With the development of integrated power and gas distribution systems(IPGS)incorporating renewable energy sources(RESs),coordinating the restoration processes of the power distribution system(PS)and the gas distributi...With the development of integrated power and gas distribution systems(IPGS)incorporating renewable energy sources(RESs),coordinating the restoration processes of the power distribution system(PS)and the gas distribution system(GS)by utilizing the benefits of RESs enhances service restoration.In this context,this paper proposes a coordinated service restoration framework that considers the uncertainty in RESs and the bi-directional restoration interactions between the PS and GS.Additionally,a coordinated service restoration model is developed considering the two systems’interdependency and the GS’s dynamic characteristics.The objective is to maximize the system resilience index while adhering to operational,dynamic,restoration logic,and interdependency constraints.A method for managing uncertainties in RES output is employed,and convexification techniques are applied to address the nonlinear constraints arising from the physical laws of the IPGS,thereby reducing solution complexity.As a result,the service restoration optimization problem of the IPGS can be formulated as a computationally tractable mixed-integer second-order cone programming problem.The effectiveness and superiority of the proposed framework are demonstrated through numerical simulations conducted on the interdependent IEEE 13-bus PS and 9-node GS.The comparative results show that the proposed framework improves the system resilience index by at least 65.07%compared to traditional methods.展开更多
An active pipe-embedded building envelope, which is an external wall or roof with pipes embedded inside, was presented. This structure may utilize the circulating water in the pipe to transfer heat or coolth inside di...An active pipe-embedded building envelope, which is an external wall or roof with pipes embedded inside, was presented. This structure may utilize the circulating water in the pipe to transfer heat or coolth inside directly. This kind of structure is named ＂active pipe-embedded building envelope＂ due to dealing with the thermal energy actively inside the structure mass by circulating water. This structure not only deals with thermal energy before the external disturbance becomes cooling/heating load by using the circulating water, but also may use low-grade energy sources such as evaporative cooling, solar energy, and geothermal energy. In the meantime, this structure can also improve the indoor thermal comfort by tempering the internal wall surface temperature variation due to the thermal removal in the mass. This work further presents the thermal performance of this structure under a typical hot summer weather condition by comparing it with that of the conventional external wall/roof with numerical simulation. The results show that this pipe-embedded structure may reduce the external heat transfer significantly and reduce the internal wall surface temperature for improving thermal comfort. This work also presents the effects of the water temperature and the pipe spacing on the heat transfer of this structure. The internal surface heat transfer may reduce by about 2.6 W/mE when the water temperature reduces by 1℃ as far as a brick wall with pipes embedded inside is concerned. When the pipe spacing reduces by 50 mm, the internal wall surface heat flux can also reduce by about 2.3 W/m2.展开更多
Energy optimization management can make fuel cell truck(FCT)power system more efficient,so as to improve vehicle fuel economy.When the structure of power source system and the torque distribution strategy are determin...Energy optimization management can make fuel cell truck(FCT)power system more efficient,so as to improve vehicle fuel economy.When the structure of power source system and the torque distribution strategy are determined,the essence is to find the reasonable distribution of electric power between the fuel cell and other energy sources.The paper simulates the assistance of the intelligent transport system(ITS)and carries out the eco-velocity planning using the traffic signal light.On this basis,in order to further improve the energy efficiency of FCT,a model predictive control(MPC)-based energy source optimization management strategy is innovatively developed,which uses Dijkstra algorithm to achieve the minimization of equivalent hydrogen consumption.Under the scenarios of signalized intersections,based on the planned eco-velocity,the off-line simulation results show that the proposed MPC-based energy source management strategy(ESMS)can reduce hydrogen consumption of fuel cell up to 7%compared with the existing rule-based ESMS.Finally,the Hardware-in-the-Loop(HiL)simulation test is carried out to verify the effectiveness and real-time performance of the proposed MPC-based energy source optimization management strategy for the FCT based on eco-velocity planning with the assistance of traffic light information.展开更多
We describe a specific approach to capacity man a ge ment for distribution grids. Based on simulations, it has been found that by curtailing a maximum of 5% of the yearly energy production on a per-generator basis, di...We describe a specific approach to capacity man a ge ment for distribution grids. Based on simulations, it has been found that by curtailing a maximum of 5% of the yearly energy production on a per-generator basis, distribution grid connection capacity can be doubled. We also present the setting and fi rst results of a fi eld test for validating the approach in a rural distribution grid in northern Germany.展开更多
Ochrobactrum anthropi CTS-325 isolated from a chromium-contaminated site had better resistance to Cr（Ⅵ） in LB medium under aerobic condition.Meanwhile,it was found that the reduction of Cr（Ⅵ） is not complete dur...Ochrobactrum anthropi CTS-325 isolated from a chromium-contaminated site had better resistance to Cr（Ⅵ） in LB medium under aerobic condition.Meanwhile,it was found that the reduction of Cr（Ⅵ） is not complete during the experimental process.Therefore,a series of small molecule energy sources including nitrogen and carbon sources were added into the LB medium in the bacterial stationary phase to promote the chromium reducibility.The result showed that the bacterial growth was positively correlated with the chromium reduction.SDS-PAGE analysis indicated that the protein groups were changed when the bacteria were stimulated by the chromium.Additionally,it was revealed that O.anthropi CTS-325 could utilize the cheaper alternative of sugar（sucrose residue leaching solution） well for further growth and restart the chromium reduction,which offered a new method for practical appli-cations.展开更多
