Browsing by Author "Zhao, Pengfei"

Now showing 1 - 13 of 13
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    Ageing mitigation for battery energy storage system in electric vehicles
    (IEEE, 2022-09-27) Li, Shuangqi; Zhao, Pengfei; Gu, Chenghong; Li, Jianwei; Huo, Da; Cheng, Shuang
    Battery energy storage systems (BESS) have been extensively investigated to improve the efficiency, economy, and stability of modern power systems and electric vehicles (EVs). However, it is still challenging to widely deploy BESS in commercial and industrial applications due to the concerns of battery aging. This paper proposes an integrated battery life loss modeling and anti-aging energy management (IBLEM) method for improving the total economy of BESS in EVs. The quantification of BESS aging cost is realized by a multifactorial battery life loss quantification model established by capturing aging characteristics from cell acceleration aging tests.Meanwhile, a charging event analysis method is proposed to deploy the built life loss model in vehicle BESS management. Two BESS active anti-aging vehicle energy management models: vehicle to grid (V2G) scheduling and plug-in hybrid electric vehicle (PHEV) power distribution, are further designed, where the battery life loss quantification model is used to generate the aging cost feedback signals. The performance of the developed method is validated on a V2G peak-shaving simulation system and a hybrid electric vehicle. The work in this paper presents a practical solution to quantify and mitigate battery aging costs by optimizing energy management strategies and thus can further promote transportation electrification.
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    CO2 capture performance of gluconic acid-modified limestone-dolomite mixtures under realistic conditions
    (American Chemical Society , 2019-07-10) Wang, Ke; Gu, Feng; Clough, Peter T.; Zhao, Pengfei; Anthony, Edward J.
    Calcium Looping (CaL) technology has become one of the most attractive ways to capture CO2 from fossil fuel power plants. However, with increasing numbers of cyclic reactions, the CO2 capture capacity rapidly decreases. To address this shortcoming, limestone-dolomite mixtures modified by gluconic acid were explored to prepare highly effective, MgO-stabilized, CaO sorbents that exhibited a high and stable CO2 capture capacity over multiple cycles. The sorbents were all tested over 10 carbonation-calcination cycles and were performed under realistic CaL conditions (calcination in a high CO2 concentration). The results of this research have demonstrated that the inhomogeneous composition that occurs between CaO and MgO - caused by the small CaO crystallite size, porous texture, nanosheet (~100 nm thick) morphology - provides sufficient void space for the volume expansion during carbonation to mitigate the effects of repeated cycle sintering and retain structural stability. A MgO content as low as 10 mol% was able to ensure a superior CO2 capture performance with a fast carbonation rate, high CO2 carrying capacities and remarkable stability. Furthermore, these sorbents retained a conversion (above 90%) over multiple cycles following a recarbonation step
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    Economic-effective multi-energy management with voltage regulation networked with energy hubs
    (IEEE, 2020-10-15) Zhao, Pengfei; Gu, Chenghong; Hu, Zechun; Zhang, Xin; Chen, Xinlei; Hernando-Gil, Ignacio; Ding, Yucheng
    This paper develops a novel two-stage coordinated volt-pressure optimization (VPO) for integrated energy systems (IES) networked with energy hubs considering renewable energy sources. The promising power-to-gas (P2G) facilities are used for improving the interdependency of the IES. The proposed VPO contains the traditional volt-VAR optimization functionality to mitigate the voltage deviation while ensuring a satisfying gas quality due to the hydrogen mixture. In addition to the conventional voltage regulating devices, i.e., on-load tap changers and capacitor banks, P2G converter and gas storage are used to address the voltage fluctuation problem caused by renewable penetration. Moreover, an effective two-stage distributionally robust optimization (DRO) based on Wassersteain metric is utilized to capture the renewable uncertainty with tractable robust counterpart reformulations. The Wasserstein-metric based ambiguity set enables to provide additional flexibility hedging against renewable uncertainty. Extensive case studies are conducted in a modified IEEE 33-bus system connected with a 20-node gas system. The proposed VPO problem enables to provide a voltage-regulated economic operation scheme with gas quality ensured that contributes high-quality but low-cost multi-energy supply to customers.
