To address the problem of poor drainage of high pressure heaters under deep peak regulation conditions， taking a 650 MW unit as the research object and combining the operating characteristics of high pressure heaters during deep peak regulation of the unit， an optimized drainage system for high pressure heaters based on a booster pump was proposed. This system adds a drainage bypass to the original normal drainage pipeline， uses a booster pump to overcome the water level pressure difference between the high pressure heater and the deaerator， and realizes the automatic switching of the drainage pipeline at low loads through the coordination of valve groups， meeting the requirements for normal operation of high pressure heaters drainage under deep peak regulation.

Under the dual carbon policy framework， the new power system introduces new flexibility requirements for coal-fired power units，including rapid start-stop operations and deep peak regulation. During deep peak regulation，the rapid load fluctuations of units lead to substantial variations in water-steam flow rates and steam parameters. This significantly complicates the maintenance of water-steam quality control and increases the risks of stress corrosion fatigue on thermal equipment，thereby threatening the safe and stable operation of the units. A systematic analysis was conducted on how the deep peak regulation process affects steam-water parameters and quality control，as well as corrosion and scaling in thermal equipment，and the underlying causes of these issues were examined. Six major problems were summarized，including inadequate feedwater control and increased steam carryover，corrosion and scaling of the furnace heating surfaces and hydrodynamic instability，abnormal fluctuations in steam temperature，intensified water erosion of the final stage blades of the steam turbine，excessive dissolved oxygen in condensate water and feedwater，and lagging regulation of the chemical dosing system. The proposed multi-dimensional risk prevention measures provide theoretical guidance and practical reference for the optimal control of water-steam systems in coal-fired power enterprises during deep peak regulation operations.

With the development of thermal power units towards higher parameters and larger capacities，the amount of data that needs to be monitored during the operation of turbo-generator set is increasing. The widely used expert diagnosis systems have severely impacted fault discrimination accuracy. To address this problem，a new steam turbine fault diagnosis method based on deep learning technology was proposed. Firstly，the original signals were reconstructed and output by using the autoencoder network. Secondly，the convolutional neural network（CNN）was employed to reduce the number of input parameters in the fully connected layers through convolution and pooling operations，while extracting data features and combining them into deeper，higher-dimensional data. Finally，the fully connected layers were used for output prediction and classification. Engineering application results demonstrate that this method can adaptively extract features of different fault locations and types in steam turbine systems under various operating conditions，accurately identifying equipment health status. Its discrimination accuracy is significantly higher than that of the currently widely used expert diagnosis systems.

Aiming at the problems of low initial discharge field strength and easy occurrence of corona in stator coil bars and windings under high-altitude conditions，the research on the anti-corona performance of stator coil bars and windings was conducted. Firstly，the impact of different altitudes on the initial discharge field strength at the end of stator coil bars was analyzed. Secondly，the key parameter ranges of anti-corona materials，the basic requirements for the optimization design of anti-corona structures，the field strength distribution at the corners of stator coil bar conductors，and the equipotential layer treatment technology in the slot section of conductors were introduced. Finally， anti-corona technologies for the end of stator windings were presented，and the influence of the ground clearance at the end of stator windings on end discharge was analyzed. The research results indicate that the anti-corona technologies for individual stator coil bars and stator windings have laid a solid foundation for enhancing the anti-corona performance of stator coil bars and windings in high-altitude impulse hydrogenerator units.

Establishing an accurate and efficient integrated energy system model on the source side of thermal power plants is crucial for optimizing the system management process and improving the safety and economy of operation，and is an important reference for the planning and transformation of thermal power plants. A digital twin operation and maintenance model of the integrated energy system on the source side of thermal power plants based on feedforward neural networks was proposed. This system took the thermal power unit as the core，coupled three types of renewable energy，namely biomass gasification，waste gasification and dried sludge，at the input end，and supplied four types of energy products，namely cold，heat，steam and electricity，at the output end. The feedforward neural network was trained using the computational data provided by the physical model，and its optimal hyperparameters were calculated. The corresponding neural network model was constructed，and finally a digital twin model was formed. Through comparison and verification with the physical model，it is found that this digital twin model has good calculation accuracy and high calculation efficiency，and can complete the prediction within milliseconds.

