The working environment of the ring main unit (RMU) in large solar photovoltaic power plants is complex and variable, faced with harsh environments such as temperature differences and humidity, it is extremely easy to cause operational failures of the ring grid cabinet, which seriously affects the safe and stable connection of solar photovoltaic to transmission lines. Based on the measured temperature and humidity data inside the RMU, utilizing the advantages of ARIMA and RBF model in linear and nonlinear data processing, a temperature and humidity prediction model with ARIMA-RBF weight combination is constructed to dynamically predict the temperature and humidity inside the RMU. The dynamic prediction of temperature and humidity in the actual loop cabinet of a photovoltaic power station is carried out. The prediction results show that, compared with the single model, the ARMI-RBF weight combination model has higher prediction accuracy and better stability. The combined model gives full play to the processing ability of a single model for different characteristics of data through appropriate weighting strategies, and can better evaluate the temperature and humidity state inside the RMU. It can provide a reference for the establishment of a more universal prediction model, and help to reduce the failure caused by long-term operation of the ring cabinet under ultra-mild and humid environment.

A comprehensive evaluation model for the start-up and shutdown decision-making of the milling system, taking into account the energy consumption and tracking performance of the unit load, has been proposed to address issues such as subjective decision-making based on manual experience, high labor intensity in operation, and difficulty in exploring energy-saving optimization potential. This model safely incorporates the grid load scheduling command signal as input. Furthermore, a milling system start-stop intelligent decision-making method based on deep reinforcement learning has been studied, and a closed-loop control system for the automatic start-stop of the milling system has been developed. The research results have been verified through simulation and successfully applied to a commonly used coal milling system in a certain ultra-supercritical 1 000 MW unit, achieving energy savings. The findings of this study can provide effective reference for the development of unmanned or minimally manned operation techniques for thermal power units.

Aiming at the lack of quantitative standards and assessment methods in the current comprehensive assessment of wind turbine control performance, a quantitative assessment method of control performance based on subspace linear quadratic Gaussian (LQG) is proposed. The subspace matrix method is used to solve the assessment trade-off curve, and the benchmark and assessment index of LQG control performance of wind turbines are established. By taking the turbine retrofitted by adding tower damping and load shedding control as an example of the assessment, the multivariate comprehensive quantitative assessment of pitch control performance before and after retrofitting is carried out by using two kinds of data processing strategies. The results show that, both data processing strategies can obtain accurate and effective quantitative evaluation results, and the proposed evaluation method can realize the comprehensive quantitative evaluation of the optimization effect of control strategies.

The large-scale integration of new energy into the grid has caused increased frequency fluctuations in the grid, making the frequency modulation task of thermal power units heavy and frequent, exacerbating the aging of the unit, flywheel energy storage assisted thermal power unit frequency modulation can improve the frequency modulation performance of the unit. The principle of primary frequency modulation of flywheel energy storage auxiliary unit is discussed, and the flywheel energy storage’s frequency modulation characteristics are analyzed. Combining with the world’s largest capacity flywheel energy storage, the full power control strategy for primary frequency modulation of flywheel energy storage auxiliary units is proposed, and applied to the shakedown test of China’s first set of flywheel energy storage auxiliary thermal power unit’s primary frequency modulation to verify the effectiveness of the control strategy. The field test results show that, the primary frequency modulation performance of the flywheel energy storage auxiliary thermal power unit is good. After the proposed primary frequency modulation strategy is adopted, the qualification rate of the primary frequency modulation action of the unit increases by 21.26%, and the integral electricity contribution index of the primary frequency modulation increases by 3.45 times. The primary frequency modulation mode of flywheel energy storage auxiliary thermal power unit has certain guiding significance to solve such problems.

In order to ensure safe operation of secondary cycle and reliability of steam generator, it is of great significance to reduce corrosion of equipment & piping of the cycle in nuclear power plant. With the deepening research on organic amines and the continuous accumulation of operation experience, the industry realized that the metal corrosion in the cycle during plant operation depends mainly on the pH at the operating temperature of locations of the cycle, i.e. pHt. To improve pHt at the locations of the cycle, performance characteristics of the main organic amines and their combinations are analyzed in this paper. Combined with the application experience and actual effects of organic amines at home and abroad, the application strategy of the main organic amines and their combinations are discussed and proposed, and the improvement suggestions are put forward with regard to current amine application status of the secondary cycle in China. Selections of amine or its combination should calculate the pHt at various locations to meet anti-corrosion requirements and evaluate effects on service life of resin beds in the system. Ethanolamine with stronger basicity and low volatility is suitably used in plant in which corrosion product is mainly from drain systems and condensate polishers are in continuous operation. 3-methoxyypropyl with strong basicity and moderate volatility can be used in most plants. Morpholine with weaker basicity and moderate volatility is suitably used in plants in which polishers are not in continuous operations. Dimethylamine and ammonia are suitably used with other amines because of their high volatility. Amine mixture application appears advantages on aspects of the anti-corrosion and service life of the resin beds.

