As a fundamental course in science and engineering education at universities,advanced mathematics plays an irreplaceable role in cultivating students’logical thinking,scientific spirit,and comprehensive qualities.Int...As a fundamental course in science and engineering education at universities,advanced mathematics plays an irreplaceable role in cultivating students’logical thinking,scientific spirit,and comprehensive qualities.Integrating ideological and political education into advanced mathematics teaching is not only an inevitable requirement for achieving the goal of“three-dimensional and holistic education”but also a crucial path for promoting students’comprehensive development.This article delves into the necessary logic,practical possibilities,and real-world challenges of ideological and political education in advanced mathematics courses,systematically analyzing the implementation pathways and illustrating practical approaches through specific cases.Meanwhile,to address issues such as insufficient teacher capability,lagging resource development,disconnected instructional design,and inadequate evaluation mechanisms encountered during implementation,this article proposes practical improvement strategies.It aims to provide theoretical insights and practical guidance for the further advancement of ideological and political education in advanced mathematics courses.展开更多
The complexity of distribution network model mainly depends on the model scale of grid-connected distributed photovoltaic (PV) power generation. Therefore, the simulation performance of multi-scale PV model is the key...The complexity of distribution network model mainly depends on the model scale of grid-connected distributed photovoltaic (PV) power generation. Therefore, the simulation performance of multi-scale PV model is the key factor of the simulation accuracy in the specific operating scenarios of distribution network. In this paper, a multi-scale model of grid connected PV distributed generation system is proposed based on the mathematical model of grid-connected distributed PV power generation. It is analyzed that differences of simulation performance, such as adaptability of simulation step size, accuracy of output and the effect on voltage profile of distribution network, between PV models with different scales in IEEE 33 node example. Simulation results indicate that the multi-scale model is effective in improving the accuracy and efficiency of simulation under different operating conditions of distribution network.展开更多
In this paper, a method of power quality disturbance classification based on random matrix theory (RMT) is proposed. The method utilizes the power quality disturbance signal to construct a random matrix. By analyzing ...In this paper, a method of power quality disturbance classification based on random matrix theory (RMT) is proposed. The method utilizes the power quality disturbance signal to construct a random matrix. By analyzing the mean spectral radius (MSR) variation of the random matrix, the type and time of occurrence of power quality disturbance are classified. In this paper, the random matrix theory is used to analyze the voltage sag, swell and interrupt perturbation signals to classify the occurrence time, duration of the disturbance signal and thedepth of voltage sag or swell. Examples show that the method has strong anti-noise ability.展开更多
Distribution networks(DNs)face challenges in maintaining continuous power supply for critical loads under disasters.However,from a resilience perspective,the forecast accuracy of line/component failure rates under hur...Distribution networks(DNs)face challenges in maintaining continuous power supply for critical loads under disasters.However,from a resilience perspective,the forecast accuracy of line/component failure rates under hurricanes still needs to be improved in order to gain an optimal allocation strategy for multiple emergency power supply vehicles(EPSVs),and the economics under normal state is supposed to be considered in the optimization pre-hurricane EPSV allocation.Due to the rapid development of environmentally friendly EPSVs,electric EPSVs and hydrogen fuel cell EPSVs are considered to be allocated jointly for their different advantages in enhancing DNs’resilience.Hence,to balance the resilience and economics of DNs against hurricanes,an equilibrium allocation strategy for electric EPSVs and hydrogen fuel cell EPSVs is proposed in this paper based on the Nash equilibrium.First,a statistical model for meteorological data about hurricanes is established via the conditional value at risk(CVaR)considering strong wind and the consequent rainfall.Failure rate models of DN lines/components are built on account of the damage mechanism of hurricanes.Then the emergency power supply capability of electric EPSVs and hydrogen fuel cell EPSVs are calculated considering the limited power energy stored in electric EPSVs and abundant hydrogen in a hydrogen fueling station.In addition,an equilibrium allocation strategy for sizing and locating multiple EPSVs is proposed,in which the Nash equilibrium method is utilized.Finally,simulation tests verify the superiority of the proposed failure rate models and equilibrium allocation strategy in balancing the resilience of DNs under hurricanes and the economics of DNs under normal states.展开更多
