| 1. |
- Xu, Nan, et al.
(författare)
-
Global optimization energy management for multi-energy source vehicles based on "Information layer - Physical layer - Energy layer- Dynamic programming" (IPE-DP)
- 2022
-
Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 312
-
Tidskriftsartikel (refereegranskat)abstract
- To reveal the energy-saving mechanisms of global energy management, we propose a global optimization framework of "information layer-physical layer-energy layer-dynamic programming " (IPE-DP), which can realize the unity of different information scenarios, different vehicle configurations and energy conversions. The deterministic dynamic programing (DP) and adaptive dynamic programming (ADP) are taken as the core algorithms. As a benchmark for assessing the optimality, DP strategy has four main challenges: standardization, real-time application, accuracy, and satisfactory drivability. To solve the above problems, the IPE-DP optimization framework is established, which consists of three main layers, two interface layers and an application layer. To be specific, the full-factor trip information is acquired from three scenarios in the information layer, and then the feasible work modes of the vehicle are determined in the physical layer based on the proposed conservation framework of "kinetic/potential energy & onboard energy ". The above lays a foundation for the optimal energy distribution in the energy layer. Then, a global domain-searching algorithm and action dependent heuristic dynamic programming (ADHDP) model are developed for different information acquisition scenarios to obtain the optimal solution. To improve the computational efficiency under the deterministic information, a fast DP is developed based on the statistical rules of DP behavior, the core of which is to restrict the exploring region based on a reference SOC trajectory. Regarding the stochastic trip information, the ADHDP model is established, including determining the utility function, network design and training process. Finally, two case studies are given to compare the economic performance of the vehicle under different information acquisition scenarios, which lays a foundation for analyzing the relationship between the amount of information input and energy-saving potential of the vehicle. Simulation results demonstrate that the proposed method gains a better performance in both real-time performance and global optimality.
|
|
| 2. |
- Bai, Fan, et al.
(författare)
-
Application of similarity theory in modeling the output characteristics of proton exchange membrane fuel cell
- 2021
-
Ingår i: International journal of hydrogen energy. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0360-3199 .- 1879-3487. ; 46:74, s. 36940-36953
-
Tidskriftsartikel (refereegranskat)abstract
- Proton Exchange Membrane Fuel Cell (PEMFC) has attracted widespread interest. In the present work, similarity analysis is adopted for a three-dimensional single-phase isothermal model of PEMFC to derive similarity criteria. Seven kinds of input criteria (Pi(1) similar to Pi(7)) are obtained, relevant to the fluid flow, pressure drop, flow resistance in a porous medium, activity loss, diffusion mass transfer, convective mass transfer and ohmic loss in PEMFC respectively. Dimensionless voltage and dimensionless current density are defined as two output criteria. Numerical verifications show that if the seven criteria keep their individual values with their components vary in a wide range, the dimensionless polarization curves keep the same with a deviation about 1%, showing the validity and feasibility of the present analysis. From the effect on the dimensionless polarization curve, sensibility analysis shows that the seven criteria can be divided into three categories: strong (Pi(4) and Pi(7), -94.9% similar to +349.2%), mild to minor (Pi(5) and Pi(6), -4.5% similar to +5.0%), and negligible (Pi(1), Pi(2) and Pi(3), -1.2% similar to +1.1%). The similarity analysis approach can greatly save computation time in modeling the output characteristics of PEMFC. (C) 2021 Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.
|
|
| 3. |
- Wang, Fengjuan, et al.
(författare)
-
Physical–cyber–human framework‐based resilience evaluation toward urban power system: Case study from China
- 2024
-
Ingår i: Risk Analysis. - : Wiley. - 0272-4332 .- 1539-6924.
-
Tidskriftsartikel (refereegranskat)abstract
- Because the increased frequency, intensity, and duration of extreme weather events have significantly challenged power systems, there has been an increased interest in resilient power systems. This article establishes a multicriteria resilience evaluation framework for urban power systems from a physical-cyber-human system perspective, in which the two principal elements responsible for power system function degradation are described, the three major domains comprising urban power systems are explained, four core capacities that positively contribute to power system resilience are proposed, and 15 (11 objective and four subjective) power system resilience evaluation indicators are identified. Fuzzy hesitant judgment and a Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) aggregation method are employed to minimize the expert divergence and maximize the group consensus. A validation method is designed and a comparison with commonly applied performance-based and attributes-based evaluation methods is conducted. The applicability of the evaluation framework is verified using data from four Chinese municipalities: Shanghai, Beijing, Chongqing, and Tianjin. It was found that Shanghai's resilience was the best, and Chongqing's physical resistance disadvantages would result in the greatest difficulties in coping with extreme event disturbances. Physical, cyber, and human domain resilience enhancement strategies are given for different cities separately. This study provides a practical tool to evaluate, compare, and enhance power system resilience for governments and public utilities.
|
|
| 4. |
- Yan, Y., et al.
