Taking coal-fired power units undergoing energy conservation and carbon reduction transformation as the research object， an index evaluation system for the transformation effect of coal-fired power units was constructed. Based on the analytic hierarchy process （AHP）-entropy weight method that combines subjective and objective weighting approaches， an evaluation model for the energy conservation and carbon reduction transformation effect of coal-fired power units was established， and the transformation effects of four coal-fired units were evaluated. Results demonstrate the validity and feasibility of the proposed model， providing a valuable reference for evaluation and management of energy conservation and carbon reduction transformation effects of coal-fired power units.

Addressing the limitations of dynamic sparse principal component analysis （DSPCA） in effectively analyzing nonlinear data and its low sensitivity and accuracy in fault detection for measurement points such as temperature and pressure， a fault diagnosis method suitable for thermal processes was proposed by combining dynamic kernel principal component analysis （DKPCA） with sparse principal component analysis （SPCA）， namely， dynamic sparse kernel principal component analysis （DSKPCA）. The proposed method accounts for the dynamic characteristics and high-noise nature of nonlinear data in thermal processes， reduces data redundancy， and is well suited for real-time fault detection in thermal systems. Simulation and field-data results demonstrate that it outperforms DSPCA in fault detection capability.

Taking the units burning Zhundong coal in high altitude area as the research object， this paper studied and simulated the fly ash deposition process on the heating surfaces in the furnace based on the fly ash collision model， fly ash adhesion model and deposition growth model. The results show that for the Zhundong coal burning units at high altitude， the deposition of fly ash particle is mainly in the reducing atmosphere zone between the upper burner and the over-fire air. The deposition rate of fly ash on the heating surface increases with the increase of flue gas temperature. With the increase of flue gas velocity， the deposition rate of fly ash on the heating surface increases first and then decreases. The deposition probability and rate of fly ash increase as the particle size of pulverized coal increases. For the boiler burning Zhundong coal at high altitude， it should be considered in the design stage to increase the reduction zone distance， increase the proportion of primary air volume， appropriately increase the primary air speed and the fineness of pulverized coal so as to strengthen the burning-out characteristics of Zhundong coal， strengthen the erosion and abrasion of fly ash， and weaken the slagging characteristics.

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.

To address the challenges of low natural dissolved oxygen （DO） content in demineralized water and minimal makeup water rate in indirect air-cooled units in high altitude areas， the application of conventional demineralized water feedwater oxygenation technology using standard demineralized water as the oxygen carrier was significantly constrained. A novel demineralized water feedwater oxygenation treatment technology based on "auxiliary oxygenation-multistage regulation" was proposed. By coupling the dynamic balance mechanism of dissolved oxygen in condenser makeup water and the collaborative control strategy of secondary oxygenation points， a refined and stable supply mode of dissolved oxygen in high altitude environments was established. Compared to existing technologies， the proposed approach innovatively introduces an auxiliary oxygenation module and achieves precise control of dissolved oxygen concentration （30±3 μg/L） through proportional-integral-derivative algorithm-based distributed control system， effectively resolving the issue of low oxygen mass transfer efficiency in supercritical unit feedwater oxygenation treatment process under high-altitude， low-pressure conditions. After implementation in a 350 MW supercritical unit in Qinghai province， the overall situation of dissolved oxygen control in the feedwater has been stable and reliable. The anti-corrosion effect of the thermal system has been significantly improved， the ammonia addition in the feedwater has been greatly reduced， and the water production in the fine treatment cycle has been significantly increased， achieving the expected results. This technology provides a groundbreaking solution for corrosion and scale inhibition in supercritical units operating in high altitude areas.

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.

With the rapid growth of new energy installed capacity， low-load and deep peak regulation operation has become the norm for thermal power generating units. The failure problem of metal components on high-temperature heating surfaces such as the "four tubes" of boilers is becoming increasingly prominent. Since a 660 MW unit participated in deep peak regulation， a large number of transverse cracks appeared at the position of the nozzle socket under the outlet header of the water wall at the rear wall of the boiler. By analyzing the causes of the problem， countermeasures were proposed from two aspects： on-site defect handling and long-term problem-solving. Eventually， measures such as monitoring the temperature difference between the water wall and the header wall， optimizing the header structure， increasing the length of the finless tube， and optimizing the low-load operation parameters were put forward. The research results can provide new ideas for solving similar problems.

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.

Through a comprehensive analysis of the causes and formation mechanisms of the cracks at the fusion line of the weld connecting the clamping tube and the pull plate of the platen reheater in the subcritical boiler of Unit 1 of a certain power plant， it was concluded that the alternating stress concentration in the fusion line area of the dissimilar steel weld was the main cause of the cracks at the connection of the clamping tube and the pull plate. An optimized treatment plan for preventing the generation of cracks was proposed. After the implementation of this scheme， the connection between the clamping tube and the pull plate no longer uses the welding connection method， but directly adopts the tube ring connection， effectively solving the leakage problem of the clamping tube caused by stress concentration at the weld fusion line.

An overspeed protection system for steam turbines based on mechanical control principles was introduced. This system identifies and transmits the overspeed signal of the steam turbine through the gear set， and then triggers the shutdown protection mechanism， significantly enhancing the reliability of the protection system. This system can completely eliminate the overspeed risk of rotating machinery such as steam turbines， fundamentally enhancing the level of safe production and providing innovative inspiration and valuable reference for the domestic equipment manufacturing industry.

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.

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 core objective of enhancing the construction quality of medium- and low-pressure piping in thermal power engineering， the concept of full life cycle management was applied. By introducing new-generation digital technologies such as cloud computing， big data， and building information modeling （BIM）， and adopting an advanced cloud-native technology architecture of DevOps + microservices + containerization， while integrating the design concept of the middle platform， a unified business application support platform was built. By integrating the management and data of each link in the design， production， construction， operation and maintenance of medium- and low-pressure piping， the platform can provide strong support for all relevant parties to share in real time and control the process and status of the design， production， construction and operation of medium- and low-pressure piping. This research effectively addresses the problems in thermal power engineering such as insufficient secondary design of medium- and low-pressure piping causing collisions with other structures， unreasonable design of supports and hangers leading to poor piping expansion， insufficient cleanliness of piping resulting in excessively long start-up flushing times for units， and unreasonable piping segmentation causing difficulties in on-site welding.

As new energy power generation technologies become increasingly mature and the cost per kilowatt-hour decreases， controlling the cost of photovoltaic projects has gradually become a focus in the field of engineering construction. Taking a 100 MW photovoltaic power generation project in Pingshun， Shanxi Province as an example， a study was conducted on the optimization of labor scheduling for the construction of photovoltaic areas. By constructing a mathematical model of labor scheduling with the goal of minimizing the total construction cost and combining it with the differential evolution algorithm for multi-constraint optimization solution， the optimal labor allocation scheme was proposed. The results show that the optimized scheduling scheme can reduce the installation and construction costs by 30%， relieve labor pressure， and shorten the project pay-back period. This research provides theoretical support and practical reference for the optimal allocation of resources in photovoltaic project construction.