The electric energy consumption data of marketoriented customers must be perfectly metered or accurately fitted, that is essential for the construction of electricity spot market. The electricity consumption behavior ...
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In recent years, power outages have occurred frequently around the world, and rapid load recovery after power outages can reduce economic losses caused by power outages. In the restoration model, the power flow calcul...
In recent years, power outages have occurred frequently around the world, and rapid load recovery after power outages can reduce economic losses caused by power outages. In the restoration model, the power flow calculation is a nonlinear equality constraint. The idea based on mathematical optimization is to linearize the power flow equation based on certain assumptions or perform convex relaxation. Such processing may affect the solution accuracy or speed. Therefore, a data-driven constraints linearization method is proposed, using a large amount of simulation data to linearly fit the power flow through the partial least square method. Then, based on the linear constraints, the load restoration problem is established as a mixed integer linear programming (MILP) problem to reduce the difficulty of solving, improve calculation accuracy and provide dispatchers with optimal recovery decisions. Finally, the validity of the method proposed in this paper is verified in IEEE39 node system.
River turbidity is an important index to evaluate the quality of water environment, which is of great significance to environmental monitoring. Most of the existing monitoring methods rely on turbidity labels measured...
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The high penetration of renewable energy in power systems leads to significant net load fluctuations. Coal-fired power generators conventionally designed for baseload operations are expected to be flexible with cyclin...
The high penetration of renewable energy in power systems leads to significant net load fluctuations. Coal-fired power generators conventionally designed for baseload operations are expected to be flexible with cycling operations. Necessary upgrades received by the power generators to improve their operational flexibility will cause associated costs. An upgrade planning strategy is proposed in this paper for harnessing operational flexibility of coal-fired power generators. First, a multi-objective optimization model of coal-fired power generators is established in which the upgrade cost, operating cost, and the upgraded load following capacity of three stages are comprehensively integrated. Next, an improved multi-objective particle swarm optimization algorithm is used to solve the proposed model. Finally, a multi-criteria decision making method is applied to select the best upgrade plan. The case study results of the IEEE 39-bus system demonstrate the feasibility and effectiveness of the proposed planning strategy.
The phase-locked loop provides a phase reference for the coordinate transformation in grid-connected inverters to ensure synchronous operation and power output. In the distribution network, under the conditions of thr...
The phase-locked loop provides a phase reference for the coordinate transformation in grid-connected inverters to ensure synchronous operation and power output. In the distribution network, under the conditions of three-phase unbalance because of the diversity of loads, untransposed line and the complex operating conditions, the phase-locked loop can produce phase locking errors that affect the inverter power output and thus the regulation of the active distribution network. Therefore, by analyzing the inverter control, the influence of phase error of the phase-locked loop on the Park transformation and modulation signal is deduced, and the relationship between phase error, voltage, current, current reference value, and modulation signal is quantified. The simulation results prove the correctness of the analysis.
Generation of squeezed light source is a promising technique to overcome the standard quantum limit in precision ***,we demonstrate an experimental generation of quadrature squeezing resonating on the cesium D_(2)line...
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Generation of squeezed light source is a promising technique to overcome the standard quantum limit in precision ***,we demonstrate an experimental generation of quadrature squeezing resonating on the cesium D_(2)line down to 10 Hz for the first *** maximum squeezing in audio frequency band is 5.57 ***,we have presented a singlephoton modulation locking to control the squeezing angle,while effectively suppressing the influence of laser noise on low-frequency *** whole system operates steadily for *** generated low-frequency squeezed light source can be applied in quantum metrology,light–matter interaction investigation and quantum memory in the audio frequency band and even below.
With the changes in generation and load characteristics, transient voltage problems have a serious impact on the safe and stable operation of the power system. In this paper, on the basis of constructing a fast evalua...
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Osteochondral defect caused by trauma or osteoarthritis exhibits a major challenge in clinical treatment with limited symptomatic effects at *** regeneration and remodeling of subchondral bone play a positive effect o...
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Osteochondral defect caused by trauma or osteoarthritis exhibits a major challenge in clinical treatment with limited symptomatic effects at *** regeneration and remodeling of subchondral bone play a positive effect on cartilage regeneration and further promotes the repair of osteochondral *** use of the strengths of each preparation method,the combination of 3D printing and electrospinning is a promising method for designing and constructing multi-scale scaffolds that mimic the complexity and hierarchical structure of subchondral bone at the microscale and nanoscale,*** this study,the 3D printed-electrospun poly(ɛ-caprolactone)/nano-hydroxyapatites/multi-walled carbon nanotubes(PCL/nHA/MWCNTs)scaffolds were successfully constructed by the combination of electrospinning and layer-by-layer 3D *** resulting dual-scale scaffold consisted of a dense layer of disordered nanospun fibers and a porous microscale 3D scaffold layer to support and promote the ingrowth of subchondral ***,the biomimetic PCL/nHA/MWCNTs scaffolds enhanced cell seeding efficiency and allowed for higher cell-cell interactions that supported the adhesion,proliferation,activity,morphology and subsequently improved the osteogenic differentiation of bone marrow mesenchymal stem cells in ***,this study elucidates that the construction of 3D printed-electrospun PCL/nHA/MWCNTs scaffolds provides an alternative strategy for the regeneration of subchondral bone and lays a foundation for subsequent in vivo studies.
With the penetration of renewable energy sources (RES) increasing rapidly, cascading failures become more complex due to the uncertainty and vulnerability of RES. This paper presents an online cascading failure search...
With the penetration of renewable energy sources (RES) increasing rapidly, cascading failures become more complex due to the uncertainty and vulnerability of RES. This paper presents an online cascading failure searching method based on gradient boosting decision tree (GBDT) for the hybrid AC/DC system with high penetration of wind power. First, the cascading failure risk index is established, which considers the impact, probability, and loss of failures. Then, a cascading failure searching based on Monte Carlo tree search and dynamic simulation is performed to acquire the high-risk cascading failures, which are utilized as the training samples. Finally, GBDT is deployed to construct the relationship between operating conditions and failure propagation directions. Online cascading failure searching is realized by combining GBDT failure estimation and dynamic failure simulation. Simulation results of the modified New England 39-bus test system demonstrate that the proposed method can fast and accurately online screen the high-risk cascading failures considering the uncertainty of wind power.
作者:
Wang, RuoguLi, NingShanghai Jiao Tong University
Key Laboratory of System Control and Information Processing Ministry of Education of China Shanghai Engineering Research Center of Intelligent Control and Management Department of Automation Shanghai China
Generic object detection has made great progress in recent years, yet small object detection is still facing a serious problem of missed detection. The problem is caused by two reasons: low resolution in small targets...
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