The non-minimum phase plants with unstable zeros exists widely in the process of power production. Because of the non-minimum phase characteristics, the control system should ensure internal stability while completing output tracking, and improve response speed while overcoming the undershoot. The general PID control cannot meet the requirements of engineering applications. An engineering control and tuning method for non-minimum phase plants is proposed in this paper. Firstly, a robust PID controller is designed to ensure the stability of the closed-loop control system and overcome the under shoot of the system. Secondly, design a second-order filter that includes system position error, velocity error, and acceleration error to improve the response speed and dynamic performance of the control system. This method is simple, easy to tune, easy to configure in DCS, and has strong robustness to model uncertainty, which is worth promoting in engineering.

The optimal scheduling and economy of new energy hydrogen production systems are closely related to hydrogen production efficiency. Aiming at the problem of low hydrogen production efficiency in existing new energy hydrogen production systems, this paper proposes a control strategy for new energy hydrogen production systems based on particle swarm optimization (PSO). Firstly, based on the polymer electrolyte membrane (PEM) electrolytic cell model, the relationship between the operating point of the electrolytic cell and the hydrogen production efficiency is analyzed. Secondly, a hydrogen production system operation control method based on particle swarm optimization algorithm is proposed to improve the hydrogen production efficiency of the hydrogen production system. Furthermore, an optimal scheduling model for new energy hydrogen production systems considering the efficiency of system hydrogen production was established, and particle swarm optimization algorithm was also used to solve the optimal hydrogen production power. Finally, through simulation analysis of actual power grid operation data, it is proved that the proposed control strategy can effectively improve the hydrogen production capacity and system revenue compared to traditional startup and shutdown strategies, providing a theoretical basis for the large-scale application of hydrogen production systems in power grids.

During frequent long-term standby state of gas turbine generator unit, the surface of 08Al carbon steel of waste heat boiler economizer fin tube will have serious corrosion problems. In this paper, the macroscopic corrosion phenomenon and corrosion rate of 08Al carbon steel above the critical humidity were studied by the method of hanging piece and electrical resistance probe. The results show that the corrosion rate of 08Al carbon steel is the fastest in the first 5 days under the constant environment of 20 ℃ and relative humidity of 70%, and the corrosion depth reaches up to 0.85 μm, accounting for 47.7% of the total change in the whole process. However, the most obvious corrosion phenomenon, including the change of weight and the surface corrosion area, occurred from about the 19th to the 25th day. With the relative humidity gradually increasing from the critical humidity of 70% (ambient temperature 20 ℃), the corrosion evaluation indexes of 08Al carbon steel show a linear upward trend. Nitrogen filling maintenance strategy under long-term standby state was formulated, effectively alleviating the corrosion condition of economizer fin tube of waste heat boiler.

The high-performance supercritical CO₂ heat exchanger is the key core equipment to realize the efficient and compact S-CO₂ Brayton cycle system. S-CO₂ has a low heat transfer coefficient in the smooth channel, and seeking high heat transfer performance and low-resistance heat transfer structure is the key to the development of efficient and compact heat exchangers. Five-axis EDM was used to fabricate the straightly ribbed tube, and the heat transfer behaviors of S-CO₂ in the four-headed straight rib tube was experimentally studied, the effect of flow parameters on the heat transfer characteristics of the straight rib tube was systematically analyzed, and the difference in the heat transfer performance between the straight rib tube and the smooth tube was quantitatively evaluated. The influence of structural parameters on the enhanced heat transfer and resistance characteristics was studied by numerical simulation method, and the optimal straight rib tube structure was obtained. The results show that increasing the pressure and mass flow rate can reduce the wall temperature, improve the convective heat transfer coefficient, and the average heat transfer capacity of straight rib tube is about 1.96 times that of smooth tube. Compared with smooth tubes, straight ribbed tubes can effectively delay the occurrence of heat transfer deterioration, the ability to delay the occurrence of heat transfer deterioration by using straightly-ribbed tubes is increased by 0.3~1.8 times. When the fixed rib width W=0.5 mm and the rib height H=2.5 mm, the PEC is the best, and the value of PEC is1.58. However, the fixed rib height is H=0.5 mm, ε=0.33, and PEC of the straightly-ribbed tube is the best, with the value of PEC is 1.22.

To solve the problems of uneven distribution of NO_x concentration at the outlet and excessive ammonia escape in the actual SCR operation of power plants, the SCR DeNO_x reactor was simulated numerically and a new ammonia injection optimization method for dual control of ammonia slip and nitrogen oxides emission was proposed. Taking the SCR DeNO_x system of a 660 MW unit as an example, a numerical model of visual flow field and DeNO_x reaction was established, and the change of the partitioned outlet NO_x concentration, ammonia slip and partitioned DeNO_x efficiency under different total ammonia nitrogen ratios were analyzed and compared. The results show that the relationship between partitioned DeNO_x efficiency, outlet NO_x and ammonia concentration, with the partitioned ammonia-nitrogen ratio is a two-parts linear relation separated by an inflection point, and the inflection point occurs when partitioned ammonia-nitrogen ratio is about 1.15. On this basis, the present study proposes a new optimization method for ammonia/nitrogen dual control optimization based on the combination of piecewise fitting function and optimization matrix equation. It is predicted that the 660 MW unit by using 5 zones and 42 nozzles for ammonia injection regulation, and the optimized total ammonia injection volume will decrease by 7.2% at the best compared with the uniform ammonia injection working condition. Relative standard deviation of outlet NO_x concentration and ammonia slip volume will decrease to 9.4% and 4.2% respectively, and the outlet uniformity will be significantly improved, and there is no locally over DeNO_x phenomenon.

