The downstream wind turbines suffered by the deflected wake are subjected to unbalanced aerodynamic loads and resulting in a significant increase in fatigue loads. Two NREL 5 MW wind turbines have been adopted to study the influence of the yaw control of upstream wind turbine on the aerodynamic characteristics of downstream wind turbine under staggered arrangement, based on open source software FAST.Farm. The results show that the downstream wind turbine is gradually in the core area of wind velocity deficit with the increase of yaw angle of the upstream wind turbine, the reduction of rotor power of the downstream wind turbine is significantly increased, and the rotor thrust suffered by the downstream wind turbine is gradually reduced. The yaw control of the upstream wind turbine will significantly affect the fluctuation characteristics of the aerodynamic load of the downstream wind turbine. When the yaw angle of the upstream wind turbine is 40°, the standard deviation of the flapwise moment at the blade root of the downstream wind turbine increases by 50.5% compared with the case that the upstream wind turbine is not yawed. This study can provide a reference for the whole wind farm control collaborative optimization and aerodynamic characteristics analysis under yaw inflow.

The unique heatdetermined power working mode of coalfired cogeneration units and the antipeaking characteristics of wind power lead to the problems of insufficient peaking capacity and high carbon emissions in virtual power plants. In this paper, we propose an optimal scheduling technology of virtual power plant based on antlion optimization algorithm. The carbon capture technology is supplemented by a reasonable demand response mechanism to realize the flexible and lowcarbon operation of the virtual power plant. Firstly, an optimal scheduling model was established with the objective of the highest economic efficiency in one scheduling cycle. Secondly, a hybrid strategy based on chaotic mapping and tournament selection is designed. The boundary checking mechanism on the search space is utilized to effectively avoid the situation that too many potential solutions are at the same boundary. Finally, the simulation results show that the planned virtual power plant has a reasonable structure, and the proposed scheduling strategy can improve the system's new energy consumption capacity and total revenue while reducing carbon emissions by coordinating the resources on both the source and load sides.

In view of the problem that data center evaporative cooling technology limited by the ambient wet bulb temperature, a solar energy and heat pump complementary drive the desiccant wheel evaporative cooling air conditioning system in data center was proposed. The system uses the waste heat of photovoltaic modules to provide thermal energy complementary heat pump system to drive the dehumidification regeneration. According to the outdoor meteorological conditions, the system can realize three operation modes: fresh air, evaporative cooling and dehumidification & evaporative cooling. The TRNSYS software is used to simulate the thermal, power and energy consumption characteristics of the three typical regional data centers in Shanghai, Guangzhou and Kunming. The results show that in the typical daily dehumidification +evaporative cooling mode in Shanghai, Guangzhou and Kunming area, the desiccant wheel pretreatment reduced the air wet bulb temperature by 10.9 °C, 11.6 °C and 10.3 °C on average compared with the outdoor wet bulb temperature. The average typical monthly system COP values in Shanghai, Guangzhou and Kunming were 4.9, 5.1 and 3.6, respectively, and the maximum instantaneous COP value was 12.1, 11.4 and 8.1.

The wide shallow bucket foundation with concrete arc transition section is subjected to significantly larger wave loads which will easily affect the vibration response of the entire structural system. For an offshore wind turbine (OWT) supported by bucket foundation, a finite element model of the whole wind turbine was established based on the measured vibration data, and then the influence of wave loads on the vibration response of the tower top of the OWT supported by bucket foundation was simultaneously analyzed through the established finite element model. It is shown in the analysis results that the vibration response of the tower top caused by wind load is greater than that caused by wave load during the operation period. Subsequently, the influence of the wave load can be ignored compared to the wind load when the wave height is small. In addition, the impact of wave loads on the vibration response of the tower top increases with the increase of external wind speed and wave height and the corresponding impact on the vibration displacement response of the tower top is greater than the vibration acceleration.

In order to explore the potential of fruit peel waste conversion to produce highvalue platform chemicals, the hydrothermal conversion of citrus peel to furfural (FF) and 5hydroxymethylfurfural (5HMF) was conducted in the choline chloride (ChCl)/ carboxylic acid based deep eutectic solvents (DES) system. Conclusions can be drawn from experiments in xylose and glucose: The carboxylic acid performance was ranked lactic acid > acetic acid > glycolic acid. The optimal molar ratio of choline chloride to carboxylic was 1:2. The optimal water content of solvent system was 20%. The effects of temperature and time on citrus peel conversion were studied based on the optimized operating conditions. Since the pectin component in the citrus peel was mainly converted to 5HMF in DES, the yield of the peel converted to 5HMF was significantly higher than that of FF. The maximum mass yield of 5HMF from citrus peel was 8.6% (molar yield was 43.1%). The maximum mass yield of furfural reached 2.4% (molar yield was 19.1%).

