The Experts below are selected from a list of 24021 Experts worldwide ranked by ideXlab platform
Juan C. Vasquez - One of the best experts on this subject based on the ideXlab platform.
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multiagent based Distributed state of charge balancing control for Distributed Energy Storage units in ac microgrids
IEEE Transactions on Industry Applications, 2017Co-Authors: E A A Coelho, Tomislav Dragicevic, Josep M. Guerrero, Juan C. VasquezAbstract:In this paper, a multiagent-based Distributed control algorithm has been proposed to achieve state of charge (SoC) balance of Distributed Energy Storage (DES) units in an ac microgrid. The proposal uses frequency scheduling instead of adaptive droop gain to regulate the active power. Each DES unit is taken as an agent and it schedules its own frequency reference given of the real power droop controller according to the SoC values of all other DES units. Further, to obtain the average SoC value of DES, the dynamic average consensus algorithm is utilized by each agent. A generalized small-signal model of the proposed frequency scheduling for the proposed frequency scheduling is developed in order to verify the stability of the control system and to guide control parameters design. The convergence characteristics for the dynamic consensus adopted in the multiagent system are also analyzed to choose the proper control parameter. Experimental results verified the effectiveness, the robustness against communication topology changes, and capability of “plug & play” for the proposed multiagent system through different case studies.
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Energy management system with equalization algorithm for Distributed Energy Storage systems in pv active generator based low voltage dc microgrids
IEEE International Conference on DC Microgrids, 2015Co-Authors: Nelson L. Diaz, Juan C. Vasquez, Adriana C Luna, Josep M. GuerreroAbstract:This paper presents a centralized strategy for equalizing the state of charge of Distributed Energy Storage systems in an islanded DC microgrid. The proposed strategy is based on a simple algorithm called equalization algorithm, which modifies the charge or discharge rate by weighting the virtual resistor of local droop control loops at each Distributed Energy Storage system. The proposed strategy, can be used as an additional function of the microgrid Energy management system where the state of charge of Distributed ESS is equalized within a determined window of time. Finally, real-time simulation results of a low voltage DC microgrid are presented in order to verify the performance of the proposed approach.
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Double-Quadrant State-of-Charge-Based Droop Control Method for Distributed Energy Storage Systems in Autonomous DC Microgrids
2015Co-Authors: Xiaonan Lu, Kai Sun, Juan C. Vasquez, Lipei HuangAbstract:In this paper, a double-quadrant state-of-charge (SoC)-based droop control method for Distributed Energy Storage system is proposed to reach the proper power distribution in autonomous dc microgrids. In order to prolong the lifetime of the Energy Storage units (ESUs) and avoid the overuse of a certain unit, the SoC of each unit should be balanced and the injected/output power should be gradually equalized. Droop control as a decentralized approach is used as the basis of the power sharing method for Distributed Energy Storage units. In the charging process, the droop coefficient is set to be proportional to the nth order of SoC, while in the discharging process, the droop coefficient is set to be inversely proportional to the nth order of SoC. Since the injected/output power is inversely proportional to the droop coefficient, it is obtained that in the charging process the ESU with higher SoC absorbs less power, while the one with lower SoC absorbs more power. Meanwhile, in the discharging process, the ESU with higher SoC delivers more power and the one with lower SoC delivers less power. Hence, SoC balancing and injected/output power equalization can be gradually realized. The exponent n of SoC is employed in the control diagram to regulate the speed of SoC balancing. It is found that with larger exponent n, the balancing speed is higher. MATLAB/simulink model comprised of three ESUs is implemented and the simulation results are shown to verify the proposed approach.
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Fuzzy-logic-based gain-scheduling control for state-of-charge balance of Distributed Energy Storage systems for DC microgrids
Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC, 2014Co-Authors: Nelson L. Diaz, Tomislav Dragicevic, Juan C. VasquezAbstract:A microgrid is an integration of Distributed Energy sources, loads and Energy Storage systems. Indeed, Energy Storage systems are required in order to ensure reliability and power quality because of the intermittent nature of renewable Energy sources and changes of load demand. Apart from that, the use of Distributed Energy Storage units provides redundancy to the system and support possible increments in load consumption. In consequence, the control strategy used in the microgrid must take into account the stored Energy balance between Distributed Energy Storage units in order to avoid over-charge or deep-discharge in one of the Energy Storage units. Primary control in a microgrid is responsible for power sharing among units; and droop control is typically used in this stage. This paper proposes a modular and decentralized gain-scheduling control strategy based on fuzzy logic that ensures balanced stored Energy among Distributed Energy Storage units, as well as low voltage deviation in a DC microgrid. Hardware in the loop simulations show the performance of the proposed control strategy.
