were bench-marked against an aPID controller, and each proposed control scheme, for a simulation time of a complete solar day.
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Jiang, Ke, Feng Wu, Xuanjun Zong, Linjun Shi i Keman Lin. "Distributed Dynamic Economic Dispatch of an Isolated AC/DC Hybrid Microgrid Based on a Finite-Step Consensus Algorithm". Energies 12, nr 24 (6.12.2019): 4637. http://dx.doi.org/10.3390/en12244637.
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The AC/DC hybrid microgrid is the main trend of microgrids’ development, and the dynamic economic dispatch is regarded as an important way to ensure the economic and safe operation of a microgrid system. In this paper, a dynamic economic dispatch model of the isolated AC/DC hybrid microgrid is developed with the objective of minimizing the daily operation cost of controllable units. Furthermore, a distributed algorithm based on the finite-step consensus algorithm is proposed, in which the incremental cost of each distributed generation unit is set as a consensus variable, and all units obtain the optimal values by exchanging information only with their neighbors. In addition, the algorithm converges to the optimal solutions in finite steps, and the efficiency is improved significantly. The effectiveness of the proposed model and the algorithm were verified by simulation.
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Wu, Xiong, Zhao Wang, Tao Ding i Zhiyi Li. "Hybrid AC/DC Microgrid Planning with Optimal Placement of DC Feeders". Energies 12, nr 9 (9.05.2019): 1751. http://dx.doi.org/10.3390/en12091751.
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With the significant increase in DC loads (such as data and telecommunication centers) at the power distribution level, an additional set of power electronic converters are required to connect these DC loads to the AC-dominant power network. Notably, hybrid AC/DC microgrids (MGs) serve as promising solutions to satisfying both the AC and DC loads with a reduced number of installed converters. Since DC loads may be randomly distributed in the MG, how to place DC feeders to simultaneously fulfill the economic and security requirements of MG operations remains a challenging problem. To address this issue, this paper proposes a hybrid AC/DC MG planning model to determine the optimal placement of DC feeders with the objective of minimizing the total cost of the investment of distributed energy resources (DERs), converters, and AC/DC distribution lines, as well as the operation of DERs. In particular, the power flow of the hybrid AC/DC MG is derived in a unified manner and then incorporated in the planning model. Eventually, the proposed model suffices to find the optimal number and siting for both DERs and DC feeders while ensuring the continuality of the DC feeders. The proposed model is tested in two MG-based distribution systems, and its effectiveness is validated by the results of numerical experiments.
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Aljohani, Tawfiq M., Ahmed F. Ebrahim i Osama Mohammed. "Hybrid Microgrid Energy Management and Control Based on Metaheuristic-Driven Vector-Decoupled Algorithm Considering Intermittent Renewable Sources and Electric Vehicles Charging Lot". Energies 13, nr 13 (2.07.2020): 3423. http://dx.doi.org/10.3390/en13133423.
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Energy management and control of hybrid microgrids is a challenging task due to the varying nature of operation between AC and DC components which leads to voltage and frequency issues. This work utilizes a metaheuristic-based vector-decoupled algorithm to balance the control and operation of hybrid microgrids in the presence of stochastic renewable energy sources and electric vehicles charging structure. The AC and DC parts of the microgrid are coupled via a bidirectional interlinking converter, with the AC side connected to a synchronous generator and portable AC loads, while the DC side is connected to a photovoltaic system and an electric vehicle charging system. To properly ensure safe and efficient exchange of power within allowable voltage and frequency levels, the vector-decoupled control parameters of the bidirectional converter are tuned via hybridization of particle swarm optimization and artificial physics optimization. The proposed control algorithm ensures the stability of both voltage and frequency levels during the severe condition of islanding operation and high pulsed demands conditions as well as the variability of renewable source production. The proposed methodology is verified in a state-of-the-art hardware-in-the-loop testbed. The results show robustness and effectiveness of the proposed algorithm in managing the real and reactive power exchange between the AC and DC parts of the microgrid within safe and acceptable voltage and frequency levels.
