To solve the problem of low recognition accuracy of transformer insulation oil gas fault diagnosis, the slime mold algorithm (SMA) is improved by the reverse learning strategy to form the improved slime mold algorithm (ISMA), thus to improve the global optimization ability and optimize the support vector machine (SVM). An ISMA-SVM optimized fault diagnosis model is established, and the sample set is used for learning and training. The diagnosis and recoginition results are compared with that of the greywolf algorithm (GWO-SVM) and the particle swarm optimization (PSO-SVM), it shows that the accuracy of the ISMA-SVM fault diagnosis and recognition is 93.3%, which is 6.66 and 10.66 percentage points higher than that of the GWO-SVM and PSO-SVM, respectively.

Large-scale grid connection of new energy power generation makes cogeneration units need flexible operation to smooth out the fluctuation brought by new energy access. In order to meet the control requirements of flexible operation of the unit and the safety of the unit operation, a flexible control strategy for cogeneration units based on flexibility evaluation is designed. Firstly, according to the response characteristics of electrical load, thermal load and throttle pressure of the unit, a calculation method of flexibility evaluation indexes which can represent the load adaptability and operation safety of the unit are proposed, and these indexes are used as the basis for selecting the optimal flexibility factors. Then, the influence of flexibility factor on the system performance under a single working condition is simulated. Finally, on the basis of determining the optimal flexibility factors under different working conditions, the adaptive flexibility factors that changing with working conditions are designed and applied to the flexible control. The simulation results show that, the control strategy can not only achieve a better control effect when the unit runs under large-scale conditions change, but also achieve a better control for the unit after the low-pressure cylinder is cut off, which can meet the control requirements of flexible operation of the unit and ensure the safety of the unit operation..

As a nondestructive testing method, magnetic particle testing is widely used in power industry. The comprehensive sensitivity of the magnetic particle detection can be tested by A1 standard shims. However, at present, the evaluation of the clarity of magnetic trace on standard shims still depends on subjective judgment of the tester. In order to eliminate the subjective factors in the evaluation, this paper proposes a standard magnetic trace evaluation method based on machine vision. Based on Python programming language and OpenCV function library, the initial obtained magnetic trace is processed by image correction, magnetic trace extraction, quantitative analysis and evaluation using computer program. On this basis, the influence of the thickness of non-magnetic layer on the comprehensive sensitivity of magnetic particle detection is investigated using this method. It is shown that the magnetic trace evaluation method based on machine vision is more objective and accurate than the conventional manual evaluation.

In order to realize zero liquid discharge, a power plant treated circulating wastewater by the combination process of two stage softening and clarification, media filtration, ultrafiltration, nanofiltration (NF) and reverse osmosis (RO), and treated terminal wastewater by the combination process of chemical softening, tubular microfiltration (MF), NF, seawater desalination reverse osmosis, electrodialysis (ED) and evaporative crystallization. After the above measures were taken for 1 year, insufficient NF output was found in the circulating wastewater treatment system, and serious MF membrane organic fouling and ED silicon scaling was observed in the terminal wastewater treatment system. Thus, the causes of the membrane fouling was analyzed and the desulfurization process water was optimized to reduce the chemical oxygen demand (COD) of desulfurization wastewater from the source. Moreover, the MF operation mode was optimized, so as to slow down the MF organic pollution phenomenon. In addition, the RO concentrated water of circulating water treatment mode was adjusted, and the total silicon mass concentration was reduced to less than 1 mg/L before being fed into the ED equipment, to solve the problem of the ED silicon scaling.

By taking a supercritical 600 MW opposed firing boiler as the research object, the temperature deviation law of main steam on both sides is analyzed and verified through hydrodynamic modeling, and a technical scheme is put forward to optimize the temperature deviation of main steam from the perspective of water side. After adopting this steam temperature optimization scheme, the main steam temperature deviations on both sides of the boiler reduced by 44.6%, 95.8% and 28.0% respectively under 50%, 75% and 100% BRL conditions. This scheme can realize safe and economical operation of the unit, and has good guidance and reference value for the same type of boiler.

In order to build a new power system with new energy as the main body, thermal power unit should undertake the new task of flexible operation and deep peak-regulating while maintaining power and heating supply. However, the conventional detection and communication technology is limited by the problems of poor real-time performance, slow transmission and high investment, which is difficult to support the new demand of thermal power units. Advanced detection technology and communication technology represented by 5G provide solid technical support for the state research, judgment and operation adjustment of thermal power units represented by boiler system by building a complete perceptual transmission chain, but they also face problems such as high construction investment, lack of professionals and standards. Only by setting out from the actual production, perfecting the mechanism and changing the concept, can the application effect of advanced detection and communication technology be realized. As an important part of smart power plant, the advanced detection and 5G technology will provide a solid foundation for improving the overall intelligent level of thermal power generation.

