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In order to improve the economy of microgrid construction and operation, and meet the personalized demand for reliability of various types of microgrids, an integrated flexible planning method for microgrid is proposed to adapt to multiple scenarios. Based on the judgment results of type and composition, a two-layer model including capacity planning and grid planning is established. The lower-level capacity planning takes the minimum operation cost of micro-source construction as the goal and adopts the mixed integer optimization algorithm to solve it. The upper layer grid planning takes the minimum cost of network construction and operation as the goal, and uses the particle swarm optimization algorithm to solve it. A closed-loop integrated planning system consisting of judgment, capacity planning, and grid planning is formed. The system can meet the personalized reliability requirements of different microgrids by flexibly adjusting the independent operation duration constraints and the load outage attention parameters. The example shows that the proposed method can effectively reduce the construction and operation cost of microgrid, and has a good adaptability to different types and components and different reliability requirements.

The performance of tritium-based nuclear batteries based on two different energy conversion modes, the irradiated voltaic effect and irradiated photovoltaic effect, was studied by using the Monte Carlo method. The influence of the geometrical-physical parameters of energy conversion materials on the electrical output performance of batteries wais investigated. Single-layer and stacked-layer tritium-based nuclear batteries were designed and prepared. The effects of increasing the tritium source intensity and adopting the stacked-layer configuration on the enhancement of the electrical output of the batteries were analyzed. The simulation results showed that Si, SiC, and GaAs photovoltaic modules could be used for irradiated voltaic effect tritium-based nuclear batteries and that their respective optimal thickness parameters allow the electrical output performance to be optimized; the optimal thicknesses were 3.8 μm, 2.2 μm, and 1.7 μm, respectively. For irradiated photovoltaic effect tritium-based nuclear batteries, the thickness of the ZnS:Cu fluorescent layer could be adjusted to maximize the emitted fluorescence irradiance and optimized the electrical output performance. The experimental results showed that increasing the radiation intensity of the tritium source and adopting the stacked-layer configuration could effectively enhance electrical parameters such as the maximum output power of tritium-based nuclear batteries. The maximum output power of the stacked-layer nuclear battery could reach 106.138 nW, which was an increase of more than 64% compared with that of the single-layer configuration.

BackgroundA general-purpose heat source (GPHS) is the most established heat source module for radioisotope thermoelectric generators (RTGs) and a key reference for the equivalence of electrically heated analog heat sources during the development and testing of radioisotope power supplies.PurposeThe study aims to develop a highly efficient electric heating simulation heat source to meet the requirements for equivalent testing and verification of non-nuclear units of radioisotope power systems.MethodsFirstly, an electrically heated analog heat source was designed and imitated based on various actual GPHS performance parameters. Based on the simulation calculations, the thermodynamic equivalent substitutability between the simulated heat source and real GPHS in terms of material and dimensional differences was evaluated. Then, the performance of its operation in different application scenarios was analyzed, and an optimized application environment was proposed. Finally, based on the experimental test results, the uniformity of the thermal output characteristics of the imitation GPHS-simulated heat source was compared with that of a real GPHS, and the practical application characteristics of the imitation GPHS in RTGs were also evaluated.ResultsAt an input power of 250 W, the average surface temperature of the GPHS-simulated heat source reaches 515 K. The temperature variation trend with power is consistent with that of the simulation results. Experimental test results show that the energy conversion efficiency of the RTG module is increased to ~6% with a 250-W heat source power supply.ConclusionsThe proposed and constructed good equivalent simulated GPHS heat source with reference to the thermal properties of a real GPHS can be applied to RTGs and provides an effective and unified reference standard for the performance evaluation of radioisotope power sources.

The soil structure was severely destroyed, and the content of organic matter and fertility was extremely low in reclaimed soil in the coal-mining subsidence area. How to improve the soil fertility and recover soil productivity was a critical problem for sustainable agriculture in this area. Nitrogen fertilizer was one of the largest amounts of fertilizers used in agricultural production, and the nitrification of ammonium to nitrate was an important nitrogen transformation process in dryland soil. Numerous evidences showed that biochar could improve soil fertility and affect nitrogen transformation in soil. However, little attention was paid to compare the difference in nitrogen transformation affected by biochar addition in soils with different fertility levels, especially in the extremely infertile reclaimed soil in the coal-mining subsidence area. In this paper, the effect of biochar addition on the nitrification in the reclaimed soil from a coal-mining subsidence area was examined by using a laboratory aerobic incubation method with constant temperature and controlled humidity under different nitrogen supply levels. In addition, vegetable soil with high fertility was used as the comparation. The experimental factors included three levels of biochar (0, 1.5% and 3%), two levels of nitrogen (at the rates of 200 and 400 mg/kg, respectively), and two kinds of soil (vegetable soil and reclaimed soil with extremely low fertility). In addition, soils without any biochar or nitrogen addition were cultured at the same condition to provide background nitrification information. Nitrate nitrogen and ammonium nitrogen concentration in soils were monitored during the cultivation period. The variation of nitrate nitrogen concentration in the cultivated soils was simulated by Logistic function and the significance values of the model were analyzed. It showed that, compared with the vegetable soil, the nitrification was slow in the reclaimed soil. The maximum rate of nitrification in the reclaimed soil was only 17.32% of that in the vegetable soil, and the time the maximum nitrification rate occurred delayed 4.2 days in the reclaimed soil compared with the vegetable soil. The inhibition of biochar addition on the nitrification was obvious especially in nitrification acceleration stage, and was affected interactively by nitrogen supply level and soil type. Compared with low nitrogen supply, biochar exerted greater inhibition on the nitrification so that the nitrification acceleration stage extended 6 days (for the reclaimed soil) or 11 days (for the vegetable soil) in the soil with high nitrogen supply. However, the nitrification acceleration stages were all terminated before the 18th day under both of the two nitrogen supply levels. In the reclaimed soil, especially under high nitrogen supply, the time the maximum nitrification rate occurred was obviously delayed as the increasing of biochar amount, but the maximum rate of nitrification was not affected by biochar and nitrogen supply level. However, in the vegetable soil, the value of maximum rate of nitrification was significantly affected by nitrogen or biochar supply. Hence, biochar addition could suppress soil nitrification, and this suppression was especially obvious in the nitrification acceleration stage, which could be affected interactively by nitrogen level and soil type. The outcome of this research will provide a theoretical guide for improving the fertility of the reclaimed soil in the coal-mining subsidence area. [ABSTRACT FROM AUTHOR]