The purpose of this research was to study economic incentives to use renewable energy sources in the Republic of Kazakhstan and to give suggestions for production and circulation of the ＂green＂ certificates as a new...The purpose of this research was to study economic incentives to use renewable energy sources in the Republic of Kazakhstan and to give suggestions for production and circulation of the ＂green＂ certificates as a new financial instrument. The author analyzed European Union and Kazakhstani experience of economic incentives to reduce emissions and introduction of renewable energy sources. As a result of conducted research, the proposal to produce and circulate new financial instruments in Kazakhstan is made; as well as economic and environmental factors of renewable energy sources in the Republic of Kazakhstan are defined.展开更多
In recent times, renewable energy production from renewable energy sources is an alternative way to fulfill the increased energy demands. However, the increasing energy demand rate places more pressure, leading to the...In recent times, renewable energy production from renewable energy sources is an alternative way to fulfill the increased energy demands. However, the increasing energy demand rate places more pressure, leading to the termination of conventional energy resources. However, the cost of power generation from coal-fired plants is higher than the power generation’s price from renewable energy sources. This experiment is focused on cost optimization during power generation through pumped storage power plant and wind power plant. The entire modeling of cost optimization has been conducted in two parts. The mathematical modeling was done using MATLAB simulation while the hydro and wind power plant’s emulation was performed using SCADA (Supervisory control and data acquisition) designer implementation. The experiment was conducted using ranges of generated power from both power sources. The optimum combination of output power and cost from both generators is determined via MATLAB simulation within the assumed generated output power range. Secondly, the hydro-generator and wind generator’s emulation were executed individually through synchronizing the grid to determine each generator’s specification using SCADA designer, which provided the optimum power generation from both generators with the specific speed, aligning with results generated through MATLAB. Finally, the operational power cost (with no losses consideration) from MATLAB was compared with the local energy provider to determine the cost-efficiency. This experiment has provided the operational cost optimization of the hydro-wind combined power system with stable wind power generation using SCADA, which will ultimately assist in operations of large-scale power systems, remotely minimizing multi-area dynamic issues while maximizing the system efficiency.展开更多
A newly developed energy source basein China,Huaibei City,is located inthe northern part of Anhui Province,under the direct control of the provincialgovernment.Under its jurisdiction,there arethree districts and one c...A newly developed energy source basein China,Huaibei City,is located inthe northern part of Anhui Province,under the direct control of the provincialgovernment.Under its jurisdiction,there arethree districts and one county,covering atotal area of 2725 sq km and with a populationof 1.8 million. The city boasts unique mineralresources.A total of 13 minerals have beensurveyed,including coal,iron and kaoline.The reserves of coal,the richest of all,areestimated at about 10 billion tons and theprospective reserves 35 billion tons.Basedon its coal resources,the city has set up 24pairs of large and modern mines with anannual production capacity of 20 milliontons,ranking fifth in the country.The展开更多
Mining industry is a substantial consumer of the energy indispensable to power mining and mineral processing equipment and processes. As more and more mine operations move to remote locations, the access to reliable, ...Mining industry is a substantial consumer of the energy indispensable to power mining and mineral processing equipment and processes. As more and more mine operations move to remote locations, the access to reliable, secure and environment friendly energy sources becomes a key concern. At present, a great majority of remote mines relies heavily on diesel fuel that has to be transported over long distances. In this context, some of the renewable energy sources such as wind power or solar energy seem to provide potentially interesting and viable alternatives. Mine operations, however, have a very particular character, much different from other industries and from other potential applications of renewable power sources. This paper presents operational conditions of some mining operations, particularly those in remote regions, in the context of their energy needs. The authors analyse current and future capacities to decrease a reliance of remote mines on conventional fuels and energy. The paper also analyses and discusses the conditions to be met by alternative energy sources so that they might become a viable alternative for remote mining operations.展开更多
We discuss novel advanced concepts suitable for the practical design of gamma-ray sources of directed energy. One concept is based on the self-channeling of a powerful optical laser in a gas within a metal tube. Anoth...We discuss novel advanced concepts suitable for the practical design of gamma-ray sources of directed energy. One concept is based on the self-channeling of a powerful optical laser in a gas within a metal tube. Another concept employs a direct excitation of a quadrupole nuclear level by a powerful optical laser. The third concept is based on the process of a high-order harmonic generation by an x-ray laser. All three concepts can be used for designing gamma-ray lasers that would have significant advantages over x-ray lasers. First, missile defense systems employing gamma-ray lasers would be weather independent. Second, the gamma-ray laser radiation can penetrate through the sand, which could be suspended in the air in a desert either naturally (due to strong winds) or artificially (as a protective “shield”). Besides, the first out of the three concepts can beemployed for creating non-laser gamma-ray sources of directed energy to be used for detecting stored radioactive materials, including the radioactive materials carried by an aircraft or a satellite. Last but not least: these concepts can be also used for remotely destroying biological and chemical weapons as a preemptive strike or during its delivery phase, as well as for distinguishing a nuclear warhead from decoy warheads. Thus, the defense capabilities of the proposed gamma-ray lasers can save numerous lives.展开更多
