Pub Date : 2024-10-30DOI: 10.1016/j.apenergy.2024.124651
Ke Wu , Lei Wang , Hengxu Ha , Zhiyuan Wang
Renewable energy sources (RES), such as wind and photovoltaic, has been widely integrated into power systems. However, the phenomenon of “wind curtailment” and “sunlight curtailment” is still a critical issue, resulting in the sharp decline of renewable resource utilization. The factors of reducing the renewable resources injection are the limited line thermal capacity, voltage magnitude limit, and voltage stability issues. This paper presents a maximizing RES injection (MRI) problem with voltage stability constraints, AC power flow constraints and operating constraints. A novel dynamic line rating (DLR) technique is proposed for dynamically assessing transmission line capacity of transmission line. By jointly DLR and optimal transmission switching (OTS), the proposed model’s solution can maximize power network’s transmission capacity and ensure the technique and physical operation requirements of power systems. Due to the difficulty in solving the proposed model, a prescreening technique is presented to screen out the ineffective lines by three indicators. The proposed approach has been applied to the IEEE 24-bus RTS system, the IEEE 118-bus power system, and the IEEE 3120-bus power system. The computational results show the effectiveness of the conducted model in maximizing the utilization of RES and improving the acceptable level of power grid for renewable resources.
{"title":"Dynamic line rating and optimal transmission switching for maximizing renewable energy sources injection with voltage stability constraint","authors":"Ke Wu , Lei Wang , Hengxu Ha , Zhiyuan Wang","doi":"10.1016/j.apenergy.2024.124651","DOIUrl":"10.1016/j.apenergy.2024.124651","url":null,"abstract":"<div><div>Renewable energy sources (RES), such as wind and photovoltaic, has been widely integrated into power systems. However, the phenomenon of “wind curtailment” and “sunlight curtailment” is still a critical issue, resulting in the sharp decline of renewable resource utilization. The factors of reducing the renewable resources injection are the limited line thermal capacity, voltage magnitude limit, and voltage stability issues. This paper presents a maximizing RES injection (MRI) problem with voltage stability constraints, AC power flow constraints and operating constraints. A novel dynamic line rating (DLR) technique is proposed for dynamically assessing transmission line capacity of transmission line. By jointly DLR and optimal transmission switching (OTS), the proposed model’s solution can maximize power network’s transmission capacity and ensure the technique and physical operation requirements of power systems. Due to the difficulty in solving the proposed model, a prescreening technique is presented to screen out the ineffective lines by three indicators. The proposed approach has been applied to the IEEE 24-bus RTS system, the IEEE 118-bus power system, and the IEEE 3120-bus power system. The computational results show the effectiveness of the conducted model in maximizing the utilization of RES and improving the acceptable level of power grid for renewable resources.</div></div>","PeriodicalId":246,"journal":{"name":"Applied Energy","volume":"378 ","pages":"Article 124651"},"PeriodicalIF":10.1,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142553140","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-30DOI: 10.1016/j.apenergy.2024.124782
Junhua Zhang , Xin Hui , Xin Xue , Lei Li , Jianchen Wang , Chih-Jen Sung
Centrally-staged combustors, characterized by a center pilot flame surrounded by an annual main stage flame, are widely used in modern aeroengines to achieve low NOx emissions. However, due to the premixed combustion of the main stage, centrally-staged combustors are prone to combustion instability. This paper experimentally investigates the bifurcation behaviors and nonlinear dynamics of combustion instabilities in a centrally-staged swirl-stabilized combustor fueled by aviation kerosene fuel. The current study reveals that the swirling flame transitions from a stable state to a limit-cycle oscillation state either by increasing the overall equivalence ratio of the dome or by decreasing the fuel split ratio. This transition manifests as a supercritical Hopf bifurcation and is essentially governed by the main stage equivalence ratio. Synchronization between pressure and heat release rate fluctuations is found to occur when the main stage equivalence ratio surpasses a threshold, resulting in large-amplitude oscillations and ultra-harmonics that stem from nonlinear interactions. Bispectral mode decomposition is further employed to elucidate the nonlinear triadic interactions of the thermoacoustic system, successfully revealing the interaction routes among different modes. This analysis indicates that the triadic mode interactions predominately occur in the main flame region, while the pilot flame region is insignificant as long as the oscillation amplitude remains low. These findings provide a deeper understanding of the combustion instability in stratified swirling flames in general and contribute to the development of better strategies for controlling combustion instability in centrally-staged combustors in particular.