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Dehnavi, Saeed Daneshvar, i Ehsan Shayani. "Compensation of Voltage disturbances in hybrid AC/DC Microgrids using series converter". Ciência e Natura 37 (19.12.2015): 349. http://dx.doi.org/10.5902/2179460x20794.
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In this paper a series power electronic converter is proposed to improve power quality of AC/DC hybrid microgrids. An injection transformer which is series with AC microgrid is used beside the series converter to inject voltage for the purpose of voltage disturbances compensation. The series converter by using a simple and effective control system in stationary reference framework of d-q-0 is proposed to compensate voltage sag and swell, source unbalanced voltages, voltage harmonics of the utility. In these types of micrigrids a lot of voltage disturbances have occurred due to large number of converters. Moreover, it is not required to use a storage energy system like battery; the required power is supplied by DC microgird, so the proposed system is very efficient. Simulation results in the MATLAB/Simulink environment have verified the appropriate performance of the proposed method.
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Sahoo, Saroja Kanti, Avinash Kumar Sinha i N. K. Kishore. "Control Techniques in AC, DC, and Hybrid AC–DC Microgrid: A Review". IEEE Journal of Emerging and Selected Topics in Power Electronics 6, nr 2 (czerwiec 2018): 738–59. http://dx.doi.org/10.1109/jestpe.2017.2786588.
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Alhasnawi, Bilal Naji, Basil H. Jasim, Walid Issa i M. Dolores Esteban. "A Novel Cooperative Controller for Inverters of Smart Hybrid AC/DC Microgrids". Applied Sciences 10, nr 17 (3.09.2020): 6120. http://dx.doi.org/10.3390/app10176120.
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This paper presents a novel cooperative control technique concerning fully-distributed AC/DC microgrids. Distributed generation based on inverters has two types, i.e., Current Source Inverter (CSI), also referred to as PQ inverter, and Voltage Source Inverter (VSI). Both inverter forms have a two-layer coordination mechanism. This paper proposes a design method for the digital Proportional-Resonant (PR) controller that regulates the current inside an inverter. The inverters will improve the voltage quality of the microgrid while maintaining the average voltage of buses at the same desired level. There is comprehensive detail on the computations specific to resonant and proportional gains and digital resonance path coefficients. The paper includes a digital PR controller design and its analysis in the frequency domain. The analysis is based on the w-domain. The main contribution of this paper is the proposed method, which not only focuses on the transient response but also improves the steady-state response which smoothens the voltage; furthermore, all inverters are effectively involved to increase the capacity of the microgrid for better power management. The suggested cooperative control technique is used on an IEEE 14-bus system having fully distributed communication. The convincing outcomes indicate that the suggested control technique is an effectual means of regulating the microgrid’s voltage to obtain an evener and steady voltage profile. The microgrid comprises distributed resources and is used as the primary element to analyse power flow and quality indicators associated with a smart grid. Lastly, numerical simulation observations are utilised for substantiating the recommended algorithm.
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Chen, Yaling, Luxi Hao i Gaowen Yin. "Distributed Energy Management of the Hybrid AC/DC Microgrid with High Penetration of Distributed Energy Resources Based on ADMM". Complexity 2021 (14.09.2021): 1–9. http://dx.doi.org/10.1155/2021/1863855.
