Second-order ripples occur in the voltage and current during any DC–AC power conversion. These conversions occur in the voltage source inverters (VSIs), current source inverters (CSIs), and various single-stage inverters (SSIs) topologies. The second-order ripples lead to oscillating source node currents and DC bus voltages when there is an interconnection between the AC and DC microgrids or when an AC load is connected to the DC bus of the microgrid. Second-order ripples have various detrimental effects on the sources and the battery storage. In the storage battery, they lead to the depletion of electrodes. They also lead to stress in the converter or inverter components. This may lead to the failure of a component and hence affect the reliability of the system. Furthermore, the second-order ripple currents (SRCs) lead to ripple torque in wind turbines and lead to mechanical stress. SRCs cause a rise in the temperature of photovoltaic panels. An increase in the temperature of PV panels leads to a reduction in the power generated. Furthermore, the second-order voltage and current oscillations lead to a varying maximum power point in PV panels. Hence, the maximum power may not be extracted from it. To mitigate SRCs, oversizing of the components is needed. To improve the lifespan of the sources, storage, and converter components, the SRCs must be mitigated or kept within the desired limits. In the literature, different methodologies have been proposed to mitigate and regulate these second-order ripple components. This manuscript presents a comprehensive review of different effects of second-order ripples on different sources and the methodologies adopted to mitigate the ripples. Different active power decoupling methodologies, virtual impedance-based methodologies, pulse width modulation-based signal injection methodologies, and control methods adopted in distributed power generation methods for DC microgrids have been presented. The application of ripple control methods spans from single converters such as SSIs and VSIs to a network of interconnected converters. Furthermore, different challenges in the field of virtual impedance control and ripple mitigation in distributed power generation environments are discussed. This paper brings a review regarding control methodologies to mitigate and regulate second-order ripples in DC–AC conversions and microgrids.
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Sliding Mode Control Based Energy Harvesting System For Low Power Applications
As technology advances and cities become more
innovative, the need to harvest energy to power intelligent devices
at remote locations, such as wireless sensors, is increasing. This
paper focuses on studying and simulating an energy management
system (EMS) for energy harvesting with a battery and a
supercapacitor for low power applications. Lithium-ion batteries
are the primary energy storage source for low power applications
due to their high energy density and efficiency. On the other hand,
the supercapacitors excel in fast charge and discharge.
Furthermore, supercapacitors tolerate high currents due to their
low equivalent series resistance (ESR). The supercapacitor in the
system increases the time response of the power delivery to the
load, and it also absorbs the high currents in the system.
Moreover, the supercapacitor covers short-time load demand due
to the fluctuation of the renewable source. The EMS monitors the
proposed system to maintain power to the load either from the
renewable source or the energy storage. The power flow of the
energy storage is controlled via DC-DC bidirectional converters.
The lithium-ion battery is charged via a constant current (CC)
using a sliding mode controller (SMC) and a constant voltage (CV)
via a typical PI controller. The response of the SMC current
controller is compared with PI and Fuzzy current controller.
Furthermore, the performance of a system having and not having
a supercapacitor is compared. Finally, MATLAB modeling system
simulation and experimental implementation results are analyzed
and presented.