{"title":"Supercritical bifurcations and nonlinear mode interactions of combustion instabilities in a centrally-staged swirl spray combustor","authors":"Junhua Zhang , Xin Hui , Xin Xue , Lei Li , Jianchen Wang , Chih-Jen Sung","doi":"10.1016/j.apenergy.2024.124782","DOIUrl":"10.1016/j.apenergy.2024.124782","url":null,"abstract":"<div><div>Centrally-staged combustors, characterized by a center pilot flame surrounded by an annual main stage flame, are widely used in modern aeroengines to achieve low NO<sub>x</sub> emissions. However, due to the premixed combustion of the main stage, centrally-staged combustors are prone to combustion instability. This paper experimentally investigates the bifurcation behaviors and nonlinear dynamics of combustion instabilities in a centrally-staged swirl-stabilized combustor fueled by aviation kerosene fuel. The current study reveals that the swirling flame transitions from a stable state to a limit-cycle oscillation state either by increasing the overall equivalence ratio of the dome or by decreasing the fuel split ratio. This transition manifests as a supercritical Hopf bifurcation and is essentially governed by the main stage equivalence ratio. Synchronization between pressure and heat release rate fluctuations is found to occur when the main stage equivalence ratio surpasses a threshold, resulting in large-amplitude oscillations and ultra-harmonics that stem from nonlinear interactions. Bispectral mode decomposition is further employed to elucidate the nonlinear triadic interactions of the thermoacoustic system, successfully revealing the interaction routes among different modes. This analysis indicates that the triadic mode interactions predominately occur in the main flame region, while the pilot flame region is insignificant as long as the oscillation amplitude remains low. These findings provide a deeper understanding of the combustion instability in stratified swirling flames in general and contribute to the development of better strategies for controlling combustion instability in centrally-staged combustors in particular.</div></div>","PeriodicalId":246,"journal":{"name":"Applied Energy","volume":"378 ","pages":"Article 124782"},"PeriodicalIF":10.1,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142553218","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-30DOI: 10.1016/j.apenergy.2024.124726
Lefu Maqelepo , Fhazhil Wamalwa , Nathan Williams , Jay Taneja
Universal access to electricity is an important milestone featured in countries development plans. It is well understood within the energy practitioner and research communities that to reach this milestone, distributed energy resources, especially mini grids, are to play a crucial role as they represent a least cost alternative to reach most rural communities. The success of mini grids though is highly reliant on favorable policies, particularly regulations pertaining to tariffs (i.e., electricity rates). In this research, we use Tanzania as a case study to investigate the likely consequences of grid and mini grid tariff equalization regulation which ignores the fact that the tariff charged on the grid is highly subsidized compared to mini grid tariffs that must be cost reflective for mini grid utilities to be financially sustainable. We recognize that a private mini grid operator has an obligation to make profits for the investors. Because of this, they have two critical yet divergent operating points from which to choose: (1) serving 100% of the demand at all times, potentially incurring operating losses during some periods and (2) partially serving the demand to maximize returns, potentially compromising customer satisfaction. Using an empirically-informed model of a mini grid sized to minimize net present cost that supplies power to 500 customers, we quantify the cost of reliability between these two key operating points and trace the curve relating profit and reliability, for two types of load scenarios: fixed loads and fixed plus flexible loads. We found that profit is optimized at a reliability of 92.3% and 86.0% for systems that meet fixed loads and fixed plus flexible loads respectively. This reduced reliability can have crucial implications on the viability of mini grids for providing electricity access, as customer dissatisfaction and profits may erode. We show that under the policy of tariff equalization between the centralized grid and mini grids, the latter is challenged to survive and therefore the communities which are being served through mini grids may experience de-electrification, which would represent a huge regression with regards to meeting the United Nations Sustainable Development Goal 7 (SDG7) of universal electricity access.