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    Linearizing battery degradation for health-aware vehicle energy management
    (IEEE, 2023-09) Li, Shuangqi; Zhao, Pengfei; Gu, Chenghong; Huo, Da; Li, Jianwei; Cheng, Shuang
    The utilization of battery energy storage systems (BESS) in vehicle-to-grid (V2G) and plug-in hybrid electric vehicles (PHEVs) benefits the realization of net-zero in the energy-transportation nexus. Since BESS represents a substantial part of vehicle total costs, the mitigation of battery degradation should be factored into energy management strategies. This paper proposes a two-stage BESS aging quantification and health-aware energy management method for reducing vehicle battery aging costs. In the first stage, a battery aging state calibration model is established by analyzing the impact of cycles with various Crates and depth of discharges based on a semi-empirical method. The model is further linearized by learning the mapping relationship between aging features and battery life loss with a linear-in-the-parameter supervised learning method. In the second stage, with the linear battery life loss quantification model, a neural hybrid optimization-based energy management method is developed for mitigating vehicle BESS aging. The battery aging cost function is formulated as a linear combination of system states, which simplifies model solving and reduces computation cost. The case studies in an aggregated EVs peak-shaving scenario and a PHEV with an engine-battery hybrid powertrain demonstrate the effectiveness of the developed method in reducing battery aging costs and improving vehicle total economy. This work provides a practical solution to hedge vehicle battery degradation costs and will further promote decarbonization in the energy-transportation nexus.
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    Molten shell-activated, high-performance, un-doped Li4SiO4 for high-temperature CO2 capture at low CO2 concentrations
    (Elsevier, 2020-10-16) Wang, Ke; Gu, Feng; Clough, Peter T.; Zhao, Youwei; Zhao, Pengfei; Anthony, Edward J.
    Lithium orthosilicate (Li4SiO4) represents a potential class of high-temperature sorbents for CO2 capture in power plants and sorption enhanced methane reforming to produce H2. However, conventional wisdom suggests that pure Li4SiO4 should have extremely slow sorption kinetics at realistic low CO2 concentrations. Here, we report the opposite result: using a simple and cost-effective glucose-based mild combustion procedure, an unusually efficient and pure form of Li4SiO4 (MC-0.6) was synthesized to achieve a maximum uptake capacity of 35.0 wt% at 580 °C for CO2 concentrations under 15 vol% and maintained this capacity over multiple cycles. The characterization results showed that highly porous nano-agglomerate-like (50–100 nm) morphologies were apparent and ensured a rapid surface-sorption of CO2. In this process, a macroporous nano-sized Li2SiO3 cover on the melt layer of Li2CO3 was identified for the first time. This special structure appeared to accelerate the transportation of CO2 and the diffusion of Li+ and O2− through a molten layer enhancing contact with CO2. Thus, the sample MC-0.6 reduced both the surface-sorption and diffusion kinetics dependence on low CO2 concentrations. Rather than use traditional approaches (controlled morphologies combined with doping), we have demonstrated that the slow kinetics can be overcome simply by a controlled morphologies strategy, which opens up a new direction for the synthesis of high-performance Li4SiO4 sorbents.
