The effects of reaction temperature and alkaline catalyst on the yield of pyrolysis products and the selectivity of methoxy-aromatic compounds were studied during microwave-assisted pyrolysis of eucalyptus sawdust in a fixed-bed reactor. The results showed that 400 °C was the optimum temperature for methoxy-aromatic compounds production, where the yield of bio-oil was 28.4%, and the concentration of methoxy-aromatic compounds in the bio-oil reached to 70.4%. The dominant methoxy-aromatic compounds were identified as guaiacyl and syringyl derivatives. Weakly alkaline catalysts (K₂CO₃ and Na₂CO₃) enhanced both bio-oil yield and the methoxy-aromatic compounds selectivity. However, the strong base NaOH reduces methoxy-aromatic compounds content. The catalytic efficiency for methoxy-aromatic compounds selectivity followed the order: Na₂CO₃ >K₂CO₃ >NaHCO₃ >NaOH. Furthermore, the reaction mechanisms underlying the formation of MACs from woody biomass and their subsequent conversion into benzoquinone, phenol, and catechol were elucidated, with guaiacol serving as a key structural model.

This study provides an indepth analysis of the distribution characteristics, combustion characteristics, and energy utilization potential of wheat root stubble resources in Henan Province through comprehensive research, experimental testing, and statistical analysis. The results showed that the total theoretical amount of wheat root stubble resources in Henan Province was 54.304 million tons, and the total amount that could be collected was 39.642 million tons, which could be converted to 23.911 million tons of standard coal, among which the root stubble resources in the four cities of Zhumadian, Shangqiu, Zhoukou, and Nanyang were more abundant, accounting for about 1/2 of the total theoretical amount of root stubble resources in Henan Province; The industrial analysis of wheat stubble samples from different areas in Henan Province showed that the ash content was 10.3%~16.3%, the volatile content was 62.8%~69.1%, the fixed carbon content was 8.50%~14.74%, and the calorific value was 17.10~18.31 MJ/kg, and the total heat of wheat stubble fuel for possible resource utilization was 6.99×10¹¹ MJ. The preliminary analysis of the distribution and energy utilization potential of wheat root stubble resources can provide an important reference and basis for the rational development and utilization of wheat root stubble resources.

The article first collects near infrared spectra and corresponding COD mass concentrations of standard water samples containing Cl, Br, and NO2. Subsequently, the optimal combination of nearinfrared characteristic wavelengths is determined using the interval random frog algorithm, and a COD mass concentration prediction model for highconcentration inorganic anion digestate is established via partial least squares regression. Finally, the model is applied to predict COD mass concentrations in actual biogas slurry. The results show that the determination coefficients (R2) of the COD prediction models for standard water samples with added Cl, Br¯, and NO2 are 0.98, 0.99, and 0.99, respectively, with relative prediction deviations (RPD) of 8.89, 8.95, and 11.75, respectively. For the COD prediction models in biogas slurry, the R² values are 0.77, 0.95, and 0.76, respectively, and the RPD values are 2.23, 5.02, and 2.19, respectively. The model effectively extracts spectral features from nearinfrared data of COD in highconcentration inorganic anion biogas slurry.

The structure of flow channel is a critical factor affecting the performance of proton exchange membrane fuel cell (PEMFC). Optimizing the structure of the flow channel is essential for enhancing the performance and service life of PEMFC. Compared to straight channels, channels with varying shapes can improve reactant gas transport, thereby improving the output performance of the cell. In this study, a serrated channel with periodic crosssectional contraction is proposed. To analyze the transport characteristics and performance of this design, a three dimensional, Multiphysics coupled PEMFC model was developed using computational fluid dynamics (CFD) in COMSOL Multiphysics. The effects of the width and cycle length of the flow channel crosssection on the performance of the fuel cell was investigated. The results show that under high current density, the maximum net power of the serrated channel is increased by 6.12% compared to the straight channel, along with enhanced oxygen transport and liquid water removal. For the serrated flow channel, under the same flow rate conditions, moderate narrowing of the periodic contraction's minimum width improves oxygen distribution uniformity and drainage efficiency. Additionally, moderately reducing the contraction periodicity promotes gas flow velocity uniformity. The serrated channel with a narrowest width of 0.8 mm and a periodicity of 10 mm exhibits the highest net power improvement. However, excessive reduction in the narrowest width and shape variation period increases inlet pressure losses, ultimately degrading system net power.