The CAP1000 unit is a representative of advanced pressurized water reactor nuclear power technology independently developed in China. The overspeed protection system of its steam turbine is the core to ensure the safe operation of the unit. To identify an optimal solution，the traditional "mechanical and electrical overspeed" scheme and the innovative "dual electrical overspeed" scheme were compared，and an analysis was conducted from the aspects of technical compliance，safety redundancy，operation and maintenance efficiency，and economy，supported by a case study. The results demonstrate that upgrading from mechanical overspeed protection to independent electrical overspeed protection conforms to the technical trends and relevant standards of the nuclear power industry. It enhances protection response speed，simplifies operation and maintenance，and delivers both safety and economic benefits. The research findings can serve as a reference for the design and retrofit of CAP1000 units.

Under special operating conditions， such as in the event of a condensate system accident or condensate throttling for primary frequency regulation of the unit， the deaerator water level may drop. Blindly and rapidly replenishing condensate when the deaerator water level is low can lead to a rapid decrease in deaerator pressure， resulting in insufficient net positive suction head （NPSH） available for the feedwater pump. By simplifying the transient mass-energy balance calculation model of the deaerator， the calculation formula for the conservative maximum condensate flow rate allowed to prevent insufficient NPSH of the feedwater pump was obtained. The calculation results using design parameters are consistent with the parameter variation laws of deaerator simulation modeling and transient calculation. Based on this， a deaerator water level control method was proposed to prevent insufficient NPSH for the feedwater pump by limiting the condensate flow rate. The method has been verified through experiments and can ensure that the NPSH of the feedwater pump is always sufficient.

To address the hydrodynamic instability and combustion disturbances of a 600 MW supercritical oncethrough boiler at Ligang power plant during deep peak regulation down to 20% rated load，a hydrodynamic calculation model for the water wall and a coupled simulation platform for the combustion system were established based on the actual boiler structure and operational parameters. Through the combination of numerical simulations and field tests， the mass velocity distribution characteristics，wall temperature deviation，and pulsation risks under low-load conditions were quantitatively analyzed. A dynamic control strategy based on the optimization of coal mill combinations was proposed. The results show that adopting the mid-upper coal mill combination（B+C+D）with a staged air distribution strategy can reduce the water wall mass velocity deviation to 18.7%. The research findings provide a theoretical basis for the deep peak regulation of supercritical units.

In order to consume green electricity and promote the construction of low carbon industrial parks， a system integration solution of "green electricity-energy storage-heating" based on molten salt energy storage technology was proposed. By constructing a molten salt energy storage system， the renewable energy consumption capacity can be effectively improved， while significantly reducing the carbon emissions of industrial parks. Based on the current situation of using thermal power plants to supply steam for an industrial park， a design was conducted using an electric heating molten salt energy storage system. The economy of using the molten salt energy storage system was evaluated by analyzing equipment selection and system operation. The results show that this scheme is expected to reduce the annual heating cost by 22% and the annual carbon emissions by approximately 3 241 t of the park. The molten salt energy storage system provides a replicable solution for building low carbon energy systems in industrial parks， and has important practical value for promoting energy structure adjustment in the industrial field.

In order to achieve the economic evaluation and decision-making guidance of peak regulation in the operation mode of cogeneration units coupled with electric boilers，a peak regulation decision-making model for the unit was established. Through big data tools such as data mining technology and back propagation （BP） neural network，a prediction model for energy consumption indicators of cogeneration units was constructed to achieve precise calculation of various cost and revenue indicators of the unit revenue model. Meanwhile，an economic evaluation method for peak regulation of thermal power units was proposed. It comprehensively considered the coupled operation modes such as peak regulation，steam extraction heating，and electric boilers. By calculating the revenue of the full-load operation in real time，it provided guidance for peak regulation decisions based on the optimal operating income. The results show that when the heat load is higher than the critical value，the operation mode of giving priority to starting the electric boiler of the unit is more economical. The critical heat load of the unit is determined by the ratio of the unit price of standard coal to the heat price. During the heating period，to maximize the revenue of the electric boiler，the unit should operate below the critical heat load. The critical peak regulation compensation correction coefficient of the unit is mainly affected by the heat load and the non-peak regulation allocation electricity price. Referring to this coefficient to guide the peak regulation decision-making of the cogeneration units can maximize the operating income of the unit.