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This paper aims to investigate energy management of the hybrid AC/DC microgrid with the high penetration of distributed energy resources (DERs), such as electrical vehicles, heat pumps, and photovoltaics. In the previous studies, energy management of the hybrid microgrid is usually carried out by the system operator in a centralized manner, which suffers from the compromise of privacy information protection and the risk of single-point failure. Therefore, this paper proposes a distributed energy management scheme of the hybrid microgrid using the projection function-based alternating direction method of multipliers (P-ADMM), which allows each subgrid, i.e., AC subgrid and DC subgrid, to make day-ahead schedules independently with information exchanges while obtaining the optimal energy management solution. The energy management problem of the hybrid microgrid is formulated as a mixed-integer quadratic programming (MIQP) model, considering DER and energy storage system operation constraints, system operation constraints, and converter operation constraints. Then, the MIQP model is decomposed and distributed into smaller-scale QP models between subgrids using the P-ADMM algorithm, which can handle binary variables through projection functions. The numerical results conducted on the hybrid microgrid demonstrate that the proposed distributed scheme can effectively achieve optimal energy management for the hybrid AC/DC microgrid in a distributed manner.
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Afianti, Hasti, Ontoseno Penangsang i Adi Soeprijanto. "Stability and reliability of low voltage hybrid AC-DC microgrids power flow model in islanding operation". Indonesian Journal of Electrical Engineering and Computer Science 19, nr 1 (1.07.2020): 32. http://dx.doi.org/10.11591/ijeecs.v19.i1.pp32-41.
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The problem of decreasing and increasing power flow in hybrid AC-DC microgrids in island operations is the concern of this research. This condition arises if one sub-microgrid cannot supply load power requirements, either due to a decrease in power at the source or an increase in load on the sub-microgrid network. As a result, in this research used the bidirectional converter as an interlinking converter, the converter can change the power flow from the ac sub microgrid to the dc sub microgrid and vice versa. With this bidirectional converter, load power requirements can be met even though there is a power change in one of the sub microgrid. The simulation in this research support by Simulink/Matlab software. The model is built in a low voltage system, and the power flow analysis is in steady-state condition with two different cases. The simulation results show the stability and reliability of the power flow in both sub microgrid with stable frequency and voltage when power and load change occur.
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Gontijo, Gustavo, Matheus Soares, Thiago Tricarico, Robson Dias, Mauricio Aredes i Josep Guerrero. "Direct Matrix Converter Topologies with Model Predictive Current Control Applied as Power Interfaces in AC, DC, and Hybrid Microgrids in Islanded and Grid-Connected Modes". Energies 12, nr 17 (27.08.2019): 3302. http://dx.doi.org/10.3390/en12173302.
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This paper presents an analysis of a new application of different direct matrix converter topologies used as power interfaces in AC, DC, and hybrid microgrids, with model predictive current control. Such a combination of a converter and control strategy leads to a high power quality microgrid voltage, even with a low power quality main grid voltage and even during the connection and disconnection of a variety of loads and generation sources to the microgrids. These robust systems are suitable for applications in which sensitive loads are to be supplied and these loads are connected close to distributed-generation sources with inherent intermittent behavior. The authors also propose the use of new direct matrix converter configurations with a reduced number of switches in order to achieve reduced cost, reduced failure rate, and higher reliability, which are very desirable in microgrids. Finally, the authors also introduce new hybrid direct matrix converter topologies that provide interesting options for the islanded operation of the microgrids with the use of a battery system. In other words, the proposed hybrid direct matrix converters result in flexible hybrid microgrid configurations integrating DC and AC devices with high power quality and high power supply reliability.
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Aljafari, Belqasem, Subramanian Vasantharaj, Vairavasundaram Indragandhi i Rhanganath Vaibhav. "Optimization of DC, AC, and Hybrid AC/DC Microgrid-Based IoT Systems: A Review". Energies 15, nr 18 (18.09.2022): 6813. http://dx.doi.org/10.3390/en15186813.