The fouling of heat exchangers and cooling tower fill surfaces in the external cooling water system of synchronous condenser can significantly impede the heat transfer efficiency of cooling towers, posing a serious threat to the safe operation of synchronous condenser. In order to propose more effective anti-fouling measures and elucidate the causes of fouling, this study employed characterization techniques such as SEM-EDS, XRD, FTIR, etc., to analyze the microscopic morphology and chemical composition of fouling samples. Additionally, chemical analysis methods and ICP-MS were used to analyze the makeup of makeup water and circulating water in the system. The test results revealed that the primary components of fouling in the external cooling system are CaCO₃, SiO₂and CaSiO₃. The fouling in the cooling system is closely related to the absence of wastewater discharge measures in the system, high concentration ratios during operation, and the infiltration of regional windblown sand. This research contributes to proposing targeted anti-fouling measures for on-site operation of such cooling systems, ensuring the economic and operational safety of synchronous condenser.

A feedback control strategy based on Kalman filter was proposed to quantitatively study the drive train torsional vibration mitigation of doubly-fed wind turbine, and the control effect of drive train torsional vibration was compared through simulation calculation. Taking the drive train of 7.0 MW doubly-fed wind turbine as the research object, the Kalman filter was used to estimate the twist angle of the drive train, and an additional electromagnetic torque of the generator was designed for torque control based on the estimated torsional speed of low-speed shaft. The load and power generation calculations were compared with virtual damping control and no-damping control over 20 years full life cycle. The results show that, the correlation between the twist angle of the low-speed shaft estimated by the Kalman filter and the actual value can reach 0.99. The key differences between the feedback control based on the Kalman filter, the virtual damping control and the non-damping control are as follows. The equivalent fatigue load of the low-speed shaft of the drive train reduces by 2.11% and 4.89%, respectively. The equivalent fatigue load of the high-speed shaft of the drive train reduces by 1.99% and 4.78%, respectively. The power generation reduces by 200 kW·h and 700 kW·h, respectively. It can be concluded that the Kalman filter has a good estimating effect on the twist angle of drive train, and the designed additional electromagnetic torque based on the estimated torsional speed of low-speed shaft obtained by Kalman filtering has a very good suppression effect on the torsional vibration of the drive train.

The efficient drying pre-treatment and gasification resource utilization of sewage sludge is one of the important ways to realize green and sustainable city development. Firstly, the thermogravimetric reactor was used to study the drying kinetics of sludge. Then, the influence of high temperature-low speed flue gas and low temperature-high speed flue gas on the sludge drying process was clarified based on Fluent numerical simulation. Finally, a new type of sludge and biomass co-gasification co-generation system was established by Aspen Plus, and the thermodynamic performance of the system was discussed. The results show that, the drying process of sludge in thermogravimetric reactor can be divided into the ascending stage, the first decreasing stage and the second decreasing stage, and the decreasing stage is the main stage. The water diffusion coefficients of SW-60 and SW-80 ranged from 6.34×10–6 to 3.72×10–5 m²/s and 3.69×10–5 to 2.60×10–4 m²/s, respectively. The drying activation energy of SW-60 and SW-80 was 9.55 kJ/mol and 28.25 kJ/mol, respectively, with the increase of initial moisture content. In the drying bed, the drying efficiency of high temperature-low speed flue gas is about 2.67 times that of low temperature-high speed flue gas. In the co-generation system, as the biomass blending ratio increases, the input heat, air flow, low heating value of syngas, yield of syngas and potential of co-generation all increase. However, the electrical efficiency, thermal efficiency and system efficiency will decrease slowly. When the biomass blending ratio is 20%, the blend of 30% moisture dry sludge and biomass can produce electrical energy potential and thermal energy potential of 0.61 kW·h and 4.212 MJ per kg, respectively.

Labyrinth seals are widely used in various types of turbomachinery due to their simple structure, convenient maintenance, and long service life. The shunt injection devices can reduce the flow-induced vibration caused by the spiral effect and improve the stability of the sealing system by affecting the circumferential flow inside the seal cavity. The three-dimensional numerical models of shunt injection labyrinth seal were established to calculate and analyze the impact of the shunt injection nozzle on the dynamic characteristics of the seal under different structural parameters. The results show that the smaller the tilt angle of the anti-swirl nozzle, the greater the system damping and stability. When the tilt angle is 30°, the effective damping is 4 times that of the vertical angle incident; the shape of the anti-swirl nozzle has a small impact on the sealing dynamic and flow characteristics. The cross stiffness of both nozzle hole types is negative, and the difference in cross stiffness between the two is about 5 kN/m at low frequencies and 1~2 kN/m at high frequencies; the more nozzles there are, the more they can suppress the circumferential flow of the rotor, which is beneficial for system stability.

In order to achieve the desired flexibility, high efficiency, and cost-effectiveness in the startup and operation of thermal power units, the utilization of the BEST small steam turbine with a small generator for the implementation of a double-turbine reheat system unit is crucial for enhancing the operational economy of the unit. According to the starting mode of the BEST system and unit, combined with the historical process and data of the starting and operation of the debugging and adjustment test, a characteristic analysis test of the BEST system in multi-mode startup and operation was conducted. The existing control logic was optimized, and an operation control strategy for the BEST small steam turbine with a small generator was proposed. The system addresses the issue of lacking control strategies in various aspects, such as the starting and control of the BEST system, converter start-stop control, BEST small steam turbine and converter non-disturbance switching, run back, load dumping conditions, and ensures uninterrupted operation control of the entire process of the BEST system. After optimization, the crucial parameters of the BEST system remain secure and stable during operation. The control method holds significant reference value for similar units equipped with the BEST system.