To improve the control effect of key parameters and energy conversion efficiency of ultra-supercritical coal-fired power generation units during load cycling process, 600 MW class ultra-supercritical coal-fired power generation units are taken as the research objects to carry out modeling and verification. The deviation of key thermal parameters meets the specified range of thermal power simulation standard. The spatiotemporal distribution model of internal heat storage in thermal system of coal-fired power generation units is established, and the water-fuel ratio and flue gas damper opening control logic of the feedforward internal heat storage state of the unit are proposed. The real-time heat storage state of the unit during the load cycling process is fed forward to the flow rate of feed water, coal, and flue gas damper control. The simulation results show that, when the unit load cycling rate varies from 1.0% Pe/min to 3.0%Pe/min within 40%~70% THA load range, the absolute value of the cumulative main steam temperature deviation rate decreases by 27%~31%. The average power generation standard coal consumption rate of the unit decreases by 0.37~0.65 g/(kW·h) during the transient process. The proposed control strategies improve the control accuracy of key thermal parameters and the energy conversion efficiencies of the ultra-supercritical coal-fired power generation units during load cycling transient processes.

Energy storage system assisted thermal power unit frequency regulation is limited by the capacity of storage device, and its output power can not track the command power for a long time. At the same time, lithium battery energy storage technology also exists problems in safety hazards, cycle life limitations, limited enhancement of unit frequency gain gain and other issues. For this reason, the characteristics of high cycle life and high safety of supercapacitor are used to construct the simulation model of hybrid energy storage system assisted coal-fired thermal power unit frequency regulation in Matlab/Simulink platform. Combining with the operating state of thermal power unit and energy storage system, a set of control strategy based on index calculation and fuzzy control synergy is designed to achieve the adaptive adjustment of hybrid energy storage system output under dynamic operating conditions. Simulations show that, the control strategy can effectively extend the service life of lithium batteries and efficiently utilize the residual power of the hybrid energy storage system. Compared with the conventional control strategy of hybrid energy storage system, the proposed control strategy reduces the average daily use time of lithium battery by 60%, improves the comprehensive index of frequency regulation performance by 34%, and increases the average daily revenue by 20 000 yuan, which has high engineering application value.

Flow batteries are considered as one of the most promising technologies for large-scale energy storage, due to their inherent safety, long cycle life, environmental friendliness and robust scalability. As the key material of flow batteries, electrodes have a significant influence on battery performance. The research advancements of electrospun carbon nano-fiber electrodes in flow batteries are reviewed. The fabrication principles of electrospun carbon nano-fibers and their influence on the critical fabrication parameters are elucidated. It provides a comprehensive review of preparation methods for electrospun carbon nano-fiber electrodes with controllable structure and chemistry, properties and their effect on battery performance, including microstructural modulation of carbon nano-fibers, heteroatom doping, and catalytic modification. The key of electrode optimization is synergies between electrochemical activity and mass transport of electrodes, which are associated with the active areas and chemistry properties. The microstructure and surface properties of fibers can be controlled by strategies involving fiber porosity or new structural designs. Doping heteroatoms and introducing catalysts can increase the active area and hydrophilicity of the electrodes to promote the electrochemical activity of the electrodes. Lastly, the challenges and future developments of the electrospun carbon nano-fiber electrodes from laboratory preparation to scaling-up are outlined.

Under deep peak shaving and variable operating conditions of thermal power units, significant changes in steam temperature have caused a significant increase in thermal stress in some structures of the units, which accelerated structural damage, and resulted in frequent safety accidents. To solve these problems, by taking the regulating stage rotor of a 300 MW steam turbine as the object, and Ansys software is used to analyze the thermal stress, aerodynamic force, and centrifugal force of the blades. Firstly, structural optimization is carried out on root of the blade to significantly eliminate the unreasonable local stress concentration phenomenon commonly found in conventional calculations. Then, the distribution laws of temperature and stress fields in the regulating stage under different conditions such as steady-state and transient during the deep peak shaving process of thermal power units are revealed. Moreover, the effects of the temperature and stress fields on safety performance of the unit are also investigated. The results indicate that, the maximum equivalent stress increases by about 24% under steady-state conditions with temperature difference of different nozzle groups of 50 ℃. The transient load increase rate of 5% THA/min is about three times higher than that of 2% THA/min, causing low cycle fatigue damage to the rotor. Compared with steady-state operating conditions, increasing the load once a day at a rate of 2% THA/min from half load to full load increases the overall damage by about 38%.

Due to factors such as coal quality and combustion, coarse fly ash particles in flue gas of coal-fired boiler can easily cause varying degrees of wear and tear on tail flue and denitrification catalysts. An “A-V-T” type pre-removal structure for coarse particle fly ash before denitrification is established using the flue from the economizer outlet to the denitrification system inlet of a 300 MW unit as the research object. The structure is composed of “A-type baffle enrichment + V-type high-efficiency ash collection + T-type coarse ash channel” and is placed in a large cross-section low flow velocity flue at the economizer outlet. The influence rules of different particle size distribution trajectories, removal effects and resistance before and after the arrangement of the coarse particle fly ash pre-removal device are studied through numerical simulation, and engineering application is conducted to verify the effectiveness. The numerical simulation results indicate that, the use of coarse particle removal technology has little effect on flow field state of the original system at flue gas side. As the particle size of fly ash increases, the removal rate of fly ash increases. The removal rates of fly as particles with size of 50, 200, 500, and 1 000 μm are 12.15%, 59.40%, 87.01%, and 93.62%, respectively. The removal efficiency for coarse particles with size of 200 μm and above is 85.15%. The overall ash collection rate is 15.50%, with an additional resistance of 78 Pa. For this 300 MW unit, the tests after retrofitting show that, the removal rate of coarse ash particles with size of 200 μm and above is 83.96%, the overall removal rate of ash is 14.91%, and the net increase in resistance is 73 Pa. The experimental results verify the rationality of the numerical simulation results.