(författare)
-
Roadmap to hybrid offshore system with hydrogen and power co-generation
- 2021
-
Ingår i: Energy Conversion and Management. - : Elsevier Ltd. - 0196-8904 .- 1879-2227. ; 247
-
Tidskriftsartikel (refereegranskat)abstract
- Constrained by the expansion of the power grid, the development of offshore wind farms may be hindered and begin to experience severe curtailment or restriction. The combination of hydrogen production through electrolysis and hydrogen-to-power is considered to be a potential option to achieve the goal of low-carbon and energy security. This work investigates the competitiveness of different system configurations to export hydrogen and/or electricity from offshore plants, with particular emphasis on unloading the mixture of hydrogen and electricity to end-users on land. Including the levelized energy cost and net present value, a comprehensive techno-economic assessment method is proposed to analyze the offshore system for five scenarios. Assuming that the baseline distance is 10 km, the results show that exporting hydrogen to land through pipelines shows the best economic performance with the levelized energy cost of 3.40 $/kg. For every 10 km increase in offshore distance, the net present value of the project will be reduced by 5.69 MU$, and the project benefit will be positive only when the offshore distance is less than 53.5 km. An important finding is that the hybrid system under ship transportation mode is not greatly affected by the offshore distance. Every 10% increase in the proportion of hydrogen in the range of 70%–100% can increase the net present value by 1.43–1.70 MU$, which will increase by 7.36–7.37 MU$ under pipeline transportation mode. Finally, a sensitivity analysis was carried out to analyze the wind speed, electricity and hydrogen prices on the economic performance of these systems.
|
|
| 5. |
- Zhang, Haoran, et al.
(författare)
-
Urban power load profiles under ageing transition integrated with future EVs charging
- 2021
-
Ingår i: Advances in Applied Energy. - : Elsevier BV. - 2666-7924. ; 1, s. 100007-100007
-
Tidskriftsartikel (refereegranskat)abstract
- Understanding ageing transition caused fine-grained changes of electricity profile is the significant insight for coping with future threatens in grid flexibility management. The research gaps for the hourly-basis knowledge exist due to challenges in microanalysis on user-side behavior. Based on billions of users’ behavior data, we investigated the changes on the load profiles due to population aging. We found that owing to ageing transition, the participation population in high electricity-density activities decreases by about 8%. The corresponding shift in driving behavior rises the 14% difference between peak charging load and valley. We concluded that population aging will dramatically change both the magnitude and shape of future dynamic-load profiles. Therefore, we further suggested a new solution with comprehensive and quantitative management for PVs development and the smart charging market with smooth operation of the grid in coupling the potential challenges caused by the ageing issue.
|
|
| 6. |
- Bao, Minglei, et al.
(författare)
-
Modeling and evaluating nodal resilience of multi-energy systems under windstorms
- 2020
-
Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 270
-
Tidskriftsartikel (refereegranskat)abstract
- With the growing frequency and extent of extreme weather events, the resilient operation of multi-energy systems (MESs) has drawn attention nowadays. However, there is little study on the methodology with a set of key indicators to quantify the resilience of MESs with the consideration of the impacts of extreme weather. To address the problem, this paper proposes a framework to evaluate the time-dependent resilience of MESs considering energy interactions during extreme weather events, such as windstorms. Firstly, the multi-phase performance curve is utilized to describe the response behavior of MESs at different phases under the impacts of windstorms. Secondly, a service-based optimal energy flow model is developed to minimize the consequences caused by windstorms through the coordination among different energy subsystems. In order to model the chaotic failures and restoration of components, the Monte-Carlo simulation technique is applied. Furthermore, nodal resilience metrics for different energy carriers are proposed to quantify the resilience in MESs. Numerical studies demonstrate the capability of the proposed technique to quantify the resilience of MESs under windstorms. The results show that the resilience performance level of MESs can differ in different regions with the impacts of windstorms. The findings can provide a useful reference for system operators to constitute targeted resilience improvement measures.
|
|
| 7. |
- Campana, Pietro Elia, 1984-, et al.