Under the background of low-carbon demand, an integrated energy system is the main direction of energy system development. Integrated Energy System (IES) breaks through technical, market and management barriers of tra...Under the background of low-carbon demand, an integrated energy system is the main direction of energy system development. Integrated Energy System (IES) breaks through technical, market and management barriers of traditional energy systems, and it makes unified planning and scheduling for electricity, gas, heat, cold, etc. However, IES contains a variety of energy forms, and those energy forms are coupled with each other. Its planning and operation are challenging problems. Therefore, this paper proposes an IES planning model, which comprehensively considers optimization of the equipment configuration, interconnection of multiple energy stations, renewable energy integration, and optimal operation strategy. During the planning decision-making, planners can use this model to analyze and evaluate the impact of various factors on the planning indicators. Using the proposed model, an IES composed of several buildings in a street block is planned in detail and the effectiveness of the proposed planning model and its solution method is proved. The case study results show the total cost and carbon emission of the model considering both energy station interconnection and RES integration are reduced by 20.2% and 41.5%.展开更多
For fault characteristics of cyber-physical-systems(CPS)based distribution network,a spatiotemporal incidence matrix to represent correlation of concurrent faults on cyberspace and physical space is proposed,and strat...For fault characteristics of cyber-physical-systems(CPS)based distribution network,a spatiotemporal incidence matrix to represent correlation of concurrent faults on cyberspace and physical space is proposed,and strategies of fault location,removal,and recovery of concurrent faults are analyzed in this paper.Considering the multiple objectives of minimum network loss,voltage deviation,and switching operation times,a collaborative power supply restoration model of a CPS-based distribution network with the strategy that restoration of the communication layer is prior to the physical layer is constructed using the Dijkstra’s dynamic routing algorithm and second-order cone relaxation distribution network reconfiguration method,to realize orderly recovery of a distribution network during CPS concurrent faults.Related investigations are made based on the DCPS-160 case,and the accuracy and effectiveness of the proposed model are also verified.展开更多
In the CPS-oriented power distribution system,a large number of the existing test cases cannot be accessed and reused.That is not conducive to the continuity of the CPS research of the distribution network.In response...In the CPS-oriented power distribution system,a large number of the existing test cases cannot be accessed and reused.That is not conducive to the continuity of the CPS research of the distribution network.In response to above problem,based on an actual distribution network and considering the mapping relationship between cyber systems and physical systems,a computation test case that covers multiple power sources,and multiple types of load is proposed in this paper,and it is suitable for the simulation of multiple types of information system scenarios.In order to satisfy the specific needs of researchers for system topology and data,how to perform cyber contingency analysis,vulnerability assessment and distributed control are also discussed based on the existing topology and data.Researchers can utilize the test case presented in this paper to test their innovative methods in operational analysis,optimization control,and safety analysis for distribution networks.They can also utilize the published topologies and data to design their own test cases based on the methods in this paper.展开更多
The decomposition and identification of signals are crucial for flow vector acquisition in a multi-dimensional measurement. Here, we proposed a two-dimensional(2D) flow vector measurement system based on all-fiber las...The decomposition and identification of signals are crucial for flow vector acquisition in a multi-dimensional measurement. Here, we proposed a two-dimensional(2D) flow vector measurement system based on all-fiber laser feedback frequency-shifted multiplexing technology. The reliable performance of the system is characterized by experimental verification and numerical simulation. An orthogonal dual-beam structure is employed to eliminate the impact of an unknown incident angle in the practical application. Meanwhile, the vector velocity signals in 2D can be decomposed into one-dimensional(1D) scalar signals by adopting the frequency-shifted multiplexing,which makes it easy to obtain the vector information and velocity distribution of fluid motion through the self-mixing interference frequency spectrum.展开更多
