Pretreatment and enzymatic hydrolysis of straw type biomass are among the key technologies for its high value conversion and utilization. Using corn stover as the raw material, pretreatment methods with formic acid, sodium chlorite, and alkaline hydrogen peroxide were studied and compared. Methods such as scanning electron microscopy, Xray diffraction, and Fouriertransform infrared spectroscopy were employed to analyze the composition, morphology, crystal structure, and functional groups of corn straw before and after pretreatment. After pretreatment with formic acid, sodium chlorite, and alkaline hydrogen peroxide, the lignin removal rates were 66.71%, 97.12%, and 91.88% respectively, and the enzymatic hydrolysis rates reached 63.26%, 71.83%, and 95.14% respectively. Under the conditions where the cellulase dosage is 19.6 FPU/g, the xylanase dosage is 35.44 IU/g, and the Tween 80 dosage is 20.96 mg/g, the predicted enzymatic hydrolysis rate of corn straw pretreated with alkaline hydrogen peroxide is 95.57%, while the actual enzymatic hydrolysis rate is 94.42%. The optimal feeding strategy for high solid enzymatic hydrolysis was an initial substrate concentration of 8%, with 4% of the substrate added at 6, 12 h, and 24 h respectively. After 120 h of enzymatic hydrolysis, the enzymatic hydrolysis rate reached 87.57%.

The low energy consumption and mild storage and transportation conditions of the clathratebased solid natural gas technology make it a key factor in promoting the development of the natural gas industry. However, the slow hydrate formation kinetics has hindered its application. This article explores the formation laws of methane hydrates supported by porous media (activated carbon and quartz sand) under the action of 1,3dioxolane. It analyzes the hydration efficiency in different systems, evaluates the synergistic and antagonistic effects of 1,3dioxolane and porous media on hydrate growth, and clarifies the influence of the pore structure. The results show that: under high pressure, the adsorption of 1,3dioxolane by the pore structure of activated carbon leads to an antagonistic effect between the two, resulting in poor hydration efficiency. Moreover, as the initial pressure and the concentration of 1,3dioxolane increase, the antagonistic effect intensifies. Under low pressure, there is a synergistic effect between 1,3dioxolane and activated carbon. The hydration efficiency is affected by pressure. The free 1,3dioxolane enhances the formation of methane hydrates and increases the gas storage capacity of hydrates. 1,3Dioxolane enhances the formation of hydrates in the quartz sand system. However, the rapidly growing hydrates limit the conversion of internal water, making this enhancement effect achieve the best performance when the initial pressure is 5 MPa.

This paper takes GE 9HA.02 combined cycle unit as the research object, and innovatively proposes the design scheme of a hydrogen natural gas mixing integrated system in gas turbine power plant, with gas hydrogen long tube trailers as the main hydrogen transmission method and reserved pipeline gas inlet interface. Through the configuration of a hydrogen compressor bypass system, the residual hydrogen stored in the long tube trailer was fully utilized, improving the utilization rate of trailer hydrogen storage. At the same time, a comparative analysis was conducted on the economic feasibility of adding hydrogen to the 9H class gas turbine power plant. Electricity price and natural gas price are more sensitive to the impact on the internal earing rate of return. And in order to meet the requirements, hydrogen price cannot exceed 38.5 yuan/kg. With the development of renewable hydrogen production technology, and driving the further reduction of hydrogen production costs, the promotion and application of hydrogennatural gas mixing integrated system will become increasingly competitive.

The study elucidated the relationship between anaerobic digestion gas production efficiency and temperature and hydraulic retention time (HRT) using synthetic glucose wastewater as a substrate. Gas production under different temperatures (37,55 °C) and HRTs (25, 30, 50 d) was compared. The results indicated that the hydrolysis rate of glucose was higher at thermophilic temperature than at mesophilic temperature. However, volatile fatty acids, especially propionic acid, tended to accumulate at thermophilic temperature. Additionally, Methanomicrobiaes and Methanosarcinales were enriched at both moderate and high temperatures, suggesting the presence of pathways for methane production from acetic acid and acetate oxidation at both temperatures, with the acetate oxidation pathway exhibiting greater environmental resilience. The recommended optimal fermentation conditions for treating heavy glucosecontaining wastewater through anaerobic digestion are 37 °C and an HRT of 30 days.