{"title":"Two sides of a coin: Assessing trade-offs between reliability and profit in mini grids and the policy implications for subsidies","authors":"Lefu Maqelepo , Fhazhil Wamalwa , Nathan Williams , Jay Taneja","doi":"10.1016/j.apenergy.2024.124726","DOIUrl":"10.1016/j.apenergy.2024.124726","url":null,"abstract":"<div><div>Universal access to electricity is an important milestone featured in countries development plans. It is well understood within the energy practitioner and research communities that to reach this milestone, distributed energy resources, especially mini grids, are to play a crucial role as they represent a least cost alternative to reach most rural communities. The success of mini grids though is highly reliant on favorable policies, particularly regulations pertaining to tariffs (i.e., electricity rates). In this research, we use Tanzania as a case study to investigate the likely consequences of grid and mini grid tariff equalization regulation which ignores the fact that the tariff charged on the grid is highly subsidized compared to mini grid tariffs that must be cost reflective for mini grid utilities to be financially sustainable. We recognize that a private mini grid operator has an obligation to make profits for the investors. Because of this, they have two critical yet divergent operating points from which to choose: (1) serving 100% of the demand at all times, potentially incurring operating losses during some periods and (2) partially serving the demand to maximize returns, potentially compromising customer satisfaction. Using an empirically-informed model of a mini grid sized to minimize net present cost that supplies power to 500 customers, we quantify the cost of reliability between these two key operating points and trace the curve relating profit and reliability, for two types of load scenarios: fixed loads and fixed plus flexible loads. We found that profit is optimized at a reliability of 92.3% and 86.0% for systems that meet fixed loads and fixed plus flexible loads respectively. This reduced reliability can have crucial implications on the viability of mini grids for providing electricity access, as customer dissatisfaction and profits may erode. We show that under the policy of tariff equalization between the centralized grid and mini grids, the latter is challenged to survive and therefore the communities which are being served through mini grids may experience de-electrification, which would represent a huge regression with regards to meeting the United Nations Sustainable Development Goal 7 (SDG7) of universal electricity access.</div></div>","PeriodicalId":246,"journal":{"name":"Applied Energy","volume":"378 ","pages":"Article 124726"},"PeriodicalIF":10.1,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142539112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-30DOI: 10.1016/j.apenergy.2024.124767
Guiyue Duan , Daniele Gattari , Fernando Porté-Agel
Understanding the effects of platform motion on the performance of floating wind turbines is essential to optimize the exploitation of deep-ocean wind resources. In this work, theoretical analyses and wind tunnel experiments are conducted to study the effects of cyclic pitch motion on the power performance and wake characteristics of floating wind turbines. Theoretical analyses reveal that the rotor-available power, power variation and wake state of a floating wind turbine all depend on the Strouhal number (i.e., the normalized pitch frequency), the pitch amplitude and the pitch-radius-to-rotor-diameter ratio of the turbine (here pitch radius refers to the distance from the rotor center to the pitch rotation center). Critical Strouhal numbers are further proposed to distinguish the power performance and wake state. Power measurements show that cyclic pitch motion results in a periodic power variation. The mean power production increases with increasing pitch frequency but decreases with increasing amplitude. Both the upper and lower bounds of power variation are found to be dependent on the pitch dynamics. Wake measurements show that, for the range of pitch dynamics tested in this study, cyclic pitch motion can accelerate wake recovery and growth, depending on pitch amplitude but not on pitch frequency. Phase-averaged results suggest that the wake behavior is periodic and consequently, predictable. The cyclic pitch motion of the upstream turbine enhances its vertical wake meandering, leading to higher power production but stronger power fluctuations at downstream turbines. The propagation of periodic wake dynamics also leads to the periodicity in power outputs of downstream wind turbines.