A large number of load power and power output of distributed generation in an active distribution network(ADN)are uncertain,which causes the classical affine power flow method to encounter problems of interval expansi...A large number of load power and power output of distributed generation in an active distribution network(ADN)are uncertain,which causes the classical affine power flow method to encounter problems of interval expansion and low efficiency when applied to an AND.This then leads to errors of interval power flow data sources in the cyber physical system(CPS)of an ADN.In order to improve the accuracy of interval power flow data in the CPS of an ADN,an affine power flow method of an ADN for restraining interval expansion is proposed.Aiming at the expansion of interval results caused by the approximation error of non-affine operations in an affine power flow method,the approximation method of the new noise source coefficient is improved,and it is proved that the improved method is superior to the classical method in restraining interval expansion.To overcome the decrease of computational efficiency caused by new noise sources,a novel merging method of new noise sources in an iterative process is designed.Simulation tests are conducted on an IEEE 33-bus,PG&E 69-bus and an actual 1180-bus system,which proves the validity of the proposed affine power flow method and its advantages in terms of computational efficiency and restraining interval expansion.展开更多
Virtual synchronous control has been widely studied for the advantages of emulating inertia for voltage source converters (VSCs). A constant dc-link voltage is usually assumed in existing literature to estimate transi...Virtual synchronous control has been widely studied for the advantages of emulating inertia for voltage source converters (VSCs). A constant dc-link voltage is usually assumed in existing literature to estimate transient stability of virtual synchronous generators (VSGs). However, actual power supply in the dc-side of VSGs is limited and different dc-link voltage controllers are needed to achieve power balance between DC side and AC side. Addition of dc-link voltage controller has great influence on transient behavior of VSGs, which has not been investigated by previous research. To fill this gap, this paper gives insights into the effect of dc-link voltage dynamics on transient stability of VSGs. First, two typical kinds of VSGs with dc-link voltage controllers are introduced. Then, mathematical models considering dc-link dynamics are established and the effect of dc-link voltage controllers on transient synchronization stability of VSGs is revealed through equal area criterion (EAC). It is found that dc-link voltage controller would reduce stability margin of VSGs and design-oriented transient stability analysis is carried out quantitively using critical clearing time (CCT). Finally, simulation results are given to validate correctness of theoretical analysis.展开更多
The use of frequency-changers is widespread in daily electric power generation.If a frequency-changer could automatically adjust its power output according to the load status and power network operation,it would have ...The use of frequency-changers is widespread in daily electric power generation.If a frequency-changer could automatically adjust its power output according to the load status and power network operation,it would have a positive impact on power system stability.To achieve this a novel control strategy based on virtual synchronous motors(VSM)is proposed in this paper.The frequency-changer consists of two main parts:the rectifier and the inverter.In the rectifier part,a UDC-Q control strategy is adopted to control the DC-link voltage and the reactive power.In the inverter part,a VSM control strategy is used;it includes a power-frequency controller and an excitation controller,and can change the inverter’s output frequency and voltage with the variation of load,can adjust the active power with change of the power system frequency.The proposed control strategy is simulated using Simulink/Matlab.The simulation results show that the proposed control strategy can follow the mechanical inertia and electrical characteristics of the synchronous moto and can effectively improve the system power quality and system stability.展开更多