In order to comprehensively evaluate the power generation performance of solar cells, aiming at solving the problem that the existing photovoltaic (PV) equivalent circuit model cannot estimate its spectral response characteristics, in this paper, an equivalent physical model of solar cells and its parameter identification method based on the finite element method is proposed to estimate its electrical characteristics and spectral response. Firstly, the influence of key parameters in the finite element model on the estimation results of electrical characteristics is analyzed. Six parameters, including the thickness of the emitter region, the thickness of the base region, the doping concentration of the emitter region, the doping concentration of the base region, the series resistance, and the parallel resistance, are determined as the model parameter identification objects. Then, based on the measured currentvoltage (IV) characteristic data under high irradiation conditions, the particle swarm optimization algorithm is used to identify the above parameters. Finally, the IV characteristics under different irradiation and temperature conditions are measured and compared with the model estimation results. Meanwhile, the solar spectrum curves are measured to indirectly verify the accuracy of the spectral response of the solar cell estimated by the model. The experimental results show that the root mean square error (RMSE) of the estimated current for monoSi and polySi cell models are in the range of 0.019 2 A to 0.030 2 A and 0.018 0 A to 0.051 5 A, respectively. The absolute percentage error between the estimated shortcircuit current and the measured shortcircuit current is concentrated below 15%. The proposed equivalent physical model of solar cell and corresponding parameter identification method can comprehensively reflect its actual performance.

Due to the selection of solar radiation spectrum by solar cells in semi transparent photovoltaic windows, the energy consumption, indoor daylight and thermal environment of photovoltaic window buildings are different with clear glass window buildings. When semitransparent photovoltaic windows are applied to building, specific design values for thermal parameters are required for reference, but there is a lack of basis. Therefore, this paper took an office building in Taiyuan as an example, established a reference building model and a design building model, and explored the influence of the Heat Transfer Coefficient (Uvalue) and Solar Heat Gain Coefficient (SHGC) on the energy consumption of semi transparent photovoltaic window buildings. The recommended range of Uvalue and SHGC value of photovoltaic window is obtained by the method of tradeoff judgment. The results show that smaller Uvalue and larger SHGC value are more beneficial to energy saving when photovoltaic windows are used in Taiyuan. When the windowwall ratio of photovoltaic window building is greater than 0.60 and the transmittance is equal to 0.46, the maximum Uvalue limit is 1.9 times the existing energysaving standard limit. By comparing the recommended range of SHGC value with different window wall ratio, the lower limit of SHGC decreases by 25%.

Steam methane reforming membrane reactor removes hydrogen through a hydrogen selective permeation membrane, which can promote the forward movement of the reaction, improve methane conversion rate with reduced reaction temperature, and achieve thermochemical storage under mediumtemperature of trough solar collector. However, the characteristics of multiphysical field coupling in the reactor are complex, and the influence of operating parameters on the performance of the reactor needs to be further investigated. The steam methane steam reforming reaction in the membrane reactor driven by solar at mid temperature was taken as the research object in this paper. The multiphysics coupling model of fluid flow, heat/mass transfer and chemical reactions in the reactor was established by using ANSYS FLUENT, and the effects of the key operating parameters (i.e., inlet mass flow rate, temperature, reaction pressure, water to carbon ratio and permeation pressure) on the reactor chemical and thermodynamic performances were studied. The results show that the methane conversion rate and energy efficiency are negatively correlated with the inlet flow rate. The conversion rate of methane is positively correlated with reaction temperature. The energy efficiency first increases and then decreases with the increase of temperature, existing a peak value. When the inlet flow rate is low, the methane conversion rate and energy efficiency increase with the increase of the reaction pressure, while the methane conversion rate and energy efficiency decrease with the increase of reaction pressure when the inlet flow rate is high. The increase of the water to carbon ratio can significantly improve the chemical reaction performance but reduce the energy efficiency. The lower the pressure on the permeation side, the better the reactor performance. The research results are of great significance for highgrade solar thermal utilization.

This paper intends to design a deep water spiral pile jacket foundation structure for offshore wind power, and use finite element analysis to simulate the load of wind, wave, current, wind turbine, and the bearing capacity and stability of the foundation structure under the conditions of silt and silty soil, and provide a feasible reference for the design of the finite element model of pilesoil interaction of spiral pile structure. This paper also designs a common pile control foundation model without helical blade structure by means of lateral comparison, and explores the influence of single helical blade on the bearing capacity and stability of the foundation structure. The research shows that the addition of singlelayer helical twist blade structure can significantly improve the bearing capacity and stability of offshore wind power pile foundation structure, and has little influence on the natural vibration frequency under the constraint state of the foundation structure. The relevant data can provide suggestions and references for the design of helical pile foundation in practical engineering.