In the long-term operation of the pulverized coal pipelines in the No. 4 ultra-supercritical unit of a power plant， frequent issues such as support and hanger failure， crossarm deformation， and pulverized coal leakage posed serious safety risks to the unit. The causes of abnormal pipeline expansion were studied through on-site cold and hot state inspection of supports and hangers， disassembly analysis of bellows compensators， and stress simulation calculation using CAESAR Ⅱ software. The results show that improper installation and vibration of the V-type compensator at the coal mill outlet cause the hanger unloading. The bellows compensator at the burner inlet fails due to pulverized coal blockage and hardening of aluminosilicate fibers， unable to compensate for the thermal expansion of the boiler， causing the rigid hanger of the crossarm to be overloaded and deformed. By repairing the blockage in the inner cavity of the compensator， optimizing the pre-tension amount and adjusting the force on the hanger， the abnormal problems of the pulverized coal pipeline， as well as the overloading and complete unloading of the hanger， are successfully solved， providing an important reference for the design， installation and maintenance of the pulverized coal pipeline and its supports and hangers in coal-fired boilers.

In order to enhance the competitive advantage of industrial steam turbines in the thermoelectric field， increasing the pressure in the turbine impeller chamber can effectively improve the internal efficiency of the entire machine. However，the increase of impeller chamber pressure poses higher requirements for the strength and low cycle fatigue life of the high pressure inner cylinder. Therefore，the finite element method and the theory of low cycle fatigue life were adopted to analyze the strength and low cycle fatigue life of the high pressure inner cylinder. The research results show that stress concentrations are prone to appearance at the connection points of the inner cylinder structure and the areas with sudden shape changes，leading to fatigue damage. The research results can provide a theoretical basis for the design and optimization of the inner cylinder of industrial steam turbines.

In order to ensure the safe operation of the generating set， a detailed analysis was conducted on the typical corrosion problems of two waste heat boilers in a gas-fired power plant. Specific types of corrosion included low-temperature corrosion， erosion corrosion， corrosion under insulation layer， uniform dissolved oxygen corrosion， atmospheric oxygen corrosion and stress corrosion. The results show that the main causes of corrosion include low-pressure recirculation system not being put into operation， the outer protection of the insulation layer not being tight， internal leakage of the valve， impurities in the pipeline， small curvature radius of the elbow， moisture in the equipment after the furnace is shut down， rainwater seeping into the insulation layer， and the pipe material being sensitive to stress corrosion. Therefore， effective corrosion prevention and control measures are proposed to ensure the safe operation of the equipment throughout its service life.

In order to optimize the control effect of the boiler fans in cogeneration power plants and improve the combustion efficiency and energy efficiency level，a frequency prediction model suitable for boiler fans was developed. Two prediction models were constructed using the fan performance method and the boiler operating condition method， and the two models were verified based on the actual data. The results show that the boiler operating condition method has higher accuracy in fan frequency prediction compared with the fan performance method. The frequency prediction relative errors of the primary fan and the secondary fan have decreased to 0.03% and 0.39%，respectively. Therefore， the prediction model established by the boiler operating condition method can provide more reliable fan frequency prediction results for the operators of cogeneration power plants，which is conducive to achieving the optimal control of boiler fans operation，reducing fan energy consumption，and improving the overall production efficiency of cogeneration power plants.

Experimental study was carried out to investigate the effect of H₂O on the mercury removal performance of modified rice straw coke under conventional combustion conditions. Experiments were conducted to get rice straw coke particles prepared from rice straw in Jiangsu region and modified by chemical impregnation of NH₄Cl combined with HNO₃. A fixed-bed experimental platform was utilized to simulate the flue gas environment of coalfired power plants，through which the mercury removal effect of the modified rice straw coke was tested. The results show that the addition of H₂O inhibits the mercury removal effect of modified rice straw coke under conventional combustion atmosphere（composed of N₂ and 6% O₂）. Further analysis reveals that the increase of H₂O concentration leads to a gradual decrease of mercury adsorption，and the mercury adsorption forms on the surface of coke samples are mainly Hg⁰ and HgO under the H₂O-containing atmosphere，without changing the main adsorption forms. However，H₂O dissociates the oxidizable OH，weakens the Hg⁰ competitive adsorption，and provides additional electrons for the reduction of Hg²⁺. Excessive H₂O concentration will exacerbate the segregation of Hg⁰ and CO₂， leading to the decomposition of unstable oxidation products such as HgCl₂，thus inhibiting the overall Hg removal effect of the adsorbent.