Sustainable development of power and energy systems(PES)can effectively handle challenges of fuel shortage,environmental pollution,climate change,energy security,etc.Data of PES presents distinctive characteristics in...Sustainable development of power and energy systems(PES)can effectively handle challenges of fuel shortage,environmental pollution,climate change,energy security,etc.Data of PES presents distinctive characteristics including large collection,wide coverage,diverse temporal and spatial scales,inconsistent sparsity,multiple structures and low value density,putting forward higher requirements for real-time and accuracy of data analysis,and bringing great challenges to operation analysis and coordinated control of PES.In order to realize data quality improvement and further support flexible choice of operating mode,safe and efficient coordinated control,dynamic and orderly fault recovery of sustainable PES,this paper proposes an unscented particle filter algorithm,adopting unscented Kalman filter to construct importance density functions and KLD resampling to dynamically adjust the particle number.Simulation results obtained by taking an 85-node system as a benchmark for simulation verification show that compared with traditional PF algorithm and UKF algorithm,UPF algorithm has higher estimation accuracy.展开更多
Facile and efficient photocatalysts using sunlight,as well as fast and sensitive surface-enhanced Raman spectroscopy(SERS)substrates,are urgently needed for practical degradation of tetracycline(TC).To meet these requ...Facile and efficient photocatalysts using sunlight,as well as fast and sensitive surface-enhanced Raman spectroscopy(SERS)substrates,are urgently needed for practical degradation of tetracycline(TC).To meet these requirements,a new paradigm for PI/TiO_(2)/Ag organic‒inorganic ternary flexible microfibers based on semiconducting titanium dioxide(TiO_(2)),the noble metal silver(Ag)and the conjugated polymer polyimide(PI)was developed by engineering a simple method.Under sunlight,the photocatalytic characteristics of the PI/TiO_(2)/Ag flexible microfibers containing varying amounts of Ag quantum dots(QDs)were evaluated with photocatalytic degradation of TC in aqueous solution.The results demonstrated that the amount of Ag affected the photocatalytic activity.Among the tested samples,PI/TiO_(2)/Ag-0.07(93.1%)exhibited a higher photocatalytic degradation rate than PI/TiO_(2)(25.7%),PI/TiO_(2)/Ag-0.05(77.7%),and PI/TiO_(2)/Ag-0.09(63.3%).This observation and evaluation conducted in the present work strongly indicated a charge transfer mechanism.Moreover,the PI/TiO_(2)/Ag-0.07 flexible microfibers exhibited highly sensitive SERS detection,as demonstrated by the observation of the Raman peaks for TC even at an extremely low concentration of 10–10 moles per liter.The excellent photocatalytic performance and SERS detection capability of the PI/TiO_(2)/Ag flexible microfibers arose from the Schottky barrier formed between Ag and TiO_(2)and also from the outstanding plasmonic resonance and visible light absorptivity of Ag,along with immobilization by the PI.The successful synthesis of PI/TiO_(2)/Ag flexible microfibers holds significant promise for sensitive detection and efficient photocatalytic degradation of antibiotics.展开更多
This study introduces a multifunctional device based on Cu_(2)O/g-C_(3)N_(4) monitoring and purification p–n heterojunctions(MPHs),seamlessly integrating surface-enhanced Raman scattering(SERS)detection with photocat...This study introduces a multifunctional device based on Cu_(2)O/g-C_(3)N_(4) monitoring and purification p–n heterojunctions(MPHs),seamlessly integrating surface-enhanced Raman scattering(SERS)detection with photocatalytic degradation capabilities.The SERS and photocatalytic performances of the Cu_(2)O in various morphologies,g-C_(3)N_(4) nanosheets(NSs)and Cu_(2)O/g-C_(3)N_(4) MPHs with different g-C_(3)N_(4) mass ratios were systematically evaluated,with a particular emphasis on the Cu_(2)O/g-C_(3)N_(4)-0.2 MPH,where g-C_(3)N_(4) constituted 20%of the total mass.Multiple optical and electrochemical tests revealed that the Cu_(2)O/g-C_(3)N_(4)-0.2 MPH effectively enhances charge separation and reduces charge transfer resistance.The Cu_(2)O/g-C_(3)N_(4)-0.2 SERS sensor exhibited a relative standard deviation(RSD)below 15%and achieved an enhancement factor(EF)of 2.43×106 for 4-ATP detection,demonstrating its high sensitivity and consistency.Additionally,it demonstrated a 98.3%degradation efficiency for methyl orange(MO)under visible light within 90 min.Remarkably,even after 216 days,its photocatalytic efficiency remained at 93.7%,and it retained an 84.0%efficiency after four cycles.XRD and SEM analyses before and after cycling,as well as after 216 days,confirmed the structural and morphological stability of the composite,demonstrating its cyclic and long-term stability.The excellent performance of the Cu_(2)O/g-C_(3)N_(4) MPH is attributed to its Z-type mechanism,as verified by radical trapping experiments.The evaluation of the self-cleaning performance of the Cu_(2)O/g-C_(3)N_(4)-0.2 SERS sensor demonstrated that its Z-scheme structure not only provides excellent self-cleaning capability but also enables the detection of both individual and mixed pollutants,while significantly enhancing the SERS signal response through an effective charge transfer enhancement mechanism.展开更多
