The fluctuation of wind power affects the operating safety and power consumption of the electric power grid and restricts the grid connection of wind power on a large scale.Therefore,wind power forecasting plays a key...The fluctuation of wind power affects the operating safety and power consumption of the electric power grid and restricts the grid connection of wind power on a large scale.Therefore,wind power forecasting plays a key role in improving the safety and economic benefits of the power grid.This paper proposes a wind power predicting method based on a convolutional graph attention deep neural network with multi-wind farm data.Based on the graph attention network and attention mechanism,the method extracts spatial-temporal characteristics from the data of multiple wind farms.Then,combined with a deep neural network,a convolutional graph attention deep neural network model is constructed.Finally,the model is trained with the quantile regression loss function to achieve the wind power deterministic and probabilistic prediction based on multi-wind farm spatial-temporal data.A wind power dataset in the U.S.is taken as an example to demonstrate the efficacy of the proposed model.Compared with the selected baseline methods,the proposed model achieves the best prediction performance.The point prediction errors(i.e.,root mean square error(RMSE)and normalized mean absolute percentage error(NMAPE))are 0.304 MW and 1.177%,respectively.And the comprehensive performance of probabilistic prediction(i.e.,con-tinuously ranked probability score(CRPS))is 0.580.Thus,the significance of multi-wind farm data and spatial-temporal feature extraction module is self-evident.展开更多
Dear Editor, As a promising multi-agent systems(MASs) operation, autonomous interception has attracted more and more attentions in these years, where defenders prevent intruders from reaching destinations.So far, most...Dear Editor, As a promising multi-agent systems(MASs) operation, autonomous interception has attracted more and more attentions in these years, where defenders prevent intruders from reaching destinations.So far, most of the relevant methods are applied in ideal environments without agent damages. As a remedy, this letter proposes a more realistic interception method for MASs suffered by damages.展开更多
The system performance of grid-connected photovoltaic(PV)has a serious impact on the grid stability.To improve the control performance and shorten the convergence time,a predefined-time controller based on backsteppin...The system performance of grid-connected photovoltaic(PV)has a serious impact on the grid stability.To improve the control performance and shorten the convergence time,a predefined-time controller based on backstepping technology and dynamic surface control is formulated for the inverter in the grid-connected photovoltaic.The time-varying tuning functions are introduced into state-tracking errors to realize the predefined-time control effect.To address the“computational explosion problem”in the design process of backstepping control,dynamic surface control is adopted to avoid the analytical calculations of virtual control.The disturbances of the PV system are estimated and compensated by adaptive laws.The control parameters are chosen and the global stability of the closed-loop is ensured by Lyapunov conditions.Simulation results confirm the effectiveness of the proposed controller and ensure the predefined time control in the photovoltaic inverter.展开更多
In order to effectively imitate the dynamic operation characteristics of the HVDC （high voltage direct current） power transmission system at a real ±500kV HVDC transmission project, the electromechanical-electr...In order to effectively imitate the dynamic operation characteristics of the HVDC （high voltage direct current） power transmission system at a real ±500kV HVDC transmission project, the electromechanical-electromagnetic transient hybrid simulation was carried out based on advanced digital power system simulator （ADPSS）. In the simulation analysis, the built hybrid model＇s dynamic response outputs under three different fault conditions are considered, and by comparing with the selected fault recording waveforms, the validities of the simulation waveforms are estimated qualitatively. It can be ascertained that the hybrid simulation model has the ability to describe the HVDC system＇s dynamic change trends well under some special fault conditions.展开更多
With the advance in renewable generation technologies, the cost of renewable energy becomes increasingly competitive when compared to fossil fuel-based generation resources. It is economically beneficial to integrate ...With the advance in renewable generation technologies, the cost of renewable energy becomes increasingly competitive when compared to fossil fuel-based generation resources. It is economically beneficial to integrate large amounts of renewable capacity in power systems. Unlike traditional generation facilities, however, using renewable resources for generation presents technical challenges in producing continuous power. In this report, an Energy Storage System (ESS) is integrated to smooth the variations in renewable power production and ensure the output power more controllable. Since it requires capital investment for the storage devices, it is important to obtain reasonable estimate of the storage capacities. This project is therefore formulated as an optimization problem in determining the two dominating factors of the capital cost for the ESS: the power capacity and the energy capacity. The objective is to make the renewable power more reliable and simultaneously maximize the economic benefits that can be obtained from the scheme. To make the results more convincing, analyses in this report start with wind generation, for wind has greater variability and unpredictability than other renewable sources. Selection of ESS type is narrowed down to battery energy storage system (BESS) in the scheme. However, the methods presented here are suitable for any type of energy storage methods and are also useful for intermittent renewable energy resources other than wind.展开更多