Theoretical modeling and simulation analyses of primary frequency control for the digital electric hydraulic control system （DEH） of 1 000 MWclass thermal power generating units were carried out. Firstly， an electro-hydraulic servo system model considering nonlinear factors was established. Secondly， a variable-parameter steam turbine model was proposed， in which the error does not change with the variation of the operating point of the unit load. A DEH optimization model considering nonlinear factors and the influence of load changes was established. This model is more consistent with the actual operating characteristics of deep peak regulation units and can maintain good accuracy and consistency within a wide range of deep peak regulation load intervals. A Simulink simulation model was established for a 1 000 MW class unit to analyze its primary frequency control performance under deep peak regulation conditions， and the results were compared with the unit’s actual test data， validating the accuracy of the established primary frequency control model.

A 2×600 MW unit in a power plant employs a dual-tower series desulfurization technology. During operation， the oxidation air ducts inside the tower frequently broke， resulting in a deterioration of the slurry quality in the absorption tower and difficulties in gypsum dewatering. Field inspection and analysis revealed that insufficient mechanical strength and improper support arrangement were the primary causes of duct failure. Based on an in-depth analysis of the corrosive environment inside the tower， the differences in performance and price among three commonly used stainless steels for desulfurization were analyzed. It is recommended to replace the material of the oxidation air duct with 2205 duplex stainless steel， which has high strength and excellent corrosion resistance， to meet the performance requirements and achieve a higher cost-effectiveness. Increasing the wall thickness of the air duct and optimizing its fixation method can effectively reduce stress concentration and prevent the deformation of the air duct. The transformation has achieved remarkable results， providing valuable reference experience for similar upgrades.

In order to solve the problem of reheat steam temperature deviation during the comprehensive upgrading and transformation for a unit，the inter-tube panel flow distribution curve of the high-temperature reheater before the transformation was obtained through mathematical modeling. Combined with the measured values of the operating wall temperature，the heat exchange deviation on the flue gas side was calculated. Under the new transformation boundary，based on the known deviation of the flue gas side，the structural form of the header was renovated and optimized，and the optimization plan was determined. Results show that a high heat-transfer zone exists slightly right of the furnace center because of the residual swirl at the furnace exit and the size of the imaginary circle. By reducing the temperature rise amplitude of the high-temperature reheaters and adjusting the positions of the radial inlet and outlet tees，the temperature deviation level of the reheat steam can be significantly reduced，achieving the transformation goal.

Yaw deviation of wind turbines is commonly observed in operational wind farms， and the lack of appropriate measurement methods hinders accurate deviation assessment， preventing turbines from achieving optimal performance. To address the issue of static yaw deviation in wind turbine generator system， a quantitative analysis method based on operating condition segmentation and bidirectional binning was proposed. Utilizing big data technology and feature models， the method conducted both qualitative and quantitative analyses of historical operational data to achieve precise identification and quantification of static yaw deviation. Based on the operation data of a wind farm， support vector regression （SVR） was used for data preprocessing， and the yaw deviation was quantitatively evaluated by combining the operating condition segmentation and bidirectional binning method of wind speed and power. Results show that this method can effectively identify the yaw static deviation of wind turbine generator system， providing quantitative input for the yaw correction control and power curve optimization of wind farms， thereby providing effective support for improving the operation and maintenance efficiency of wind farms.

The full life cycle aging management of nuclear power plants is a key task for the "Hualong One" nuclear power units. In order to effectively manage the aging issues of the "Hualong One" nuclear power units， it is necessary to retain material aging samples for concrete and cables. By analyzing the failure mechanisms of concrete and cable materials and combining with the actual operating conditions of the nuclear power plant， the concrete in the reactor pressure vessel pit area and the top of the outer dome of the containment vessel， and the cables in the steam generator， pressure stabilizer， and main steam pipeline room were finally selected for sample retention， forming a list of aging samples for concrete and cables. The implementation nodes for the regular inspection of subsequent aging management were planned， and finally the problems encountered during the implementation of the retained samples were summarized.

With the rapid development of steam turbine technology and the continuous emergence of various new types of steam turbine generator sets， the traditional frame-type foundation has been continuously optimized into a complex foundation with irregular structure. It is difficult to establish a concise and reasonable mechanical model and carry out a correct dynamic analysis for this kind of irregular space structure with multiple mass points and degrees of freedom. Taking the 9F-class gas generator set as an example， based on the vibration response characteristics of components such as the foundation base plate， column pier， and frame under the action of horizontal radial， axial， and vertical disturbing forces， four basic vibration modes with single mass points and single degrees of freedom were established by applying the principle of structural dynamics. Simple dynamic analysis and vibration verification were carried out， and the theoretical calculation values were verified with the on-site measured data. The research results prove that the dynamic analysis and vibration calculation method for the complex foundation of this large-scale power machine is reasonable and feasible， and has certain reference value.