An efficient integrated power generation system of solid waste coupled with anaerobic fermentation and incineration is proposed. Solid waste anaerobic fermentation is adopted to generate biogas, which enters the biogas burner to burn and generates high-temperature flue gas, and the flue gas heats the steam-water system and the primary and secondary air through the heater and air preheater in the unit. Under the condition that the heat generated by solid waste incineration in the boiler is not changed, the energy entering the steam turbine to do work is increased, thus the power generation efficiency of the whole unit increases. At the same time, according to the first law of thermodynamics and the second law of thermodynamics, the reasons for power generation efficiency and exergy efficiency improvement are analyzed. The results show that, compared with the case unit, the proposed high-temperature flue gas system with biogas combustion can increase the net power generation by 8.69 MW. In addition, the power generation efficiency and power generation exergy efficiency of the new system has increased by 3.56 percentage points and 9.74 percentage points, respectively. Economic analysis shows that the proposed coupling system is equipped with an anaerobic fermentation biogas combustion system, and the dynamic recovery period is 3.78 years, which has obvious economic advantages.

With the proposal of "carbon peaking and carbon neutral", the total installed capacity of renewable energy power units continues to increase. This may greatly challenge the safety and stability of power grid. The characteristics of flywheel energy storage system (FESS) are fast response, unlimited times of charge and discharge and deep depth of discharge. FESS has been widely used in frequency modulation and frequency safety improvement of power grid. In order to make full use of the advantage of flywheel energy storage in auxiliary frequency modulation of the power grid, an adaptive coordinated droop control strategy of primary frequency regulation coordinated with thermal power units was designed, which realized the power cooperative adaptive adjustment of the combined coal-fired thermal power units and storage systems. Simulation results show that, the proposed control strategy can effectively improve the frequency modulation performance of the combined fire-storage system. Compared with the conventional droop control, the maximum dynamic frequency difference and steady frequency difference of the system reduces by 29.00% and 25.50% respectively, which eases the frequency modulation pressure of thermal power unit, and is benefit to safety and stability of the thermal power unit.

In order to select high activity catalysts for urea hydrolysis, the kinetic and thermodynamic characteristics of urea catalytic hydrolysis reaction were studied by using batch reactor and continuous operation pilot plant, and the effects of different catalysts on hydrolysis reaction temperature, energy consumption and variable load response time were compared. The results show that, the activation energy of the hydrolysis reaction can be reduced by adding catalyst (the activation energy of the liquid diammonium hydrogen phosphate is 65.3 kJ/mol, and that of the solid alumina is 52.9 kJ/mol), and the urea conversion can be improved. The addition of catalyst increases the hydrolysis reaction rate and decreases the hydrolysis reaction temperature. Due to uneven distribution and insufficient contact, the catalytic activity of solid alumina catalyst decreases in the continuous operation reactor. The energy consumption of ammonia production by catalytic hydrolysis is about 1%~3% lower than that of ordinary hydrolysis, and the response time of hydrolyzer changing load is not shortened by adding diammonium phosphate and alumina catalyst.

Blade fractures and cracks occurred on low pressure second last stage moving blade of a steam turbine before and after the blade optimization. In order to find out the cause of this type blade failures and prevent subsequent reoccurrence, the blade failure, operating parameters and historical records were checked, and the materials and fractures of some failed blades were analyzed through physical and chemical inspection. Moreover, the centrifugal stress of the blade and the vibration characteristics of the gear train before and after optimization were numerically analyzed by finite element method. The results show that, the blade fracture is a high peripheral fatigue fracture. Before optimization, the main reason for cracks and fractures at the connection transition between the top of the inner cambered surface and the shroud on the steam outlet side of the blade is that the blade has a large torsional recovery under working conditions, resulting in severe compression of the shroud, and stress concentration and fatigue damage occur at the connection transition between the top of the inner cambered surface and the shroud on the steam outlet side. The unreasonable design of blade root structure is the main factor for high cycle fatigue cracking of blade root, while the vibration of the sixth pitch diameter of the first stage of blade impeller system falling into the "3-coincide point" resonance area is the secondary factor for blade failure. After optimization, the main reason for the fracture is the unreasonable design of the blade root structure, and the vibration of the eleventh pitch diameter of the second stage of the blade impeller system falling into the "3-point" resonance area is the secondary factor causing the blade root failure.