Aiming at the problem of lack of a large number of actual fault image training samples during the fault diagnosis and modeling of offshore wind turbine blades, an image recognition method for offshore wind turbine blade faults based on small data sets is proposed. In this method, the Kmeans clustering algorithm is improved to identify blade segmentation according to the color and shape characteristics of blades and their faults in wind turbine blade images, an adaptive algorithm is designed to adjust the Canny operator parameters to identify the segmentation of early fault areas on the blade surface, and the Kmeans clustering algorithm is used to extract the color and shape features of faults and design corresponding classifiers to achieve fault classification. Simulation examples show that this method is effective for the identification of early faults on the blade surface, and can provide an accurate diagnostic model for the blade fault identification of offshore wind turbines on the basis of a small number of fault samples, which can improve the operation and maintenance efficiency of offshore wind farms.

The fluctuation of renewable energy unit output and the unreasonable grid connection position lead to voltage fluctuations, power deviation, and increased investment costs in the coupled system. A discrete particle swarm optimization method for multi photovoltaic power supply access site selection is proposed to meet the optimization and regulation requirements of wind solar thermal coupling system. Analyzed the reactive power compensation characteristics of photovoltaic power sources and the impact of their connection positions on system voltage deviation and grid losses, established a power generation system model that couples renewable energy and thermal power, and used photovoltaic power sources as reactive power regulation devices for the coupled system. Taking the comprehensive optimization of voltage deviation and line loss as the objective function, the discrete particle swarm optimization algorithm is used to solve the photovoltaic power supply access point. The analysis results of the example show that the multi photovoltaic power station access point optimization method ensures the voltage deviation of each node, reduces line loss, and improves the safety and stability of the wind solar thermal coupling system.

With the largescale integration of wind power, power system subsynchronous oscillation (SSO)events occur frequently, which seriously threatens the safe and stable operation of the power grid. The accurate detection of SSO in wind power gridconnected system is of great significance to ensure the stable operation of the power systems. Most of the existing SSO detection methods are singlechannel methods, which are difficult to take into account the global SSO characteristics of the systems. Therefore, this paper proposes a SSO detection method for wind power gridconnected system based on multivariate empirical mode decomposition (MEMD). Firstly, the multivariate empirical mode decomposition is performed on the measurements of wind power gridconnected points, and then the IMF components with SSO mode are screened out via TeagerKaiser energy operator (TKEO). Then, the HilbertHuang transform (HHT) is used to identify the SSO frequency and damping ratio. Finally, the proposed detection method is analyzed by the improved 4machine 2area system simulation data, and the results verify the effectiveness of the proposed method.

The abandoned mines contains abundant geothermal resources.This article takes the mine water of gob area as the research object; in order to ensure the stability of pumping temperature during the heating season, the layout and parameter sensitivity of pumpingrecharging wells of water source heat pump of abandoned mine are studied. Firstly, based on the Darcy's law and the theory of heat transfer in porous media, the twodimensional numerical calculation models of the coupled multiphysical fields of the pumpingrecharged well are established.Secondly, the pumping water's temperature variation of 14 arrangement forms of pumpingrecharging wells are analyzed while the theoretical models are employed. The most reasonable arrangement form can be selected according to the degree of the heat transfixion. Finally, when the selected pumping recharging wells'arrangement form is taken into consideration, the effects of different factors including the recharge temperature, the pumpingrecharging water's flow rate, the wells' spacing, the hydraulic slope, the aquifer thickness and the porosity on the pumping temperature are discussed. The results of the analysis show that the well placement method of triangle 4 only decreases the pumping temperature by 0.148 K at the end of the system operation, and the occurrence of "thermal penetration" is the least and the well placement method is the most reasonable. The occurrence of "heat transfixion" in the aquifer is more sensitive to parameters such as pumping flow rate, well spacing, hydraulic gradient, and aquifer thickness, while it is less sensitive to recharge temperature and porosity.

In order to suppress the false information existing in the interactive information between microgrid (MG) and microgrid cluster operator (MGCO), a trading mechanism with the Stackelberg game is proposed, and a dynamic integrity factor is used to consider the honesty behavior of the MG. Firstly, a reward and punishment mechanism based on the reported electricity quantity and the actual trading quantity is established. Transaction price can be adjusted by credit factor. Secondly, a Stackelberg game model with MGCO as leader and MGs as followers is developed. The upper level minimizes fluctuation of power for microgrid cluster, where a contract mechanism of transaction is established to adjust basic transaction prices within the cluster. In the lower level, the cost of MG operation is minimized. Each MG acts as the follower responding to the dayahead trading price and decides the electricity of exchange power with MGCO. Finally, the study prove that the presented transaction mechanism effectively suppresses the false information.