Real-world networks exhibit complex topological interactions that pose a significant computational challenge to analyses of such networks.Due to limited resources,there is an urgent need to develop dimensionality redu...Real-world networks exhibit complex topological interactions that pose a significant computational challenge to analyses of such networks.Due to limited resources,there is an urgent need to develop dimensionality reduction techniques that can significantly reduce the structural complexity of initial large-scale networks.In this paper,we propose a subgraph extraction method based on the node centrality measure to reduce the size of the initial network topology.Specifically,nodes with smaller centrality value are removed from the initial network to obtain a subgraph with a smaller size.Our results demonstrate that various real-world networks,including power grids,technology,transportation,biology,social,and language networks,exhibit self-similarity behavior during the reduction process.The present results reveal the selfsimilarity and scale invariance of real-world networks from a different perspective and also provide an effective guide for simplifying the topology of large-scale networks.展开更多
Effective monitoring and early warning of overhead power lines are critical for ensuring power supply stability and personnel safety.However,existing methods that rely solely on single vision or light detection and ra...Effective monitoring and early warning of overhead power lines are critical for ensuring power supply stability and personnel safety.However,existing methods that rely solely on single vision or light detection and ranging(LiDAR)have limitations such as numerous invalid alarms,hardware equipment constraints,and lack of real-time monitoring capabilities.This article proposes an intelligent monitoring method for safety distance of the powerline corridor based on heterogeneous sensor information.Firstly,an optimised single-stage detector is designed to detect safety hazard objects.In the detector,the backbone network and the sample matching strategy are improved;in addition,the learning strategy is adjusted.Next,the pose transformation relationship is obtained through the visual matching of prior LiDAR information and images.The back projection transformation of 2D–3D is achieved according to the relationship.Finally,a monocular camera-based end-to-end distance measurement scheme is proposed by combining 2D object information with coordinate transformation relationships.The scheme is applied to the distance measurements from hazard objects to powerlines.The experimental results show that the optimisation method improves the detection accuracy and reduces the computational complexity of the model.Also,case experiments with continuous frame data verify the effectiveness of the safety distance monitoring scheme.展开更多
According to the demand of substation secondary device dynamic performance testing, a smart substation field testing technique based on recurrence principle is proposed in the paper, and the characteristics of smart s...According to the demand of substation secondary device dynamic performance testing, a smart substation field testing technique based on recurrence principle is proposed in the paper, and the characteristics of smart substation secondary device digitization and information sharing are used by the technique. The principle of testing technique is as follow: the digital simulation model is constructed on the basis of the substation’s actual construction, then the simulating data highly similar to substation’s actual electric quantity transient process is generated, at last, the substation digital secondary device can be tested by using data “recurrence” technique. The testing technique is verified and applied by constructing testing system, the application results show that the technique can effectively perform field test on the dynamic performance of digital secondary device, and the technique has good engineering implementation and application value.展开更多
The power router(PR)is a promising piece of equipment for realizing multi-voltage level interconnection and flex-ible power control in the future distribution power grid.In this paper,a hybrid PR(HPR)topology based on...The power router(PR)is a promising piece of equipment for realizing multi-voltage level interconnection and flex-ible power control in the future distribution power grid.In this paper,a hybrid PR(HPR)topology based on power-frequency transformer electromagnetic coupling with converters is proposed for the medium distribution power grid.The power-frequency transformer is used to undertake power transmission,voltage conversion,and other main tasks,while the power electronic converters are combined to achieve active control.Equivalent magnetic and electrical circuit models are established to help discuss the operating principle of the proposed HPR.Additionally,the power flow and control principle of the HPR in different operating conditions are analyzed,with the control system design scheme presented.The theoretical analysis results are verified by MATLAB/Simulink+Plecs simulation and a controller hardware-in-the-loop study,as well as a down-scale experimental test,indicating that the proposed HPR is flexible in active voltage support and current control.展开更多