With the depletion of resources in flat terrain, the site selection for wind farms is gradually shifting towards complex terrains. Complex terrain presents geographical conditions distinct from flat terrain, the undulating topography leads to intricate flow patterns, and the wind characteristics in complex terrains are also different. Therefore, studying the distribution patterns of flow fields in complex terrain is significant for micrositing of wind farms and wind power prediction. This paper, based on the opensource software OpenFOAM, establishes geometric and numerical simulation models for complex terrain. It investigates and analyzes grids, boundary conditions, and turbulence models suitable for complex terrain. The reliability of the numerical model for complex terrain is compared and analyzed using real measurement data from the Askervein mountain. The paper solves the flow field distribution for typical complex terrains such as isolated peaks, plateaus, and peak clusters, studying the impact of slope and height on the flow fields in different terrains. The research reveals that different terrains satisfy the Reynolds number independence principle. In isolated peak topography, the influence of slope becomes more pronounced in the lee zone behind the mountain as the slope increases. Plateau terrain is more affected by changes in height. For peak cluster topography, the flow field development remains consistent under varying slopes and heights, with height having a greater impact compared to slope. The provided distribution ranges of flow field characteristic values in this paper can serve as a reference for wind farm micrositing and wind power prediction in complex terrain.

In order to improve the accuracy of ultrashortterm power prediction of wind turbines, this paper proposes a CNNBiLSTM ultrashortterm power prediction method considering the health status of wind turbines and dual attention mechanism. Firstly, considering the influence of the interaction between the environmental factors and the components of the wind turbine on the output power of the wind turbine, he relative error of the normal operation of each component of the wind turbine is used as the deterioration degree of the monitoring index. Secondly, the fuzzy comprehensive evaluation method assesses the health of wind turbines, and the historical data set is categorized based on the evaluation results. Finally, the dual attention mechanism CNN BiLSTM model is used to construct an ultrashortterm power prediction model for the classified data set. The experimental results show that the RMSE and MAE considering the health status of wind turbines are reduced by 17.3% and 20.5% respectively compared with the RSME and MSE without considering the health status of wind turbines.

Aiming at the unbalanced load that the wind turbine is subjected to when it operates above the rated wind speed, an independent pitch control strategy that combines the Radial Basis Function (RBF) neural network and Model Predictive Control (MPC) is proposed. A meanperiod statespace model suitable for controller design is established by means of wind turbine dynamics equations and coordinate transformations. On the basis of Kalman state observer, the model predictive control is used to adjust the pitch angle of the wind turbine instantaneously and the RBF controller to suppress the loads, and then the required independent pitch controller is designed. Taking the NERL 5 MW wind turbine platform as an example, the load characteristics of the independent pitch control strategies based on Proportional Integral (PI), MPC, and MPCRBF are analysed under turbulent winds, as well as their operating characteristics. Simulation results indicate that the method can reduce the load efficiently, improve the operating life of the wind turbine, and have a better suppression effect on the power fluctuation.

In the security and stability analysis of largescale power grid, the wind farm models are usually simplified with the dynamic equivalent modeling method. For a largescale wind farm, due to the large number of wind turbines and the divergences in their characteristics, the wind farm is generally aggregated into multiple equivalent wind turbines. When estimating the parameters of the equivalent wind turbines, in order to avoid identification of a large number of parameters at the same time, the existing method only selects the key parameters with large sensitivity for identification, and the remaining nonkey parameters are not identified by giving the theoretical values. Therefore, the accuracy and robustness of the equivalent model are greatly affected by the accuracy of the assignment of nonkey parameters. In order to solve this problem, the paper proposes a dynamic equivalent modeling method for wind farms based on multistep parameter identification. Firstly, the clustering method is used to group the wind turbines, and the wind turbines within each subgroup are aggregated into one equivalent wind turbine to establish a simplified wind farm model. Secondly, based on the hybrid dynamic simulation technology, the external system of each equivalent wind turbine is replaced with a variable impedance to realize the independent identification of each equivalent wind turbine. Finally, the equivalent parameters of wind turbine are classified based on the trajectory sensitivity, and the classified parameters are identified with a multistep identification method. The effectiveness of the proposed method is verified in a modified IEEE 39 bus system.

