This study aims to address the challenges of phosphorus recovery and solid waste treatment by preparing biochar composites(OSCS) using a copyrolysis method with cotton straw stalk and oil shale as raw materials. The physicochemical properties of the biochar were analyzed using SEMEDS, BET and FTIR tests. The influence of pyrolysis temperature, adsorbent dosage, and solution pH on phosphate adsorption was investigated, and both the adsorption kinetics and isotherm models were studied. The results indicated that the structural properties and surface morphology of the biochar were significantly enhanced through oil shale modification, leading to a notable improvement in phosphate adsorption capacity. At an injection level of 4.0 g/L and pH5.0, the maximum adsorption capacity reached 7.01 mg/g, which was 2.47 times higher than that of cotton straw biochar and 3.52 times higher than that of oil shale char. The adsorption process followed the proposed secondary kinetics and Langmuir isothermal adsorption model, and the mechanisms involved surface precipitation, ligand exchange, and electrostatic attraction. This approach of oil shale modified biochar composites provides a novel strategy for both phosphorus removal and solid waste resource utilization.

LiN2 battery is a new type of energy storage system with the function of electrochemical nitrogen fixation, and the electrochemical model established in the article used finite element software COMSOL coupled with multiphysics field can reveal the influence of various factors on its discharge performance. The simulation results show that: the discharge current density, temperature, cathode porosity and N2 solubility factor in the electrolyte have an effect on the discharge performance of LiN2 battery; a larger discharge current density will reduce the voltage and capacity of the battery; cathode porosity and N2 solubility factor in the electrolyte are the key factors that affect the voltage and capacity of the battery, and increasing the cathode porosity and N2 solubility factor in the electrolyte can increase the voltage and capacity of the battery; With the temperature rising, the voltage of the discharge platform of the battery increases, but the discharge capacity is almost unaffected by temperature.

At this stage, the power generation performance of photovoltaic power plant is usually evaluated by performance ratio (PR). In the field test of short term, the PR of whole photovoltaic system will be affected by the temperature, leading to an obvious deviation of PR, which causes interference for the power generation evaluation of plant. Based on the system PR correction calculation method in IEC 617241 2016 standard, this paper analyzes and studies the modules temperature calculation method and temperature correction calculation method. Through the comparative analysis of examples, the system PR temperature correction method with higher accuracy is summarized and given, which brings convenience for the rapid system measurement and calculation, and increases the reliability and accuracy of the system PR evaluation. The analysis results show that the method of weighted average temperature of the module which considers the temperature and irradiation weight is more accurate than the method of module average temperature correction; the system PR can be evaluated much more accurately by the method that is corrected to the annual weighted average temperature of the module.

The instantaneous heat collection of the nontracing compound parabolic concentrator is greatly affected by the incident angle. Therefore, in this paper, the PV module with a mirror on its backside was arranged above the focal spot of the traditional compound parabolic concentrator to realize the reuse of the escaped light and improve the solar energy conversion efficiency of the device. The ray tracing of the novel compound parabolic concentrator based on photothermal photovoltaic coupling energy supply was carried out with optical software, and the influence of radial incident angle on the light receiving rate was compared and analyzed. In the actual environment, the variation of the inlet and outlet temperature, instantaneous heat collection and output power of the novel compound parabolic concentrator with time were tested and studied. The results indicate that the light receiving rate of the novel compound parabolic concentrator is consistent with that of the traditional compound parabolic concentrator. When the radial incident angle is 20°, the light receiving rate of the novel compound parabolic concentrator is 89.00%, which is 72.82% higher than that of the traditional compound parabolic concentrator. In sunny days, the maximum outlet temperature, the photothermal conversion efficiency and the daily output power of the novel compound parabolic concentrator. are 34.20 °C, 73.40% and 118.40 W, respectively.

This study addresses challenges associated with conventional parabolic trough solar power systems, including limited operating temperature and excessive thermal stress caused by uneven energy flux density distribution on the vacuum absorber tube's surface. Rather than altering the parabolic trough collector's structure, we introduce an innovative vacuum absorber tube design. This design involves reducing the diameter of the inner metal tube, shifting it downward, and adding a hyperbolic secondary concentrator above it to enhance solar energy concentration and improve energy flux distribution on the inner metal tube's surface. Simulation results for the new vacuum absorber tube yield promising outcomes. Optically, this novel design increases the concentration ratio from 62 to 71 and improves the uniformity of energy flux distribution by 55.05%. Importantly, these improvements come at the cost of only a 1.88% reduction in optical efficiency compared to traditional vacuum absorber tubes. Consequently, these modifications offer a substantial boost to the overall performance of the parabolic trough collector.

