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%.

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.

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.

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.

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.

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.

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.

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 rotating blade of wind turbine generates trailing vortex, which affects the flow on the surface of the blade. The vortex generator is installed on the blade surface, and its flow control effect is inevitably affected by the trailing vortex. In order to explore the influence of the trailing vortex, this paper takes the PhaseVI wind turbine as the research object, and establishes a simulated blade with the same spanwise circulation distribution under its rotation condition for numerical calculation. The results are compared with the smooth blade and the airfoil section with VG respectively. It is found that the airflow velocity on the suction surface is larger, the Cp value is smaller, and the pressure difference between the suction and pressure surfaces is increased.