Lithium argyrodites Li_(6)PS_(5)X(X=Cl,Br,I)show great potential as solid electrolytes for solid-state lithium batteries due to their high Li-ion conductivities and excellent electrode compatibility.However,the relati...Lithium argyrodites Li_(6)PS_(5)X(X=Cl,Br,I)show great potential as solid electrolytes for solid-state lithium batteries due to their high Li-ion conductivities and excellent electrode compatibility.However,the relatively low conductivity of Li_(6)PS_(5)I(10^(-6)m S/cm)compared to the other two compositions limits its applications.Herein,Si-doped Li_(6.5)P_(0.5)Si_(0.5)S_(5)I electrolyte is designed and synthesized with superior high conductivity of 3.6 mS/cm.Structural characterization proves the increase due to the anion disorder and volume expansion caused by Si-doping.However,the poor interfacial stability between layered oxide cathode Li Ni_(0.6)Co_(0.2)Mn_(0.2)O_(2)and Li_(6.5)P_(0.5)Si_(0.5)S_(5)I inhibits its battery performance.By introducing Li_(3)InCl6electrolyte in the configuration,the corresponding battery delivers high initial discharge capacity of 150.2m Ah/g and superior cyclability during 250 cycles at 0.5 C.This work offers design strategy to obtain Li_(6)PS_(5)I-based electrolytes for high performance solid-state batteries.展开更多
Direct wind power purchase for large industrial users is a meaningful way to improve wind power consumption and decrease industrial production costs.Short-term wind power fluctuations may lead to large-scale wind powe...Direct wind power purchase for large industrial users is a meaningful way to improve wind power consumption and decrease industrial production costs.Short-term wind power fluctuations may lead to large-scale wind power curtailment problems.To promote use of wind energy,a demand side control method is proposed based on output regulator theory for a grid-connected industrial microgrid with electrolytic aluminum loads to continuously track and respond to wind power fluctuations.The control model of the EALs and the dominant frequencies of the wind power fluctuation signals are analyzed and incorporated into the demand side control plant.The feedback control signals with active power deviations on the tie-line are used to design the demand side controller.Simulations are conducted for an actual industrial microgrid to validate the feasibility and effectiveness of the proposed method.The results demonstrate that the proposed controller based on output regulator theory is able to effectively track wind power fluctuations.展开更多
In order to improve the sensitivity and accuracy of oil‐paper insulation partial discharge detection by the fibre‐optic Fabry-Perot(FP)ultrasonic sensor,this work studied the ultrasonic signal’s frequency character...In order to improve the sensitivity and accuracy of oil‐paper insulation partial discharge detection by the fibre‐optic Fabry-Perot(FP)ultrasonic sensor,this work studied the ultrasonic signal’s frequency characteristics of typical oil‐paper insulation partial dis-charges and the vibration characteristics of the FP sensor’s diaphragm in the liquid environment.Based on the works above,a multifrequency FP sensor array is proposed,consisting of several FP sensors with different resonant frequencies to detect partial discharges.The experimental results show that the liquid environment has a significant effect on the vibration characteristics of the FP sensor’s diaphragm,and the sensitivity and accuracy of partial discharge detection can be improved based on the multifrequency FP sensing array,which can also be applied in the pattern recognition and localisation of partial discharges.展开更多
In this study,based on two CMOS cameras,an orthogonal optical observation platform has been set up for positive streamer branches under 1 m rod-plate air gap.The Monopodia branch and the Dichotomous branch have been p...In this study,based on two CMOS cameras,an orthogonal optical observation platform has been set up for positive streamer branches under 1 m rod-plate air gap.The Monopodia branch and the Dichotomous branch have been proposed for steamer branch classification.The branch length,the branch angle and the optical diameter are statistical obtained and compared for the two branch types under different impulse voltages.The empirical function between the branch length Ls and the inception voltage Ui of the Monopodia branch has been obtained.The distributions of the branch angle and the axial angle of the two types have been given,and the mean optical diameters have been provided.Based on the comparisons,the formation mechanism of the two branch types has been proposed.This experimental result can provide the basic data to the numerical calculation of positive long air gap discharge.展开更多
基金supported by the Science and Technology Project of State Grid Corporation of China(4000-202122070A-0-0-00).