To address the limitations of existing methods in handling non-stationary data and extracting salient features for monitoring ash blockage in rotary air preheaters of power station boilers， a hybrid differential pressure prediction model that integrates variational mode decomposition （VMD）， convolutional neural network （CNN）， bidirectional long short-term memory （BiLSTM）， and frequency-enhanced channel attention mechanism （FECAM） was proposed. To further improve the decomposition quality of VMD， the goose optimization algorithm （GOOSE） was employed to adaptively optimize the number of modes and the penalty factor， thereby enhancing the model’s ability to suppress noise interference. Experimental validation using real-world operational data from a coal-fired power plant demonstrates that the proposed model reduces root mean square error （RMSE）， mean absolute error （MAE）， and mean absolute percentage error （MAPE） by 42.93%， 43.58%， and 44.72%， respectively， in single-step forecasting compared to the baseline BiLSTM model. Additionally， the model exhibits superior robustness and predictive stability in multi-step forecasting tasks， outperforming other time series prediction models.

Under deep peak regulation operations， the primary air temperature of a subcritical 300 MW lignite-fired boiler in the eastern part of Inner Mongolia was relatively low， resulting in insufficient drying capacity of the pulverizing system and adversely affecting the combustion process inside the furnace. Therefore， a retrofit plan was proposed to install a steam heater in the primary air duct of the air preheater to increase the hot primary air temperature. The results show that the scheme can increase the primary air temperature by at least 35 ℃， and the effect of temperature improvement is remarkable under deep peak regulation operations. The technology can also optimize the distribution of air volume in the furnace and improve the boiler thermal efficiency.

In photovoltaic power stations，high-power string inverters often employ forced air cooling as a heat dissipation method to control the operating temperature of the equipment. During actual operation，the air inlets of these inverters are prone to being blocked by dust， willow catkins and other impurities in the surrounding environment，which can lead to thermal failure. To address this issue，a numerical simulation method was adopted for analysis and research. A numerical model with engineering accuracy was constructed，and based on the simulation results，a self-cleaning solution that takes into account the heat dissipation performance was designed. The results show that this solution not only ensures the heat dissipation performance of the inverter under normal operation but also has strong self-cleaning ability for the air inlets. Field test results have verified the feasibility and actual operation effect of the solution，providing an efficient solution for the problem of air inlet blockage in in-service inverters in photovoltaic power stations and having significant application reference value.

To address the growing flexibility demands of future new power systems dominated by renewable energy， coupling a molten salt thermal energy storage system with conventional thermal power units is an effective solution. Based on a 660 MW ultra-supercritical once-reheat condensing unit， three system configurations integrating molten salt and ultra-high-temperature heat pumps were designed. A thermodynamic simulation model of the unit was established using Ebsilon software， and the efficiency of the coupled system was analyzed. The results show that the technical scheme of extracting high-pressure steam as the heat source for thermal energy storage， with the condensed water returned to the feedwater system， exhibits a significantly higher exergy efficiency compared to the electric heating scheme. The pressure of the heating steam is a critical parameter affecting the temperature difference during heat exchanging for thermal energy storage， and using high-pressure heating steam can improve the exergy efficiency. The adoption of ultra-high-temperature heat pumps can enhance the thermal energy quality of the latent heat section of heating steam， which is an effective solution to improve the exergy efficiency of the thermal energy storage process. Using high-temperature molten salt to generate high-pressure and high-temperature steam is an effective way to reduce the heat exchange temperature difference and improve the exergy efficiency during the thermal energy release process.

To address the hydrodynamic safety issue of a 1 000 MW ultra‐supercritical boiler during deep peak regulation to 30% boiler maximum continuous rating （BMCR） load， a hydrodynamic calculation model of the water‐cooled wall system was established based on the actual structural parameters of the boiler. The mass flow rate distribution， temperature deviation and safety of the water-cooled wall under different coal mill combinations were analyzed. Through numerical simulation and theoretical calculation， the operation characteristic data of four typical coal mill combinations were obtained， and an optimized operation strategy was proposed. The results show that when the upper layer coal mill combination （D+E+F） is used in conjunction with a uniform burner arrangement， the mass flow rate deviation of the water-cooled wall can be controlled within 22.8%， and the wall temperature safety is significantly better than other combination schemes， with a pulsation margin reaching the safety threshold of 1.32. The on-site test has verified that the proposed optimized operation strategy can effectively alleviate the local water-cooled wall heat transfer deterioration.