Pitch control of large wind turbine is a complex nonlinear control task. How to achieve power regulation and load reduction under system constraints and wind speed disturbance has become a problem. For this problem, a controloriented linear parameter varying (LPV) model is constructed by using mechanism and parameter identification methods. The gap metric theory is introduced to reduce the complexity of the model, which provides a more accurate linear model for control design. Based on the obtained optimal states, an adaptive model prediction pitch controller (MPC)is proposed with the change of realtime wind speed. The coordinated control of powerload for large wind turbine can be realized under the conditions of system constraints. The simulation examples of OpenFAST show the effectiveness of the proposed model and controller.

In the construction of floating wind farms, various soil conditions may be faced. Based on the needs in practice, a kind of anchor named gravity penetration column anchor is proposed for the soil with high permeability, where has high risk of installation by suction. The finite element method was used to analyze the penetration process and bearing characteristics of this kind of anchor. The analysis results show that in the coarse sand, the gravity penetration column anchor can penetrate to the design depth by its own weight. Unlike ordinary gravity anchors, which mainly provide anti sliding force through friction at the anchor bottom, the gravity penetration column anchor is shallow failure under horizontal load, and can mobilize more soil resistance during the failure improving its anti sliding ability effectively. The gravity penetration column anchor can provide a horizontal bearing capacity of more than 2 000 t, which is nearly twice that of conventional gravity anchors, and can meet the bearing requirements of floating wind turbine. This kind of anchor could provide more choices for offshore floatingturbine in China.

In response to stability issues caused by the dynamic response of wind turbines, in order to study the numerical response of the wind turbine under different wind speeds, a threedimensional structural model of the wind turbine is established based on SolidWorks, the blade root and tip particles are extracted, and the stress and displacement trends under different wind speeds are analyzed by using the finite element analysis method. The wind speed attenuation in the pendulum direction and the brandishing direction of the wind turbine is studied and the shear stress distribution of the flow field near the blade surface is discussed. The results show that the stress and displacement of blade tip and blade root have certain regularity under different wind speeds. When the natural wind passes through the wind turbine, the wind energy is effectively captured, and then shows regular attenuation. This study provides reference value for the dynamic parameters of wind turbine operation and improves the stability of wind turbine operation.

Offshore wind turbines installed close to earthquakeprone zones are not only affected by wind and wave loadings, but also threatened by earthquakes. In order to reduce the earthquake impacts on the structural vibration and load of largescale wind turbines, a seismic coupled analysis and structural control architecture has been developed by improving FAST based on the modal acceleration method and the Tuned Mass Damper (TMD). The control effects of TMD on tower vibration and load reduction of the IEA 15 MW monopile wind turbine due to different ground motions are investigated. The results show that the TMD can significantly reduce the towertop displacement and towerbase load for each examined ground motion. The best effect on alleviating towertop vibration is achieved when the tuning frequency ratio of the TMD is 0.9, reducing the tower top displacement by 89.8%. The fluctuation amplitude of towerbase bending moment following the earthquake event is significantly reduced by the TMD with a tuning frequency ratio of 0.8 that is capable of reducing the standard deviation by up to 99%.

With the continuous development of renewable energy, a large number of inverter interfaced distributed generations (IIDG) are connected to the distribution network, which puts forward new requirements for the traditional relay protection technology. In order to improve the power supply reliability of distribution network and adapt to the new power system with large penetration of renewable energy, an adaptive distance protection is proposed for distribution network with Tconnected IIDG. Firstly, the influence of fault at different locations on the protection is analyzed. According to the output characteristics of IIDG in case of system fault, the output current of IIDG is calculated by BP neural network using the local electrical information of the protection, and the action value is set immediately. Because this method does not need to communicate with the remote, the action speed is fast, and the investment of the communication system is reduced. Finally, the 10 kV distribution network model with Tconnected IIDG is established in MATLAB, and compared with the traditional distance protection to verify the superiority of this protection method.