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    Online battery-protective vehicle to grid behavior management
    (Elsevier, 2022-01-03) Li, Shuangqi; Zhao, Pengfei; Gu, Chenghong; Huo, Da; Zeng, Xianwu; Pei, Xiaoze; Cheng, Shuang; Li, Jianwei
    With the popularization of electric vehicles, vehicle-to-grid (V2G) has become an indispensable technology to improve grid economy and reliability. However, battery aging should be mitigated while providing V2G services so as to protect customer benefits and mobilize their positivity. Conventional battery anti-aging V2G scheduling methods mainly offline operates and can hardly be deployed online in hardware equipment. This paper proposes a novel online battery anti-aging V2G scheduling method based on a novel two-stage parameter calibration framework. In the first stage, the V2G scheduling is modeled as an optimization problem, where the objective is to reduce grid peak-valley difference and mitigate battery aging. The online deployment of the developed optimization-based V2G scheduling is realized by a rule-based V2G coordinator in the second stage, and a novel parameter calibration method is developed to adjust controller hyper-parameters. With the parameter calibration process, the global optimality and real-time performance of V2G strategies can be simultaneously realized. The effectiveness of the proposed methodologies is verified on a practical UK distribution network. Simulation results indicate that it can effectively mitigate battery aging in providing V2G services while guaranteeing algorithm real-time performance.
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    Porous MgO-stabilized CaO-based powders/pellets via a citric acid-based carbon template for thermochemical energy storage in concentrated solar power plants
    (Elsevier, 2020-01-21) Wang, Ke; Gu, Feng; Clough, Peter T.; Zhao, Pengfei; Anthony, Ben
    The reversible CaO/CaCO3 carbonation reaction (CaL) is one of the most promising candidates for high-temperature thermochemical energy storage (TCES) in concentrated solar power plants (CSP). Here, a sacrificial citric acid-based carbon template was developed to produce high-performance CaO-based sorbents to mitigate the progressive deactivation with sequential carbonation-calcination cycling. The carbon template was formed through in situ pyrolysis of citric acid in a simple heating process under nitrogen. After a secondary calcination step in air, a stable porous MgO-stabilized nano-CaO powder was generated and achieved high long-term effective conversion due to its resistance to pore plugging and sintering. By dry mixing citric acid with limestone-dolomite mixtures, this procedure can also be applied to synthesize MgO-stabilized CaO pellets via an extrusion–spheronization route, which resulted in comparably stable and effective conversion as the optimized CaO powder. Additionally, the considerable mechanical strength of MgO-stabilized CaO pellets should enable their realistic application in fluidized bed reactors. Thus, this simple, cost-effective and easily-scalable synthesis technique appears to have great potential for CSP-TCES under high temperature operation.
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    Reactive power optimization in integrated electricity and gas systems
    (IEEE, 2020-05-28) Zhao, Pengfei; Gu, Chenghong; Xiang, Yue; Zhang, Xin; Shen, Yichen; Li, Shuangqi
    Volt/VAR optimization (VVO) is one important operation in distribution systems to maintain acceptable voltage profiles. However, the high penetration of renewable generation poses severe challenges to VVO, leading to voltage deviation and fluctuation. This is further complicated by the growing coupling between the electricity and natural gas systems. To resolve the unacceptable voltage deviation under energy system interdependency, this article proposes a cooptimization of VVO for an integrated electricity and gas system (IEGS) with uncertain renewable generation. A two-stage data-driven distributionally robust optimization is developed to model the coordinated optimization problem, which determines the two-stage VVO and operation schemes with dispatch and corrective adjustment through active power regulation and reactive power support in both day-ahead and real-time stage. A semidefinite programming is reformulated to ensure the tractability and the proposed problem is solved by a constraint generation framework. Simulation studies are conducted on a 33-bus-6-node IEGS. Case studies demonstrate that the interdependency between electricity and gas systems reduces the significant operation cost and voltage rise. It, thus, can benefit integrated system operators with a powerful operation tool to manage the systems with fewer costs but integrate more renewable energy while maintaining the high supply quality.