{"title":"Theoretical and experimental study on power performance and wake characteristics of a floating wind turbine under pitch motion","authors":"Guiyue Duan , Daniele Gattari , Fernando Porté-Agel","doi":"10.1016/j.apenergy.2024.124767","DOIUrl":"10.1016/j.apenergy.2024.124767","url":null,"abstract":"<div><div>Understanding the effects of platform motion on the performance of floating wind turbines is essential to optimize the exploitation of deep-ocean wind resources. In this work, theoretical analyses and wind tunnel experiments are conducted to study the effects of cyclic pitch motion on the power performance and wake characteristics of floating wind turbines. Theoretical analyses reveal that the rotor-available power, power variation and wake state of a floating wind turbine all depend on the Strouhal number (i.e., the normalized pitch frequency), the pitch amplitude and the pitch-radius-to-rotor-diameter ratio of the turbine (here pitch radius refers to the distance from the rotor center to the pitch rotation center). Critical Strouhal numbers are further proposed to distinguish the power performance and wake state. Power measurements show that cyclic pitch motion results in a periodic power variation. The mean power production increases with increasing pitch frequency but decreases with increasing amplitude. Both the upper and lower bounds of power variation are found to be dependent on the pitch dynamics. Wake measurements show that, for the range of pitch dynamics tested in this study, cyclic pitch motion can accelerate wake recovery and growth, depending on pitch amplitude but not on pitch frequency. Phase-averaged results suggest that the wake behavior is periodic and consequently, predictable. The cyclic pitch motion of the upstream turbine enhances its vertical wake meandering, leading to higher power production but stronger power fluctuations at downstream turbines. The propagation of periodic wake dynamics also leads to the periodicity in power outputs of downstream wind turbines.</div></div>","PeriodicalId":246,"journal":{"name":"Applied Energy","volume":"378 ","pages":"Article 124767"},"PeriodicalIF":10.1,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142553142","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-30DOI: 10.1016/j.apenergy.2024.124722
Hao Li, Ting Yang, Hengyu Wang, Yanhong Chen
Distributed secondary control is widely used in the hierarchical control structure of islanded microgrids. However, the information exchanged between distributed generators (DGs) may be intercepted by eavesdroppers, leading to the risk of privacy leakage and even data poisoning attacks that affect the stability of microgrids. Existing privacy-preserving distributed secondary control strategies suffer from low accuracy, high communication and computational overhead, and the poor convergence properties. Moreover, the objectives of multi-bus voltage regulation and proportional reactive power sharing cannot be achieved. To overcome these shortcomings, a privacy-preserving distributed average estimator is innovatively designed, where the states containing privacy information are decomposed into two parts based on the state decomposition method. The average estimation relies on the partial information exchange between neighboring DGs, thus avoiding the leakage of sensitive information. Furthermore, to address the difficulty that the state difference generated by the state decomposition leads to a long convergence time, a time-based generator is designed to effectively resolve the conflict between the privacy-preserving level and the convergence time. On this basis, a privacy-preserving distributed secondary voltage control is proposed, which preserves the privacy of the microgrid states while achieving average voltage regulation and proportional reactive power sharing within a predefined time, maintaining the system voltage stability and preventing the DGs from being heavily or lightly loaded. Finally, a hardware-in-the-loop platform for an islanded microgrid is built and the convergence and privacy-preserving performance of the proposed control strategy is verified.
{"title":"Privacy-preserving distributed secondary voltage control with predefined-time convergence for microgrids","authors":"Hao Li, Ting Yang, Hengyu Wang, Yanhong Chen","doi":"10.1016/j.apenergy.2024.124722","DOIUrl":"10.1016/j.apenergy.2024.124722","url":null,"abstract":"<div><div>Distributed secondary control is widely used in the hierarchical control structure of islanded microgrids. However, the information exchanged between distributed generators (DGs) may be intercepted by eavesdroppers, leading to the risk of privacy leakage and even data poisoning attacks that affect the stability of microgrids. Existing privacy-preserving distributed secondary control strategies suffer from low accuracy, high communication and computational overhead, and the poor convergence properties. Moreover, the objectives of multi-bus voltage regulation and proportional reactive power sharing cannot be achieved. To overcome these shortcomings, a privacy-preserving distributed average estimator is innovatively designed, where the states containing privacy information are decomposed into two parts based on the state decomposition method. The average estimation relies on the partial information exchange between neighboring DGs, thus avoiding the leakage of sensitive information. Furthermore, to address the difficulty that the state difference generated by the state decomposition leads to a long convergence time, a time-based generator is designed to effectively resolve the conflict between the privacy-preserving level and the convergence time. On this basis, a privacy-preserving distributed secondary voltage control is proposed, which preserves the privacy of the microgrid states while achieving average voltage regulation and proportional reactive power sharing within a predefined time, maintaining the system voltage stability and preventing the DGs from being heavily or lightly loaded. Finally, a hardware-in-the-loop platform for an islanded microgrid is built and the convergence and privacy-preserving performance of the proposed control strategy is verified.</div></div>","PeriodicalId":246,"journal":{"name":"Applied Energy","volume":"378 ","pages":"Article 124722"},"PeriodicalIF":10.1,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142553572","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-30DOI: 10.1016/j.apenergy.2024.124730