The solar heating system coupled with seasonal thermal storage is a promising solution to solve the seasonal mismatch between the solar energy supply and heating demand. The thermal performance of the system in the heat storage season has a significant impact on the system's annual operation performance, and has a direct impact on the discharging process of the seasonal storage in the heating season. Therefore, based on the solar heating system coupled with seasonal thermal storage in Fanshan Town, Zhangjiakou, a dynamic simulation platform is built. The influence of different operation strategies on the performance of the system is analyzed by experiment and simulation methods. Results showed that the control strategies were significant for improving the heat collection performance of solar receiver and the exergy efficiency of the UWPS. The stratification of the seasonal storage has an impact on the collection efficiency of the receiver, especially at the end of the nonheating season. In addition, at the end of the nonheating season in typical year, the monthly solar collection efficiency could be increased by 4.8% in variable flow control compared to the temperature difference control.

Due to the intermittency and uncertainty of wind power on the time scale and complementarity on the spatial scale, the line capacity is underutilized and the cost of wind power is high in traditional planning. Combined with the output characteristics of largescale wind power, considering the smoothing effect, the construction cost of transmission projects, the cost of wind power curtailment, and the income, the economic evaluation model of offshore wind farm aggregation system is established, and the model is solved by using an improved genetic algorithm. The genetic algorithm is improved based on the minimum spanning tree of dynamic weight variation, and the coding, selection, crossing, and mutation links in the genetic algorithm are improved to promote the efficiency of the algorithm. Taking a wind farm cluster in Jiangsu Province as an example, the topology of wind turbines and the convergence and connection mode of wind farms are optimized, and the results show that the proposed algorithm has good optimization and convergence. And the established topology optimization model of wind farm and internal wind turbines can effectively reduce the engineering investment.

This thesis constructs a coupling system inactive adjustment model for system voltage output of wind power fluctuations in renewable energy and thermal power generation coupling systems, and constructing coupling system reactive modulation models, on the basis of considering communication delays, The voltage deviation is quantified index to analyze the effect of reactive power control on voltage stability in coupling system. A coupling system bilateral reactive control optimization strategy for fusion SVG and wind turbines as reactive modulated resources is proposed. The upper layer is based on SVG as an inactive adjustment device, and the system's overall power factor optimization model is constructed by the respective node voltage deviation. The lower layer is a node having a large voltage deviation. The wind turbine near the node is used as an inactive adjustment device. The system voltage deviation is optimal, and the wind turbine reactive optimization model is constructed, and the algorithm combined with Ybus and LinWPSO is used. Solve the optimization model and derive the wind power unit reactive reference value. The case simulation results show that the twolayer reactive policies mentioned in this paper make full exertion of the powermodulated potential of the wind and motor sets, which can take care of the voltage fluctuations and web damage of the coupling system, and reduce the disturbance of the renewable energy power fluctuations on the coupling system, improve coupling the voltage stability of the system.

In recent years, with the rapid growth of the scale of distributed photovoltaic deployment in cities and towns, the impact of random fluctuation characteristics of its output on urban load is also increasing. The traditional method is difficult to accurately predict the complex load fluctuation after largescale deployment of distributed photovoltaic system, which is not conducive to the safe and stable operation of power grid. To solve these problems, this paper proposes a shortterm load forecasting method considering distributed PV. Since the net load including distributed PV is the difference between the actual consumption load of the user side and the PV output, this paper first adopts the big data mining technology to analyze the characteristics of PV output and the userside load as well as the correlation between the two and their respective influencing factors before constructing input data, and selects the influential factors with high correlation as the input feature set of the net load prediction model. Secondly, the LSTM neural network prediction model integrating selfattention mechanism is constructed to deeply explore the characteristics of load sequence. The grey Wolf algorithm is used to optimize the parameters of the prediction model and determine the model with the best prediction effect. Finally, an example simulation shows that the proposed method can effectively improve the prediction accuracy of net load with distributed PV.