This paper focused on generation scheduling problem with consideration of wind, solar and PHES （pumped hydro energy storage） system. Wind, solar and PHES are being considered in the NEPS （northeast power system） o...This paper focused on generation scheduling problem with consideration of wind, solar and PHES （pumped hydro energy storage） system. Wind, solar and PHES are being considered in the NEPS （northeast power system） of Afghanistan to schedule all units power output so as to minimize the total operation cost of thermal units plus aggregate imported power tariffs during the scheduling horizon, subject to the system and unit operation constraints. Apart from determining the optimal output power of each unit, this research also involves in deciding the on/off status of thermal units. In order to find the optimal values of the variables, GA （genetic algorithm） is proposed. The algorithm performs efficiently in various sized thermal power system with equivalent wind, solar and PHES and can produce a high-quality solution. Simulation results reveal that with wind, solar and PHES the system is the most-cost effective than the other combinations.展开更多
Worldwide,there are many options to ensure domestic hot water(DHW)provision in dwellings.This study aimed to depict the distribution of energy sources and DHW production systems in the Calabria region.The research was...Worldwide,there are many options to ensure domestic hot water(DHW)provision in dwellings.This study aimed to depict the distribution of energy sources and DHW production systems in the Calabria region.The research was focused on understanding which variables,among contextual variables and building characteristics,may influence the adoption of a particular energy source or production system.Descriptive statistics and chi-square test of independence have been developed.Significant relationships were found between the climatic zone and the energy source used as well as between the climatic zone and the production system installed in both households with a separated and a combined DHW production system.Furthermore,the population of the municipality and the dwelling type resulted to be significant variables for the preference of an energy source or the diffusion of a combined production system.展开更多
RES （renewable energy sources）, such as wind and photovoltaic power plants, suffer from their stochastic nature that is why their behavior on market is very delicate. In order to diversify risk, a concept of VPP （v...RES （renewable energy sources）, such as wind and photovoltaic power plants, suffer from their stochastic nature that is why their behavior on market is very delicate. In order to diversify risk, a concept of VPP （virtual power plant） has been developed. The VPP is composed of several RES, from which at least one of them is fully controllable. Because the production of noncontrollable RES can not be forecasted perfectly, therefore an optimal dispatch schedule within VPP is needed. To address this problem, an APSO （accelerated particle swarm optimization） is used to solve the constrained optimal dispatch problem within VPP. The experimental results show that the proposed optimization method provides high quality solutions while meeting constraints.展开更多
Ambient temperature is an important factor affecting metabolic processes in animals,and its effect on energy metabolism is becoming more evident.Yet,integrative analysis of energy metabolism in finishing pigs at diffe...Ambient temperature is an important factor affecting metabolic processes in animals,and its effect on energy metabolism is becoming more evident.Yet,integrative analysis of energy metabolism in finishing pigs at different combinations of ambient temperature,energy density and energy sources,still remain underexplored.In order to determine the special characteristics of energy metabolism of finishing pigs in low-temperature environment,the effects of different combinations of ambient temperature,energy density,and energy source on underlying mechanisms were elucidated by assessing energy metabolism using integrative indirect calorimetry and non-targeted plasma metabolomics analyses.Thirty-two finishing pigs(Duroc×Large White×Landrace)with similar body weight of 85.44±2.04 kg were allotted in a 2×2×2 factorial arrangement(8 treatment groups,4 replicates per group,1 pig per replicate),which included two ambient temperatures(low temperature[10℃]and normal temperature[20℃]),two energy densities(normal energy density[NE,14.02 MJ/kg]and high energe density[HE,15.14 MJ/kg]),and two energy sources(low-oil source and high-oil source).The experiment period lasted 11 days.Increasing the energy density of the diet by adding oil changed the energy source in a low-temperature environment,improved crude fat digestibility(P<0.001),and reduced the feed/gain ratio of pigs(P=0.004),with a tendency for higher average daily gain(P=0.098),which would increase energy utilization.Adding oil to the diet altered energy sources at low temperature,reducing carbon dioxide emission by 3.10%,increasing energy retention and fat oxidation(P<0.05).Further,optimizing energy sources by adding oil significantly improved serum glucose(GLU)content(P<0.001)and reduced urea nitrogen(UN)content at normal temperature(P<0.001),with the same trend observed at low temperature.The metabolites in the eight groups were mainly enriched in the sphingolipid signaling pathway,insulin resistance,and glycerophospholipid metabolism(P<0.05).Energy metabolism in finishing pigs was not only affected by ambient temperature and energy density,but also by energy source,leading to variations in metabolic pathways for different energy substances.Increasing the dietary energy density by increasing oil supplementation at low temperature is an effective way to improve the growth performance of finishing pigs while reducing pollutant emissions.The study provides a new solution for optimizing energy nutrition for finishing pigs in low-temperature environment.展开更多
To achieve more precise monitoring of state fluctuations in the power network close to renewable energy sources, it is necessary to utilize phasor measurements and shorten the time interval between state estimations. ...To achieve more precise monitoring of state fluctuations in the power network close to renewable energy sources, it is necessary to utilize phasor measurements and shorten the time interval between state estimations. For large-scale power systems, however, estimating all of their states with shorter time intervals means a drastic increase in computational burden. As a tradeoff between accuracy and computational efficiency, a multi-time interval forecasting-aided state estimation approach is proposed in this paper, where states with various degrees of fluctuations are estimated asynchronously with different time intervals. Based on the newest state estimate, forecasting-aided state estimators are employed to predict states at time moments prior to the next round of measurement update and state estimation. Extensive numerical tests have demonstrated the effectiveness of the proposed approach.展开更多