Aiming at the problem of low prediction accuracy of single power prediction model due to the impact of photovoltaic power fluctuation, a combined photovoltaic power prediction model based on similar day clustering is proposed. Firstly, k-means clustering is selected to divide the original power data into three similar day sample sets of sunny, rainy and cloudy according to different weather types, and the variational mode decomposition (VMD) is used to decompose the similar day samples; Secondly, the convolution neural network is used to optimize the support vector machine (CNN-SVM) and bidirectional short-term and short-term memory (BiLSTM) neural network, respectively, to predict and superimpose the decomposed power data and combine the prediction results with weights, and the grid search algorithm (GS) is used to find the optimal combination weight to improve the performance of the combination prediction model. Finally, the validity of the PV power prediction model proposed in this paper is verified by the one-year measured data of a photovoltaic power station in Australia. The experimental results show that the model proposed in this paper can predict the photovoltaic power well and has strong adaptability no matter what weather type.

Test for large-size wind turbine rotor under static and rotating conditions have been carried out for rotor dynamic characteristis. Based on experimental modal and operational deflection shape, firstly this test obtained modal data using LMS TEST.Lab system by calculating FRFs and curve fitting. Secondly the resonate speed was obtained according to the vibration sweep test. Then modal parameters were analyzed through operational deflection shape test under the resonate speed. The results show that the resonate frequency under rotating condition is different from the resonate frequency under the static condition. And the modal shape of rotor under rotating condition is travelling wave while it is standing wave under static condition. In conclusion, the integral stiffness is decreased when the rotor is rotating which results in the decrease of the resonate frequency, the modal shape turns to be the travelling wave resulting from the rotating magnetic force. This research results can offer a reference and guidance for rotor dynamics evaluation, simulation model modification and parameter input, and optimization design of rotor structure .

With the transformation of the power system to low-carbon, the proportion of new energy installed capacity is increasing year by year, renewable energy power generation has the characteristics of intermittent, the main power generation period and peak power consumption period are misaligned, there is an imbalance between supply and demand, and the demand for flexibility in power balance is intensified, and long-term energy storage power stations have become a magic weapon to solve the problem. According to the development of long-term energy storage technology, the technical characteristics, advantages and current bottlenecks of pumped storage, compressed air, lithium-ion batteries, flow batteries, molten salt heat storage, and hydrogen energy are analyzed, and the typical application projects of the above energy storage technologies are analyzed. Then, the typical scenario applications of energy storage are analyzed from different sides of the power supply side, the power grid side and the user side, and the application comparison of seven energy storage technologies in multiple scenarios such as energy transfer, auxiliary services, black start, and smooth new energy output is expounded. The technical parameters, battery selection, system wiring, energy management and other issues of chemical energy storage demonstration project, heat storage demonstration project and mechanical energy storage demonstration project were summarized and analyzed, and finally the future energy storage power station technology was prospected.

During the operation of SCR flue gas denitrification system in coal-fired units, ammonium bisulfate (ABS) in flue gas causes ash scale slabbing at the cold end of the air preheater and increases the difficulty of purging and cleaning ash. To this end, ABS premixed ash samples were prepared and pressed and heated at different temperatures, and a new test method was designed to compare the changes in compressive strength of the samples and explore the influence law of ABS on the mechanical strength of ash scale. The experimental results showed that: 1) ABS premixed ash samples underwent physical agglomeration and chemical reaction during the heating of slabbing at 147-220 ℃, and the compressive strength was increased by about 95.50% at maximum, among which physical agglomeration played a dominant role with about 88%-89% influence and the influence of chemical reaction accounted for about 10%-12%; 2) ABS slabbed ash samples under heating at 220-300 ℃, ABS vaporization precipitation rate reached up to 96.43%, the ash sample from the slab state to loose, compressive strength from 195.50% of the blank sample to 110.17%. It is proved that the means of high temperature heating is feasible to reduce the ABS content in the blockage and create conditions for improving blowing and cleaning from the perspective of ash scale.

The carbon dioxide (CO₂) Brayton cycle system is compact, efficient and flexible, and has a good application prospect in the third generation photothermal system and the fourth generation nuclear power system. The deterioration of CO₂ heat transfer affects the safe operation of the unit. In order to study the deterioration of CO₂ heat transfer in the vertical riser, a CO₂ heat transfer characteristic system is established for experimental research, and the CO₂ heat transfer characteristics under subcritical and supercritical conditions are compared. The influence of thermal parameters on the deterioration of CO₂ heat transfer is obtained, and the prediction correlation of CO₂ critical heat flux is established. The predicted value is in good agreement with the experimental value (error ±30%). It is found that the peak value of wall temperature is higher when CO₂ heat transfer deteriorates at subcritical pressure. Far away from the critical pressure and increasing the mass flow rate are conducive to restraining the occurrence of heat transfer deterioration.