文摘As a fundamental course in science and engineering education at universities,advanced mathematics plays an irreplaceable role in cultivating students’logical thinking,scientific spirit,and comprehensive qualities.Integrating ideological and political education into advanced mathematics teaching is not only an inevitable requirement for achieving the goal of“three-dimensional and holistic education”but also a crucial path for promoting students’comprehensive development.This article delves into the necessary logic,practical possibilities,and real-world challenges of ideological and political education in advanced mathematics courses,systematically analyzing the implementation pathways and illustrating practical approaches through specific cases.Meanwhile,to address issues such as insufficient teacher capability,lagging resource development,disconnected instructional design,and inadequate evaluation mechanisms encountered during implementation,this article proposes practical improvement strategies.It aims to provide theoretical insights and practical guidance for the further advancement of ideological and political education in advanced mathematics courses.
文摘The complexity of distribution network model mainly depends on the model scale of grid-connected distributed photovoltaic (PV) power generation. Therefore, the simulation performance of multi-scale PV model is the key factor of the simulation accuracy in the specific operating scenarios of distribution network. In this paper, a multi-scale model of grid connected PV distributed generation system is proposed based on the mathematical model of grid-connected distributed PV power generation. It is analyzed that differences of simulation performance, such as adaptability of simulation step size, accuracy of output and the effect on voltage profile of distribution network, between PV models with different scales in IEEE 33 node example. Simulation results indicate that the multi-scale model is effective in improving the accuracy and efficiency of simulation under different operating conditions of distribution network.
文摘In this paper, a method of power quality disturbance classification based on random matrix theory (RMT) is proposed. The method utilizes the power quality disturbance signal to construct a random matrix. By analyzing the mean spectral radius (MSR) variation of the random matrix, the type and time of occurrence of power quality disturbance are classified. In this paper, the random matrix theory is used to analyze the voltage sag, swell and interrupt perturbation signals to classify the occurrence time, duration of the disturbance signal and thedepth of voltage sag or swell. Examples show that the method has strong anti-noise ability.
基金supported by Funds for International Cooperation and Exchange of the National Natural Science Foundation of China(Grant No.52061635104).
文摘Distribution networks(DNs)face challenges in maintaining continuous power supply for critical loads under disasters.However,from a resilience perspective,the forecast accuracy of line/component failure rates under hurricanes still needs to be improved in order to gain an optimal allocation strategy for multiple emergency power supply vehicles(EPSVs),and the economics under normal state is supposed to be considered in the optimization pre-hurricane EPSV allocation.Due to the rapid development of environmentally friendly EPSVs,electric EPSVs and hydrogen fuel cell EPSVs are considered to be allocated jointly for their different advantages in enhancing DNs’resilience.Hence,to balance the resilience and economics of DNs against hurricanes,an equilibrium allocation strategy for electric EPSVs and hydrogen fuel cell EPSVs is proposed in this paper based on the Nash equilibrium.First,a statistical model for meteorological data about hurricanes is established via the conditional value at risk(CVaR)considering strong wind and the consequent rainfall.Failure rate models of DN lines/components are built on account of the damage mechanism of hurricanes.Then the emergency power supply capability of electric EPSVs and hydrogen fuel cell EPSVs are calculated considering the limited power energy stored in electric EPSVs and abundant hydrogen in a hydrogen fueling station.In addition,an equilibrium allocation strategy for sizing and locating multiple EPSVs is proposed,in which the Nash equilibrium method is utilized.Finally,simulation tests verify the superiority of the proposed failure rate models and equilibrium allocation strategy in balancing the resilience of DNs under hurricanes and the economics of DNs under normal states.
