Solar power plants can be complementary to other new energy power generation stations, and can also undertake the task of peak modulation and frequency modulation of power grid, which have attracted more and more attentions. In this paper, the dynamic simulation model of thermal storage system and power generation system is built and verified by Apros software. The coordinated control system of solar power plant considering the influence of heat storage is designed, and the maximum variable load rate of the solar power plant in different load intervals is studied. The results show that the proposed coordinated control strategy has a good control effect. Compared with the control without heat storage control, the deviation of main steam pressure with heat storage control reduces from 0.17 MPa to 0.07 MPa. Under the set limit conditions, the maximum load rise rate of 100%THA~75%THA load interval is 11.57%/min, and the maximum load reduction rate is 8.94%/min. The results can provide reference for peak shaving and frequency modulation operation of photothermal power plants.

At present, domestic research on gas control valves or other equipment in gas turbines is still lacking, while most of these researches’ models remain in a single hydraulic valve or a hydraulic cylinder. So this paper uses Simulink/Simscape software to model the entire gas turbine’s gas control valve including the PI controller to the gas pipeline, and conduct simulation analysis for faults such as fixed orifice blockage, wear of the spool valve core and hydraulic oil contamination to discuss their forms and causes. The result shows that, the blockage of the one-sided fixed orifice of the nozzle damper valve, the wear of the slide valve core and the impurities in the hydraulic oil will all cause the valve to respond slowly, or even become clogged and stuck to varying degrees. Finally, for the monitoring of valve data in current power plants some suggestions are thrown out: according to the actual operating conditions, monitoring of the parameters such as the servo valve spool displacement signal and hydraulic cylinder piston displacement can be introduced by using electronic feedback servo valve, to better judge the health status of the valve.

In view of the increasingly serious problem of power grid peak regulation caused by the instability of new energy, combined with the relatively mature photo-coal complementary power generation technology and the multi-heat source combined heating peak shaving system, the light-coal mixed heating power generation system was designed to make the cogeneration unit have a certain peak regulation capacity. Based on the actual operating conditions of the heating unit and the premise of ensuring the heating load, the coupling mode of the solar-assisted dual-engine cogeneration unit was analyzed, and the peak regulation performance of the two-engine was compared before and after coupling. The results show that, a dynamic throttle valve is installed on the pipeline between the condenser outlet and the heat exchanger of the solar collector system, and the operation mode of the auxiliary heating unit of the solar collector system can be changed, which can realize flexible operation of the integrated system of power generation, heating and peak regulation. Among them, the solar thermal collection system is only used for supplementary heating, the peak regulation capacity ratio is 0.76, and the ratio of solar auxiliary double-heating supply before and after peak regulation capacity is 0.55. The No.1 unit which is assisted by solar energy to bear the maximum heating load has the best performance in peak regulation capacity and peak regulation compensation.

Due to the characteristics of the medium transported by medium speed coal mill and the limitations of the inlet pipeline and space, the testing method under cold pure air conditions cannot guarantee the timeliness of the calibration test for the inlet air volume. Under hot conditions, the outlet pipeline of the coal mill was selected as test object for its stable flow field. The dynamic pressure and pulverized coal distribution characteristics of each powder pipe were tested by the equal cross-section grid method. The flow velocity of the air-powder mixture was obtained by the cyclic iterative method. Finally, the inlet air volume of the coal mill was compared and calibrated by the difference between the measured air-powder mixture flow rate, the coal quantity and the design sealing air volume. The practical results show that, on the basis of the same measured original data, the inlet flow rate obtained by the method above is closer to the real value, the accuracy can be improved by about 15 percentage points compared with the calculation results with cold conditions method. This method is simple to test and practical, which can effectively improve the timeliness and accuracy of the inlet air volume calibration results of medium-speed coal mill under hot conditions, and at the same time, it also has a certain guiding role in test of the flow rate of powder-containing gas in similar industrial environments.

To unveil the ultra-low load operating characteristics and performance optimization method of large-scale units burning high moisture lignite, the influences of burners operating scheme under 33%BMCR condition on the coal combustion, heat transfer and NO_x transformation characteristics of a 660 MW unit utility boiler were investigated, based on an established and validated simulation model of coal-fired boiler. The results show that, well-organized flow and combustion field can still be formed inside the furnace under ultra-low load condition, but the overall boiler performance deteriorates evidently, such as obvious decreases in combustion temperature and heat transfer intensity, and increase in NO_x emission at outlet of the furnace. When 4 layers of burners are in-service, continuous lower-middle groups or middle-upper groups of burners should be put into operation, to prevent the significant deteriorations of combustion and heat transfer processes and the significant increase in NO_x emissions. The number of in-service burners layers significantly affects the overall boiler performance. When there are only two layers of burners in-service, the intense coal combustion area is too concentrated, which is not conducive to maintaining a high combustion temperature and heat transfer intensity, and NO_x emissions at the furnace outlet increase at the same time. These findings reveal the influences of burner operating scheme under ultra-low load condition on the overall performance of a 660 MW lignite boiler, which can provide guidance for deep peak shaving operation adjustment and optimization of coal-fired units in the context of large-scale renewable energy power grid connection in the future.