The virtual synchronous generator （VSG） model is designed to emulate the key characteristics of conventional synchronous generators， enabling inverters to replicate their mechanical inertia and electromagnetic response. This capability supports the stability of grid frequency and voltage， while enhancing the overall damping and inertia of the system. In the event of a grid fault， the standard VSG control strategy may fail to maintain the stability of the synchronous generator and exhibit a slower response than an actual synchronous generator. To address the dynamic response lag caused by the fixed rotational inertia of traditional VSG during grid faults， an adaptive control strategy for rotational inertia based on the feedback of change rate of frequency was proposed. Results show that by monitoring the system's frequency deviation and its rate of change in real time， the virtual inertia value is dynamically adjusted so that the inertia gain of the VSG at the moment of the fault matches the system's acceleration/deceleration requirements. This effectively suppresses frequency fluctuations and shortens the transient response time. Furthermore， by incorporating an improved pre-synchronization control module， the smoothness of the transition between off-grid and grid-connected after a fault is further optimized， achieving a dual coordination of power support and mode switching during faults. Simulation examples demonstrate that the proposed control strategy enables the system to respond rapidly and maintain stability under various fault conditions.

With the large-scale integration of renewable energy sources and the growing demand for grid flexibility， lithium batteries have become increasingly prominent in energy storage applications due to their high energy density， long cycle life， and rapid response capabilities. However， safety concerns remain one of the most critical challenges limiting their broader deployment. Electrochemical impedance spectroscopy （EIS）， as a non-destructive diagnostic technique， offers unique advantages in the investigation of battery safety. By tracking impedance variations during charge-discharge cycles， EIS enables the early detection of latent internal faults， thereby contributing to the reliable and secure operation of energy storage systems. This review provided a comprehensive overview of recent developments in the application of EIS for battery design， equivalent circuit model construction， and characteristic parameter identification. Furthermore， the current state of research on the utilization of EIS in the multi-physics coupling analysis under complex operating conditions was examined. Finally， the review discussed the potential of EIS for battery state monitoring and fault diagnosis， and presented future perspectives on the integration of multidimensional physical monitoring information through EIS-based approaches.

A calculation model of a subcritical reheat back-pressure steam turbine was established using the fixed-flow calculation method for steam turbine thermal systems. The equivalent enthalpy drop method was adopted to predict the variation curves of exhaust steam temperatures in the high-pressure and intermediate-pressure cylinders under variable load rate conditions， and the variation laws of heating and power generation performance were studied. The results show that with the decrease in load rate， the exhaust steam temperature of the high-pressure cylinder decreases， while the exhaust steam temperature of the medium-pressure cylinder shows an upward trend. As the unit load rate decreases from 110% to 50%， the thermoelectric ratio of the thermal system increases from 521.71% to 783.11%， the standard coal consumption rate for power generation increases from 152.9 g/（kW·h） to 165.4 g/（kW·h）， with an increment of 8.18%， and the average exergy efficiency of the thermal system is about 7 percentage points lower than the average thermal efficiency of the whole plant.

Against the backdrop of the "dual carbon" strategy and the construction of a new power system， coal-fired power units are confronted with multiple challenges such as frequent deep peak regulation， clean and efficient operation， and fluctuating coal quality， which seriously threaten the flexibility， safety， and economy of unit operation. Boiler combustion optimization and adjustment have become the key means to address these issues. The four core issues in the current combustion optimization and adjustment of coal-fired boilers are the control of the flame center height， the suppression of NO_x emissions， the optimization of exhaust gas temperature， and the regulation of thermal load deviation. By analyzing domestic test cases and theoretical research， and combining engineering practice experience， the influence mechanisms of key parameters such as air distribution mode， primary air pressure， coal fineness， overfire air damper opening， and burner adjustment methods on the combustion process were summarized， providing reference solutions for combustion optimization and adjustment of coal-fired power units and their safe and stable operation. Case studies show that for opposed firing boilers， the positive pyramid air distribution offers the best economy and safety， and despite slightly higher NO_x emissions， it is comprehensively recommended. For tangentially fired units， the three-step adjustment of primary air balancing， overfire air de-swirling， and reducing overfire air flow can effectively eliminate thermal load deviation and overtemperature risk.

