Issue Ebookcover story
List of IssuesDocument Types
- Abstract：Distributed energy supply system is installed close to end-users with advantages of flexible consumption of renewable energy. Distributed energy supply system with integrating solar energy and clean fuel was conducted to achieve efficient utilization of solar energy and fuel. A distributed energy supply system based on the solar thermochemistry was proposed. The system integrated solar thermochemistry conversion and distributed energy system combined cooling, heating and power. The solar and methanol were complemented at the source in a thermochemical form, and the solar was converted into chemical energy of syngas, the cold, heat and power products were then exported through the internal combustion engine electric generator and waste heat recovery units to meet the load demand of users. Through numerical calculation method, the thermodynamic performance and CO2 emission performance of the integrated system were analyzed, and the performance under design and variable operating conditions was studied. The results show that the integrated solar energy and fuel thermochemical complementary energy supply system has significant advantages of energy saving and emission reduction.Keywords：solar thermochemistry;distributed energy supply system;methanol decomposition;carbon emission56|169|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：Improving the quality of on-grid solar power has attracted worldwide attention in recent years due to the natural intermittent and instability of solar irradiance. As an emerging technology, the photovoltaic/concentrated solar power (PV-CSP) hybrid technology is considered as one of the research focuses currently in solar energy field, due to various advantages compared with the PV-alone and CSP-alone technologies. This paper introduced PV, CSP technologies, and PV-CSP hybrid technology. Through the attention to the construction and operation of some typical commercial PV-CSP hybrid power plants, the application status of commercial PV-CSP hybrid power plants was analyzed, and the technical and economic research of PV-CSP hybrid system in recent years was summarized.Keywords：solar energy;photovoltaic (PV) power generation;concentrated solar power (CSP) generation;PV-CSP hybrid system41|366|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：In order to solve the problem of large errors in the power generation of solar photovoltaic system under different conditions, a new method for power generation prediction of solar photovoltaic system was proposed. By analyzing the structure of solar photovoltaic power generation system, the influencing factors of solar photovoltaic power generation system were studied. Seasons and weather types were used as historical samples to select sample sources, and similar data points were searched in the historical database for predicting daily time-sharing meteorological data provided by meteorological departments as historical samples. The off-line parameter optimization data set was constructed with historical samples, and the generation power prediction model of power generation system was constructed with the kernel function limit learning machine algorithm, and the model parameters were optimized by the particle swarm optimization algorithm. The experimental results show that the mean absolute percent errors of the proposed method are 1.47% and 6.39% respectively under different conditions, and the relative variation of the power prediction errors of solar photovoltaic modules is less than 1% under comprehensive abnormal conditions. It is proved that the proposed method meets the actual prediction requirements.Keywords：photovoltaic;power forecasting;particle swarm optimization;kernel function limit learning machine42|1283|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：The integrated energy system (IES) includes various energy forms, complex operation modes, abundant control equipment and coupling links, which brings challenges to its steady-state modeling and steady-state power flow calculation. In order to obtain the steady-state characteristics of the thermal subsystem in the IES, the topological structure of the typical IES was provided; the steady-state models of the power subsystem, the thermal subsystem, the cold subsystem and the distributed energy station were established respectively, and then the hybrid power flow model was established, and the Newton-Raphson algorithm was used to solve the hybrid power flow; the influence of the key technical parameters (including the water supply temperature of the source node, the water outlet temperature of the load node, the length and diameter of the heat network pipe, and the heat load power) on the steady-state power flow of the IES was analyzed. The analysis results can support the planning, design and optimal operation of the IES.Keywords：integrated energy system (IES);thermal subsystem;steady-state modelling;steady-state power flow29|358|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：The multi-energy complementary distributed integrated energy supply system, which is typical of green, low carbon and high efficiency, has become the research focus in the energy sector at home and abroad. The basic concept, main technical characteristics, main components and key technologies of multi-energy complementary distributed integrated energy supply system were described. In addition, based on the energy supply needs and energy endowment of a typical science and technology innovation park in China, the comprehensive energy scheme of 'Integration of Five Aspects' was researched. The main energy supply system of this scheme includes gas distributed energy, distributed photovoltaic, distributed wind power, the sewage-source heat pump and energy storage, and the energy networks include electric power, heating power, refrigerant water, natural gas and reclaimed water. With intelligent technology, this scheme may achieve the 'source-network-load' system optimal operation and meet the different demand of energy consumers. Finally, some suggestions were given for the development and existing problems of China's multi-energy complementary distributed integrated energy supply system.Keywords：multi-energy complementation;distributed energy;integrated energy supply system;typical development scheme;development suggestion86|527|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：Combined