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    Socially governed energy hub trading enabled by blockchain-based transactions
    (IEEE, 2023-09-05) Zhao, Pengfei; Li, Shuangqi; Cao, Zhidong; Hu, Paul Jen-Hwa; Gu, Chenghong; Yan, Xiaohe; Huo, Da; Luo, Tianyi; Wang, Zikang
    Decentralized trading schemes involving energy prosumers have prevailed in recent years. Such schemes provide a pathway for increased energy efficiency and can be enhanced by the use of blockchain technology to address security concerns in decentralized trading. To improve transaction security and privacy protection while ensuring desirable social governance, this article proposes a novel two-stage blockchain-based operation and trading mechanism to enhance energy hubs connected with integrated energy systems (IESs). This mechanism includes multienergy aggregators (MAGs) that use a consortium blockchain and its enabled proof-of-work (PoW) to transfer and audit transaction records, with social governance principles for guiding prosumers’ decision-making in the peer-to-peer (P2P) transaction management process. The uncertain nature of renewable generation and load demand are adequately modeled in the two-stage Wasserstein-based distributionally robust optimization (DRO). The practicality of the proposed mechanism is illustrated by several case studies that jointly show its ability to handle an increased renewable generation capacity, achieve a 16.7% saving in the audit cost, and facilitate 2.4% more P2P interactions. Overall, the proposed two-stage blockchain-based trading mechanism provides a practical trading scheme and can reduce redundant trading amounts by 6.5%, leading to a further reduction of the overall operation cost. Compared to the state-of-the-art benchmark methods, our mechanism exhibits significant operation cost reduction and ensures social governance and transaction security for IES and energy hubs.
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    Sorption of CO2 on NaBr co-doped Li4SiO4 ceramics: Structural and kinetic analysis
    (Elsevier, 2019-07-13) Wang, Ke; Zhao, Youwei; Clough, Peter T.; Zhao, Pengfei; Anthony, Edward J.
    Structurally modified and improved NaBr-co-doped Li4SiO4 ceramics were developed for CO2 absorption in low-CO2-concentration atmospheres. Pure and NaCl-doped Li4SiO4 ceramics were also prepared for comparison. The samples were analyzed by X-ray diffraction, Scanning Electron Microscopy, N2 adsorption, X-ray photoelectron spectroscopy, differential scanning calorimetry, and thermogravimetric analyses (dynamic and isothermal). The sorption kinetics were obtained using a double exponential model. The results showed that both Na and Br can be introduced into the Li4SiO4 structure and doped on Li and oxygen sites, respectively. The doped sample presented a Li2O-enriched surface, guaranteeing abundant LiO sites and are significantly different from previous anionic (CO3, F and Cl) doping of Li4SiO4, Br doping also generated macroporous features with small particle size, these favorable characteristics promoted the surface chemisorption kinetics. Moreover, DSC analysis confirmed the formation of the molten phases during CO2 absorption, which helps improve the lithium diffusion kinetics. Here, 0.1 mol NaBr doping was used to reach a maximum absorption capacity (>30.0 wt%) in 15 vol% CO2, suggesting that NaBr-doped Li4SiO4 ceramics have great potential for CO2 capture at high temperature.
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    Structural and kinetic analysis of CO2 sorption on NaNO2-promoted MgO at moderate temperatures
    (Elsevier, 2019-04-12) Wang, Ke; Zhao, Youwei; Clough, Peter T.; Zhao, Pengfei; Anthony, Edward J.
    (200-500 °C) CO2 capture. However, the structure-performance relationship and kinetic characteristics of NaNO2-promoted MgO remain unclear. Here the effects of physical-chemical properties on the CO2 sorption performance of NaNO2-promoted MgO and the sorption kinetics were comprehensively studied to elucidate the detailed role of NaNO2. Samples were characterized by X-ray diffraction, scanning electron microscopy, N2 adsorption, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The sorption kinetics were obtained by isothermal thermogravimetry and elucidated using a double exponential model. Compared with pure MgO and NaNO3-promoted MgO, NaNO2-modified MgO had a lower initial sorption temperature and a unique bimodal sorption characteristic. Characterizations results revealed that such bimodal sorption was due to the presence of double promoters (mixture of NaNO2 and NaNO3) which implies that some of the nitrite was oxidized to nitrate during the preparation process. Deposition of double promoters further reduced the amounts of hydroxide and carbonate species for pure MgO while still preserving more hydroxide and carbonate species on the surface as compared with NaNO3-promoted MgO. The kinetics analysis demonstrated that the double exponential model can well-describe the sorption process for both NaNO3- and NaNO2-promoted MgO, suggesting that the entire sorption occurs as a double process (surface chemisorption and product layer diffusion). Significantly differences were seen from NaNO3-promoted MgO, and the surface chemisorption process of NaNO2-promoted MgO was independent of temperature, which suggests that an increased presence of hydroxide and carbonate species provide more active sites for greatly facilitating surface chemisorption.