As the proportion of renewable energy sources continues to increase,the local damping contributions of sources in power system decrease,posing a challenge to the power system stability.Therefore,online tracking of the...As the proportion of renewable energy sources continues to increase,the local damping contributions of sources in power system decrease,posing a challenge to the power system stability.Therefore,online tracking of the damping contributions of each source is crucial for the prevention of low-frequency oscillations.This paper proposes an online tracking method of local damping under ambient data.The proposed method is based on dissipation energy spectrum analysis(DESA)and the energy dissipation factor(EDF).First,the feasibility of using frequency-domain analysis for the dissipation energy of generator is analyzed.The frequency spectral function of dissipation energy of generator is then derived by integrating with Parseval’s theorem,and the EDF is defined.Second,the generator energy dissipation factor(GEDF)for the dominant oscillation mode frequency is established.The modal information of the dominant oscillation in the power system is obtained through DESA.The relationship between the frequency spectral function and eigenvalues is also established.Finally,an online tracking method of local damping is proposed based on DESA and GEDF.The effectiveness of the proposed method is validated through simulations on a four-machine 11-bus power system and an actual power system in Northwest China.展开更多
The significant increase in the proportion of renewable energy sources(RESs)has elevated risks of extreme ramp events and frequency instability in power systems.In recent years,frequency stability events have occurred...The significant increase in the proportion of renewable energy sources(RESs)has elevated risks of extreme ramp events and frequency instability in power systems.In recent years,frequency stability events have occurred in several countries/regions worldwide due to flexibility deficiencies.Generation flexibility has emerged as a critical factor influencing the frequency stability of power systems.This paper proposes a domain of attraction(DOA)-based quantitative method to assess the frequency stability region of power systems with a high proportion of RESs,considering generation flexibility constraints.First,ramp rate is adopted as the core indicator to characterize generation flexibility within automatic generation control(AGC)timescale,through which a nonlinear AGC model with rate saturation constraints is established.Second,the concept of DOA is introduced to define the stability region of the nonlinear AGC.Third,a quadratic Lyapunov-based estimation method is employed to quantitatively analyze the DOA of the nonlinear AGC at different generation flexibility levels.Simulation results demonstrate that increased generation flexibility expands the estimated DOA of the nonlinear AGC,whereas generation flexibility deficiency induces AGC instability.Moreover,state trajectory and time-domain simulation verify that the proposed estimation method accurately represents the stability region of the nonlinear AGC.展开更多
Numerous renewable energy sources(RESs)are coupled with the power grid through power electronics to advance low-carbon objectives.These RESs predominantly connect to the AC collection network via inverters,with the el...Numerous renewable energy sources(RESs)are coupled with the power grid through power electronics to advance low-carbon objectives.These RESs predominantly connect to the AC collection network via inverters,with the electricity they produce either transmitted over long distances through high-voltage lines or utilized locally within the distribution system.The unique interfacing of RESs alters their fault response characteristics,typically resulting in limited fault currents,frequency deviations,and fluctuating sequence impedance angles.Therefore,existing protection principles based on fault signatures of synchronous generators will face significant challenges including distance relays,directional elements,differential relays,phase selectors,and overcurrent relays.To solve these issues,innovative protection technologies have been developed to bolster grid stability and security.Furthermore,the superior controllability of power converters presents an opportunity to devise effective control strategies that can adapt existing protection mechanisms to function correctly in this new energy landscape.Nevertheless,the complexity of fault behaviors exhibited by RESs necessitates further refinement of these schemes.Therefore,this paper aims to consolidate current research methodologies and explore prospective avenues for future investigation.展开更多
The growing integration of renewable energy sources manifests as an effective strategy for reducing carbon emissions. This paper strives to efficiently approximate the set of optimal scheduling plans(OSPs) to enhance ...The growing integration of renewable energy sources manifests as an effective strategy for reducing carbon emissions. This paper strives to efficiently approximate the set of optimal scheduling plans(OSPs) to enhance the performance of the steady-state adaptive cruise method(SACM) of power grid, improving the ability of dealing with operational uncertainties. Initially, we provide a mathematical definition of the exact boxconstrained economic operating region(EBC-EOR) for the power grid and its dispatchable components. Following this, we introduce an EBC-EOR formulation algorithm and the corresponding bi-level optimization models designed to explore the economic operating boundaries. In addition, we propose an enhanced big-M method to expedite the computation of the EBCEOR. Finally, the effectiveness of the EBC-EOR formulation, its economic attributes, correlation with the scheduling plan underpinned by model predictive control, and the significant improvement in computational efficiency(over twelvefold) are verified through case studies conducted on two test systems..展开更多
The increasing integration of renewable energy sources(RESs)presents significant challenges for the safe and economical operation of power grids.Addressing the critical need to assess the effect of RES uncertainties o...The increasing integration of renewable energy sources(RESs)presents significant challenges for the safe and economical operation of power grids.Addressing the critical need to assess the effect of RES uncertainties on optimal scheduling schemes(OSSs),this paper introduces a convex hull based economic operating region(CH-EOR)for power grids.The CHEOR is mathematically defined to delineate the impact of RES uncertainties on power grid operations.We propose a novel approach for generating the CH-EOR,enhanced by a big-M preprocessing method to improve the computational efficiency.Performed on four test systems,the proposed big-M preprocessing method demonstrates notable advancements:a reduction in average operating costs by over 10%compared with the box-constrained operating region(BC-OR)derived from robust optimization.Furthermore,the CH-EOR occupies less than 11.79%of the generators'adjustable region(GAR).Most significantly,after applying the proposed big-M preprocessing method,the computational efficiency is improved over 17 times compared with the traditional big-M method.展开更多
基金funded by the Science and Technology Project of State Grid Shanxi Electric Power Company(5205E0230001).
