In order to make reliable dynamic prediction of the potential risk of pitch system, aiming at the problems of multiple components, complex system and difficult fault feature extraction of pitch system, the fault tree is established through the induction and analysis of its fault point and fault transmission process, and then it is transformed into a dynamic Bayesian network (DBN) integrating Leaky Noisyor nodes, which ensures the accuracy of the model and has the dynamic prediction ability. The model is optimized and verified by using a 5fold crossvalidation method. The test results show that this method has high accuracy in risk prediction, fault cause analysis and risk dynamic evolution process analysis of pitch system, and has engineering application value in guiding the preventive maintenance of pitch system and ensuring the overall safety of wind turbine.

Citric acid is one of the most productive biomass organic acids in the world and has been widely used. In this paper, we used reduced iron powder as iron source, citric acid as multidentate ligand and carbon source, and used ammonia to enhance the coordination solubilization ability of citric acid to iron powder, so that it could quickly form a homogeneous complex solgel, which was then carbonized to obtain carboncoated coreshell ironbased FischerTropsch catalyst. In the performance test, the catalyst synthesized by direct dissolution of iron powder with citric acid exhibited remarkable catalytic activity and stability, giving the CO conversion of 99.2%, C5+ hydrocarbon selectivity of 53%, and the CO conversion activity was stably kept above 97.3% for a time on stream of 168 h. The citric acid coordination method is greener and safer, which avoid the use of iron salts such as ferric nitrate, and the risk of explosion and toxic gases in the reduction process of iron salts. This synthesis method provides a new idea for the green and safe production of catalysts.

Ammonia synthesis based on hydrogen derived from renewable electricity (i.e. green hydrogen and green ammonia process) is frequently fluctuated due to weather change and the sections are highly coupled. To understand the synthesis and scheduling of power generation and transmission, hydrogen production by water electrolysis, hydrogen storage, electrochemical energy storage, and ammonia synthesis sections in green ammonia process, a generic process model for both steadystate and dynamics mode was developed using the next generation process simulation software, AVEVA Process Simulation, and the dynamics response of the model to weather fluctuation was investigated by means of multisteady state simulation. The results show that optimized design and scheduling of the hydrogen storage and electricity storage modules can significantly stabilize the ammonia production, utilize excess renewable electricity, reduce grid power input, and thus, improve the economy.

Voltage violation has become an important factor limiting the maximum integration capacity of photovoltaics. To address the issue of voltage violation caused by largescale photovoltaic grid connection, the article proposes a grouped coordinated voltage control strategy for distribution networks with high proportions of photovoltaics. Firstly, based on the different voltage sensitivities of photovoltaic connection nodes in the distribution network, the concept of grouped coordinated control for photovoltaic inverters is introduced. Then, within each group of photovoltaic inverters, voltage control is carried out using capacity utilization ratio and power factor as consistent variables, while intergroup coordination control ensures that the voltage at key nodes converges to the set value of 1.05 p.u.. Finally, through case simulations, the proposed control strategy is verified to effectively suppress voltage violations in distribution networks, avoid unnecessary active power reduction, and demonstrate strong robustness during load and photovoltaic fluctuations.

With the increasing penetration of distributed energy in the power system and its output uncertainty, the distribution system presents greater complexity and uncertainty, which will have an impact on the reliability of the power network. In order to determine the optimal installation location and capacity size of renewable units in the distribution network system, this paper proposes a reliability assessment framework by combining the stochastic fuzzy expected value operator and Markov Monte Carlo method. The model first establishes the multi state probability density functions of wind and PV outputs, and subsequently employs the stochastic fuzzy expected value operator to simulate the uncertainties of power loss and voltage stability in the distribution network. The stochastic nature of all nonsource components in the distribution system is modeled using the Markov Monte Carlo method to generate distribution network component failure events and recovery times from an exponential distribution, considering the topology of the distribution system. Three reliability indices, namely, average system outage number, average system outage duration, and power shortage expectation, are evaluated on the IEEE 33 node standard distribution network, and the experimental results demonstrate the effectiveness of the proposed method.