Caio Nogueira Chaves , Tiago Forti da Silva , João Paulo Manarelli Gaspar , André Christóvão Pio Martins , Edilaine Martins Soler , Antonio Roberto Balbo , Leonardo Nepomuceno
The long-term hydrothermal scheduling (HTS) is a multi-stage stochastic optimization problem which aims to calculate a decision policy regarding the operation of hydrothermal systems that minimizes the expected costs while taking into account physical and operational constraints of the system. The HTS problem has traditionally been solved by means of stochastic dual dynamic programming (SDDP). Despite its successful utilization for solving large-scale HTS problems, the computation times for solving the HTS problem by means of an SDDP approach may become prohibitive in the context of energy markets (where the HTS model generally appears in the lower level of bilevel equilibrium problems) and also in the context of risk-averse decision making policies. In these contexts, rolling horizon (RH) approaches can provide a good trade-off between optimality and computational effort. The RH approach approximates expected future costs by means of a single forward procedure. Although the RH approach is able to fully explore uncertainties embedded in the set of scenarios, it does not present a mechanism for evaluating the errors in the expected future costs, which may result in some level of cost sub-optimality. In this paper, an adaptive stochastic (AS) approach is proposed for solving multi-stage stochastic optimization problems that enhances the level of optimality of the RH approach. Two HTS models are proposed, involving the adoption of the RH and the AS approaches, respectively. The decision-making policies calculated by these models are compared in terms of the evolution of the expected values for power dispatches, optimality, prices, and reservoir volumes. Numerical results confirm the higher levels of optimality achieved by the proposed AS approach where reduction costs of near 20% were achieved for a portion of the Brazilian system with a total of 48.4 GW, which represents 47.4% of the installed hydraulic capacity of this system, as well as significant improvements in the hydraulic and economic aspects (e.g. prices were reduced around 50% in peak periods for a 10-power plant study) of the HTS problem. A post-optimization simulation procedure conducted to evaluate the quality of the uncertainty modeling within the proposed RH-HTS and AS-HTS models demonstrates that the decisions calculated by both models have proven to be highly robust in withstanding random water inflows.
{"title":"Adaptive stochastic approach for solving long-term hydrothermal scheduling problems","authors":"Caio Nogueira Chaves , Tiago Forti da Silva , João Paulo Manarelli Gaspar , André Christóvão Pio Martins , Edilaine Martins Soler , Antonio Roberto Balbo , Leonardo Nepomuceno","doi":"10.1016/j.apenergy.2024.124730","DOIUrl":"10.1016/j.apenergy.2024.124730","url":null,"abstract":"<div><div>The long-term hydrothermal scheduling (HTS) is a multi-stage stochastic optimization problem which aims to calculate a decision policy regarding the operation of hydrothermal systems that minimizes the expected costs while taking into account physical and operational constraints of the system. The HTS problem has traditionally been solved by means of stochastic dual dynamic programming (SDDP). Despite its successful utilization for solving large-scale HTS problems, the computation times for solving the HTS problem by means of an SDDP approach may become prohibitive in the context of energy markets (where the HTS model generally appears in the lower level of bilevel equilibrium problems) and also in the context of risk-averse decision making policies. In these contexts, rolling horizon (RH) approaches can provide a good trade-off between optimality and computational effort. The RH approach approximates expected future costs by means of a single forward procedure. Although the RH approach is able to fully explore uncertainties embedded in the set of scenarios, it does not present a mechanism for evaluating the errors in the expected future costs, which may result in some level of cost sub-optimality. In this paper, an adaptive stochastic (AS) approach is proposed for solving multi-stage stochastic optimization problems that enhances the level of optimality of the RH approach. Two HTS models are proposed, involving the adoption of the RH and the AS approaches, respectively. The decision-making policies calculated by these models are compared in terms of the evolution of the expected values for power dispatches, optimality, prices, and reservoir volumes. Numerical results confirm the higher levels of optimality achieved by the proposed AS approach where reduction costs of near 20% were achieved for a portion of the Brazilian system with a total of 48.4 GW, which represents 47.4% of the installed hydraulic capacity of this system, as well as significant improvements in the hydraulic and economic aspects (e.g. prices were reduced around 50% in peak periods for a 10-power plant study) of the HTS problem. A post-optimization simulation procedure conducted to evaluate the quality of the uncertainty modeling within the proposed RH-HTS and AS-HTS models demonstrates that the decisions calculated by both models have proven to be highly robust in withstanding random water inflows.</div></div>","PeriodicalId":246,"journal":{"name":"Applied Energy","volume":"378 ","pages":"Article 124730"},"PeriodicalIF":10.1,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142553220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-30DOI: 10.1016/j.apenergy.2024.124783
