This paper designs a hierarchical controlsystem to improve control performance in a multi-terminal high voltage direct current based on the voltage source converter (VSC-MTDC) transmission system. In this control sch...
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This paper designs a hierarchical controlsystem to improve control performance in a multi-terminal high voltage direct current based on the voltage source converter (VSC-MTDC) transmission system. In this control scheme, the primary control layer employs droop control, while the secondary control layer has developed optimal power flow control (OPF) for maintaining the variation of DC voltage and regulating the active power, and simultaneously minimizing power loss. In the event of a power disturbance or a change in power generation or consumption in the DC system, based on OPF results a new stable droop operating mode is established to stabilize DC voltage variation and regulate active power in the network. A ±400 kV four-terminal VSC-MTDC test network has been developed by using PSCAD and MATlab simulation tools to assess the proposed control scheme. The primary controller is designed in PSCAD, and the secondary optimum control technique is applied in MATlab. The results of steady-state and transient operating modes demonstrate that the planned control technique can achieve DC voltage regulation and keep active power, and minimize the power losses in the MTDC system.
The present paper considers the model-based and data-driven control of unknown linear time-invariant discretetime systems under event-triggering and self-triggering transmission schemes. To this end, we begin by prese...
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This paper proposes a novel approach to managing distributed energy resources (DERs) through peer-to-peer (P2P) energy trading among smart homes, incentivizing peers to trade surplus energy to maximize social welfare....
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To realize the dual carbon policy, the goal of energy saving, and emission reduction, it is important to develop ways to better promote the low carbon economic operation of energy systems. Therefore, this research pro...
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To realize the dual carbon policy, the goal of energy saving, and emission reduction, it is important to develop ways to better promote the low carbon economic operation of energy systems. Therefore, this research proposes an optimal operation strategy considering the electric-gas-cooling-heat demand response. Considering the demand response of each participant, an integrated energy system model with photovoltaic, wind energy, and traditional grid as energy supply. Also, electric energy, natural gas, cooling, and heating subsystems with co-production are established. With minimizing the overall system operation cost and optimizing environmental protection, the improved particle swarm optimization algorithm is used to solve the multi-constrained objective optimization problem. Finally, the optimized model is tested. The results from this study show that the energy system under cogeneration can find a balance between economy and environmental friendliness, and provide a reference for the subsequent energy supply configuration.
Achieving precise robotic assembly is paramount for safety and performance in industrial settings. Conventional assembly methods require tedious manual adjustment of many parameters, and it is challenging to meet the ...
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This study presents a contactless current traveling wave fault location scheme for a two-terminal overhead transmission line based on a tunnel Magnetoresistive sensor. The proposed method is implemented by installing ...
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In many-objective optimization problems (MaOPs), it is a difficult task for evolutionary algorithms to balance convergence and diversity while rapidly converging to the Pareto front. As the number of objectives increa...
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Star anise, rich in effective active constituents, is extensively employed in the pharmaceutical and food industries. The drying temperature can irreversibly damage these constituents. To enhance the drying quality an...