Dust accumulation in the cover plate of flatpanel solar collector will reduce the heat collection performance, but there are few studies on selfcleaning of the cover plate. The mechanism of particle deposition was analyzed, and superhydrophobic and hydrophobic coatings were selected for dust suppression in flat plate collector. In order to verify the feasibility and quantify the dust suppression effect of the selected coating, natural dust accumulation experiments were carried out on three sets of collectors using superhydrophobic coating, hydrophobic coating and uncoated glass cover plate in Urumqi city, and the performance parameters of each system were analyzed. The results show that the superhydrophobic coating can effectively improve the heat collection performance of the plate collector under the condition of natural dust accumulation, but the effect of the hydrophobic coated glass plate is inferior to that of the bare glass plate. After 16 days of natural dust accumulation,compared with the bare glass cover collector, the transmission ratio of the superhydrophobic coating cover collector is increased by 3.6%, the heat collector temperature is increased by 3.96%, and the heat collection efficiency is increased by 2.94%. In the 16 d overall comparison, compared with the bare glass cover collector, the transmission ratio of the superhydrophobic coating cover collector is increased by 1.66%, the heat collector temperature is increased by 4.09%, and the heat collection efficiency is increased by 2.90%.

Ubend Deep Borehole Heat Exchanger (UDBHE) has attracted much attention because it can effectively exploit deep geothermal energy and has high heat transfer performance. The thermophysical properties of mediumdeep ground generally change with depth, but there is a lack of indepth study on the influence of thermophysical properties of stratified ground on the heat transfer performance of Ubend deep borehole heat exchanger. Based on the UDBHE semi analytical heat transfer model established by the authors, the influence of thermophysical properties (thermal conductivity and volumetric heat capacity)of stratified ground on the heat transfer performance of UDBHE is studied. The results show that the thermal conductivity of each layer of ground has a great influence on the heat transfer performance of UDBHE, while the volumetric heat capacity of ground in each layer also has a certain influence, and the influence increases with the increase of ground layer depth. With the increase of time, the influence of ground thermal conductivity on the heat transfer performance of UDBHE gradually increases, while the influence of ground volumetric heat capacity on the heat transfer performance of UDBHE is basically unchanged. By keeping the weighted average values of the thermal conductivities of all ground layers constant, the heterogeneity of ground thermal conductivity has a great influence on the heat transfer performance of UDBHE, and the larger degree of heterogeneity of ground thermal conductivity would promote the heat transfer performance of UDBHE, otherwise it will inhibit the heat transfer performance of UDBHE. Similarly, the heterogeneity of volumetric heat capacity of ground also has a certain influence on the heat transfer performance of UDBHE, but its influence changes slightly with time. The research results provide important reference value for UDBHE performance prediction and optimization.

Based on the porous medium model, a threedimensional double Utube heat exchanger heat transfer model considering groundwater seepage was established, and the effects of seepage velocity and tube flow velocity on the temperature field of the heat exchanger were investigated by numerical simulation method. Moreover, the comparison of heat transfer performance was completed for the round tube (the crosssectional aspect ratio =1) with the flatoval tube ( is 0.54, 0.44, 0.34, respectively). The results show that increasing the seepage velocity and the tube flow velocity can increase the heat transfer capacity of the tube. When decreases, the heat transfer capacity increases more in the inlet tube than the outlet tube, and more in the vertically arranged tube than the horizontally arranged one. Reducing the aspect ratio of the tube crosssection can reduce the thermal resistance of the borehole and improve the heat exchange capacity of the tube, but it will also make the pressure drop of the tube increase, and the thermal shortcircuit loss is increase. When v=1.50×105 m/s, u=1.3 m/s, compared to the round tube, the heat exchange capacity of the flatoval tube with (=0.34 increases by 11.4%, the thermal resistance of the borehole decreases by 20.52%, and the pressure drop increases by 24.32%.

In order to achieve good aerodynamic and structural performance of wind turbine airfoils simultaneously, an integrated optimization method for aerodynamic shape and internal topology of airfoils is proposed. The airfoil aerodynamic shape is represented using the Hicks Henne type function, and its aerodynamic performance is calculated by using XFOIL. A finite element model of the airfoil is established by using ANSYS, and the structural topology performance is computed. Based on this, a MATLAB program is developed by using a genetic algorithm with the objectives of maximizing the lifttodrag ratio and minimizing the compliance. Five basic airfoils of a 1.5 MW wind turbine blade are optimized under 3 objective weight factors, and the results showed that compared to the initial airfoils, all optimized airfoils exhibit increase in maximum lifttodrag ratio and decrease in structural compliance. At the same time, basically consistent internal structural conceptual design solutions are obtained with the spar caps on the upper and lower surfaces offset towards the leading and trailing edges, respectively. A comparison is made between the new blade using the optimized airfoils and the original blade, and the results indicate that the application of optimized airfoils combined with minor main spar caps offset, the aerodynamic and structural performance of the blades could be effectively improved.