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    Synthesis of highly effective stabilized-CaO sorbents via a sacrificial N-doped carbon nanosheet template
    (Royal society of Chemistry, 2019-03-18) Wang, Ke; Clough, Peter T.; Zhao, Pengfei; Anthony, Edward J.
    Calcium looping, a promising high-temperature CO2 capture technique, offers a midterm economic solution to mitigate anthropogenic CO2 emissions. The main challenge for calcium looping is the synthesis of highly efficient CaO-based sorbents that can be used over many reaction cycles. Here, a sacrificial N-doped carbon nanosheet template was developed which produces MgO-stabilized, CaO sorbents with fast adsorption rates, high capacities and remarkable long term performance over many cycles. The characterization results show that such a template was formed through in situ pyrolysis of an organic acid and nitrates in a simple heating process under nitrogen. The presence of a carbonaceous template prevented crystallite growth, featured highly macroporous nanosheet (~60 nm thick) morphologies, ensured homogeneously mixing of Ca and Mg, which is essential to attain minimal diffusion limitations, mitigated sintering, and produced structural stabilization. Thus, 10 mol% MgO acting as an inert stabilizer was sufficient to achieve a CO2 uptake of 0.65 g/g (corresponding to a capacity retention of 89.9%) after 10 cycles in realistic conditions, as confirmed by TGA analyses. This N-doped carbon template can be applied generally to form a wide range of porous and nanostructured stabilized-CaO sorbents with stable CO2 uptakes.
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    Two-stage co-optimization for utility-social systems with social-aware P2P trading
    (IEEE, 2022-08-30) Zhao, Pengfei; Li, Shuangqi; Hu, Paul Jen-Hwa; Cao, Zhidong; Gu, Chenghong; Yan, Xiaohe; Huo, Da; Hernando-Gil, Ignacio
    Effective utility system management is fundamental and critical for ensuring the normal activities, operations, and services in cities and urban areas. In that regard, the advanced information and communication technologies underpinning smart cities enable close linkages and coordination of different subutility systems, which is now attracting research attention. To increase operational efficiency, we propose a two-stage optimal co-management model for an integrated urban utility system comprised of water, power, gas, and heating systems, namely, integrated water-energy hubs (IWEHs). The proposed IWEH facilitates coordination between multienergy and water sectors via close energy conversion and can enhance the operational efficiency of an integrated urban utility system. In particular, we incorporate social-aware peer-to-peer (P2P) resource trading in the optimization model, in which operators of an IWEH can trade energy and water with other interconnected IWEHs. To cope with renewable generation and load uncertainties and mitigate their negative impacts, a two-stage distributionally robust optimization (DRO) is developed to capture the uncertainties, using a semidefinite programming reformulation. To demonstrate our model’s effectiveness and practical values, we design representative case studies that simulate four interconnected IWEH communities. The results show that DRO is more effective than robust optimization (RO) and stochastic optimization (SO) for avoiding excessive conservativeness and rendering practical utilities, without requiring enormous data samples. This work reveals a desirable methodological approach to optimize the water–energy–social nexus for increased economic and system-usage efficiency for the entire (integrated) urban utility system. Furthermore, the proposed model incorporates social participations by citizens to engage in urban utility management for increased operation efficiency of cities and urban areas.