Peimiao Li , Shibo Wang , Hui Wang , Yun Feng , Hongliang Li , Heye Xiao
The heat dissipation scheme design of power cabin is limited by complex configuration and slow iteration speed. Given the considerable time and computing resources required by numerical experiment, this work proposes a fast zero dimensional integrating accurate three-dimensional optimization model to calculate the heat dissipation and optimize the thermal management in electric vehicle power cabin. Based on the existing thermal equivalent circuit model, the heat capacity and thermal resistance network among each equipment is established in fast zero-dimensional model, and the output of fast zero-dimensional model is corrected by referring to the accurate initial three-dimensional simulation results. Then, the optimal heat dissipation configuration is searched by zero-dimensional model and validated by experimental data. Results show that the optimization result of fast zero dimensional integrating accurate three-dimensional optimization model is well verified by three-dimensional model. The chip temperature of the power cabin motor controller can be reduced from 551.73 K to 352.31 K after optimizing the number and size of the pin-fins of the motor controller using the proposed model. The time consumption of fast zero dimensional integrating accurate three-dimensional optimization model is 72.0872 h, while the time consumption of three-dimensional model is about 576 h with 224 cores of computer. The proposed model can be used to achieve the purpose of rapidly predicting the temperature change of the complex vehicle design, and provide theoretical reference for the reasonable formulation of the heat dissipation scheme.
{"title":"Thermal management of electric vehicle power cabin based on fast zero-dimensional integrating accurate three-dimensional optimization model","authors":"Peimiao Li , Shibo Wang , Hui Wang , Yun Feng , Hongliang Li , Heye Xiao","doi":"10.1016/j.apenergy.2024.124783","DOIUrl":"10.1016/j.apenergy.2024.124783","url":null,"abstract":"<div><div>The heat dissipation scheme design of power cabin is limited by complex configuration and slow iteration speed. Given the considerable time and computing resources required by numerical experiment, this work proposes a fast zero dimensional integrating accurate three-dimensional optimization model to calculate the heat dissipation and optimize the thermal management in electric vehicle power cabin. Based on the existing thermal equivalent circuit model, the heat capacity and thermal resistance network among each equipment is established in fast zero-dimensional model, and the output of fast zero-dimensional model is corrected by referring to the accurate initial three-dimensional simulation results. Then, the optimal heat dissipation configuration is searched by zero-dimensional model and validated by experimental data. Results show that the optimization result of fast zero dimensional integrating accurate three-dimensional optimization model is well verified by three-dimensional model. The chip temperature of the power cabin motor controller can be reduced from 551.73 K to 352.31 K after optimizing the number and size of the pin-fins of the motor controller using the proposed model. The time consumption of fast zero dimensional integrating accurate three-dimensional optimization model is 72.0872 h, while the time consumption of three-dimensional model is about 576 h with 224 cores of computer. The proposed model can be used to achieve the purpose of rapidly predicting the temperature change of the complex vehicle design, and provide theoretical reference for the reasonable formulation of the heat dissipation scheme.</div></div>","PeriodicalId":246,"journal":{"name":"Applied Energy","volume":"378 ","pages":"Article 124783"},"PeriodicalIF":10.1,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142553143","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-30DOI: 10.1016/j.apenergy.2024.124710
Sinan Li , Yuning Chen , Tao Li , Zhenpeng Li , Tao Ma
Considering the less appealing aesthetics of traditional photovoltaics (PV) panels, the colorization process is a crucial step towards their broader application in building-integrated photovoltaics (BIPV) systems, thus facilitating carbon peak and neutrality. For achieving colored PVs in a full-color gamut including neutral colors like grey and white, this research proposes a design method for multilayer dielectric thin films based on a pre-configured structure. The optimized design ensures that most reflected light is concentrated on the regions easily perceptible to human eyes, enabling colored PVs to achieve high power conversion efficiency (PCE) and perceptual lightness (L⁎) simultaneously. With a color difference to the objective color coordinates smaller than 3, the designed colored PVs corresponding to RAL 9006, RAL 7035, and RAL 9003 can achieve 89.20 %, 78.69 %, and 64.78 % of the power generation compared to the reference module. The PCEs of the neutral-colored PVs are even higher than those in the normal case where a constant reflectivity in the VIS region is set. For further improvements, the maximum color difference derived from thickness errors is reduced from 33.01 to 8.57 with the absolute PCE sacrifice of 1.56 %. The mitigation of angular dependence also leads to a 2.46 % drop in PCE when the maximum color difference caused by tilted incidence is only 4.07. The proposed optimization method provides a theoretical guide for designing multilayer thin film filters applied on high-efficiency colored PVs, which will contribute to the future advancement of BIPV technology.