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- Award ID(s):
- 1816197
- NSF-PAR ID:
- 10330603
- Date Published:
- Journal Name:
- IEEE Energy Conversion Congress & Expo 2021
- Page Range / eLocation ID:
- 302 to 309
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Conventional lithium-ion batteries are unable to meet the increasing demands for high-energy storage systems, because of their limited theoretical capacity. 1 In recent years, intensive attention has been paid to enhancing battery energy storage capability to satisfy the increasing energy demand in modern society and reduce the average energy capacity cost. Among the candidates for next generation high energy storage systems, the lithium sulfur battery is especially attractive because of its high theoretical specific energy (around 2600 W h kg-1) and potential cost reduction. 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Catalysts such as MnO 2 and Co dopants were employed to accelerate the sulfur conversion reaction during the charge and discharge process. 5 However, catalysts based on transition metals suffer from poor electronic conductivity. Other catalysts such as transition metal dopants are also limited due to the increased process complexities. . In addition, the severe shuttle effects in Li-S batteries may lead to fast failures of the battery. Constructing a protection layer on the separator for limiting the transmission of soluble polysulfides is considered an effective way to eliminate the shuttle phenomenon. However, the soluble sulfides still can largely dissolve around the cathode side causing the sluggish reaction condition for sulfur conversion. 5 To mitigate the issues above, herein we demonstrate a novel sulfur electrode design strategy enabled by additive manufacturing and oxidative vapor deposition (oCVD). 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Density functional theory calculation reveals the electronic state variance between the structures with and without defects, the structure with defects demonstrates the higher kinetic condition for sulfur conversion. To further identify the favorable reaction dynamic process, the in-situ XRD is used to characterize the transformation between soluble and insoluble polysulfides, which is the main barrier in the charge and discharge process of Li-S batteries. The results show the oCVD coated 3D printed sulfur cathode exhibits a much higher kinetic process for sulfur conversion, which benefits from the highly tailored hierarchal hollow structure and the defects engineering on the cathode. Further, the oCVD coated 3D printed sulfur cathode also demonstrates higher stability during long cycling enabled by the oCVD PEDOT protection layer, which is verified by an absorption energy calculation of polysulfides at PEDOT. 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Ever-increasing demands for energy, particularly being environmentally friendly have promoted the transition from fossil fuels to renewable energy.1Lithium-ion batteries (LIBs), arguably the most well-studied energy storage system, have dominated the energy market since their advent in the 1990s.2However, challenging issues regarding safety, supply of lithium, and high price of lithium resources limit the further advancement of LIBs for large-scale energy storage applications.3Therefore, attention is being concentrated on an alternative electrochemical energy storage device that features high safety, low cost, and long cycle life. Rechargeable aqueous zinc-ion batteries (ZIBs) is considered one of the most promising alternative energy storage systems due to the high theoretical energy and power densities where the multiple electrons (Zn2+) . In addition, aqueous ZIBs are safer due to non-flammable electrolyte (e.g., typically aqueous solution) and can be manufactured since they can be assembled in ambient air conditions.4As an essential component in aqueous Zn-based batteries, the Zn metal anode generally suffers from the growth of dendrites, which would affect battery performance in several ways. Second, the led by the loose structure of Zn dendrite may reduce the coulombic efficiency and shorten the battery lifespan.5
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Obama, B., The irreversible momentum of clean energy.
Science 2017, 355 (6321), 126-129.Goodenough, J. B.; Park, K. S., The Li-ion rechargeable battery: a perspective.
J Am Chem Soc 2013, 135 (4), 1167-76.Li, C.; Xie, X.; Liang, S.; Zhou, J., Issues and Future Perspective on Zinc Metal Anode for Rechargeable Aqueous Zinc‐ion Batteries.
Energy & Environmental Materials 2020, 3 (2), 146-159.Jia, H.; Wang, Z.; Tawiah, B.; Wang, Y.; Chan, C.-Y.; Fei, B.; Pan, F., Recent advances in zinc anodes for high-performance aqueous Zn-ion batteries.
Nano Energy 2020, 70 .Yang, J.; Yin, B.; Sun, Y.; Pan, H.; Sun, W.; Jia, B.; Zhang, S.; Ma, T., Zinc Anode for Mild Aqueous Zinc-Ion Batteries: Challenges, Strategies, and Perspectives.
Nanomicro Lett 2022, 14 (1), 42.Yang, Q.; Li, Q.; Liu, Z.; Wang, D.; Guo, Y.; Li, X.; Tang, Y.; Li, H.; Dong, B.; Zhi, C., Dendrites in Zn-Based Batteries.
Adv Mater 2020, 32 (48), e2001854.Acknowledgment
This work was partially supported by the U.S. National Science Foundation (NSF) Award No. ECCS-1931088. S.L. and H.W.S. acknowledge the support from the Improvement of Measurement Standards and Technology for Mechanical Metrology (Grant No. 22011044) by KRISS.
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1109/ECCE47101.2021.9595302