Because of offshore wind turbine fully coupling calculation software FAST V8 can not simulate pile soil interaction, the updated FAST V8 is introduced by distributed linear spring boundary constraint condition and the coupled motion equation of substructure is derived. A coupled numerical simulation model of rotor nacelle –hub towerpile foundation structure with distributed linear spring boundary condition is established. The dynamic characteristics of the base fixed boundary and distributed linear coupled spring boundary model under the combined action of wind and wave are analyzed. The results show that the time history and frequency domain responses of the tower top displacement and the base bending moment change significantly, especially for the secondorder frequency of the structure. At the same time, it can be observed that the distribution spring boundary constraint condition has a more obvious effect on low wind speeds, while the fixed boundary constraint condition model has a more significant effect on high wind speeds.

In view of the declining performance of wind turbines, it is of great significance to construct a set of objective, comprehensive and accurate dynamic modeling methods of wind turbine power generation performance for the identification of equipment operating conditions, operation and maintenance, and assessment of gridconnected performance. This paper establishes a framework for modeling the power generation performance of wind turbines, and establishes a hierarchical "inputoutput" index system for wind turbine power generation performance based on three types of criteria, namely, wind resource characteristics, output characteristics and operation characteristics; and utilizes the fuzzy hierarchical clustering analysis method and fusion data characterization method to construct a subjective and objective combination of multiindicator empowerment scheme, and constructs an absolute performance evaluation model for the power generation performance of the turbine. The absolute performance evaluation model of power generation performance is constructed; the relative power generation performance scale evaluation model of wind turbine is constructed by using the data inclusion analysis method to characterize the operation efficiency of the turbine; the information entropy and temporal degree are introduced to calculate the dynamic timesequence weighting matrix, so as to realize the dynamic evaluation of absolute and relative performance of wind turbine, and to analyze the operation condition and evolution trend; the operation data of wind turbine in a wind farm verify the effectiveness and reasonableness of the proposed system. A case study of wind turbine operation data from a wind farm verifies the effectiveness and rationality of the proposed system.

To solve the problem of multitime scale power and energy imbalance in clean energyrich areas, this paper proposes a collaborative configuration method for seasonal and shortterm hybrid energy storage systems based on the principle of coconstruction and sharing on the power generation side. First, a crossseason sequential coupled operation model of the hydrogen energy storage system is established according to the seasonal output characteristics of hydropower. Second, a coupled operation mechanism of the hydrogenelectric energy storage system on the intraday time scale is proposed. A planning model for the hybrid energy storage system is developed to maximize the annual net income of the generation side after the system is configured. The nonconvex nonlinear programming model is converted into a mixed integer linear programming model. Then, the investment cost of the hybrid energy storage system is reasonably apportioned, considering the differentiated investment risks faced by different stakeholders on the power generation side. Finally, actual data from a region in Zhejiang Province is analyzed. The results show that the proposed method can effectively mitigate seasonal energy imbalance and intraday power imbalance in the region while ensuring the stability of cooperative energy storage system construction among stakeholders on the generation side.

The networking of multiple DC microgrids under DC distribution network will become an effective means to accept largescale distributed energy and load with DC characteristics. The stability research of multivoltage levels DC distribution system is an important issue in its design and operation. Therefore, a stability analysis method suitable for multi voltage levels DC distribution system with multi DC microgrids was proposed. Firstly, the equivalent admittance of each microgrid subsystem is derived according to the control mode of the interconnected converter, and the equivalent openloop gain when each microgrid operates alone is used to judge whether there are right half plane poles in its equivalent admittance; Secondly, the multi voltage level DC distribution system is further simplified into a single voltage level DC system containing only medium voltage bus, and the stability of the medium voltage side subsystem is judged by the equivalent impedance ratio. When and only when the equivalent openloop gain of each microgrid and the equivalent impedance ratio of the medium voltage side of the system meet the Nyquist criterion, the system can operate stably; Finally, based on PSCAD / EMTDC simulation platform, a multi voltage level DC distribution system including two DC microgrids is built for verification. The simulation results show that the proposed stability analysis method can accurately determine the stability of multi voltage DC distribution system with multi DC microgrid.