{"title":"Multilayer thin film design for neutral-colored opaque photovoltaics","authors":"Sinan Li , Yuning Chen , Tao Li , Zhenpeng Li , Tao Ma","doi":"10.1016/j.apenergy.2024.124710","DOIUrl":"10.1016/j.apenergy.2024.124710","url":null,"abstract":"<div><div>Considering the less appealing aesthetics of traditional photovoltaics (PV) panels, the colorization process is a crucial step towards their broader application in building-integrated photovoltaics (BIPV) systems, thus facilitating carbon peak and neutrality. For achieving colored PVs in a full-color gamut including neutral colors like grey and white, this research proposes a design method for multilayer dielectric thin films based on a pre-configured structure. The optimized design ensures that most reflected light is concentrated on the regions easily perceptible to human eyes, enabling colored PVs to achieve high power conversion efficiency (PCE) and perceptual lightness (L<sup><em>⁎</em></sup>) simultaneously. With a color difference to the objective color coordinates smaller than 3, the designed colored PVs corresponding to RAL 9006, RAL 7035, and RAL 9003 can achieve 89.20 %, 78.69 %, and 64.78 % of the power generation compared to the reference module. The PCEs of the neutral-colored PVs are even higher than those in the normal case where a constant reflectivity in the VIS region is set. For further improvements, the maximum color difference derived from thickness errors is reduced from 33.01 to 8.57 with the absolute PCE sacrifice of 1.56 %. The mitigation of angular dependence also leads to a 2.46 % drop in PCE when the maximum color difference caused by tilted incidence is only 4.07. The proposed optimization method provides a theoretical guide for designing multilayer thin film filters applied on high-efficiency colored PVs, which will contribute to the future advancement of BIPV technology.</div></div>","PeriodicalId":246,"journal":{"name":"Applied Energy","volume":"378 ","pages":"Article 124710"},"PeriodicalIF":10.1,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142553573","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-30DOI: 10.1016/j.apenergy.2024.124784
Yicheng Zhou , Boqiang Lin
Fiscal policy is a crucial tool to achieve energy conservation and emission reduction (ECER), and can provide necessary fiscal support for the green economic transformation. This paper systematically discusses the influencing mechanism of green fiscal policy (GFP) on electricity consumption, and then constructs a time-varying difference-in-difference (DID) model based on the quasi-natural experiment of comprehensive demonstration cities of energy conservation and emission reduction fiscal policy (ECERFP), and empirically tests the relationship between GFP and urban electricity consumption by combining urban panel data. The results show that ECERFP can not only significantly reduce urban electricity consumption directly, but also reduce urban electricity consumption through industrial structure upgrading, public transportation development and green technological innovation. Meanwhile, economic growth targets and fiscal decentralization can regulate the energy-saving effect of ECERFP. Specifically, fiscal decentralization can enhance the energy-saving effect of ECERFP, but the economic growth targets are not conducive to exerting the energy-saving effect of ECERFP. More importantly, there is the urban heterogeneity impact of ECERFP on urban electricity consumption. In the east, west, big cities and developed cities, the energy-saving effect of ECERFP is more obvious. In addition, ECERFP can reduce electricity consumption not only in the industrial sector, but also in the household sector. The findings present empirical evidence for the application of GFP in ECER.