文摘The fluctuation of wind power affects the operating safety and power consumption of the electric power grid and restricts the grid connection of wind power on a large scale.Therefore,wind power forecasting plays a key role in improving the safety and economic benefits of the power grid.This paper proposes a wind power predicting method based on a convolutional graph attention deep neural network with multi-wind farm data.Based on the graph attention network and attention mechanism,the method extracts spatial-temporal characteristics from the data of multiple wind farms.Then,combined with a deep neural network,a convolutional graph attention deep neural network model is constructed.Finally,the model is trained with the quantile regression loss function to achieve the wind power deterministic and probabilistic prediction based on multi-wind farm spatial-temporal data.A wind power dataset in the U.S.is taken as an example to demonstrate the efficacy of the proposed model.Compared with the selected baseline methods,the proposed model achieves the best prediction performance.The point prediction errors(i.e.,root mean square error(RMSE)and normalized mean absolute percentage error(NMAPE))are 0.304 MW and 1.177%,respectively.And the comprehensive performance of probabilistic prediction(i.e.,con-tinuously ranked probability score(CRPS))is 0.580.Thus,the significance of multi-wind farm data and spatial-temporal feature extraction module is self-evident.
基金supported by the Science and Technology Project of State Grid Corporation of China, China (5100202199557A-0-5-ZN)。
文摘Dear Editor, As a promising multi-agent systems(MASs) operation, autonomous interception has attracted more and more attentions in these years, where defenders prevent intruders from reaching destinations.So far, most of the relevant methods are applied in ideal environments without agent damages. As a remedy, this letter proposes a more realistic interception method for MASs suffered by damages.
基金supported by the State Grid Corporation of China Headquarters Science and Technology Project under Grant No.5400-202122573A-0-5-SF。
文摘The system performance of grid-connected photovoltaic(PV)has a serious impact on the grid stability.To improve the control performance and shorten the convergence time,a predefined-time controller based on backstepping technology and dynamic surface control is formulated for the inverter in the grid-connected photovoltaic.The time-varying tuning functions are introduced into state-tracking errors to realize the predefined-time control effect.To address the“computational explosion problem”in the design process of backstepping control,dynamic surface control is adopted to avoid the analytical calculations of virtual control.The disturbances of the PV system are estimated and compensated by adaptive laws.The control parameters are chosen and the global stability of the closed-loop is ensured by Lyapunov conditions.Simulation results confirm the effectiveness of the proposed controller and ensure the predefined time control in the photovoltaic inverter.
基金supported by the General Program of Chinese Postdoctoral Science Foundation under Grant No.2012M511595
文摘In order to effectively imitate the dynamic operation characteristics of the HVDC （high voltage direct current） power transmission system at a real ±500kV HVDC transmission project, the electromechanical-electromagnetic transient hybrid simulation was carried out based on advanced digital power system simulator （ADPSS）. In the simulation analysis, the built hybrid model＇s dynamic response outputs under three different fault conditions are considered, and by comparing with the selected fault recording waveforms, the validities of the simulation waveforms are estimated qualitatively. It can be ascertained that the hybrid simulation model has the ability to describe the HVDC system＇s dynamic change trends well under some special fault conditions.