基金supported by the project of“Sustainable urban power supply through intelligent control and enhanced restoration of AC/DC networks(SUPER)”(52061635104).
文摘Under the background of low-carbon demand, an integrated energy system is the main direction of energy system development. Integrated Energy System (IES) breaks through technical, market and management barriers of traditional energy systems, and it makes unified planning and scheduling for electricity, gas, heat, cold, etc. However, IES contains a variety of energy forms, and those energy forms are coupled with each other. Its planning and operation are challenging problems. Therefore, this paper proposes an IES planning model, which comprehensively considers optimization of the equipment configuration, interconnection of multiple energy stations, renewable energy integration, and optimal operation strategy. During the planning decision-making, planners can use this model to analyze and evaluate the impact of various factors on the planning indicators. Using the proposed model, an IES composed of several buildings in a street block is planned in detail and the effectiveness of the proposed planning model and its solution method is proved. The case study results show the total cost and carbon emission of the model considering both energy station interconnection and RES integration are reduced by 20.2% and 41.5%.
基金This work is supported by Funds for International Cooperation and Exchange of the National Natural Science Foundation of China(Grant No.52061635104,Sustainable urban power supply through intelligent control and enhanced restoration of AC/DC networks).
文摘For fault characteristics of cyber-physical-systems(CPS)based distribution network,a spatiotemporal incidence matrix to represent correlation of concurrent faults on cyberspace and physical space is proposed,and strategies of fault location,removal,and recovery of concurrent faults are analyzed in this paper.Considering the multiple objectives of minimum network loss,voltage deviation,and switching operation times,a collaborative power supply restoration model of a CPS-based distribution network with the strategy that restoration of the communication layer is prior to the physical layer is constructed using the Dijkstra’s dynamic routing algorithm and second-order cone relaxation distribution network reconfiguration method,to realize orderly recovery of a distribution network during CPS concurrent faults.Related investigations are made based on the DCPS-160 case,and the accuracy and effectiveness of the proposed model are also verified.
基金supported in part by the National Key Research and Development Program of China (Basic Research Class 2017YFB0903000,Basic Theories and Methods of Analysis and Control of the Cyber Physical Systems for Power Grid).
文摘In the CPS-oriented power distribution system,a large number of the existing test cases cannot be accessed and reused.That is not conducive to the continuity of the CPS research of the distribution network.In response to above problem,based on an actual distribution network and considering the mapping relationship between cyber systems and physical systems,a computation test case that covers multiple power sources,and multiple types of load is proposed in this paper,and it is suitable for the simulation of multiple types of information system scenarios.In order to satisfy the specific needs of researchers for system topology and data,how to perform cyber contingency analysis,vulnerability assessment and distributed control are also discussed based on the existing topology and data.Researchers can utilize the test case presented in this paper to test their innovative methods in operational analysis,optimization control,and safety analysis for distribution networks.They can also utilize the published topologies and data to design their own test cases based on the methods in this paper.
基金National Natural Science Foundation of China(62275001, 62105001, 62205001)。
文摘The decomposition and identification of signals are crucial for flow vector acquisition in a multi-dimensional measurement. Here, we proposed a two-dimensional(2D) flow vector measurement system based on all-fiber laser feedback frequency-shifted multiplexing technology. The reliable performance of the system is characterized by experimental verification and numerical simulation. An orthogonal dual-beam structure is employed to eliminate the impact of an unknown incident angle in the practical application. Meanwhile, the vector velocity signals in 2D can be decomposed into one-dimensional(1D) scalar signals by adopting the frequency-shifted multiplexing,which makes it easy to obtain the vector information and velocity distribution of fluid motion through the self-mixing interference frequency spectrum.
基金supported by International Cooperation and Exchange of the National Natural Science Foundation of China(Grant No.52061635104).