{"title":"The energy-saving effect of green fiscal policy: Empirical evidence from China's comprehensive demonstration cities of energy conservation and emission reduction fiscal policy","authors":"Yicheng Zhou , Boqiang Lin","doi":"10.1016/j.apenergy.2024.124784","DOIUrl":"10.1016/j.apenergy.2024.124784","url":null,"abstract":"<div><div>Fiscal policy is a crucial tool to achieve energy conservation and emission reduction (ECER), and can provide necessary fiscal support for the green economic transformation. This paper systematically discusses the influencing mechanism of green fiscal policy (GFP) on electricity consumption, and then constructs a time-varying difference-in-difference (DID) model based on the quasi-natural experiment of comprehensive demonstration cities of energy conservation and emission reduction fiscal policy (ECERFP), and empirically tests the relationship between GFP and urban electricity consumption by combining urban panel data. The results show that ECERFP can not only significantly reduce urban electricity consumption directly, but also reduce urban electricity consumption through industrial structure upgrading, public transportation development and green technological innovation. Meanwhile, economic growth targets and fiscal decentralization can regulate the energy-saving effect of ECERFP. Specifically, fiscal decentralization can enhance the energy-saving effect of ECERFP, but the economic growth targets are not conducive to exerting the energy-saving effect of ECERFP. More importantly, there is the urban heterogeneity impact of ECERFP on urban electricity consumption. In the east, west, big cities and developed cities, the energy-saving effect of ECERFP is more obvious. In addition, ECERFP can reduce electricity consumption not only in the industrial sector, but also in the household sector. The findings present empirical evidence for the application of GFP in ECER.</div></div>","PeriodicalId":246,"journal":{"name":"Applied Energy","volume":"378 ","pages":"Article 124784"},"PeriodicalIF":10.1,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142553219","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-30DOI: 10.1016/j.apenergy.2024.124384
Luis Sánchez-García , Helge Averfalk , Nekane Hermoso-Martínez , Patxi Hernández-Iñarra , Erik Möllerström , Urban Persson
District heating and cooling systems can aid in decarbonisation and the provision of efficient heating and cooling in Europe. However, whereas these systems have achieved high penetration rates in colder climates of Northern, Central and Eastern Europe, they remain marginal in milder climates of Southern Europe. In terms of network design, district heating and cooling systems can be configured in different ways. In so-called warm networks, the required temperature for all the consumers is attained city-wide, and in so-called cold systems, the necessary temperature is achieved at the consumers' premises by ancillary equipment. The most cost-effective heating and cooling solution for urban areas requires investigation. This research models and compares cold and warm district energy systems with other heating and cooling solutions through a comprehensive case study executed in the city of Bilbao, Spain. The city is characterised by a mild climate and a high population density which is characteristic of many Southern European cities. The results show that district energy systems are economically advantageous compared to other low-carbon solutions, such as air-source heat pumps. However, these systems are not able to outcompete natural gas under current cost and taxation levels. Warm networks provide a cheaper source of heat compared to cold networks, but both network types lead to similar expenditures for combined heating and cooling supply. This paper, presents the study context and its results, and is complemented by an exhaustive detailed methodology document and a separate supplementary material repository.
{"title":"Feasibility of district heating in a mild climate: A comparison of warm and cold temperature networks in Bilbao","authors":"Luis Sánchez-García , Helge Averfalk , Nekane Hermoso-Martínez , Patxi Hernández-Iñarra , Erik Möllerström , Urban Persson","doi":"10.1016/j.apenergy.2024.124384","DOIUrl":"10.1016/j.apenergy.2024.124384","url":null,"abstract":"<div><div>District heating and cooling systems can aid in decarbonisation and the provision of efficient heating and cooling in Europe. However, whereas these systems have achieved high penetration rates in colder climates of Northern, Central and Eastern Europe, they remain marginal in milder climates of Southern Europe. In terms of network design, district heating and cooling systems can be configured in different ways. In so-called warm networks, the required temperature for all the consumers is attained city-wide, and in so-called cold systems, the necessary temperature is achieved at the consumers' premises by ancillary equipment. The most cost-effective heating and cooling solution for urban areas requires investigation. This research models and compares cold and warm district energy systems with other heating and cooling solutions through a comprehensive case study executed in the city of Bilbao, Spain. The city is characterised by a mild climate and a high population density which is characteristic of many Southern European cities. The results show that district energy systems are economically advantageous compared to other low-carbon solutions, such as air-source heat pumps. However, these systems are not able to outcompete natural gas under current cost and taxation levels. Warm networks provide a cheaper source of heat compared to cold networks, but both network types lead to similar expenditures for combined heating and cooling supply. This paper, presents the study context and its results, and is complemented by an exhaustive detailed methodology document and a separate supplementary material repository.</div></div>","PeriodicalId":246,"journal":{"name":"Applied Energy","volume":"378 ","pages":"Article 124384"},"PeriodicalIF":10.1,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142553141","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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