cooling, heating and power (CCHP) system is a new type of distributed energy supply technology, which is small scale and close to users. It can avoid the energy loss during long-distance energy transmission process, and has the characteristics of flexibility, high efficiency and environmental protection. It is an important supplement to large-scale and centralized energy supply. Small and medium-scale power generation devices are the core of CCHP system, and both refrigeration and heating are carried out around the surplus heat of power generation devices. The basic working principle, thermal performance and related research progress of two types of small and medium-scale power generation devices for CCHP system were reviewed. One type is those using fossil fuels as energy input, including micro-turbines, internal combustion engines, small gas turbines and fuel cells. The other type is those using surplus heat from power generation devices or other heat sources such as concentrated solar heat, including organic Rankine cycles (ORC), power/cooling cogeneration cycles and thermoacoustic generators. Finally, the advantages and disadvantages of the two types of small and medium-scale power generation devices were compared and analyzed, which provided a reference for the selection of small and medium-scale power generation devices and system design of CCHP system.Keywords：distributed energy supply system;fossil fuels;concentrated solar heat;combined cooling, heating and power (CCHP);small and medium-scale power generation devices33|348|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：In terms of the first and second laws of thermodynamics and economy, the thermo-economic analysis of a new ejector combined cooling and power cycle based on zeotropic working fluids was carried out. On this basis, the parameters of the cycle were analyzed. The effects of the five key parameters of composition ratio, evaporation temperature, condensing temperature, expansion ratio of expander, outlet temperature of steam generator on the thermal efficiency, exergy efficiency and capital cost rate were studied. Finally, taking the maximization of exergy efficiency and the minimization of cost rate as the objective function, Pareto optimal front was acquired by using NSGA-II. An exergy efficiency of 0.131 9 and capital cost rate of 1.94×10-5 $/s were selected as the best decision point by using TOPSIS decision method.Keywords：distributed energy;ejector combined cooling and power cycle;zeotropic working fluids;thermo-economic analysis;multiobjective optimization39|252|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：The thermal power plant is rich in waste heat resources, and there is a phenomenon of "white feather" caused by the exhaust of boiler flue gas into the atmosphere. Domestic and foreign scholars have carried out a lot of research on the utilization of waste heat of flue gas. Absorption heat pump is widely used in the field of district central heating and cooling for energy level lifting device driven by waste heat. The regenerative, multi-effect, multi-stage and compression-absorption composite absorption heat pump technologies used in the field of waste heat recovery was reviewed. A flue gas waste heat recovery system consisting of a two-stage absorption heat pump, a temperature rising compression absorption coupling heat pump and a three-stage flue gas heat exchanger was proposed. The system is based on the principle of use of flue as waste heat energy cascade, reducing the flue gas from 145℃ to below 40℃, and obtaining a heating network hot water above 70℃, which can effectively improve the energy efficiency and reduce the "white feather" phenomenon.Keywords：flue gas waste heat recovery;absorption heat pump;multi-effect;multi-stage;compressionabsorption composite122|102|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：In view of the increasing proportion of distributed energy in the energy internet, the feasibility and necessity of the active regulation of energy storage system with multiple distributed energy systems were discussed. According to the power system stability and economic operation requirements, the key of energy storage active control strategy is the active assistance in balancing power changes, regulation time, regulation frequency and regulation amount are the key factors that affect the active regulation. The energy storage system was built in Powerfactory software for simulation, and the influence of the active regulation of power storage system on the system was analyzed. Combined with the experience of actual engineering construction and equipment development, the active regulation strategy of energy storage system was summarized. The effectiveness of the active regulation strategy was verified through simulation analysis and experimental data.Keywords：energy internet;energy storage system;active regulation strategy;charge and discharge control35|347|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：Gas-fired combined cooling, heating and power (CCHP) distributed energy system has made certain progress in China. However, because of unreasonable system design scale and configuration compared with demand, the CCHP system has low operating efficiency, poor economy, unsatisfactory operation effect, and even some of the CCHP systems have been shut down. Taking a middle first-class hospital in Sichuan province as an example, by analyzing current hospital's cooling, heating and power loads on typical day, the cooling, heating and power loads in the newly built hospital branch were projected, and the installed scale and system configuration of CCHP system were specifically determined to realize the economical and efficient operation of CCHP system. Compared with the traditional energy supply system, the rationality of CCHP system in hospital was analyzed from three aspects including economic benefit, energy utilization efficiency and environmental benefit.Keywords：distributed energy system;combined cooling, heating and power (CCHP);hospital building;system configuration26|160|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
Distributed Energy System