With the increasing penetration rate of new energy in the distribution network, the bearing capacity of new energy in the distribution network is facing challenges; The electric heating load has a certain degree of adjustability and has the potential to participate in the load dispatch of the distribution network. How to improve the new energy bearing capacity of the distribution network through load dispatch has important practical significance. The article proposes a dynamic optimization scheduling strategy for electric heating loads in distribution networks that considers the bearing capacity of new energy. Firstly, a regulation model for the load of thermal storage electric heating was constructed; Then, with the goal of bearing capacity of new energy in the distribution network substation area, and with the constraints of smoothing load fluctuations, stable and safe operation of the distribution network, and user comfort of the heating load, a dynamic optimization scheduling model for the heating load of the distribution network was established, and a solution strategy based on quantum genetic algorithm was proposed. The Latin hypercube sampling method is used to generate typical application scenarios for the applicability analysis of dispatching strategies for the new energy bearing capacity of distribution networks. The calculation results show that the proposed method can fully consider the potential for regulating the electric heating load and improve the application level of new energy in the distribution network.

With the construction and promotion of greener grid, the old electricity marketing process is facing new challenges. Therefore, in order to suit the new requirements of electricity marketing, this paper proposes an electricity pricing method based on the careful consideration of regional carbon emissions. Firstly, consider the economic compensation of carbon emission reduction incentive and controllable load participating in peak regulation response, a load mobilization cost model considering carbon emission and peak regulation cost is established. Then, based on the idea of game theory, the demandside controllable load and energy storage device are used as schedulable resources to construct a 1K Stackelberg masterslave game decision model. Finally, the inverse induction method is attached to solve the model. We can see from the results that the proposed electricity pricing method of new energy power grid considering regional carbon emissions can promote the optimal operation of power system and realize the double improvement of efficiency and benefit of new distribution network.

With the rapid penetration of new energy sources such as photovoltaic power generation, the power system has put forward higher requirements for its participation in primary frequency regulation, requiring it to support the power grid in a more flexible way. In order to achieve more comprehensive frequency regulation, the key indicators for evaluating frequency quality are first determined according to the relevant grid specifications. Then, with the help of the motion equation of synchronous generator rotor, the effects of the constant of inertia and damping gain on the frequency quality are analyzed. Based on these research results, a coordinated control strategy of virtual inertia and frequency damping is designed, aiming to achieve the optimal frequency support of photovoltaic system with a certain power reserve. Finally, the performance of the proposed control strategy is verified by simulation, and the advantages and effectiveness of PV system participating in primary frequency regulation are displayed. By coordinating between virtual inertial control and frequency damping control, photovoltaic systems can support the frequency stability of the grid in an efficient manner.

In order to solve the problem of integrated energy coordinated dispatching, the design of virtual power plant based dispatching platform and the application of integrated energy coordinated dispatching model were proposed. The basic grid structure of virtual power plant is analyzed, and the overall architecture of virtual power plant is designed, which is divided into resource layer, platform layer and application layer. A network architecture and data flow architecture are designed. Based on this architecture, a virtual power plant scheduling application model for comprehensive energy coordination is established. The models for photovoltaic, wind power generation, electrolyzers, fuel cells, hydrogen energy storage, and battery energy storage are built, with reliability indicators as the starting point, an objective function with the lowest cost throughout the whole life cycle is proposed, and numerical examples are analyzed to illustrate the advantages of the proposed model in terms of reliability and cost.

Considering the inconvenient installation and the poor ability to capture wave energy in the traditional directdrive wave energy converter (DDWEC), a series connection floating twobody DDWEC is proposed in this paper. Two rectangular bodies of the WEC float horizontally in the waves bodies and both capture the wave energy. The primary and secondary of the Halbach array permanent magnet linear generator(HPMLG) are respectively installed on the lateral surface between the two floating bodies. Because both floating bodies capture wave energy, the ability of the WEC to capture wave energy is improved, and the structure of the WEC is simple and easy to manufacture and maintain. Then, the prototype of the twobody DDWEC is manufactured and tested in the wave tank in this paper. The experimental results show that in the case with the wave height of 16 cm and the draft of 16 cm, the average generated power of the prototype reaches the maximum value of 6.54 W at the wave period of 1.8 s, when the wave period ranges from 1.2 s to 2.4 s. Finally, the twobody DDWEC prototype is compared with the singlebody DDWEC prototype. The results show that the average power output of the twobody DDWEC prototype is always higher than that of the singlebody DDWEC prototype in a large range of wave period.