The beam-down concentrating solar power plant has the advantages of high concentrating ratio, low installation and maintenance requirements, and low pump consumption. Relying on the 50 MW beam-down tower concentrating solar power station in Yumen Xinneng First Power Co., Ltd., the mathematical models of the heliostat field, hyperboloid mirror, receiver, molten salt tank, and power generation cycle are established and verified. The run-test results reveal that, the maximum outlet temperature of the molten salt can be maintained at 559 ℃ for 50 minutes at an average direct normal irradiation of 739.70 W/m². The cosine efficiency, shading and blocking efficiency, shading efficiency of the hyperboloid mirror, and attenuation efficiency of the heliostat field at 12:00 are 0.856 8, 0.999 7, 0.994 1, and 0.974 6, respectively. The average hyperboloid mirror flux density and receiver flux density are 11.3 kW/m² and 400.5 kW/m², respectively. Meanwhile, the power station is maintained for 16 h at the rated generation power of 50 MW. The research has certain reference significance for the operation of a beam-down concentrating solar power plant.

Compressed air energy storage (CAES) technologies have garnered widespread attention due to their large scale, high efficiency, and environmental friendliness. Among them, the non-combustion compressed air energy storage technology is mature, and produces no carbon emissions during operation. There are already several adiabatic non-combustion compressed air energy storage power stations in operation, under construction, and in planning in China. However, the design parameters of the CAES system lack a unified standardization system, which poses many challenges in system design and performance optimization of CAES. To solve this problem, the design of medium-temperature and high-temperature thermal energy storage system schemes for a 200 MW class CAES system is presented, the key equipment parameters and system boundary conditions are determined. Moreover, the performance and technical economy of the medium- and high-temperature thermal energy storage system schemes is compared. The results show that, the high-temperature thermal energy storage system is superior to the medium-temperature thermal energy storage system in performance indicators, but it has a higher investment cost, indicating that when choosing the thermal energy storage technology route for large-capacity CAES systems, it is necessary to consider comprehensively based on specific application scenarios and economic budgets.

In view of the electricity demand of users and the power generation of renewable energy, an optimal scheduling model of grid-connected wind-optical-battery-waste mine pumped storage combined power generation system is established, with the optimization objective of minimizing the total operating cost of the system. Moreover, the results of the optimal scheduling are measured with the evaluation indexes of the equivalent load variance, the fluctuation rate of the contact line, and the power supply loss rate. The optimal solution is performed using CPLEX solver for the scheduling model. Through simulation on the optimal scheduling models of three different energy storage forms, it is concluded that the total cost of the hybrid energy storage in the form of storage battery and abandoned mine pumped storage reduces by 62.21% and 49.18% compared with that of the battery alone and abandoned mine pumped storage alone, respectively. The optimization results are ranked and evaluated by using the combined entropy weight rank sum ratio method, and the weighted rank-sum ratio of the wind-solar-battery-abandoned mine pumped storage combined power generation system is 0.833, with the highest score ranking. The results show that the proposed model not only improves the operation economy of the system, but also enhances the reliability of the system power supply, which verifies the rationality and effectiveness of the proposed model.

Wind power generation and solar thermal power generation have complementary advantages in terms of time characteristics, and the heat storage system equipped with solar thermal power station can effectively alleviate the peak regulation pressure and improve the wind power absorption capacity. On this basis, a solar thermal-wind combined power generation system is proposed. The Latin hypercube sampling method is used to effectively reduce the uncertainty of wind power output and solar irradiation intensity. Then, a two-stage double-layer optimal allocation method is proposed to rationally allocate the heat storage capacity. The upper layer model aims to minimize the investment cost of comprehensive operation of the system and the lowest curtailment of the system. The optimal heat storage capacity is determined by a fuzzy multi-attribute decision scheme. In the lower layer model, the operation is optimized with the goal of maximizing the net benefit of the cogeneration system in the scenario. The results show that the optimal heat storage capacity of the heat storage system of the solar thermal power station is 906 MW·h, and the comprehensive operating cost for the optimal heat storage capacity configuration is 2 430 000 yuan. Through the comparison between the results of different scenarios, the curtailment of the system with this configuration method reduces by 69.615 MW, and the net revenue of the system increases by 7.7%.

Decarbonization in thermal power industry is directly related to the realization of the “double carbon” target, while the circulating fluidized bed boiler has the advantages of wide fuel applicability and can carry out large-scale fuel blending. Biomass fuel is a renewable “zero-carbon” energy source, its blending can greatly reduce the carbon emissions of thermal power plants. Based on the existing circulating fluidized bed boilers and coal-fired conditions, biomass co-firing tests were conducted, and comprehensively evaluation was also carried out on combustion stability, pollutant emissions, and thermal efficiency. The co-firing experiments results showed that, as the co-firing ratio increased, the coal consumption rate per unit of steam production significantly decreased, with stable combustion conditions maintained throughout the process. Under co-firing conditions, the consumption of limestone decreased to approximately 4.5 kg for 1 ton steam production, with SO₂ emissions meeting the standards. Blending raised the furnace temperature, elevated the exhaust temperature, increased the fly ash content, and slightly increased the heat loss. Through regulating the air volume ratio, material layer pressure difference and excess air coefficient, the overall thermal efficiency closely approached the design value. Under long-term operating conditions, the blending ratio of biomass reached about 30%, and the emissions of SO₂ and NO_x were qualified. The tail heat exchanger was not corroded obviously, and the CO₂ emission reduction amount reached about 480 kg for 1 ton steam production.