文摘With the development of integrated power and gas distribution systems(IPGS)incorporating renewable energy sources(RESs),coordinating the restoration processes of the power distribution system(PS)and the gas distribution system(GS)by utilizing the benefits of RESs enhances service restoration.In this context,this paper proposes a coordinated service restoration framework that considers the uncertainty in RESs and the bi-directional restoration interactions between the PS and GS.Additionally,a coordinated service restoration model is developed considering the two systems’interdependency and the GS’s dynamic characteristics.The objective is to maximize the system resilience index while adhering to operational,dynamic,restoration logic,and interdependency constraints.A method for managing uncertainties in RES output is employed,and convexification techniques are applied to address the nonlinear constraints arising from the physical laws of the IPGS,thereby reducing solution complexity.As a result,the service restoration optimization problem of the IPGS can be formulated as a computationally tractable mixed-integer second-order cone programming problem.The effectiveness and superiority of the proposed framework are demonstrated through numerical simulations conducted on the interdependent IEEE 13-bus PS and 9-node GS.The comparative results show that the proposed framework improves the system resilience index by at least 65.07%compared to traditional methods.
基金Project(51178201) supported by the National Natural Science Foundation of China Project(2011CDB292) supported by the Natural Science Foundation of Hubei Province,China
文摘An active pipe-embedded building envelope, which is an external wall or roof with pipes embedded inside, was presented. This structure may utilize the circulating water in the pipe to transfer heat or coolth inside directly. This kind of structure is named ＂active pipe-embedded building envelope＂ due to dealing with the thermal energy actively inside the structure mass by circulating water. This structure not only deals with thermal energy before the external disturbance becomes cooling/heating load by using the circulating water, but also may use low-grade energy sources such as evaporative cooling, solar energy, and geothermal energy. In the meantime, this structure can also improve the indoor thermal comfort by tempering the internal wall surface temperature variation due to the thermal removal in the mass. This work further presents the thermal performance of this structure under a typical hot summer weather condition by comparing it with that of the conventional external wall/roof with numerical simulation. The results show that this pipe-embedded structure may reduce the external heat transfer significantly and reduce the internal wall surface temperature for improving thermal comfort. This work also presents the effects of the water temperature and the pipe spacing on the heat transfer of this structure. The internal surface heat transfer may reduce by about 2.6 W/mE when the water temperature reduces by 1℃ as far as a brick wall with pipes embedded inside is concerned. When the pipe spacing reduces by 50 mm, the internal wall surface heat flux can also reduce by about 2.3 W/m2.
基金the National Natural Science Foundation of China(No.U1564208).
文摘Energy optimization management can make fuel cell truck(FCT)power system more efficient,so as to improve vehicle fuel economy.When the structure of power source system and the torque distribution strategy are determined,the essence is to find the reasonable distribution of electric power between the fuel cell and other energy sources.The paper simulates the assistance of the intelligent transport system(ITS)and carries out the eco-velocity planning using the traffic signal light.On this basis,in order to further improve the energy efficiency of FCT,a model predictive control(MPC)-based energy source optimization management strategy is innovatively developed,which uses Dijkstra algorithm to achieve the minimization of equivalent hydrogen consumption.Under the scenarios of signalized intersections,based on the planned eco-velocity,the off-line simulation results show that the proposed MPC-based energy source management strategy(ESMS)can reduce hydrogen consumption of fuel cell up to 7%compared with the existing rule-based ESMS.Finally,the Hardware-in-the-Loop(HiL)simulation test is carried out to verify the effectiveness and real-time performance of the proposed MPC-based energy source optimization management strategy for the FCT based on eco-velocity planning with the assistance of traffic light information.
文摘We describe a specific approach to capacity man a ge ment for distribution grids. Based on simulations, it has been found that by curtailing a maximum of 5% of the yearly energy production on a per-generator basis, distribution grid connection capacity can be doubled. We also present the setting and fi rst results of a fi eld test for validating the approach in a rural distribution grid in northern Germany.