In the context of current energy structure transformation, conventional thermal power would gradually transform into grid source support and system regulation. Coupling with distributed photovoltaic power is an effective attempt for thermal power enterprises to achieve cost reduction and efficiency improvement. However, due to the lack of relevant guidance for the connection of non centralized power sources for the factory use, there is a lack of evaluation strategies and empirical references for system security and stability. For this purpose, taking the thermal photovoltaic complementary energy supply system of a thermal power plant in northwest China as an example, its operating characteristics are analyzed and a technical framework for stability evaluation is provided. In examples of different power units, grid connection levels, and minimum photovoltaic unit layout, application evaluation issues such as static power flow, transient stability, and power quality are discussed. It is calculated that the power consumption reduction efficiency of thermal power units in this case achieves an improvement of 18%~42%. This conclusion has typical reference significance for the application of the power generation technology model of “distributed photovoltaic access to plant use systems” in thermal power plants.

In order to explore the film cooling potential of crater holes, numerical simulations are performed to investigate the film cooling characteristics of equal-section crater hole, concentric elliptical crater hole, and two types of rounded corner crater holes proposed on the basis of these two types of crater holes. Cooling efficiency curves are analyzed for four types of crater holes at blowing ratios of 0.5, 1.0 and 1.5. The results show that, the crater spreading width of crater holes and crater film holes with rounded corners increases, which is beneficial to spreading coverage of the cooling film. After the crater holes are rounded at three blowing ratios, the Coanda effect strengthenes the ability of the cooling jet to adhere to the wall, and the film cooling efficiency in the near-hole region improves significantly. As the blowing ratio increases, the area-averaged film cooling efficiency after the rounded corner treatment increases by 76%, 139% and 155%, respectively, for the equal-section crater hole. The area-averaged film cooling efficiency improves by 18%, 27%, and 29%, respectively, for the concentric-elliptical crater hole with rounded corner compared with that of the concentric-elliptical crater hole.

It is difficult to control NO_x emissions during full load operation of a 660 MW supercritical circulating fluidized bed (CFB) boiler in a certain power plant, and its instantaneous value is prone to exceed the ultra-low emission limit. In addition, the selective non-catalytic reduction (SNCR) system has a high ammonia consumption and severe ammonia escape issues. To solve these problems, on-site experiments on NO_x original emissions, SNCR denitrification efficiency, CO mass concentration and bottom slag combustibles were conducted, and optimization experiments on secondary air volume layout were also performed. It was found that, the original NO_x emissions of the CFB boiler were relatively low, with a maximum of 120 mg/m³ (standard condition) during full load operation and a NO_x mass concentration below 50 mg/m³ during medium and low loads. However, there was a significant deviation in NO_x mass concentration between the front and rear ends of the furnace, and the NO_x in flue gas was mainly generated in front of the furnace. The reason why NO_x emissions are difficult to control is due to the low denitrification efficiency of SNCR and uneven coal feeding in the furnace. The SNCR denitrification efficiency at inlet of the 6 separators was all below 50%, among which the denitrification efficiency of four separators B, C, E, and F was below 40%. Furthermore, according to the distribution of parameters in the furnace depth direction, such as the bed temperature, the content of combustible materials in bottom slag, and the variation of CO mass concentration, it can be determined that the uniformity of coal feeding in the furnace also had a significant effect on the control of NO_x emissions at full load. Currently, the power plant cannot achieve uniform coal feeding without renovation, but the original NO_x generation can be reduced by adjusting the secondary air volume ratio in the depth direction of the furnace, with a reduction of up to 9.77%.

With the increase of various types of cyber-attacks, the security of industrial control systems in energy and power infrastructures has gradually become a focus of attention. Combined with the characteristics of power system, the CNN-LSTM-Attention network intrusion detection algorithm model integrating convolutional neural network (CNN), long and short-term memory (LSTM) neural network and Attention mechanism is proposed. By constructing and collecting the operating state data sets of the pulverizing system of a 600 MW coal-fired unit under three typical operating conditions under cyber-attacks in a laboratory simulation environment, the proposed detection algorithm model is trained and evaluated. The results show that, the proposed intrusion detection algorithm model has the best performance compared with the CNN and LSTM models. The model has the best rating indexes such as accuracy, precision, recall, etc., and the comprehensive evaluation is better than other intrusion detection methods. The intrusion detection algorithm model is highly innovative and practical.

In order to solve the problem of low accuracy of wind power prediction caused by wind speed uncertainty and volatility, this paper proposes a VMD-ISSA-GRU combination model based on variational mode decomposition (VMD), improved sparrow search algorithm (ISSA) and gated recurrent neural network (GRU). Firstly, the center frequency method is used to determine the number of modal components after VMD decomposition, which can effectively avoid over-decomposition or insufficient decomposition. Then, chaotic mapping, nonlinear decreasing weights and a mutation strategy are introduced to improve the sparrow search algorithm to optimize the gated recurrent neural network, and then an ISSA-GRU prediction model is established for each decomposed subsequence. Finally, the predicted value of each subseries is superimposed and the final predicted value is obtained. The experimental results show that, the mean absolute error, mean absolute percentage error and root mean square error of the VMD-ISSA-GRU model are 1.211 8, 1.890 0 and 1.591 6 MW, respectively. Compared with the conventional GRU, long short-term memory (LSTM) neural network, Bi-directional LSTM (BiLSTM) neural network model and other combination models, the prediction accuracy has been significantly improved, which can solve the problem of low prediction accuracy of wind power.