With the deregulation of the power sector, the power exchange between regions of the power system becomes more frequent, and the stability of the new energy power system is also affected. In order to solve the regional power market power trading and denial of service attacks on the interference of wind power system, a datadriven load frequency control method is designed in this paper. An improved modelfree adaptive control algorithm is designed by collecting the input and output data and estimating the pseudopartial derivative using the compact form dynamic linearization, the antisaturation compensation control algorithm is introduced to solve the output disfollowing problem caused by input saturation, and the stability of the control algorithm is proved theoretically. Finally, taking threeregion wind power system as an example, the validity of the proposed algorithm is verified by MATLAB simulation.

Droop control is a common current sharing method for parallel converters in DC microgrid. However, due to the inconsistency of line parameters and the sampling error of sensors, the current distribution accuracy of traditional droop control is low. In order to solve this problem, this paper proposes a parallel current sharing strategy based on AC signal injection. Firstly, by superimposing an AC voltage small signal on the output voltage of the converter, the droop characteristic between the frequency of the AC voltage and the output current of the converter is constructed, and the reactive power generated by the signal and the feedback mechanism are used to realize the accurate current sharing of the converter. Secondly, the compensation virtual resistance is introduced to improve the stability of the system when the load changes greatly. Then, the design mode switching link stops the injection of AC signals in the steady state, so that the power quality can be improved. Finally, the effectiveness of the proposed control strategy is verified by simulation results.

With the largescale integration of clean energy sources such as photovoltaics and energy storage into the power grid, grid type control technology has obvious advantages in dealing with voltage stability issues in new energy power systems that lack synchronization. However, how to adaptively control the parameters of grid type photovoltaic storage inverters to maintain voltage stability even when the impedance of the power grid changes is an urgent problem that needs to be solved. Based on this, a method for optimizing the control of optical storage grid inverters using a convolutional neural network optimized by the gazelle algorithm is proposed. Firstly, build a control model for grid type inverters and analyze the stability of output voltage; Secondly, based on the convolutional neural network, an inverter parameter control model is established, and the Gazelle optimization algorithm is utilized to optimize the hyperparameters of the convolutional neural network with strong optimization ability and fast search speed, improving the model's feature learning ability and outputting inverter control parameters; Finally, a certain photovoltaic power generation area was selected for simulation verification. The experiment showed that the proposed grid type photovoltaic inverter control method can adaptively optimize control parameters based on realtime changes in grid impedance, achieve stable voltage output, and have strong practical engineering significance.

In Active Distribution Network (ADN), the penetration rate of Renewable Energy Sources (RES) is continuously increasing, leading to more complex and uncertain operational scenarios. This complexity introduces significant risks in the daily operations of ADN. This study proposes a collaborative configuration of distributed power sources within ADN to enhance the absorption capacity for renewable power. The proposed model thoroughly considers the variability of RES, the characteristics of adjustable demand response resources, the bidirectional flow of ADN, and the constraints of safe operation. To address the contradiction between the effective absorption of renewable energy and the economic operation of ADNs, this paper introduces a multiobjective Bayesian optimization algorithm based on hyperspace indicators (EBO). This method probabilistically models multiple objective functions, effectively balancing the exploration of solution space and the unidirectionality of optimization. Moreover, its computational efficiency surpasses traditional heuristicbased multiobjective planning algorithms.

With the development of new power system construction, various energy sources are integrated into the distribution network in the form of clusters and networks, making the distribution network exhibit active characteristics. Fully leveraging the complementary characteristics of multiple energy sources can alleviate the uncertainty of the distribution network while providing sufficient demand for electricity, heat, gas, cooling, heating, and other resources on the demand side. The existing distributed coordinated control methods only consider the gas network, heat network, and power network, without considering the hydrogen energy network. Provide a comprehensive and distributed coordinated control method for active distribution network, heating network, natural gas network, and hydrogen energy network, as well as energy interconnection. Firstly, the economic goal of minimizing operating costs was established, and the constraints of each network were provided; Secondly, a hierarchical control strategy is proposed for the active distribution network, heating network, natural gas network, and hydrogen energy network, and an improved consistency algorithm and particle swarm optimization method are used for solution comparison; Finally, a simulation example of an actual power grid is given, and it is found that the distributed comprehensive energy interconnection scheduling control method can achieve the same results as traditional methods, and the effectiveness of the proposed scheduling control strategy is verified.