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.

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.

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.

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.

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.

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.

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.

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 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.

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.