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Smart microgrids, as the foundations of the future smart grid, combine distinct Internet of Things (IoT) designs and technologies for applications that are designed to create, regulate, monitor, and protect the microgrid (MG), particularly as the IoT develops and evolves on a daily basis. A smart MG is a small grid that may operate individually or in tandem with the electric grid, and it is ideal for institutional, commercial, and industrial consumers, as well as urban and rural societies. A MG can operate in two methods (stand-alone and grid-connected), with the ability to transition between modes due to local grid faults, planned maintenance, expansions, deficits and failures in the host system, and other factors. Energy storage is the process of storing and converting energy that can be used for a variety of purposes, including voltage and frequency management, power backup, and cost optimization. IoT is designed to deliver solutions for optimal energy management, security protocols, control methods, and applications in the MG, with numerous distributed energy resources (DER) and interconnected loads. The use of IoT architecture for MG operations and controls is discussed in this research. With the use of power grid equipment and IoT-enabled technology, MGs are enabling local networks to give additional services on top of the essential supply of electricity to local networks that operate simultaneously or independently from the regional grid. Additionally, this review shows how hybrid AC/DC MGs are advantageous compared to AC and DC MGs. The state-of-the-art optimization techniques and trends in hybrid MG research are included in this work.
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Wang, Guishuo, Xiaoli Wang, Fuan Wang i Zhao Han. "Research on Hierarchical Control Strategy of AC/DC Hybrid Microgrid Based on Power Coordination Control". Applied Sciences 10, nr 21 (28.10.2020): 7603. http://dx.doi.org/10.3390/app10217603.
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The AC/DC hybrid microgrid has a large-scale and complex control process. It is of great significance and value to design a reasonable power coordination control strategy to maintain the power balance of the system. Based on hierarchical control, this paper designs a reasonable power coordination control strategy for AC/DC hybrid microgrid. For lower control, this paper designs a variety of control modes for each converter in different application scenarios. For the higher control, this paper analyzes the working mode of the system and designs the power coordination control strategy under the grid-connected and isolated island mode. In grid-connected operation, the DC bus voltage can be stabilized by adjusting the operation mode of the DC energy storage and the on-off of the secondary load. In isolated island operation, the DC sub-microgrid is the main microgrid, and the DC energy storage is the main power regulating equipment. This is based on the principle of “energy is in short supply in the system, DC energy storage finally discharge, energy supply exceeds demand in the system, DC energy storage gives priority to charging” of DC energy storage. By adjusting the control strategy of the micro-source, the reference power, and the on-off of the secondary load, the overall power balance is maintained. The Matlab/Simulink simulation software was used to build the AC/DC hybrid microgrid simulation model, which verified the effectiveness and stability of the proposed power coordination control strategy under various operating conditions.
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Tricarico, Thiago, Gustavo Gontijo, Marcello Neves, Matheus Soares, Mauricio Aredes i Josep Guerrero. "Control Design, Stability Analysis and Experimental Validation of New Application of an Interleaved Converter Operating as a Power Interface in Hybrid Microgrids". Energies 12, nr 3 (30.01.2019): 437. http://dx.doi.org/10.3390/en12030437.
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This paper presents a new and specific use of a bidirectional interleaved converter to perform a power interface in hybrid microgrids. The converter is responsible for regulating the power flow between the direct-current (DC) microgrid and the rest of the hybrid microgrid by controlling the DC microgrid voltage. The authors present a detailed modeling of the mentioned system in order to develop the system control design and a stability analysis. In addition, the authors propose a new control design strategy aiming at improving the voltage control disturbance rejection characteristic, while maintaining a good dynamic behavior regarding the reference tracking functionality. In this hybrid microgrid topology, a back-to-back converter connects the main grid to the AC microgrid. The main objective of this converter is to provide a high-power-quality voltage to critical and sensitive loads connected to the microgrid. The interleaved converter adjusts the DC microgrid voltage according to the operational voltage of the back-to-back converter DC link. In the DC microgrid case, the variation of load and generation connection could lead to serious voltage sag and oscillations that could be harmful to the sensitive loads. The voltage controller must be capable of rejecting these disturbances in order to maintain a high-power-quality voltage. Furthermore, experimental results are provided in order to validate this specific application of the interleaved converter and the presented control design strategy.