文摘With the advance in renewable generation technologies, the cost of renewable energy becomes increasingly competitive when compared to fossil fuel-based generation resources. It is economically beneficial to integrate large amounts of renewable capacity in power systems. Unlike traditional generation facilities, however, using renewable resources for generation presents technical challenges in producing continuous power. In this report, an Energy Storage System (ESS) is integrated to smooth the variations in renewable power production and ensure the output power more controllable. Since it requires capital investment for the storage devices, it is important to obtain reasonable estimate of the storage capacities. This project is therefore formulated as an optimization problem in determining the two dominating factors of the capital cost for the ESS: the power capacity and the energy capacity. The objective is to make the renewable power more reliable and simultaneously maximize the economic benefits that can be obtained from the scheme. To make the results more convincing, analyses in this report start with wind generation, for wind has greater variability and unpredictability than other renewable sources. Selection of ESS type is narrowed down to battery energy storage system (BESS) in the scheme. However, the methods presented here are suitable for any type of energy storage methods and are also useful for intermittent renewable energy resources other than wind.
基金the Science and Technology Project of State Grid Corporation of China(Grant No.5100-202199557A-0-5-ZN)。
文摘Real-world networks exhibit complex topological interactions that pose a significant computational challenge to analyses of such networks.Due to limited resources,there is an urgent need to develop dimensionality reduction techniques that can significantly reduce the structural complexity of initial large-scale networks.In this paper,we propose a subgraph extraction method based on the node centrality measure to reduce the size of the initial network topology.Specifically,nodes with smaller centrality value are removed from the initial network to obtain a subgraph with a smaller size.Our results demonstrate that various real-world networks,including power grids,technology,transportation,biology,social,and language networks,exhibit self-similarity behavior during the reduction process.The present results reveal the selfsimilarity and scale invariance of real-world networks from a different perspective and also provide an effective guide for simplifying the topology of large-scale networks.
基金National Natural Science Foundation of China,Grant/Award Numbers:52277139,52367014Guangxi Science Fund for Distinguished Young Scholars,Grant/Award Number:2024GXNSFFA999017。
文摘Effective monitoring and early warning of overhead power lines are critical for ensuring power supply stability and personnel safety.However,existing methods that rely solely on single vision or light detection and ranging(LiDAR)have limitations such as numerous invalid alarms,hardware equipment constraints,and lack of real-time monitoring capabilities.This article proposes an intelligent monitoring method for safety distance of the powerline corridor based on heterogeneous sensor information.Firstly,an optimised single-stage detector is designed to detect safety hazard objects.In the detector,the backbone network and the sample matching strategy are improved;in addition,the learning strategy is adjusted.Next,the pose transformation relationship is obtained through the visual matching of prior LiDAR information and images.The back projection transformation of 2D–3D is achieved according to the relationship.Finally,a monocular camera-based end-to-end distance measurement scheme is proposed by combining 2D object information with coordinate transformation relationships.The scheme is applied to the distance measurements from hazard objects to powerlines.The experimental results show that the optimisation method improves the detection accuracy and reduces the computational complexity of the model.Also,case experiments with continuous frame data verify the effectiveness of the safety distance monitoring scheme.
文摘According to the demand of substation secondary device dynamic performance testing, a smart substation field testing technique based on recurrence principle is proposed in the paper, and the characteristics of smart substation secondary device digitization and information sharing are used by the technique. The principle of testing technique is as follow: the digital simulation model is constructed on the basis of the substation’s actual construction, then the simulating data highly similar to substation’s actual electric quantity transient process is generated, at last, the substation digital secondary device can be tested by using data “recurrence” technique. The testing technique is verified and applied by constructing testing system, the application results show that the technique can effectively perform field test on the dynamic performance of digital secondary device, and the technique has good engineering implementation and application value.
基金supported in part by the National Natural Science Foundation of China(Grant No.52007010)in part by State Key Laboratory of Advanced Electromagnetic Engineering and Technology(Grant No.AEET 2022KF003).
文摘The power router(PR)is a promising piece of equipment for realizing multi-voltage level interconnection and flex-ible power control in the future distribution power grid.In this paper,a hybrid PR(HPR)topology based on power-frequency transformer electromagnetic coupling with converters is proposed for the medium distribution power grid.The power-frequency transformer is used to undertake power transmission,voltage conversion,and other main tasks,while the power electronic converters are combined to achieve active control.Equivalent magnetic and electrical circuit models are established to help discuss the operating principle of the proposed HPR.Additionally,the power flow and control principle of the HPR in different operating conditions are analyzed,with the control system design scheme presented.The theoretical analysis results are verified by MATLAB/Simulink+Plecs simulation and a controller hardware-in-the-loop study,as well as a down-scale experimental test,indicating that the proposed HPR is flexible in active voltage support and current control.