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Star anise, rich in effective active constituents, is extensively employed in the pharmaceutical and food industries. The drying temperature can irreversibly damage these constituents. To enhance the drying quality and efficiency, this study undertook experiments using three drying methods on star anise including microwave vacuum drying, hot air drying, and a combination of microwave vacuum and hot air drying. The research examined the impacts of varying drying conditions on the drying characteristics of star anise, the moisture diffusion coefficient, and the primary component contents (anethole and shikimic acid). Models were separately established for microwave vacuum and hot air thin-layer drying kinetics including Lewis, Weibull distribution, two-term exponential, Wang, and Singh models, and a Weibull distribution model for combined microwave vacuum-hot air drying. The results indicated that drying with microwave vacuum and hot air primarily proceeded in a falling rate drying phase, whereas combined microwave vacuum and hot air drying encompassed both falling rate and constant rate stages. The effective moisture diffusion coefficients (Deff) for microwave vacuum drying and hot air drying of star anise ranged from 3.4423E-07 to 8.8239E-07 m2/s and 2.0386E-08 to 8.8239E-07 m2/s, respectively, while the Deff for combined microwave and hot air drying ranged from 2.8683E-07 to 4.8014E-07 m2/s and 7.9516E-8 to 2.0964E-7 m2/s, respectively. Evidently, segmented combined drying facilitated more convenient moisture diffusion, and both coefficients increased with microwave power and hot air temperature. During the microwave vacuum and hot air drying processes, both the Wang and Singh models and the Weibull distribution models showed good fitting effects. The Weibull distribution model could effectively predict the drying behavior of segmented microwave vacuum and hot air drying of star anise. In comparison with hot air drying time, combined microwave vacuum and hot air dr
Exocarpium citreic grandis is the immature outer peel of grapefruit and contains active ingredients such as naringin and rhoifolin. The drying temperature can have a significant effect on the constituents. In order to...
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Exocarpium citreic grandis is the immature outer peel of grapefruit and contains active ingredients such as naringin and rhoifolin. The drying temperature can have a significant effect on the constituents. In order to explore the rules of moisture and quality changes in exocarpium citreic grandis during microwave vacuum drying, this study investigated the effects of different microwave intensities (0.75, 1.25, 1.50, 1.75, 2.00 W/g) on the drying characteristics and main component content of exocarpium citreic grandis. The results showed that, at a microwave intensity of 0.75 W/g, the drying process was controlled by a constant speed stage. At microwave intensities of 1.25 W/g and 1.50 W/g, the drying process was divided into three parts including acceleration stage, constant speed stage, and deceleration stage. When the microwave intensity increased to 1.75 W/g and 2.00 W/g, the drying process was divided into acceleration and deceleration stages with no constant speed drying stage. The resulted data suggested that the thin-layer drying kinetics model of exocarpium citreic grandis was fitted. The selection principle of the model was analyzed from four aspects including modification of the original model, transformation of dependent and independent variables, complex model, and initial and terminal conditions. Lewis, Page, Two-term exponential, and Weibull distribution models were selected for fitting analysis. The optimal thin-layer drying models were the Page model and the Weibull distribution model. The scale parameter α of the Weibull distribution function decreased with the increase in microwave intensity. The shape parameter β underwent slight changes with moisture migration mechanisms being the combined effect of surface moisture evaporation and internal moisture diffusion. The effective moisture diffusion coefficient Deff was increasing with the increase in microwave intensity. The activation energy Ea for microwave vacuum drying of exocarpium citreic grandis
This paper demonstrates the design and fabrication of three-dimensional(3 D) hexagonally ordered microbowl arrays(MBAs) decorated with Cu In S2 nanosheets for enhanced photoelectrochemical(PEC) performance. The 3 D MB...
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This paper demonstrates the design and fabrication of three-dimensional(3 D) hexagonally ordered microbowl arrays(MBAs) decorated with Cu In S2 nanosheets for enhanced photoelectrochemical(PEC) performance. The 3 D MBAs are fabricated by a micro-fabrication technique. The ultrathin CuInS2 nanosheets are grown on the 3 D electrodes by solvothermal transformation of Cu film. The photocurrent density of 3 D photocathode(CuInS2@MBAs) is about two times higher than that of the planar counterpart(CuInS2@Planar). The improved PEC performance can be ascribed to the elevated light trapping ability and the increased surface area for loading photocatalysts. In addition, CdS quantum dots as cocatalysts are modified onto the Cu In S2 nanosheets to further enhance the PEC activity because the formed p-n heterojunction can accelerate the separation of photogenerated carriers. As a result, the 3 D photocathode of CuInS2/CdS@MBAs shows an optimal incident photon to current efficiency of 10% at the wavelength of400 nm. It is believed that this work can be generalized to design other hierarchical 3 D photoelectrodes for improved solar water splitting.
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