The typical faults of wind turbines are summarized. The fault data and non-fault data of converter system, generator system, variable propeller system and auxiliary power system with high fault frequency of wind turbines in a wind farm are selected for fault diagnosis research. The fault diagnosis model is established by ELM, SVM, KELM and WOA-KELM algorithms respectively. At the same time, Laplacian scores are used to sort and select the importance degree of model characteristic variables. WOA-KELM algorithm achieves better diagnostic effect by optimizing the regularization parameter C and kernel parameter γof KELM algorithm. The results show that, the diagnostic accuracy of the four algorithms for non-fault types is 100% under different sample numbers. The average diagnostic accuracy of WOA-KELM algorithm improves from 88.0% to 93.2% after feature screening by using Laplace scores. In the range of 250~500 samples, the diagnostic accuracy of WOA-KELM algorithm reaches the maximum of 96.0% after feature screening. It is proved that this model can effectively realize the fault diagnosis of wind turbine, and provide guidance and reference for field operation and maintenance personnel.

For the analysis of the heat applied to equipment outside the system boundary, the energy utilized was outside the GB/T 10184 standard, and the boiler efficiency calculation could not take advantage of the existing standard. The external heat loss of hot air was divided into two categories: hot air reuse and hot air non-reuse. Based on the GB/T 10184 calculation framework, the calculation methods of these two categories of external heat loss of hot air were proposed. Taking a 350 MW boiler as a practical example, under the same load, continuous operation of hot air external use and shutdown of hot air external use were compared. According to the actual test data and analysis results, the calculation method was used to compare the actual operating conditions. The influence of external loss of hot air on boiler efficiency was analyzed. The results showed that the test results of combustible materials in two working conditions were basically the same. The external loss of hot air in T01 (cold air recovery) was 0.82%, the external loss of hot air (cold air nonrecovery) was 0.13%, and the external loss of hot air in T02 was 0. The measured boiler efficiency in T01 and T02 conditions was 93.10% and 94.00% respectively. The operation of external hot air system reduced the boiler efficiency by about 0.9 percentage point.

Under partial shading conditions (PSC), the P-U characteristics of a solar photovoltaic array may exhibit multi-peak phenomena. Conventional algorithms tend to fall into local maximum power point (LMPP), while maximum power point tracking (MPPT) methods based on meta heuristic algorithms are difficult to balance speed and accuracy. In this regard, this paper designs a hybrid algorithm based on the improved particle swarm optimization (IPSO) with embedded the improved perturbation and observation (IP&O). The velocity and position of the particle are first updated by the IPSO algorithm. Then, perform MPPT based on the position of particles using the IP&O algorithm. The tracked power is used as the fitness value of the particles, so that IPSO can find the global maximum power point (GMPP) among many LMPPs. Finally, with the global optimal output of IPSO as the initial position, IP&O is used again for global maximum power point tracking (GMPPT). Comparing the proposed algorithm with IP&O, IPSO, and IPSO-P&O through simulation, the simulation results show that the proposed algorithm performs excellently in tracking speed and accuracy, especially in the case of a wide voltage search range, and has smaller power oscillations during the tracking process.

The effects of tray parameters on desulfurization efficiency and energy consumption of desulfurization towers are investigated. Through the large-scale hot test platform, the effects of different pore diameters, opening ratio, opening form, weir plate height and different installation positions on desulphurization efficiency and energy consumption are studied. In this paper, the energy consumption efficiency ratio is proposed for the first time as an index to evaluate the operation economy of desulfurization tower. It is found that, under the conditions of experimental platform, when the liquid-gas ratio is not more than 13.6 L/m³, it is economically advantageous to choose sieve plate with medium aperture, high weir board, small opening rate, low-level arrangement, and new aperture design. When the liquid-gas ratio is large than 13.6 L/m³, it is economically advantageous to choose sieve plate with medium aperture, high weir board, large opening rate, high-level arrangement, and new aperture design. The conclusion is of guiding significance for the design and selection of sieve plates for desulfurization and desulfurization towers.

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.

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.

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.

Based on a DC microgrid system coupled with photovoltaic power generation, lithium battery-supercapacitor hybrid energy storage, electrolysistank and hydrogen-burning micro gas turbine, a power allocation strategy that integrates the lithium battery state of charge (SOC) and hydrogen storage tank hydrogen state (LOH) is proposed. A PV-electrolysistank-micro gas turbine DC microgrid system model is constructed. The allocation logic of the power judgment module of the coordination control layer is designed, and three operation modes are given when the residual power exists in the DC network. The power allocation strategy is simulated and verified using MATLAB/Simulink software. The simulation results show that the power allocation strategy of DC microgrid system based on hydrogen energy storage can make the lithium battery charge state gradually converge to a reasonable storage interval and can improve the service life of lithium battery.