(författare)
-
A gridded optimization model for photovoltaic applications
- 2020
-
Ingår i: Solar Energy. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0038-092X .- 1471-1257. ; 202, s. 465-484
-
Tidskriftsartikel (refereegranskat)abstract
- This study aims to develop a gridded optimization model for studying photovoltaic applications in Nordic countries. The model uses the spatial and temporal data generated by the mesoscale models STRANG and MESAN developed by the Swedish Meteorological and Hydrological Institute. The model is developed based on the comparison between five irradiance databases, three decomposition models, two transposition models, and two photovoltaic models. Several techno-economic and environmental aspects of photovoltaic systems and photovoltaic systems integrated with batteries are investigated from a spatial perspective. CM SAF SARAH-2, Engerer2, and Perez1990 have shown the best performances among the irradiance databases, and decomposition and transposition models, respectively. STRANG resulted in the second-best irradiance database to be used in Sweden for photovoltaic applications when comparing hourly global horizontal irradiance with weather station data. The developed model can be employed for carrying out further detailed gridded techno-economic assessments of photovoltaic applications and energy systems in general in Nordic countries. The model structure is generic and can be applied to every gridded climatological database worldwide.
|
|
| 8. |
- Campana, Pietro Elia, 1984-, et al.
(författare)
-
Li-ion batteries for peak shaving, price arbitrage, and photovoltaic self-consumption in commercial buildings : A Monte Carlo Analysis
- 2021
-
Ingår i: Energy Conversion and Management. - : Elsevier BV. - 0196-8904 .- 1879-2227. ; 234
-
Tidskriftsartikel (refereegranskat)abstract
- This study investigates the benefits of introducing Li-ion batteries as energy storage unit in the commercial sector by considering a representative building with a photovoltaic system. Only the costs and revenues related to the installation and operation of the battery are considered in this study. The operational strategy of the battery consists in balancing the following processes through day-ahead forecasts for both electricity consumption and photovoltaic production: shaving a targeted peak, performing price arbitrage, and increasing photovoltaic selfconsumption. By reviewing the electricity price cost for commercial buildings from several companies around the world, a general electricity price structure is defined. Afterwards, a Monte Carlo Analysis is applied for three locations with different solar irradiation levels to study the impact of climate, electricity price components, and other seven sensitive parameters on the economic viability of Li-ion batteries. The Monte Carlo Analysis shows that the most sensitive parameters for the net present value are the battery capacity, the battery price, and the component of the electricity price that relates to the peak power consumption. For Stockholm, one of the investigated locations, the corresponding Pearson correlation coefficients are -0.67, -0.66, and 0.19 for the case were no photovoltaic system is installed. For the considered battery operational strategies, the current investment and annual operation costs for the Li-ion battery always lead to negative net present values independently of the location. Battery prices lower than 250 US$/kWh start to manifest positive net present values when combining peak shaving, price arbitrage, and photovoltaic self-consumption. However, the integration of a photovoltaic system leads to a reduced economic viability of the battery by reducing the revenues generated by the battery while performing peak shaving.
|
|
| 9. |
- Campana, Pietro Elia, 1984-, et al.
(författare)
-
Photovoltaic water pumping systems for irrigation : Principles and advances
- 2022
-
Ingår i: Solar Energy Advancements in Agriculture and Food Production Systems. - : Elsevier BV. - 9780323898669 - 9780323886253 ; , s. 113-157
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Agriculture is one of the most water- and energy-intensive sectors of the economy, consuming about 70% of global freshwater withdrawals. Access to clean and affordable water for irrigation is an essential step towards guaranteeing water and food security, improving incomes and living standards, decarbonizing an energy-intensive sector and attaining the United Nations Sustainable Development Goals (SDGs), in particular SDGs 2 (Zero Hunger), 6 (Clean Water and Sanitation), 7 (Affordable and Clean Energy), and 13 (Climate Action). Ensuring access to water for irrigation, as well as for other agricultural (i.e., livestock watering), domestic, and industrial purposes is a global challenge, and it is more challenging in remote areas where the grid connection is often not available. Solar-powered pumping systems represent a renewable solution for the decarbonization of the irrigation sector worldwide. While solar water pumping systems were used in the past to supply water for irrigation, livestock, and domestic purposes only in remote locations without access to the electric grid, the drastic drop in photovoltaic (PV) modules prices has made the technology also competitive for on-grid applications. This chapter reviews the configurations of solar water pumping systems for irrigation, highlighting the water–food–energy nexus aspects and recent advances, reviewing case studies, and analyzing the economics and current and future challenges.
|
|
| 10. |
|
|