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Multiagent based Distributed control for state-of-charge balance of Distributed Energy Storage in DC microgrids
2014Co-Authors: Chendan Li, Manuel Garcia Plaza, Fabio Andrade, Tomislav Dragicevic, Juan C. VasquezAbstract:In this paper, a Distributed multiagent based algorithm is proposed to achieve SoC balance for DES in the DC microgrid by means of voltage scheduling. Reference voltage given is adjusted instead of droop gain. Dynamic average consensus algorithm is explored in each agent to get the required information for scheduling voltage autonomously. State-space analysis on a single Energy Storage unit and simulation verification shows that the proposed method has two advantages. Firstly, modifying the reference voltage given has less impact on system stability compared to gain scheduling. Secondly, by adopting multiagent methodology, the proposed Distributed control has less communication dependence and more reliable during communication topology changes.
Josep M. Guerrero - One of the best experts on this subject based on the ideXlab platform.
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multiagent based Distributed state of charge balancing control for Distributed Energy Storage units in ac microgrids
IEEE Transactions on Industry Applications, 2017Co-Authors: E A A Coelho, Tomislav Dragicevic, Josep M. Guerrero, Juan C. VasquezAbstract:In this paper, a multiagent-based Distributed control algorithm has been proposed to achieve state of charge (SoC) balance of Distributed Energy Storage (DES) units in an ac microgrid. The proposal uses frequency scheduling instead of adaptive droop gain to regulate the active power. Each DES unit is taken as an agent and it schedules its own frequency reference given of the real power droop controller according to the SoC values of all other DES units. Further, to obtain the average SoC value of DES, the dynamic average consensus algorithm is utilized by each agent. A generalized small-signal model of the proposed frequency scheduling for the proposed frequency scheduling is developed in order to verify the stability of the control system and to guide control parameters design. The convergence characteristics for the dynamic consensus adopted in the multiagent system are also analyzed to choose the proper control parameter. Experimental results verified the effectiveness, the robustness against communication topology changes, and capability of “plug & play” for the proposed multiagent system through different case studies.
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Energy management system with equalization algorithm for Distributed Energy Storage systems in pv active generator based low voltage dc microgrids
IEEE International Conference on DC Microgrids, 2015Co-Authors: Nelson L. Diaz, Juan C. Vasquez, Adriana C Luna, Josep M. GuerreroAbstract:This paper presents a centralized strategy for equalizing the state of charge of Distributed Energy Storage systems in an islanded DC microgrid. The proposed strategy is based on a simple algorithm called equalization algorithm, which modifies the charge or discharge rate by weighting the virtual resistor of local droop control loops at each Distributed Energy Storage system. The proposed strategy, can be used as an additional function of the microgrid Energy management system where the state of charge of Distributed ESS is equalized within a determined window of time. Finally, real-time simulation results of a low voltage DC microgrid are presented in order to verify the performance of the proposed approach.
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advanced control architectures for intelligent microgrids part ii power quality Energy Storage and ac dc microgrids
IEEE Transactions on Industrial Electronics, 2013Co-Authors: Josep M. Guerrero, Poh Chiang Loh, Tzunglin Lee, Mukul C ChandorkarAbstract:This paper summarizes the main problems and solutions of power quality in microgrids, Distributed-Energy-Storage systems, and ac/dc hybrid microgrids. First, the power quality enhancement of grid-interactive microgrids is presented. Then, the cooperative control for enhance voltage harmonics and unbalances in microgrids is reviewed. Afterward, the use of static synchronous compensator (STATCOM) in grid-connected microgrids is introduced in order to improve voltage sags/swells and unbalances. Finally, the coordinated control of Distributed Storage systems and ac/dc hybrid microgrids is explained.