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Das, Soumya Ranjan, Alok Kumar Mishra, Prakash Kumar Ray, Surender Reddy Salkuti i Seong-Cheol Kim. "Application of Artificial Intelligent Techniques for Power Quality Improvement in Hybrid Microgrid System". Electronics 11, nr 22 (21.11.2022): 3826. http://dx.doi.org/10.3390/electronics11223826.
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The hybrid AC-DC microgrid (MG) has gained popularity recently as it offers the benefits of AC and DC systems. Interconnecting AC-DC converters are necessary since the MG has both DC and AC sub-grids. Adding an extra harmonic adjustment mechanism to the interlinking converters is promising because non-linear AC loads can worsen the quality of the voltage on the AC bus. The interlinking converters’ primary function is to interchange real and reactive power between DC and AC sub-grids, so the typical harmonic controlling approach implemented for active power filters (APFs) might not be appropriate for them. When the MG’s capacity is high, it is desirable that the switching frequency be lesser than the APFs. The performance of harmonic correction or even system stability may suffer at low switching frequencies. In this study, a harmonic compensating technique appropriate for hybrid AC-DC interlinking converters with lower switching frequencies is planned. The suggested strategy, modeling techniques, stability analysis, and a thorough virtual impedance design are discussed in this work.
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Luo, Zhao, Zhendong Zhu, Zhiyuan Zhang, Jinghui Qin, Hao Wang, Zeyong Gao i Zhichao Yang. "Multi-Time-Scale Rolling Optimal Dispatch for Grid-Connected AC/DC Hybrid Microgrids". Processes 7, nr 12 (16.12.2019): 961. http://dx.doi.org/10.3390/pr7120961.
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In order to reduce the impact of the randomness and volatility of renewable energy on the economic operation of AC/DC hybrid microgrids, a multi-time-scale rolling optimization strategy is proposed for the grid-connected AC/DC hybrid microgrids. It considers the source-load uncertainty declined with time scale reduction, and the scheduling cooperation problem of different units on different time scales. In this paper, we propose a three-time-scale optimal strategy of the day-ahead, intraday and real-time dispatching stage and a two-level rolling optimal strategy of the intraday and real-time stage, aiming at minimizing the operating cost. We added the power penalty cost in the rolling optimization model to limit the energy state of the energy storage system in the constraint, and improve the power correction and tracking effect of the rolling optimization. A typical-structure AC/DC hybrid microgrid is analyzed in this paper and the simulation results are shown to demonstrate the feasibility and effectiveness of the proposed multi-time-scale rolling optimal dispatch.
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Kim, Tae-Gyu, Hoon Lee, Chang-Gyun An, Junsin Yi i Chung-Yuen Won. "Hybrid AC/DC Microgrid Energy Management Strategy Based on Two-Step ANN". Energies 16, nr 4 (10.02.2023): 1787. http://dx.doi.org/10.3390/en16041787.
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In grid-connected operations, a microgrid can solve the problem of surplus power through regeneration; however, in the case of standalone operations, the only method to solve the surplus power problem is charging the energy storage system (ESS). However, because there is a limit to the capacity that can be charged in an ESS, a separate energy management strategy (EMS) is required for stable microgrid operation. This paper proposes an EMS for a hybrid AC/DC microgrid based on an artificial neural network (ANN). The ANN is composed of a two-step process that operates the microgrid by outputting the operation mode and charging and discharging the ESS. The microgrid consists of an interlinking converter to link with the AC distributed system, a photovoltaic converter, a wind turbine converter, and an ESS. The control method of each converter was determined according to the mode selection of the ANN. The proposed ANN-based EMS was verified using a laboratory-scale hybrid AC/DC microgrid. The experimental results reveal that the microgrid operation performed stably through control of individual converters via mode selection and reference to ESS power, which is the result of ANN integration.
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Naji Alhasnawi, Bilal, Basil H. Jasim, Amjad Anvari-Moghaddam i Frede Blaabjerg. "A New Robust Control Strategy for Parallel Operated Inverters in Green Energy Applications". Energies 13, nr 13 (6.07.2020): 3480. http://dx.doi.org/10.3390/en13133480.
