Search

Energy storage and virtual power plant technologies have been developed and become important technical means to enhance power system stability and reduce real-time dispatching costs. In this study, the dispatching capability and dispatching cost characteristics of the virtual power plants are analysed firstly in detail, as well as the dispatching difficulties under the traditional market modes. Hence, virtual power plant real-time bidding package model and virtual auction-based real-time power market mechanism are proposed. Data-driven virtual power plant real-time packing method and bidding package model integrated virtual Vickrey–Clarke–Groves auction model are put forward. Finally, the feasibility and validity of the proposed mechanism and method are verified by case studies and result in analyses of the IEEE-30 bus test system with multiple virtual power plants, providing a scientific foundation and a practical solution to the real-time power market.

The North China Plain plays a pivotal role in China's crop production, contributing to 30% of the maize yield. Nevertheless, summer maize in this region faces challenges due to climatic constraints characterized by concurrent high temperatures and rainfall during the growing season, resulting in a relatively high evapotranspiration rate. In this study, we explored eight soil moisture-based threshold irrigation strategies, consisting of two upper limits and four lower limits, along with a rainfed mode (E). The upper and lower irrigation limits are expressed as a percentage of the field's water-holding capacity (sfc). For the four full irrigation modes (A1, A2, A3, A4), the lower limits were set at 0.6 sfc, 0.6 sfc, 0.5 sfc, and 0.5 sfc, respectively. The upper limits were defined at two levels: 0.8 sfc for A1 and A2 and sfc for A3 and A4. Similarly, for the four deficit irrigation modes (B1, B2, B3, B4), the lower limits were established at 0.4 sfc, 0.4 sfc, 0.3 sfc, and 0.3 sfc, respectively, with the upper limits set at two levels: 0.8 sfc for B1 and B2 and the full sfc for B3 and B4. To investigate the impact of rainfall and potential evapotranspiration on these irrigation modes under long-term fluctuations, we employed a stochastic framework that probabilistically linked rainfall events and irrigation applications. The Monte Carlo method was employed to simulate a long-term series (4000a) of rainfall parameters and evapotranspiration using 62 years of meteorological data from the Xinxiang region, situated in the southern part of the North China Plain. Results showed that the relative yield and net irrigation water requirement of summer maize decreased with decreasing irrigation lower limits. Additionally, the interannual variation of rainfall parameters and evapotranspiration during the growing season were remarkable, which led to the lowest relative yield of the rainfed mode (E) aligned with a larger interannual difference. According to the simulation results, mode A4 (irrigation lower limit equals 0.5 sfc, irrigation upper limit equals 0.8 sfc) could be adopted for adequate water resources. Conversely, mode B2 is more suitable for a lack of water resources. [ABSTRACT FROM AUTHOR]

Aiming at the two types of defects as affecting the quality of the 40CrMnMo seamless steel pipe, the reasons for the defects are analyzed by means of testing the alloy composition, the inclusions and the characteristics of the defect based on the manufacturing process, and accordingly corrective measures are proposed. The results show that the first type of the defect is the straight line rolling imprint which is identified via the analysis as a kind of rolling fold caused by the surface cracks of the rolling tool; the second defect is the crack of the pipe body which is recognized as quenching crack caused by excessive quenching-cooling speed. Finally the above mentioned quality problem of the pipe is fixed by means of improving the quality of the rolling tool and optimizing the quenching process. [ABSTRACT FROM AUTHOR]

A series of ZnGa2−xO4:xCr3+ phosphors with blue–red dual light emission were synthesized by microwave-assisted solid-phase method and corresponding characterizations were conducted to investigate its structure, micromorphology, and luminescence performance. Blue–red dual light emission at around 470 nm and 690 nm was successfully achieved. Quenching concentration of Cr3+ in ZnGa2O4 was 2.0 mol% and the theoretical quenching concentration was calculated to be 2.0 mol%. Quenching mechanism was discussed detailedly with the help of Dexter's theory. Emission spectra of optimal ZnGa1.98O4:0.020Cr3+ phosphor measured at T = 298–473 K were also analyzed, and zero thermal quenching was finally achieved. Both the emission spectral profile of ZnGa1.98O4:0.020Cr3+ at 298 K and 423 K can match well with the absorption spectra of four biological pigments in plants. All these findings greatly improved the possibility for its application in plant cultivation. [ABSTRACT FROM AUTHOR]

The use of Mn4+-activated deep-red phosphors has continued to increase in plant growth lighting. Of all phosphors, the complex perovskite LaMg0.66Nb0.34O3 (LMN) exhibiting high structural tunability is considered one of the most suitable structures. In this study, the representative LMN:Mn4+ was synthesized and a defect was introduced into the matrix to improve its thermal stability. Moreover, a computation method with density functional theory (DFT) was adopted to acquire the local crystal structure and the results showed that both the emission intensity and the thermal stability of the phosphors clearly improved. Importantly, we found that the emission intensity at 423 K still reached 82.4% of that at 298 K, which is crucial in plant cultivation applications. [ABSTRACT FROM AUTHOR]