基金Supported by the National Basic Research Program of China (973 program,No. 2007CB815601,2010CB933501)the National Natural Science Foundation of China (40772034, 40902097)+2 种基金 the Outstanding Youth Fund (50625205) the Opening Project of Key Laboratory of Solid Waste Treatment and Resource Recycle (No. 09zxgk05),Ministry of Educationthe CAS Foundation (KJCX1.YW.07)
文摘Ochrobactrum anthropi CTS-325 isolated from a chromium-contaminated site had better resistance to Cr（Ⅵ） in LB medium under aerobic condition.Meanwhile,it was found that the reduction of Cr（Ⅵ） is not complete during the experimental process.Therefore,a series of small molecule energy sources including nitrogen and carbon sources were added into the LB medium in the bacterial stationary phase to promote the chromium reducibility.The result showed that the bacterial growth was positively correlated with the chromium reduction.SDS-PAGE analysis indicated that the protein groups were changed when the bacteria were stimulated by the chromium.Additionally,it was revealed that O.anthropi CTS-325 could utilize the cheaper alternative of sugar（sucrose residue leaching solution） well for further growth and restart the chromium reduction,which offered a new method for practical appli-cations.
文摘The purpose of this research was to study economic incentives to use renewable energy sources in the Republic of Kazakhstan and to give suggestions for production and circulation of the ＂green＂ certificates as a new financial instrument. The author analyzed European Union and Kazakhstani experience of economic incentives to reduce emissions and introduction of renewable energy sources. As a result of conducted research, the proposal to produce and circulate new financial instruments in Kazakhstan is made; as well as economic and environmental factors of renewable energy sources in the Republic of Kazakhstan are defined.
文摘In recent times, renewable energy production from renewable energy sources is an alternative way to fulfill the increased energy demands. However, the increasing energy demand rate places more pressure, leading to the termination of conventional energy resources. However, the cost of power generation from coal-fired plants is higher than the power generation’s price from renewable energy sources. This experiment is focused on cost optimization during power generation through pumped storage power plant and wind power plant. The entire modeling of cost optimization has been conducted in two parts. The mathematical modeling was done using MATLAB simulation while the hydro and wind power plant’s emulation was performed using SCADA (Supervisory control and data acquisition) designer implementation. The experiment was conducted using ranges of generated power from both power sources. The optimum combination of output power and cost from both generators is determined via MATLAB simulation within the assumed generated output power range. Secondly, the hydro-generator and wind generator’s emulation were executed individually through synchronizing the grid to determine each generator’s specification using SCADA designer, which provided the optimum power generation from both generators with the specific speed, aligning with results generated through MATLAB. Finally, the operational power cost (with no losses consideration) from MATLAB was compared with the local energy provider to determine the cost-efficiency. This experiment has provided the operational cost optimization of the hydro-wind combined power system with stable wind power generation using SCADA, which will ultimately assist in operations of large-scale power systems, remotely minimizing multi-area dynamic issues while maximizing the system efficiency.
文摘A newly developed energy source basein China,Huaibei City,is located inthe northern part of Anhui Province,under the direct control of the provincialgovernment.Under its jurisdiction,there arethree districts and one county,covering atotal area of 2725 sq km and with a populationof 1.8 million. The city boasts unique mineralresources.A total of 13 minerals have beensurveyed,including coal,iron and kaoline.The reserves of coal,the richest of all,areestimated at about 10 billion tons and theprospective reserves 35 billion tons.Basedon its coal resources,the city has set up 24pairs of large and modern mines with anannual production capacity of 20 milliontons,ranking fifth in the country.The
文摘Mining industry is a substantial consumer of the energy indispensable to power mining and mineral processing equipment and processes. As more and more mine operations move to remote locations, the access to reliable, secure and environment friendly energy sources becomes a key concern. At present, a great majority of remote mines relies heavily on diesel fuel that has to be transported over long distances. In this context, some of the renewable energy sources such as wind power or solar energy seem to provide potentially interesting and viable alternatives. Mine operations, however, have a very particular character, much different from other industries and from other potential applications of renewable power sources. This paper presents operational conditions of some mining operations, particularly those in remote regions, in the context of their energy needs. The authors analyse current and future capacities to decrease a reliance of remote mines on conventional fuels and energy. The paper also analyses and discusses the conditions to be met by alternative energy sources so that they might become a viable alternative for remote mining operations.
文摘We discuss novel advanced concepts suitable for the practical design of gamma-ray sources of directed energy. One concept is based on the self-channeling of a powerful optical laser in a gas within a metal tube. Another concept employs a direct excitation of a quadrupole nuclear level by a powerful optical laser. The third concept is based on the process of a high-order harmonic generation by an x-ray laser. All three concepts can be used for designing gamma-ray lasers that would have significant advantages over x-ray lasers. First, missile defense systems employing gamma-ray lasers would be weather independent. Second, the gamma-ray laser radiation can penetrate through the sand, which could be suspended in the air in a desert either naturally (due to strong winds) or artificially (as a protective “shield”). Besides, the first out of the three concepts can beemployed for creating non-laser gamma-ray sources of directed energy to be used for detecting stored radioactive materials, including the radioactive materials carried by an aircraft or a satellite. Last but not least: these concepts can be also used for remotely destroying biological and chemical weapons as a preemptive strike or during its delivery phase, as well as for distinguishing a nuclear warhead from decoy warheads. Thus, the defense capabilities of the proposed gamma-ray lasers can save numerous lives.