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This research work puts forward a hybrid AC/DC microgrid with renewable energy sources pertaining to consumer’s residential area for meeting the demand. Currently, the power generation and consumption have experienced key transformations. One such tendency would be integration of microgrids into the distribution network that is characterized by high penetration of renewable energy resources as well as operations in parallel. Traditional droop control can be employed in order to get an accurate steady state averaged active power sharing amongst parallel inverters pertaining to hybrid AC/DC microgrid. It is presumed that there would be similar transient average power responses, and there would be no circulating current flowing between the units for identical inverters possessing the same droop gain. However, the instantaneous power could be affected by different line impedances considerably and thus resulting in variation in circulating power that flows amongst inverters, especially during unexpected disturbances like load changes. This power, if absorbed by the inverter, could result in sudden DC-link voltage rise and trip the inverter, which in turn causes performance degradation of the entire hybrid microgrid. When the hybrid generators act as unidirectional power source, the issue worsens further. In this research work, we have put forward a new distributed coordinated control pertaining to hybrid microgrid, which can be applied for both grid connected and islanded modes that include variable loads and hybrid energy resources. Also, in order to choose the most effective controller scheme, a participation factor analysis has been designed for binding the DC-link voltage as well as reducing the circulating power. Moreover, to both photovoltaic stations and wind turbines, maximum power point tracking (MPPT) techniques have been used in order to extract the maximum power from hybrid power system when there is discrepancy in environmental circumstances. Lastly, the feasibility and effectiveness pertaining to the introduced strategy for hybrid microgrid in various modes are confirmed via simulation results.
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Kim, Tae-Gyu, Hoon Lee, Chang-Gyun An, Yoon-Seong Lee, Kyung-Min Kang, Junsin Yi i Chung-Yuen Won. "Hybrid AC/DC Microgrid Operation Method based on Artificial Neural Network of Two-Step Structure". Journal of the Korean Institute of Illuminating and Electrical Installation Engineers 35, nr 3 (31.03.2021): 47–61. http://dx.doi.org/10.5207/jieie.2021.35.3.047.
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Lv, Yanheng. "Research on Optimization of Distribution Network based on Power Electronic Transformer". Highlights in Science, Engineering and Technology 35 (11.04.2023): 57–62. http://dx.doi.org/10.54097/hset.v35i.7030.
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As the core equipment of hybrid microgrid, power electronic transformer is a new type of multifunctional transformer which integrates power electronic technology, information communication technology and control protection technology. On the background of the Beijing Low-Carbon Winter Olympics Smart Grid Demonstration Project, this paper proposed an AC/DC hybrid microgrid topology with dual-end power supply based on power electronic transformer. Moreover, a coordinated optimization control for AC/DC hybrid microgrid based on power electronic transformer is studied. The content of the paper mainly includes: The common topology of power electronic transformer is studied, and a three stage four-port power electronic transformer is proposed according to the demand of demonstration project. The interface converter topology structure and control method of distributed generation and energy storage in hybrid microgrid are analyzed, and the system model of hybrid microgrid is established. Simulation results show that MPPT control can maximize the power output of distributed generation, and piecewise droop control can realize seamless switching between power control and voltage control in the grid-tied or autonomous mode.
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Ilyushin, Pavel, Vladislav Volnyi, Konstantin Suslov i Sergey Filippov. "State-of-the-Art Literature Review of Power Flow Control Methods for Low-Voltage AC and AC-DC Microgrids". Energies 16, nr 7 (31.03.2023): 3153. http://dx.doi.org/10.3390/en16073153.
