With the increasing penetration of new energy in new power system, the influence of the uncertainty of wind power output and the correlation with load on the system operation is increasingly prominent. Thus, the conventional transformer risk assessment can no longer meet the demand. Based on Copula model and Susa model, a joint probability assessment method of transformer operation risk considering wind power and load correlation is proposed. Monte Carlo method is used to calculate each risk index value and evaluate transformer operation risk. The research results show that, the conventional transformer evaluation system that does not consider the wind-load correlation will lead to a low overall risk assessment result, with the maximum error of the index up to 55.02%. Also, with the increase of wind-load correlation, the risk of thermal defects of the transformer is increasing. The research conclusions can assist to improve the accuracy of the operation risk level assessment of new power system transformers, and provide a reference for the later transformer condition assessment and maintenance plan formulation.

Flue gas recirculation (FGR) is an important technical mean to improve the safety of circulating fluidized bed (CFB) boiler and reduce the generation of NO_x under low-load operation. In the present work, the relationships between temperature distribution of the boiler, NO_x, CO mass concentration and O₂ volume fraction of the flue gas at furnace outlet, the combustible matter content of fly ash and bottom slag and the flow rate of FGR under the load of 20%, 30% and 40% BMCR (boiler maximum continuous rating) were studied using one-dimensional chamber CFB combustion quasi-static model at a supercritical 350 MW CFB boiler. The results show that both the bed temperature and furnace exit flue gas temperature decrease with the increase of FGR flow rate, which the former decreases less than the latter. The temperature difference between the upper and lower furnace gradually decreases with the increase of FGR flow rate, which is more significantly affected by FGR flow rate at lower loads. The NO_x mass concentration of flue gas at the furnace exit shows a trend of decreasing first and then increasing with the increase of FGR flow rate, and the existence of the optimal FGR flow rate can make the unit operation economically and environmentally friendly. In addition, with the increase of the FGR flow rate, the CO mass concentration at the furnace outlet, combustible matter content of fly ash and bottom slag shows an increasing trend. The FGR significantly reduces the primary air oxygen volume fraction while ensuring that the fluidized air flow rate in the dense phase area is always higher than the protection value, which ensures the operation safety of the boiler under low load furtherly.

The coupling of thermal units with flywheel energy storage system can effectively improve the frequency regulation performance of AGC, solve the problems of long response time, slow climbing rate and low regulation accuracy of thermal units when tracking AGC commands, and obtain the auxiliary revenue of frequency regulation. This paper proposes a flywheel energy storage system control strategy for engineering practice, taking into account the requirements of the "two rules" of the Northwest Power Grid on AGC climbing performance, to improve the performance index of the combined system participating in AGC frequency regulation while preserving flywheel power. The results show that the proposed strategy improves the performance of the combined thermal power units and storage systems in AGC, and the economic efficiency of the power plant is significantly improved.

The flue gas recirculation device in the conventional circulating fluidized bed (CFB) oxy-fuel combustion system has been taken out and replaced with pure oxygen combustion, which is expected to reduce the overall energy consumption and CO₂ capture cost of the unit. Pure oxygen combustion will bring about problems such as uneven distribution of heat load and fluidization difficulty under minimal smoke gas flow, so a new boiler design should be carried out according to the flow pattern and heating surface layout in the furnace. This paper adopts the arrangement of immersed tube heating surface in the dense phase area to solve the local over-temperature problem. At the same time, a unique furnace structure design of "wide at the bottom and narrow at the top", reducing the size of the bed material, increasing the primary air ratio and other methods are used to deal with the difficulties of material fluidization. Based on the CFB flow and heat transfer theory, a heat transfer calculation method of pure oxygen combustion CFB boiler is established, and a conceptual design of 130 t/h ultra-high pressure pure oxygen combustion CFB boiler is completed. The basic structure and overall layout scheme of boiler furnace, immersed evaporating heating tube, immersed superheater, cyclone, loop seal and economizer are given. Preliminary analysis shows that the new pure oxygen combustion CFB boiler can solve the problems of uneven distribution of heat load caused by high oxygen concentration combustion and the difficulty of material fluidization under minimal smoke gas flow. The designed boiler thermal efficiency can reach 94.83%, and the volume fraction of CO₂ and H₂O in the outlet flue gas is 57.1% and 38.4%, respectively. This paper lays a foundation for the future development of pure oxygen combustion CFB boiler technology and engineering practice for CCUS-EOR.