基金supported by the National Key Research and Development Program(No.2021YFB2400300)the National Key Research and Development Program(No.2021YFB2500200)+1 种基金supported by the National Natural Science Foundation of China(No.52177214)China Fujian Energy Devices Science and Technology Innovation Laboratory Open Fund(No.21COP202211)。
文摘Lithium argyrodites Li_(6)PS_(5)X(X=Cl,Br,I)show great potential as solid electrolytes for solid-state lithium batteries due to their high Li-ion conductivities and excellent electrode compatibility.However,the relatively low conductivity of Li_(6)PS_(5)I(10^(-6)m S/cm)compared to the other two compositions limits its applications.Herein,Si-doped Li_(6.5)P_(0.5)Si_(0.5)S_(5)I electrolyte is designed and synthesized with superior high conductivity of 3.6 mS/cm.Structural characterization proves the increase due to the anion disorder and volume expansion caused by Si-doping.However,the poor interfacial stability between layered oxide cathode Li Ni_(0.6)Co_(0.2)Mn_(0.2)O_(2)and Li_(6.5)P_(0.5)Si_(0.5)S_(5)I inhibits its battery performance.By introducing Li_(3)InCl6electrolyte in the configuration,the corresponding battery delivers high initial discharge capacity of 150.2m Ah/g and superior cyclability during 250 cycles at 0.5 C.This work offers design strategy to obtain Li_(6)PS_(5)I-based electrolytes for high performance solid-state batteries.
基金supported by Science and Technology Project of State Grid Corporation of China (5100-202199286A-0-0-00).
文摘Direct wind power purchase for large industrial users is a meaningful way to improve wind power consumption and decrease industrial production costs.Short-term wind power fluctuations may lead to large-scale wind power curtailment problems.To promote use of wind energy,a demand side control method is proposed based on output regulator theory for a grid-connected industrial microgrid with electrolytic aluminum loads to continuously track and respond to wind power fluctuations.The control model of the EALs and the dominant frequencies of the wind power fluctuation signals are analyzed and incorporated into the demand side control plant.The feedback control signals with active power deviations on the tie-line are used to design the demand side controller.Simulations are conducted for an actual industrial microgrid to validate the feasibility and effectiveness of the proposed method.The results demonstrate that the proposed controller based on output regulator theory is able to effectively track wind power fluctuations.
基金supported by the National Natural Science Foundation of China(U1766217)the State Grid Corpo-ration of China’s Science and Technology Project(5500‐202099279A‐0‐0‐00).
文摘In order to improve the sensitivity and accuracy of oil‐paper insulation partial discharge detection by the fibre‐optic Fabry-Perot(FP)ultrasonic sensor,this work studied the ultrasonic signal’s frequency characteristics of typical oil‐paper insulation partial dis-charges and the vibration characteristics of the FP sensor’s diaphragm in the liquid environment.Based on the works above,a multifrequency FP sensor array is proposed,consisting of several FP sensors with different resonant frequencies to detect partial discharges.The experimental results show that the liquid environment has a significant effect on the vibration characteristics of the FP sensor’s diaphragm,and the sensitivity and accuracy of partial discharge detection can be improved based on the multifrequency FP sensing array,which can also be applied in the pattern recognition and localisation of partial discharges.
基金the National Basic Research Program of China(973 Program)(2011CB209403)。
文摘In this study,based on two CMOS cameras,an orthogonal optical observation platform has been set up for positive streamer branches under 1 m rod-plate air gap.The Monopodia branch and the Dichotomous branch have been proposed for steamer branch classification.The branch length,the branch angle and the optical diameter are statistical obtained and compared for the two branch types under different impulse voltages.The empirical function between the branch length Ls and the inception voltage Ui of the Monopodia branch has been obtained.The distributions of the branch angle and the axial angle of the two types have been given,and the mean optical diameters have been provided.Based on the comparisons,the formation mechanism of the two branch types has been proposed.This experimental result can provide the basic data to the numerical calculation of positive long air gap discharge.