- Abstract：According to the emission concentration and emission performance of pollutants from wet flue gas desulfurization (WFGD) of coal-fired power plants. The haze control effects of ultra-low emission WFGD were analyzed. Emissions of SO2, particulate matter and SO3 are reduced by WFGD. These pollutants are precursors of haze. It shows that it has positive contribution to haze control by ultra-low emission WFGD. At the same time, the colored plume has been ability to control cooperatively by ultra-low emission. The colored plume should be controlled according to local conditions. After the extensive transformation of ultra-low emission in electricity industry, emissions of air pollutants have been continuously reduced. The quality of air environment has improved year after year. The contribution is due to WFGD and ultra-low emissions.Keywords：coal-fired power plant;wet flue gas desulfurization;ultra-low emission;haze control;colored plume63|427|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：Based on the previously established model of an endoreversible simple modified closed Brayton cycle (MCBC) coupled to variable-temperature reservoirs, the effect of parameters such as compressor pressure ratio on cycle performance was analyzed. The dimensionless power output and the dimensionless ecological function were optimized respectively by selecting cycle pressure ratio and the heat conductance distributions of heat exchangers as the design variables to optimize the performances of the endoreversible simple MCBC coupled to variable-temperature reservoirs. Finally, based on the NSGA-Ⅱ algorithm, the pressure ratio and the heat conductance distributions were optimized by taking the dimensionless power output, thermal efficiency and dimensionless ecological function as the optimization objectives, and the sensitivity of the related parameters was analyzed. The results show that there is a significant correlation between the inlet temperature ratios of the regular combustion chamber (RCC) and the converging combustion chamber (CCC) on the results of the single-objective optimization. It is found that compared with the results obtained by single-objective optimization, the optimal solutions corresponding to multi-objective optimization have smaller deviation indexes, and the deviation index is the smallest through Shannon entropy making. The sensitivity analyses show that the effects of the optimization variables changing within the range from -10% to 10% on the optimal dimensionless power output, the optimal thermal efficiency, the optimal dimensionless ecological function and its corresponding isothermal pressure drop ratio are very small, and the ranges do not exceed 5%.Keywords：finite time thermodynamics;modified closed Brayton cycle (MCBC);thermal efficiency;ecological function;isothermal pressure drop ratio;multi-objective optimization26|94|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：Compressor is an important equipment of gas turbine. The maximum output capacity and performance of the gas turbine is directly affected by the performance of the compressor. The change of inlet guide vane (IGV) opening degree has an important influence on the efficiency and performance for the compressor. The study of the relationship between the change of the IGV opening and the compressor efficiency is very important for compressor performance analysis, unit operation efficiency and safety. In this paper, the compressor operating data of MITSUBISHI M701F4 gas turbine was collected and analyzed. Through the analysis of the data in operation, we found that the influence of the opening degree of IGV on the compressor efficiency had a certain dynamic relationship when the changes of the ambient pressure and temperature were small. Before the opening degree of IGV reached a certain value, the opening degree of IGV had a greater influence on the compressor efficiency but had less influence on the outlet pressure and temperature of compressor. With the increase of the opening degree of IGV, the influence on the outlet pressure and temperature of compressor was gradually strengthened until the opening degree of IGV was fully opened, and then the outlet pressure and temperature of compressor were stable.Keywords：gas turbine;opening degree of inlet guide vane (IGV);compressor90|326|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
Power Generation and Environmental Protection
- Abstract：The access of wind power can replace the power generation of conventional units and thus has a positive value, and it will also change the operation mode of different types of units in the system and bring negative value. In order to analyze the value of wind power integration, a pre-optimized scheduling model for wind turbines was established. The characteristics of different units, the randomness and error of load and wind power were considered in the model. The influences of wind power penetration rate, load and wind power prediction error and load and wind power correlation on wind power value were analyzed. The results show that wind power has the value of reducing the operating cost of the system when the wind power penetration rate is low. When the wind power penetration rate is high, the wind power does not have the value of grid connection due to the increase of the unit's start-stop cost.Keywords：wind power;optimal scheduling model;unit type;influence factor26|351|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：The simulation platform of wind farms with fixed speed induction wind turbines and doubly-fed induction wind turbines connected to the power grid was built in the electromagnetic transient simulation software PSCAD/EMTDC. Serious three-phase faults in the power grid were carried out to analyze the low voltage ride-through (LVRT) ability of various wind turbines. The research results show that wind farm's LVRT ability with fixed speed induction wind turbines depends on the fault critical clearing time. When the fault clearing time is shorter than the fault critical clearing time, the wind farm with fixed speed induction wind turbines can have LVRT ability. Different points of faults simulations at power grid were carried out at the simulation platform. The research results show that wind farm's LVRT ability depends on the electrical distance of the point of fault. The longer the electrical distance of the point of fault to the wind farm is, the stronger the wind farm's LVRT ability.Keywords：wind farms;low voltage ride-through (LVRT);doubly-fed induction wind turbine;fixed speed induction wind turbine;PSCAD/EMTDC24|256|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
New and Renewable Energy