In response to the repeated leakage rate exceeding the allowable limit of a 1 000 MW ultra-supercritical hydrogen-cooled generator， the root cause was revealed through multi-stage progressive diagnosis and treatment measures were implemented. Before the first start-up of the unit， the leakage rate in the generator wind pressure test reaches 45.71 m³/（24 h）. After helium leak detection and location， it is found that the flange seal of the external circulation fan has failed. After treatment， the leakage rate decreases to 6.68 m³/（24 h）， meeting the manufacturer's requirement of less than 10 m³/（24 h）. During the second start-up operation of the unit， the hydrogen leakage rate abnormally soars to 105.7 m³/（24 h）. Experimental results show a significant negative correlation between the leakage rate and hydrogen temperature. Through structural analysis and disassembly inspection， it is confirmed that insufficient pre-tightening force of the seal ring pedestal bolts is caused by out-of-tolerance insulation sleeves. Thermal cycling stress relaxation results in a large gap at the joint surface of the seal ring pedestal end cover， aggravating hydrogen leakage under low-temperature conditions. Finally， by adjusting the sleeve dimensions and optimizing the installation process， the leakage rate stabilizes at 6.15 m³/（24 h）.

To address the abnormal temperature rise of the third-stage extraction steam in a 660 MW ultra-supercritical turbine， operational data from a representative faulty unit were compared and the internal structure was inspected， confirming that high-temperature steam leaking into the third-stage extraction steam system was the primary cause. Temporary operation strategies were implemented through methods such as component verification， cooling steam regulation， and operation parameter control. Combined with the results of the shutdown maintenance， it was discovered that the sealing structure of the middle-pressure inlet steam pipe had severe deformation and seal failure， resulting in reheat steam leaking into the extraction steam system. Further measures such as inserting a new pipe， reconfiguring the sealing ring and grinding the cylinder body were taken to effectively eliminate the steam leakage channels. Results indicate that， after fault handling， the third-stage extraction steam temperature falls from 527 ℃ to 471.6 ℃ and the pressure stays at 1.9 MPa， restoring design values. The research results provide an engineering reference for fault diagnosis and maintenance of similar ultra-supercritical units.

Tides can carry the warm seawater near the unit's circulating water outlet back to the inlet， consequently leading to an increase in nuclear power. To prevent the nuclear power from exceeding the operational thresholds， operators need a method to calculate the operating electric power of a nuclear power unit during flood tide. To solve the problem， a method for obtaining the electric power limit using historical data was proposed， and on this basis， an empirical formula for the electric power limit of nuclear power units was established. Analysis of historical data over the past two years reveals that when the seawater temperature is lower， its fluctuations have a smaller impact on nuclear power. Considering the seawater temperature fluctuation range during July to September， the maximum seawater temperature fluctuation was set at 6 ℃. Based on this data， the correction value （3~45 MW） for the electrical power limit during tidal periods was calculated， with the specific value dependent on seawater temperature. The empirical formula developed for the operational electric power limit of nuclear power units during flood tide can assist in the operation and control of the units under tidal conditions.

With the deepened market-oriented reform of the on-grid price for new energy and the introduction of time-of-use tariff and other policies， higher requirements have been set for the power generation capacity of new energy power stations at different grid load periods. The design of different structural photovoltaic brackets is of great significance for tapping the potential of time-of-use on-grid price benefits and optimizing the power demand at the output and load ends. To deeply reveal the output characteristics and overall power generation capacity of different types of brackets at different time periods， a comparative analysis was conducted on the overall and time-of-use power generation， power distribution in different quarters， and cost calculation based on the annual operation data of a photovoltaic station in a high-latitude area. This objectively verified the actual operation and economic performance of different types of brackets under the typical climate scenario. The results show that there are significant differences in the output power curves， time-of-use cumulative power generation， and amortized costs of different types of brackets. By combining the distribution patterns of local power grid load and typical climate characteristics， and through reasonable selection of bracket equipment， the output curve can be further optimized， the power generation capacity during peak periods can be enhanced， and the electricity revenue can be increased， which can effectively adapt to the trend of market-oriented reforms in new energy on-grid price.