文摘A large number of load power and power output of distributed generation in an active distribution network(ADN)are uncertain,which causes the classical affine power flow method to encounter problems of interval expansion and low efficiency when applied to an AND.This then leads to errors of interval power flow data sources in the cyber physical system(CPS)of an ADN.In order to improve the accuracy of interval power flow data in the CPS of an ADN,an affine power flow method of an ADN for restraining interval expansion is proposed.Aiming at the expansion of interval results caused by the approximation error of non-affine operations in an affine power flow method,the approximation method of the new noise source coefficient is improved,and it is proved that the improved method is superior to the classical method in restraining interval expansion.To overcome the decrease of computational efficiency caused by new noise sources,a novel merging method of new noise sources in an iterative process is designed.Simulation tests are conducted on an IEEE 33-bus,PG&E 69-bus and an actual 1180-bus system,which proves the validity of the proposed affine power flow method and its advantages in terms of computational efficiency and restraining interval expansion.
基金supported in part by National Natural Science Foundation of China(grant No.52207190)Funds for International Cooperation and Exchange of the National Natural Science Foundation of China(No.52061635104)。
文摘Virtual synchronous control has been widely studied for the advantages of emulating inertia for voltage source converters (VSCs). A constant dc-link voltage is usually assumed in existing literature to estimate transient stability of virtual synchronous generators (VSGs). However, actual power supply in the dc-side of VSGs is limited and different dc-link voltage controllers are needed to achieve power balance between DC side and AC side. Addition of dc-link voltage controller has great influence on transient behavior of VSGs, which has not been investigated by previous research. To fill this gap, this paper gives insights into the effect of dc-link voltage dynamics on transient stability of VSGs. First, two typical kinds of VSGs with dc-link voltage controllers are introduced. Then, mathematical models considering dc-link dynamics are established and the effect of dc-link voltage controllers on transient synchronization stability of VSGs is revealed through equal area criterion (EAC). It is found that dc-link voltage controller would reduce stability margin of VSGs and design-oriented transient stability analysis is carried out quantitively using critical clearing time (CCT). Finally, simulation results are given to validate correctness of theoretical analysis.
基金This work was supported by the State Grid Corporation of China Re-search Program under Grant:Research on Intelligent Fault Diagnosis and Prediction Technology of Active Distribution Network Based on Data Rele-vance,SGDK0000PDJS1802946.
文摘The use of frequency-changers is widespread in daily electric power generation.If a frequency-changer could automatically adjust its power output according to the load status and power network operation,it would have a positive impact on power system stability.To achieve this a novel control strategy based on virtual synchronous motors(VSM)is proposed in this paper.The frequency-changer consists of two main parts:the rectifier and the inverter.In the rectifier part,a UDC-Q control strategy is adopted to control the DC-link voltage and the reactive power.In the inverter part,a VSM control strategy is used;it includes a power-frequency controller and an excitation controller,and can change the inverter’s output frequency and voltage with the variation of load,can adjust the active power with change of the power system frequency.The proposed control strategy is simulated using Simulink/Matlab.The simulation results show that the proposed control strategy can follow the mechanical inertia and electrical characteristics of the synchronous moto and can effectively improve the system power quality and system stability.
基金supported by China Electric Power Research Institute Innovation Fund Program:Research on inexact data correction and association method for D-IoT(5242001900DS)。
文摘Sustainable development of power and energy systems(PES)can effectively handle challenges of fuel shortage,environmental pollution,climate change,energy security,etc.Data of PES presents distinctive characteristics including large collection,wide coverage,diverse temporal and spatial scales,inconsistent sparsity,multiple structures and low value density,putting forward higher requirements for real-time and accuracy of data analysis,and bringing great challenges to operation analysis and coordinated control of PES.In order to realize data quality improvement and further support flexible choice of operating mode,safe and efficient coordinated control,dynamic and orderly fault recovery of sustainable PES,this paper proposes an unscented particle filter algorithm,adopting unscented Kalman filter to construct importance density functions and KLD resampling to dynamically adjust the particle number.Simulation results obtained by taking an 85-node system as a benchmark for simulation verification show that compared with traditional PF algorithm and UKF algorithm,UPF algorithm has higher estimation accuracy.