In transmission lines, due to the influence of line impedance, it is difficult for energy storage power station systems to allocate power reasonably according to capacity. In order to better promote the stable operation of black start, this article proposes a battery power distribution scheme for energy storage power plants based on improved Virtual Synchronous Generator (VSG). This scheme first introduces virtual impedance to eliminate bus voltage fluctuations caused by line impedance, in order to improve the accuracy of power allocation in energy storage power station systems; Then, in response to the problem of uneven power distribution among multiple energy storage units in parallel in an energy storage power station due to the influence of line impedance, the power transmission and circulating characteristics of multiple energy storage devices in parallel were analyzed to continuously improve the black start system. Finally, experimental analysis was conducted using Matlab/Simulink and semi simulation platforms to verify the effectiveness of the proposed strategy, which can improve the stability and economy of system operation.

When the doublyfed machine is connected to the grid, it can support or raise the frequency of the grid by compensating the active power, but the rotor speed decreases quickly and is not controllable, the time of active power compensation and frequency support is limited, and the stability of motor can not be guaranteed. This paper presents a frequency support technique for doublyfed machine (DFIG) phase modulation system with flywheel energy storage based on virtual synchronization control and dynamic speed limit. Firstly, the flywheel is hung on the rotor shaft of the doubly fed machine to increase the inertia of the system, and the mechanical energy storage, and delay the rotor speed decline rate in the process of frequency drop. Secondly, when the frequency of power grid drops, the realtime compensation of active power is carried out by means of virtual synchronization control strategy, and the compensation time of active power is regulated on demand based on the dynamic control of the lower speed limit of rotor. Finally, the validity of the proposed frequency support technology is verified by Matlab/Simulink simulating.

With the construction of the energy internet and the proposal of the dual carbon goal, the quantitative assessment of carbon emissions of multienergy systems is a key link to achieve lowcarbon operation of the system. Therefore, an optimal operation model of multienergy system considering wind power and PV development trend and carbon emission assessment is proposed in this paper. Firstly, by analyzing the energy input and output characteristics of thermal power units, gas turbines, P2G, and multienergy storage equipment, the topology and multienergy power balance model of the multienergy system are established; Secondly, the generalized Bass model is used to quantify the development trend of wind power and photovoltaic. On this basis, a carbon emission assessment model of the multi energy system considering the development trends of wind power and photovoltaic is established; Then, with the goal of maximizing the total revenue including energy regulation revenue, carbon quota trading revenue and operating cost of multienergy system, an optimal operation model of multienergy system considering wind power and PV development trend and carbon emission assessment is proposed. Finally, the results of the example show that the optimization operation model of multienergy system proposed in this paper can effectively improve the operational benefits and reduce carbon emissions of the multi energy systems.

This article proposes an intelligent charging station energy scheduling system based on machine learning, which is applied to public fast charging station microgrids equipped with photovoltaic systems and energy storage systems using secondary life electric vehicle batteries. The energy dispatch system can be used to address the uncertainty of energy demand for electric vehicles and the power gap between grid connection and fast charging services. In addition, this article uses machine learning methods to automatically synthesize suitable energy scheduling systems based on fuzzy rules. The energy dispatch system proposed in this article considers different electric vehicle fleets and photovoltaic scales, providing a reference for the optimal scale of photovoltaic systems and the effectiveness of nanogrid systems. Finally, in the experiment, a mixed deterministic stochastic process was used to simulate the energy demand of electric vehicles, which showed an improvement in performance compared to the optimal benchmark solution. This indicates that the system can more effectively handle the energy demand uncertainty of electric vehicles and the power gap between grid connection and fast charging services.

The transient power angle stability and voltage stability issues of new energy grid connected systems like wind power are combined, and suffer the risk of short circuit current level. Current research mostly focuses on improving the stability based on single factor, without considering the multiple factors to develop optimization methods for wind turbine control parameters. To solve the issue, an optimization method for key parameters of wind turbine short circuit current and reactive power support is proposed in this paper considering transient power angle stability. Firstly, based on the simplified model of windthermal combined system, the mechanism of power angle stability problem and the influence of active power output of the wind turbine on power angle stability are analyzed. Then, the analytical expression for the shortcircuit current of the directdriven wind turbine is derived, and the key factors that influence the levels of active and reactive currents are analyzed. Finally, the influence of key parameters of short circuit current on the reactive power voltage support capacity of wind turbines are studied by simulation, based on which the optimization principles and method for key parameters of wind turbine short circuit current and reactive power support considering transient power angle stability are developed. The simulation analysis results based on actual power grids show that the proposed method can improve the reactive voltage support capacity of wind turbines while ensuring transient power angle stability margin and short circuit current level.