文摘This paper focused on generation scheduling problem with consideration of wind, solar and PHES （pumped hydro energy storage） system. Wind, solar and PHES are being considered in the NEPS （northeast power system） of Afghanistan to schedule all units power output so as to minimize the total operation cost of thermal units plus aggregate imported power tariffs during the scheduling horizon, subject to the system and unit operation constraints. Apart from determining the optimal output power of each unit, this research also involves in deciding the on/off status of thermal units. In order to find the optimal values of the variables, GA （genetic algorithm） is proposed. The algorithm performs efficiently in various sized thermal power system with equivalent wind, solar and PHES and can produce a high-quality solution. Simulation results reveal that with wind, solar and PHES the system is the most-cost effective than the other combinations.
文摘Worldwide,there are many options to ensure domestic hot water(DHW)provision in dwellings.This study aimed to depict the distribution of energy sources and DHW production systems in the Calabria region.The research was focused on understanding which variables,among contextual variables and building characteristics,may influence the adoption of a particular energy source or production system.Descriptive statistics and chi-square test of independence have been developed.Significant relationships were found between the climatic zone and the energy source used as well as between the climatic zone and the production system installed in both households with a separated and a combined DHW production system.Furthermore,the population of the municipality and the dwelling type resulted to be significant variables for the preference of an energy source or the diffusion of a combined production system.
文摘RES （renewable energy sources）, such as wind and photovoltaic power plants, suffer from their stochastic nature that is why their behavior on market is very delicate. In order to diversify risk, a concept of VPP （virtual power plant） has been developed. The VPP is composed of several RES, from which at least one of them is fully controllable. Because the production of noncontrollable RES can not be forecasted perfectly, therefore an optimal dispatch schedule within VPP is needed. To address this problem, an APSO （accelerated particle swarm optimization） is used to solve the constrained optimal dispatch problem within VPP. The experimental results show that the proposed optimization method provides high quality solutions while meeting constraints.
基金supported by the National Natural Science Foundation of China(U21A20254)the Jilin Provincial Scientific and Technological Development Program(20230202078NC).
文摘Ambient temperature is an important factor affecting metabolic processes in animals,and its effect on energy metabolism is becoming more evident.Yet,integrative analysis of energy metabolism in finishing pigs at different combinations of ambient temperature,energy density and energy sources,still remain underexplored.In order to determine the special characteristics of energy metabolism of finishing pigs in low-temperature environment,the effects of different combinations of ambient temperature,energy density,and energy source on underlying mechanisms were elucidated by assessing energy metabolism using integrative indirect calorimetry and non-targeted plasma metabolomics analyses.Thirty-two finishing pigs(Duroc×Large White×Landrace)with similar body weight of 85.44±2.04 kg were allotted in a 2×2×2 factorial arrangement(8 treatment groups,4 replicates per group,1 pig per replicate),which included two ambient temperatures(low temperature[10℃]and normal temperature[20℃]),two energy densities(normal energy density[NE,14.02 MJ/kg]and high energe density[HE,15.14 MJ/kg]),and two energy sources(low-oil source and high-oil source).The experiment period lasted 11 days.Increasing the energy density of the diet by adding oil changed the energy source in a low-temperature environment,improved crude fat digestibility(P<0.001),and reduced the feed/gain ratio of pigs(P=0.004),with a tendency for higher average daily gain(P=0.098),which would increase energy utilization.Adding oil to the diet altered energy sources at low temperature,reducing carbon dioxide emission by 3.10%,increasing energy retention and fat oxidation(P<0.05).Further,optimizing energy sources by adding oil significantly improved serum glucose(GLU)content(P<0.001)and reduced urea nitrogen(UN)content at normal temperature(P<0.001),with the same trend observed at low temperature.The metabolites in the eight groups were mainly enriched in the sphingolipid signaling pathway,insulin resistance,and glycerophospholipid metabolism(P<0.05).Energy metabolism in finishing pigs was not only affected by ambient temperature and energy density,but also by energy source,leading to variations in metabolic pathways for different energy substances.Increasing the dietary energy density by increasing oil supplementation at low temperature is an effective way to improve the growth performance of finishing pigs while reducing pollutant emissions.The study provides a new solution for optimizing energy nutrition for finishing pigs in low-temperature environment.
基金supported in part by the National Natural Science Foundation of China(No.51977115).
文摘To achieve more precise monitoring of state fluctuations in the power network close to renewable energy sources, it is necessary to utilize phasor measurements and shorten the time interval between state estimations. For large-scale power systems, however, estimating all of their states with shorter time intervals means a drastic increase in computational burden. As a tradeoff between accuracy and computational efficiency, a multi-time interval forecasting-aided state estimation approach is proposed in this paper, where states with various degrees of fluctuations are estimated asynchronously with different time intervals. Based on the newest state estimate, forecasting-aided state estimators are employed to predict states at time moments prior to the next round of measurement update and state estimation. Extensive numerical tests have demonstrated the effectiveness of the proposed approach.
基金supported by National Key Research and Development Program of China(No.2021YFB2400800).