In order to ensure that the supercritical CFB boiler has good wide-load operation characteristics and the ability of deep peak regulation, the transient heat transfer characteristics between the working fluid and the water wall under the change of transcritical pressure are experimentally studied. Experiment adopted Φ25.0 mm×3.5 mm vertical upward tube, the near-critical steady heat transfer experiment and the transcritical pressure step transient heat transfer experiment were carried out under the experimental conditions of 20~23 MPa of pressure and 400~800 kg/(m²·s) of mass flow rate. The results showed that under the near-critical pressure, increasing the flow rate, reducing the heat flux on the inner wall, and reducing the pressure can reduce the dryness when the DNB heat transfer deterioration occurs, and increase the corresponding fluid enthalpy value, and delay the occurrence of the heat transfer deterioration. When the transcritical pressure step changes, the heat transfer deterioration may occur in the heating pipe, resulting in the wall temperature rising rapidly, but the temperature will fall back to the normal value with the increase of the flow rate. The heat transfer between the wall temperature rising point and the inner wall surface goes through the heat transfer deterioration stage, the subcooled boiling heat transfer enhancement stage and the single liquid phase heat transfer stage. The influence of each parameter on the heat transfer deterioration in the transcritical pressure step change experiment is the same as that in the near-critical steady state experiment. The decrease of flow rate and the increase of heat flux on the inner wall will advance the location of the heat transfer deterioration, and the wall temperature rise will be greater.

Facing the frequency security problem caused by large-scale integrations of fluctuating new energy, the participation of thermal power units coupled with flywheel energy storage in frequency regulation can effectively improve the active power support capability of the power grid from the generation side, which is an effective guarantee for the frequency security of the power grid. According to the output control strategy and capacity configuration of flywheel energy storage systems, this paper proposed a combined method of flywheel control strategy and capacity configuration for primary frequency regulation to optimize the thermal power unit operations. Firstly, a coordinated frequency regulation control strategy of flywheel energy storage considering the real-time power output of thermal power units is designed. An economic evaluation model considering the primary frequency regulation benefit of power plants is proposed, and a refined particle swarm optimization algorithm is utilized to tackle the problem. Finally, the actual data of a 315 MW unit in a power plant from the northern part of China are simulated and verified. The result shows that the proposed integrated configuration strategy can effectively improve the frequency modulation effect of the power grid while taking the cost of energy storage investments into account. The research results are of great significance for promoting engineering applications of flywheel energy storage participating in frequency regulation services.

In order to provide methodological guidance for the load optimal distribution of thermal power units under the condition of deep peak regulation, the objective functions of optimal load distribution under medium-high load and low load are established respectively, and the load optimal distribution under different conditions is studied. The k-means clustering algorithm is used to process the data and the coal consumption characteristic curves of two units under medium-high load and low load are fitted. The objective function of load distribution is established to compare the coal consumption before and after optimization under static load distribution, incremental load distribution and continuous variable load conditions. After setting the total load instructions of the two units under the condition of deep peak shaving, the coal consumption of the two schemes of load average distribution and optimal distribution is compared. The results show that the clustering-based objective function models of optimal distribution under medium-high load and low load established by the coal consumption characteristic curve are reliable, whose optimization effect is remarkable under the condition of deep peak regulation. The k-means clustering algorithm can be used to optimize the load distribution of thermal power units and provide reference for the study of load optimal distribution under the condition of deep peak regulation of thermal power units.

In order to solve the problems of user account management and security protection in current group information system, this paper proposes a three-in-one AAA system of account, authentication and audit based on zero-trust architecture. Firstly, it describes the function of user management, authentication authorization, user audit and other modules of the AAA system. Secondly, in view of the conventional network boundary protection problem, the authentication authorization method based on zero trust architecture is applied to identify the business scenario, thus to ensure the reliability of the business system environment. Lastly, it illustrates the logic of the AAA subsystem and group-level system development platform configuration. The proposed AAA system can effectively improve the business security of group-level enterprise information system, compensate for the security issues of user login account under zero-trust environment, and further improve the security protection ability of network equipment, application equipment, system and application management in group-level enterprise.

This paper explains the overall impact of the dual carbon strategy on coal power and the development problems it faces. The status quo and key technologies of clean emissions, energy conservation and carbon reduction, heat supply and efficiency improvement, and flexible operation of coal-fired power units are sorted out and analyzed, and the development prospects of coal power are prospected, and the conclusion is drawn that the development of coal power is positively viewed based on China's resource endowment and energy strategic security, and attention should be paid to the research and development and application of clean, efficient and flexible coal power technology, and the advantages of various new energy sources are complemented and dynamically coordinated to promote the steady development of new power systems.

The dynamic model of resistive type molten salt heater was established by Dymola software, and the transient characteristics and internal temperature field of resistive type molten salt heater under electrical load and molten salt flow disturbance and different arrangement modes were studied on the basis of verifying the effectiveness of the model. The results show that the influence of large disturbance of electric load and molten salt flow on the dynamic characteristics of resistance type molten salt heater tends to be the same, and reaches its limit condition at 110 s and 105 s respectively. However, the occurrence of the limit condition can be greatly delayed when the two disturbances are coordinated. Multiple electric heaters arranged in series or in parallel can slow down the change of molten salt temperature, but increase the system cost. The research conclusion can provide reference for the design, control and debugging of resistance molten salt heater.