To address issues such as long service life， component aging， and difficulties in procuring imported spare parts for the power supply system of the control rod drive mechanism （rod power supply system）of the second-generation plus nuclear power plants in China， a control and protection system renovation plan with microcomputer protection devices as the core was proposed. The microcomputer protection devices have replaced the numerous original discrete protection devices. By integrating the built-in programmable logic controller （PLC） function of the microcomputer protection devices， adding a parallel current monitoring and protection mechanism for the rotor circuit， simplifying the hardware configuration， and optimizing the generator loss-of-excitation protection， the observability and protection level of the rod power supply system have been significantly improved， achieving an increase in system reliability and a reduction in operation and maintenance costs. Simulation and actual transformation verification show that the fault response time of the new system is shortened to within 48 hours， the types of spare parts are reduced by 45%， and the average annual maintenance cost is decreased by 52%.

To improve the operational economy and flexibility of a dual-turbine regenerative system， a balancing small generator and a converter were installed in a million-kilowatt-scale double reheat unit with a backpressure extraction steam turbine （BEST） at a plant. The control process of this unit under various operating conditions of the converter was analyzed， and the override reduction function of the total steam flow command for the small turbine during load rejection and the action logic of the quick closing of the regulating valve within 0.6 s were verified. Additionally， a control strategy was developed for the converter's transition to "constant power" mode， whereby the generator power was automatically ramped down to below 2 MW at a rate of 5 MW/min， based on its actual output and the small turbine's total steam flow command. The analysis and optimization of the relevant control logic can provide a reference for improving the operational reliability and control strategies of similar units.

To address the issues of localized vibration and abnormal noise in a steam pipeline， the vibration characteristics were investigated and the principal factors inducing vibration and noise were identified through finite element numerical simulation， vibration testing， and noise testing. The maximum response position of the pipeline under excitation was determined using finite element spectral analysis. The peak vibration velocity before and after the adjustment of the spring hangers was measured by a vibration tester， and the noise value before and after the valve replacement was measured by a noise tester. The results indicate that the maximum tensile stress under excitation occurs at the pipeline elbow. Valve defects and under-loading of the spring hangers are identified as the main causes of abnormal noise and pipeline vibration. These issues are successfully eliminated through remediation measures， ensuring the system's safe operation. This research can serve as a reference for future pipeline vibration and noise treatment.

Taking a million-kilowatt ultra-supercritical unit with double reheat as an example， several factors affecting the economic performance of the unit were summarized， and the technical optimizations that have been made for low load operation of the unit were introduced. The influence of the opening point selection of the supplementary steam valve on the economic performance of the unit was emphasized. Different opening points of the supplementary steam valves were selected， including the turbine maximum continuous rating（TMCR） condition， the turbine heat acceptance（THA） condition， the 95% THA condition， the 90% THA condition， and the 85% THA condition. The changes in parameters and thermal efficiency of the units with different load rates under each supplementary steam valve opening point design were compared. The comparison results show that when the opening point of the supplementary steam valve is lowered， the economic performance of the steam turbine under high-load operation decreases， while the economic performance improves under low-load operation. This design approach is applicable to deep peak regulation units and can effectively enhance the peak regulation operational economic performance of coal-fired power units.

In order to address the serious threat to the safe operation of large ultra-supercritical thermal power units caused by the tripping of important auxiliary machines under low load， which can lead to significant load fluctuations or even the shutdown of the unit， an automatic control method for the tripping of important auxiliary machines under low-load conditions （hereinafter referred to as LAT） was proposed. Combined with a 660 MW ultra-supercritical unit in Xinjiang， the LAT control strategy， functional design， triggering conditions and control loop were discussed. It focused on the dynamic tests of the LAT of coal mills， the LAT of forced draft fans and induced draft fans， and the LAT of primary air fans. The relevant functional designs were optimized. Results show that all functions during the test process are executed according to the design， the main parameters of the unit change stably， and the test is qualified， meeting the operation requirements.

In order to avoid unplanned shutdown of the generator set due to false operation of loss of excitation protection during deep leading phase operation， based on the GE EX2100e excitation system and G60 protection device， combined with the leading phase test data of the generator set， the cooperative verification research of under excitation limit （UEL） and generator loss of excitation protection was carried out. By mapping the asynchronous impedance circle from the impedance plane to the P-Q plane and comparing the leading phase test points under different loads， the rationality of the current excitation limit setting was verified， and parameter optimization suggestions were given. The results provide a reference for the safety of leading phase operation of the same type units.