With the proposal of the "double carbon" goal, the structure of the new power system with new energy as the main body has changed significantly, especially the access of large capacity offshore wind power units, which has brought harmonic and other power quality problems to the grid. In order to study the characteristics of low frequency harmonics generated by fan connection, firstly, a theoretical model of low frequency harmonic content in the gridconnected current of fan is established. Then, an offshore wind power simulation model is built on the simulation software ETAP to verify the output harmonic characteristics of the wind farm under different output conditions. Finally, based on the output harmonic characteristics of the wind farm, the variation coefficient synthetic weighting method is proposed to optimize the configuration of the active power filter (APF) in the wind farm to improve the control effect of the harmonic in the wind farm, and the effectiveness of the method is verified by simulation based on an actual example.

The photovoltaic (PV) module slicing technology is an effective method to improve the module power, but the change of the structure brings some difficulties to the modeling of PV module output performance under complex situations. In this paper, a performance simulation method for halfcell photovoltaic module under shading conditions is proposed. To simulate the output performance of halfcell PV module under shading conditions, the method is based on the single cell and combined with the series and parallel structure of the equivalent circuit. Finally, four different shading experiments are used to verify the accuracy of the algorithm. The average deviation between the measured values and the calculated power of the PV model is 2.42%, which proves that the method has high accuracy. In addition, the output performance of halfcell and fullcell PV module under different shading conditions is compared. The results show that halfcut PV module have more obvious advantages than fullcell module under most shading conditions.

Reverse electrodialysis (RED) technology relies on the permeation selectivity of ion exchange membranes (IEMs) and the conversion of salinity gradient energy of working solutions into membrane potential, which can be used for power generation or driving electrochemical reactions. The progress in domestic patents in RED field was introduced. First, the tradeoff assessment mechanism of suitable IEMs for a RED system was discussed from the perspectivesof membrane resistance, membrane thickness, ionic selectivity, ionic exchange capacity, fouling resistance, antibacterial ability and stability. Accordingly, the IEMs modification methods and optimization development directions were analyzed. Then, the development and patent layout of RED technology in the fields of power generation, hydrogen production, wastewater treatment, seawater desalination, were reviewed emphatically. Besides, several energy conversion technical routes were ascertained, including (thermal energy→)salinity gradient energy→(electricity→) hydrogen, etc. The regeneration methods and development process of the cycling working solutions were elucidated. The RED technology is suggested to be coupled with the electrodialysis, renewable energy generation, and lowgrade heat recovery technologies, which is an effective strategy to achieve complementary advantages of various technologies and beneficial to improve the output capacity and energy efficiency.

The INVELOX wind power generation system is a kind of wind collection system with ducts, which can obtain wind power in multiple directions and at low wind speeds. The system efficiency depends on the ratio of the wind speed of incoming wind direction to the average wind speed of the venturi, that is, the velocity ratio SR. In this paper, model optimization was carried out based on INVELOX system, and taking the design of a small style wind collection device as the research object. The fluid dynamics calculation software XFlow based on Lattice Boltzmann method (LBM) was used to numerically simulate the flow field characteristics of the device at different wind speeds. By calculating the SR ratio in the Venturi tube, the critical working wind speed was 3 m/s. Through the analysis of the VSR diagram, it can be concluded that the device enhanced the wind speed in the environment with the increase of the wind speed in the flow field. At the same time, considering the application in the environment, taking 6 m/s as the wind speed of the flow field and carrying out the simulated analysis of the horizontal and oblique incoming wind to obtain the wind speed variation in the working section of the Venturi tube at different Angle of attack, which provides a reference for the engineering application of the energy acquisition device.

In order to achieve high efficiency and clean combustion of crop straw in Bashang area, typical naked oats straw was selected as the research object to analyze the pyrolysis characteristics. The pyrolysis atmosphere environment in the combustion process was created by simulating flue gas with mixed gases. The thermogravimetric analyzer was used to study the thermogravimetric characteristics and the influence of temperature rise rate on the mixed gas atmosphere composed of air and N2, CO2, and O2 in different proportions. The AKTS software was used for kinetic analysis. The results showed that: the pyrolysis process of naked oats straw was divided into three stages, which were drying stages (30~140 °C), volatilization stages (140~370 °C), carbonization stages (370~900℃). Gas atmosphere mainly affected the pyrolysis of carbonization stage, drying and volatilization stage had little effect, heating rate affects volatilization and carbonization stage, the faster the heating rate, the greater the reaction rate. When the pyrolysis atmosphere was 15%O25% CO280% N2 mixed gas (gas 2), the activation energy required for pyrolysis process was the least, and the average activation energy was 139.86 kJ/mol. The results provided a certain theoretical basis for the energy utilization of biomass straw in the alpine Bashang area.