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soc based dynamic power sharing method with ac bus voltage restoration for microgrid applications
Conference of the Industrial Electronics Society, 2012Co-Authors: Kai Sun, Josep M. Guerrero, Lipei HuangAbstract:In a microgrid system, Distributed Energy Storage units are commonly employed as the Energy buffers. In this paper, a dynamic power sharing method based on the state-of-charge (SoC) of each Energy Storage unit is proposed. Droop control is employed as the basic control strategy for the Distributed Energy Storage units. By using the proposed method, the coefficients in the conventional droop method are adjusted according to the SoC of each Energy Storage module. The modules with higher SoC delivers more active power, while those with lower SoC delivers less. Meanwhile, the reactive power is equally shared in the Energy Storage system. The relationship between the droop coefficient and SoC are studied deeply and the small signal model is developed to verify the stability of the control system. It is found that the active power sharing speed becomes faster with higher exponent of SoC. At the same time, in order to restore the AC-bus voltage, secondary control is employed to eliminate the deviations of the voltage frequency and amplitude caused by the droop control, with the droop coefficients adjusting according to the SoCs. The model of the secondary control scheme for SoC-based droop method is developed and its stability is discussed. The theoretical analysis is demonstrated by both simulation and experimental results.
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hierarchical control of droop controlled dc and ac microgrids a general approach towards standardization
Conference of the Industrial Electronics Society, 2009Co-Authors: Josep M. Guerrero, José Matas, Juan C. Vasquez, Miguel CastillaAbstract:DC and AC Microgrids are key elements to integrate renewable and Distributed Energy resources as well as Distributed Energy Storage systems. In the last years, efforts toward the standardization of these Microgrids have been made. In this sense, this paper present the hierarchical control derived from ISA-95 and electrical dispatching standards to endow smartness and flexibility to microgrids. The hierarchical control proposed consist of three levels: i) the primary control is based on the droop method, including an output impedance virtual loop; ii) the secondary control allows restoring the deviations produced by the primary control; and iii) the tertiary control manage the power flow between the microgrid and the external electrical distribution system. Results from a hierarchical-controlled microgrid are provided to show the feasibility of the proposed approach.
Wenzhong Gao - One of the best experts on this subject based on the ideXlab platform.
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state of the art in microgrid integrated Distributed Energy Storage sizing
Energies, 2017Co-Authors: Ibrahim Alsaidan, Abdulaziz Alanazi, Wenzhong GaoAbstract:Distributed Energy Storage (DES) plays an important role in microgrid operation and control, as it can potentially improve local reliability and resilience, reduce operation cost, and mitigate challenges caused by high penetration renewable generation. However, to ensure an acceptable economic and technical performance, DES must be optimally sized and placed. This paper reviews the existing DES sizing methods for microgrid applications and presents a generic sizing method that enables microgrid planners to efficiently determine the optimal DES size, technology, and location. The proposed method takes into consideration the impact of DES operation on its lifetime to enhance the obtained results accuracy and practicality. The presented model can be used for both grid-tied (considering both grid-connected and islanded modes) and isolated microgrids.
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Distributed Energy Storage sizing for microgrid applications
IEEE PES Transmission and Distribution Conference and Exposition, 2016Co-Authors: Ibrahim Alsaidan, Amin Khodaei, Wenzhong GaoAbstract:The integration of Energy Storage system (ESS) provides various benefits to microgrids such as mitigating renewable generation variability, reducing operation cost, and supporting frequency and voltage control. Two main factors that affect the ESS function in microgrids include the size and the number of the installed ESS units. This paper investigates these two factors and develops a new mathematical model to determine the optimal size and number of the integrated ESS units in a microgrid. The proposed model is further used to perform a comparison between aggregated and Distributed ESS configurations. The proposed problem is formulated using mixed integer linear programming (MILP) and solved with CPLEX. The viability and effectiveness of the proposed model are validated by numerical simulations.
Alex Q. Huang - One of the best experts on this subject based on the ideXlab platform.
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Power management for DC microgrid enabled by solid-state transformer
IEEE Transactions on Smart Grid, 2014Co-Authors: Xunwei Yu, Xiaohu Zhou, Xu She, Alex Q. HuangAbstract:A novel Distributed power management scheme is proposed in this paper for a DC microgrid system, which is enabled by Solid-State transformer (SST). The proposed system includes Distributed renewable Energy resource (DRER) and Distributed Energy Storage device (DESD). The proposed Distributed control algorithm, which only relies on the local information and guarantees full utilization of each module in the system based on their characteristics, is applied to both SST and DC microgrid. To this end, a simulation platform is developed in MATLAB/Simulink, in which Photovoltaic (PV), fuel cell and battery are selected as the typical DRERs and DESD, respectively. Lastly, several typical case studies are carried out and the simulation results verify the proposed Distributed power management.