Pełny tekst źródłaStreszczenie:
The development of AC distribution systems provides for the seamless integration of low-voltage microgrids with distributed energy resources (DERs). This poses new challenges for the control of normal, emergency, and post-emergency states of microgrids, calling for the creation and development of information and communications technology infrastructure. Power converters/inverters that are used to integrate renewable DERs lack inertia. Along with them, fossil fuel-fired generation units are also being integrated into microgrids. These include gas generator sets, diesel generator sets, and microturbines, having small (up to 1–2 s) values of mechanical inertia constants—Tj. This leads to an increase in the rate of transients by a factor of 5–10. Under these conditions, the technical requirements for the speed of automatic power flow control systems, as well as the methods they rely on, have to be reconsidered. Microgrids include DC microgrids, AC microgrids, and hybrid (AC-DC) microgrids. In the case of hybrid microgrids, DERs are connected to the DC grid and are integrated into the AC grid through a common inverter. The complexity of the task of microgrid control is due to the need to choose properly the type and extent of control actions so as to prevent the emergence and development of accidents. The employed control methods must ensure the reliable power supply to consumers and the quality of power in microgrids, as well as the reliable operation of the external distribution systems into which they are integrated. The article gives an overview of control methods for low-voltage AC and AC-DC microgrids, which allow one to tackle effectively solve the tasks.
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Prudhvi Kumar, G. R., D. Sattianadan i K. Vijayakumar. "A survey on power management strategies of hybrid energy systems in microgrid". International Journal of Electrical and Computer Engineering (IJECE) 10, nr 2 (1.04.2020): 1667. http://dx.doi.org/10.11591/ijece.v10i2.pp1667-1673.
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The power generation through renewable energy resources is increasing vastly, Solar energy and Wind Energy are the most abundantly available renewable energy resources. The growth of small scale distributed grid networks increasing rapidly in the modern power systems and Distributed Generation (DG) plays a predominant role. Microgrid is one among the emerging techniques in power systems. Power Management is mainly required to have control over the real and reactive power of individual DG and for smooth operation, maintaining stability and reliability. This paper presents a survey of the research works already reported focusing on power management of hybrid energy systems such as mainly solar and wind systems in microgrid. Six different approaches have been studied in detail for AC,DC and hybrid AC/DC microgrid.
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Nguyen, Thanh Hai, Tan Luong Van, Asif Nawaz i Ammar Natsheh. "Feedback Linearization-Based Control Strategy for Interlinking Inverters of Hybrid AC/DC Microgrids with Seamless Operation Mode Transition". Energies 14, nr 18 (7.09.2021): 5613. http://dx.doi.org/10.3390/en14185613.
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This study proposes an advanced control scheme for the interlinking inverters of the hybrid AC/DC microgrids, which facilitates a seamless transition between grid-connected and stand-alone/islanding modes for the microgrid. Due to a nonlinear relationship between the terminal voltages of the voltage-source inverter (VSI) interfacing through inductor–capacitor (LC) filters with the grid voltages and currents, a feedback linearization technique (FLT) is employed to control the interlinking VSI under both grid-connected and islanding operations. The FLT-based current controllers are applied in the grid-connected mode, in which they adjust the power exchange between the DC and AC subgrids and mitigate the distortion of the grid currents produced by nonlinear loads. Under the stand-alone operation, the AC bus voltages are directly regulated by the FLT-voltage controllers of the interlinking VSI. In order to reduce the inrush currents and voltage overshot at the instant of mode switching, the FLT-based controllers are performed all the time regardless of the operating modes, where the voltage references for the VSI are not changed abruptly. The control performance of the VSI is highly satisfactory with low-transient overshoot values of the voltages and currents and low total harmonic distortion (THD) values of the grid currents and AC bus voltages are about 3.5% and 2.7%, respectively, under the nonlinear load condition. The validity of the new control strategy is verified by the simulation work, which investigates the operation of a hybrid AC/DC microgrid.
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Xiong Liu, Peng Wang i Poh Chiang Loh. "A Hybrid AC/DC Microgrid and Its Coordination Control". IEEE Transactions on Smart Grid 2, nr 2 (czerwiec 2011): 278–86. http://dx.doi.org/10.1109/tsg.2011.2116162.
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