文摘As the proportion of renewable energy sources continues to increase,the local damping contributions of sources in power system decrease,posing a challenge to the power system stability.Therefore,online tracking of the damping contributions of each source is crucial for the prevention of low-frequency oscillations.This paper proposes an online tracking method of local damping under ambient data.The proposed method is based on dissipation energy spectrum analysis(DESA)and the energy dissipation factor(EDF).First,the feasibility of using frequency-domain analysis for the dissipation energy of generator is analyzed.The frequency spectral function of dissipation energy of generator is then derived by integrating with Parseval’s theorem,and the EDF is defined.Second,the generator energy dissipation factor(GEDF)for the dominant oscillation mode frequency is established.The modal information of the dominant oscillation in the power system is obtained through DESA.The relationship between the frequency spectral function and eigenvalues is also established.Finally,an online tracking method of local damping is proposed based on DESA and GEDF.The effectiveness of the proposed method is validated through simulations on a four-machine 11-bus power system and an actual power system in Northwest China.
基金supported in part by Science and Technology Project of State Grid Corporation of China(No.5100-202336015A-1-1-ZN)。
文摘The significant increase in the proportion of renewable energy sources(RESs)has elevated risks of extreme ramp events and frequency instability in power systems.In recent years,frequency stability events have occurred in several countries/regions worldwide due to flexibility deficiencies.Generation flexibility has emerged as a critical factor influencing the frequency stability of power systems.This paper proposes a domain of attraction(DOA)-based quantitative method to assess the frequency stability region of power systems with a high proportion of RESs,considering generation flexibility constraints.First,ramp rate is adopted as the core indicator to characterize generation flexibility within automatic generation control(AGC)timescale,through which a nonlinear AGC model with rate saturation constraints is established.Second,the concept of DOA is introduced to define the stability region of the nonlinear AGC.Third,a quadratic Lyapunov-based estimation method is employed to quantitatively analyze the DOA of the nonlinear AGC at different generation flexibility levels.Simulation results demonstrate that increased generation flexibility expands the estimated DOA of the nonlinear AGC,whereas generation flexibility deficiency induces AGC instability.Moreover,state trajectory and time-domain simulation verify that the proposed estimation method accurately represents the stability region of the nonlinear AGC.
基金carried out with the European Union’s Horizon ResearchInnovation Programme under Marie Sklodowska-Curie Grant Agreement(No.101145934)UKRI Postdoctoral Fellowships Guarantee(No.EP/Z002168/1).
文摘Numerous renewable energy sources(RESs)are coupled with the power grid through power electronics to advance low-carbon objectives.These RESs predominantly connect to the AC collection network via inverters,with the electricity they produce either transmitted over long distances through high-voltage lines or utilized locally within the distribution system.The unique interfacing of RESs alters their fault response characteristics,typically resulting in limited fault currents,frequency deviations,and fluctuating sequence impedance angles.Therefore,existing protection principles based on fault signatures of synchronous generators will face significant challenges including distance relays,directional elements,differential relays,phase selectors,and overcurrent relays.To solve these issues,innovative protection technologies have been developed to bolster grid stability and security.Furthermore,the superior controllability of power converters presents an opportunity to devise effective control strategies that can adapt existing protection mechanisms to function correctly in this new energy landscape.Nevertheless,the complexity of fault behaviors exhibited by RESs necessitates further refinement of these schemes.Therefore,this paper aims to consolidate current research methodologies and explore prospective avenues for future investigation.
基金supported by the Science and Technology Project of State Grid Corporation(No.5400-202099286A-0-0-00).
文摘The growing integration of renewable energy sources manifests as an effective strategy for reducing carbon emissions. This paper strives to efficiently approximate the set of optimal scheduling plans(OSPs) to enhance the performance of the steady-state adaptive cruise method(SACM) of power grid, improving the ability of dealing with operational uncertainties. Initially, we provide a mathematical definition of the exact boxconstrained economic operating region(EBC-EOR) for the power grid and its dispatchable components. Following this, we introduce an EBC-EOR formulation algorithm and the corresponding bi-level optimization models designed to explore the economic operating boundaries. In addition, we propose an enhanced big-M method to expedite the computation of the EBCEOR. Finally, the effectiveness of the EBC-EOR formulation, its economic attributes, correlation with the scheduling plan underpinned by model predictive control, and the significant improvement in computational efficiency(over twelvefold) are verified through case studies conducted on two test systems..
基金supported by the National Natural Science Foundation of China(No.52007173)the National Key Research and Development Program of China(No.2023YFB3107603)the Science and Technology Project of State Grid Corporation(No.5100-20212570A-0-5-SF)。
文摘The increasing integration of renewable energy sources(RESs)presents significant challenges for the safe and economical operation of power grids.Addressing the critical need to assess the effect of RES uncertainties on optimal scheduling schemes(OSSs),this paper introduces a convex hull based economic operating region(CH-EOR)for power grids.The CHEOR is mathematically defined to delineate the impact of RES uncertainties on power grid operations.We propose a novel approach for generating the CH-EOR,enhanced by a big-M preprocessing method to improve the computational efficiency.Performed on four test systems,the proposed big-M preprocessing method demonstrates notable advancements:a reduction in average operating costs by over 10%compared with the box-constrained operating region(BC-OR)derived from robust optimization.Furthermore,the CH-EOR occupies less than 11.79%of the generators'adjustable region(GAR).Most significantly,after applying the proposed big-M preprocessing method,the computational efficiency is improved over 17 times compared with the traditional big-M method.