基金support from the Program of Science and Technology of Jilin province(Item No.20220203021SF).
文摘Facile and efficient photocatalysts using sunlight,as well as fast and sensitive surface-enhanced Raman spectroscopy(SERS)substrates,are urgently needed for practical degradation of tetracycline(TC).To meet these requirements,a new paradigm for PI/TiO_(2)/Ag organic‒inorganic ternary flexible microfibers based on semiconducting titanium dioxide(TiO_(2)),the noble metal silver(Ag)and the conjugated polymer polyimide(PI)was developed by engineering a simple method.Under sunlight,the photocatalytic characteristics of the PI/TiO_(2)/Ag flexible microfibers containing varying amounts of Ag quantum dots(QDs)were evaluated with photocatalytic degradation of TC in aqueous solution.The results demonstrated that the amount of Ag affected the photocatalytic activity.Among the tested samples,PI/TiO_(2)/Ag-0.07(93.1%)exhibited a higher photocatalytic degradation rate than PI/TiO_(2)(25.7%),PI/TiO_(2)/Ag-0.05(77.7%),and PI/TiO_(2)/Ag-0.09(63.3%).This observation and evaluation conducted in the present work strongly indicated a charge transfer mechanism.Moreover,the PI/TiO_(2)/Ag-0.07 flexible microfibers exhibited highly sensitive SERS detection,as demonstrated by the observation of the Raman peaks for TC even at an extremely low concentration of 10–10 moles per liter.The excellent photocatalytic performance and SERS detection capability of the PI/TiO_(2)/Ag flexible microfibers arose from the Schottky barrier formed between Ag and TiO_(2)and also from the outstanding plasmonic resonance and visible light absorptivity of Ag,along with immobilization by the PI.The successful synthesis of PI/TiO_(2)/Ag flexible microfibers holds significant promise for sensitive detection and efficient photocatalytic degradation of antibiotics.
基金financial support from the development of Science and Technology of Jilin province(Item No.YDZJ202401541ZYTS).
文摘This study introduces a multifunctional device based on Cu_(2)O/g-C_(3)N_(4) monitoring and purification p–n heterojunctions(MPHs),seamlessly integrating surface-enhanced Raman scattering(SERS)detection with photocatalytic degradation capabilities.The SERS and photocatalytic performances of the Cu_(2)O in various morphologies,g-C_(3)N_(4) nanosheets(NSs)and Cu_(2)O/g-C_(3)N_(4) MPHs with different g-C_(3)N_(4) mass ratios were systematically evaluated,with a particular emphasis on the Cu_(2)O/g-C_(3)N_(4)-0.2 MPH,where g-C_(3)N_(4) constituted 20%of the total mass.Multiple optical and electrochemical tests revealed that the Cu_(2)O/g-C_(3)N_(4)-0.2 MPH effectively enhances charge separation and reduces charge transfer resistance.The Cu_(2)O/g-C_(3)N_(4)-0.2 SERS sensor exhibited a relative standard deviation(RSD)below 15%and achieved an enhancement factor(EF)of 2.43×106 for 4-ATP detection,demonstrating its high sensitivity and consistency.Additionally,it demonstrated a 98.3%degradation efficiency for methyl orange(MO)under visible light within 90 min.Remarkably,even after 216 days,its photocatalytic efficiency remained at 93.7%,and it retained an 84.0%efficiency after four cycles.XRD and SEM analyses before and after cycling,as well as after 216 days,confirmed the structural and morphological stability of the composite,demonstrating its cyclic and long-term stability.The excellent performance of the Cu_(2)O/g-C_(3)N_(4) MPH is attributed to its Z-type mechanism,as verified by radical trapping experiments.The evaluation of the self-cleaning performance of the Cu_(2)O/g-C_(3)N_(4)-0.2 SERS sensor demonstrated that its Z-scheme structure not only provides excellent self-cleaning capability but also enables the detection of both individual and mixed pollutants,while significantly enhancing the SERS signal response through an effective charge transfer enhancement mechanism.
