A Coordinated Control for Photovoltaic Generators and Energy Storages in Low-Voltage AC/DC Hybrid Microgrids under Islanded Mode

Liu, Yao; Hou, Xiaochao; Lin, Chao; Guerrero, Josep M.

doi:10.3390/en9080651

Cited by 20 publications

(21 citation statements)

References 42 publications

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“…Recently, DC microgrids and distribution systems are also taken into consideration due to the widespread of DC sources and loads [21]. DC microgrids allow easier integration of renewables along with the elimination of harmonic distortion and synchronization issues inherently [22]. Therefore, integration of AC and DC microgrids is proposed, and this emerges the concept of hybrid AC/DC microgrids [19].…”

Section: Fuzzy Logic-based Operation Of Battery Energy Storage Systemmentioning

confidence: 99%

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Fuzzy Logic-Based Operation of Battery Energy Storage Systems (BESSs) for Enhancing the Resiliency of Hybrid Microgrids

2017

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Abstract:The resiliency of power systems can be enhanced during emergency situations by using microgrids, due to their capability to supply local loads. However, precise prediction of disturbance events is very difficult rather the occurrence probability can be expressed as, high, medium, or low, etc. Therefore, a fuzzy logic-based battery energy storage system (BESS) operation controller is proposed in this study. In addition to BESS state-of-charge and market price signals, event occurrence probability is taken as crisp input for the BESS operation controller. After assessing the membership levels of all the three inputs, BESS operation controller decides the operation mode (subservient or resilient) of BESS units. In subservient mode, BESS is fully controlled by an energy management system (EMS) while in the case of resilient mode, the EMS follows the commands of the BESS operation controller for scheduling BESS units. Therefore, the proposed hybrid microgrid model can operate in normal, resilient, and emergency modes with the respective objective functions and scheduling horizons. Due to the consideration of resilient mode, load curtailment can be reduced during emergency operation periods. Numerical simulations have demonstrated the effectiveness of the proposed strategy for enhancing the resiliency of hybrid microgrids.

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Section: Fuzzy Logic-based Operation Of Battery Energy Storage Systemmentioning

confidence: 99%

“…In emergency mode, the amount of power generated by AC side RDGs, AC side CGDs, the amount of power transferred between AC and DC microgrids, and amount of load shed should be balanced with total AC-side load, as given by (22). Similarly, DC side load balancing is determined by using Equation (23).…”

Section: Load Balancing Constraintsmentioning

confidence: 99%

Fuzzy Logic-Based Operation of Battery Energy Storage Systems (BESSs) for Enhancing the Resiliency of Hybrid Microgrids

2017

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“…Averaging Equation (19) within the switching period, using the small ripple approximation [43], gives Equation (20). Then, replacing Expression (20) into the averaged differential equation of the DC-bus voltage (5) leads to Equation (21), which describes the dynamic behavior of the averaged DC-bus voltage under the action of the SMC:…”

Section: Equivalent Dynamics and Parameters Designmentioning

confidence: 99%

Design and Control of a Buck–Boost Charger-Discharger for DC-Bus Regulation in Microgrids

et al. 2017

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Abstract:In DC and hybrid microgrids (MG), the DC-bus regulation using Energy Storage Devices (ESD) is important for the stable operation of both the generators and loads. There are multiple commercial voltage levels for both ESD and DC-bus; therefore, the ESD voltage may be higher, equal or lower than the DC-bus voltage depending on the application. Moreover, most of the ESD converter controllers are linear-based, hence they ensure stability in a limited operation range. This paper proposes a system to regulate the DC-bus voltage of an MG accounting for any voltage relation between the ESD and the DC-bus voltage. The proposed system is formed by an ESD connected to a DC-bus through a bidirectional Buck-Boost converter, which is regulated by a Sliding-Mode Controller (SMC) to ensure the system stability in the entire operation range. The SMC drives the Buck-Boost charger-discharger to regulate the DC-bus voltage, at the desired reference value, by charging or discharging the ESD. This paper also provides detailed procedures to design the parameters of both the SMC and the charger-dischager. Finally, simulation and experimental results validate the proposed solution and illustrate its performance.

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“…In addition to the traditional services, such as power quality improvement [5,6], load following [7], system blackout [8], system stability [9,10] and congestion management [11], energy storage is strongly promoted to increase the level of flexibility for systems to accommodate variable generation [12]. Energy storage has been found to be efficient and beneficial in mitigating fluctuations on renewable generation [13], maintaining power balance in systems with intensive wind energy [14], and providing short-term frequency response for wind farms [15].…”

Section: Introductionmentioning

confidence: 99%

Determining the Minimal Power Capacity of Energy Storage to Accommodate Renewable Generation

Han

Liao

et al. 2017

Energies

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Abstract:The increasing penetration of renewable generation increases the need for flexibility to accommodate for growing uncertainties. The level of flexibility is measured by the available power that can be provided by flexible resources, such as dispatachable generators, in a certain time period under the constraint of transmission capacity. In addition to conventional flexible resources, energy storage is also expected as a supplementary flexible resource for variability accommodation. To aid the cost-effective planning of energy storage in power grids with intensive renewable generation, this study proposed an approach to determine the minimal requirement of power capacity and the appropriate location for the energy storage. In the proposed approach, the variation of renewable generation is limited within uncertainty sets, then a linear model is proposed for dispatchable generators and candidate energy storage to accommodate the variation in renewable generation under the power balance and transmission network constraints. The target of the proposed approach is to minimize the total power capacity of candidate energy storage facilities when the availability of existing flexible resources is maximized. After that, the robust linear optimization method is employed to convert and solve the proposed model with uncertainties. Case studies are carried out in a modified Garver 6-bus system and the Liaoning provincial power system in China. Simulation results well demonstrate the proposed optimization can provide the optimal location of energy storage with small power capacities. The minimal power capacity of allocated energy storage obtained from the proposed approach only accounts for 1/30 of the capacity of the particular transmission line that is required for network expansion. Besides being adopted for energy storage planning, the proposed approach can also be a potential tool for identifying the sufficiency of flexibility when a priority is given to renewable generation.

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A Coordinated Control for Photovoltaic Generators and Energy Storages in Low-Voltage AC/DC Hybrid Microgrids under Islanded Mode

Cited by 20 publications

References 42 publications

Fuzzy Logic-Based Operation of Battery Energy Storage Systems (BESSs) for Enhancing the Resiliency of Hybrid Microgrids

Fuzzy Logic-Based Operation of Battery Energy Storage Systems (BESSs) for Enhancing the Resiliency of Hybrid Microgrids

Design and Control of a Buck–Boost Charger-Discharger for DC-Bus Regulation in Microgrids

Determining the Minimal Power Capacity of Energy Storage to Accommodate Renewable Generation

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