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the future renewable electric Energy delivery and management freedm system the Energy internet
Proceedings of the IEEE, 2011Co-Authors: Alex Q. Huang, M L Crow, G T Heydt, Jim P Zheng, S J DaleAbstract:This paper presents an architecture for a future electric power distribution system that is suitable for plug-and-play of Distributed renewable Energy and Distributed Energy Storage devices. Motivated by the success of the (information) Internet, the architecture described in this paper was proposed by the NSF FREEDM Systems Center, Raleigh, NC, as a roadmap for a future automated and flexible electric power distribution system. In the envisioned “Energy Internet,” a system that enables flexible Energy sharing is proposed for consumers in a residential distribution system. The key technologies required to achieve such a vision are presented in this paper as a result of the research partnership of the FREEDM Systems Center.
M J E Alam - One of the best experts on this subject based on the ideXlab platform.
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alleviation of neutral to ground potential rise under unbalanced allocation of rooftop pv using Distributed Energy Storage
IEEE Transactions on Sustainable Energy, 2015Co-Authors: M J E Alam, Kashem M Muttaqi, D SutantoAbstract:A high penetration of one-phase rooftop solar photovoltaic (PV) units with unbalanced allocation can create considerable neutral current and neutral potential rise in low voltage (LV) four-wire multigrounded distribution networks, even with balanced loads. Because of the limitations of traditional strategies to mitigate the combined effect of load and PV unbalance, this paper proposes the use of Distributed Energy Storage to reduce the neutral current and neutral potential under a high penetration of unbalanced rooftop solar PV allocation. A power-balancing algorithm based on charge/discharge control is developed to continuously adjust the power exchange with the grid to mitigate the neutral current and neutral potential rise, while minimizing power drawn from the Energy Storage. A dynamic model of the integrated PV-Storage system is developed to investigate the dynamic performance of the proposed strategy. An Australian LV distribution system is used to verify its performance and the results are presented.
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Mitigation of rooftop solar PV impacts and evening peak support by managing available capacity of Distributed Energy Storage systems
IEEE Transactions on Power Systems, 2013Co-Authors: M J E Alam, Kashem M Muttaqi, Danny SutantoAbstract:A high penetration of rooftop solar photovoltaic (PV) resources into low-voltage (LV) distribution networks creates reverse power-flow and voltage-rise problems. This generally occurs when the generation from PV resources substantially exceeds the load demand during high insolation period. This paper has investigated the solar PV impacts and developed a mitigation strategy by an effective use of Distributed Energy Storage systems integrated with solar PV units in LV networks. The Storage is used to consume surplus solar PV power locally during PV peak, and the stored Energy is utilized in the evening for the peak-load support. A charging/discharging control strategy is developed taking into account the current state of charge (SoC) of the Storage and the intended length of charging/discharging period to effectively utilize the available capacity of the Storage. The proposed strategy can also mitigate the impact of sudden changes in PV output, due to unstable weather conditions, by putting the Storage into a short-term discharge mode. The charging rate is adjusted dynamically to recover the charge drained during the short-term discharge to ensure that the level of SoC is as close to the desired SoC as possible. A comprehensive battery model is used to capture the realistic behavior of the Distributed Energy Storage units in a distribution feeder. The proposed PV impact mitigation strategy is tested on a practical distribution network in Australia and validated through simulations.
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Distributed Energy Storage for mitigation of voltage rise impact caused by rooftop solar pv
Power and Energy Society General Meeting, 2012Co-Authors: M J E Alam, Kashem M Muttaqi, D SutantoAbstract:A high penetration of solar photovoltaic (PV) resources into distribution networks may create voltage rise problem when the generation from PV resources substantially exceeds the load demand. To reduce the voltage rise, the excess amount of power from the solar PV units needs to be reduced. In this paper, Distributed Storage systems are proposed for the mitigation of voltage rise problem. The surplus Energy from the solar PV is used to charge the Distributed Storage units during midday, when the power from the solar PV would be typically higher than the load level. This stored Energy is then used to reduce the peak load in the evening. An intelligent strategy for charging and discharging control to make effective use of the Storage capacity is discussed. The proposed voltage rise mitigation strategy is verified on a practical low voltage distribution feeder in Australia.