This paper proposes an advanced substation integrated protection communication system based on the latest development in power system.The integrated protection communication system within a substation comprises a numb...This paper proposes an advanced substation integrated protection communication system based on the latest development in power system.The integrated protection communication system within a substation comprises a number of major components such as the merging unit, communication network and integrated protection unit.The design and capability evaluation of the communication network based on IEC61850 are focused on.Results show that huge information from 4 merging units can be transmitted real-time via adopting 100 Mbit/s optical fiber in a substation,and the proposed communication network is able to achieve required performance.展开更多
This paper presents an integrated relay and its associated protection scheme for power transmission lines.The concept of integrated protection is firstly introduced,in which a centralized protection system or relay pr...This paper presents an integrated relay and its associated protection scheme for power transmission lines.The concept of integrated protection is firstly introduced,in which a centralized protection system or relay provides the protection for multiple power plants or a substation.A novel integrated protection relay based on the combination of a number of protection principles is described.In the proposed scheme,the specially designed protection relays are installed at each substation of a network and are responsible for the protection of every line section connected to the substation busbar.The combined algorithms with multiple settings are implemented into the relay to cover all the protected line sections.Simulation studies show that the proposed protection scheme is able to produce desirable performance and may offer many advantages over the existing one and great potential for future applications.展开更多
In the development and operation of real estate, real estate development enterprises as the principal subject would often establish contractual relationships with subjects of diverse interests including removed househ...In the development and operation of real estate, real estate development enterprises as the principal subject would often establish contractual relationships with subjects of diverse interests including removed households, banks, construction project contractors, and buyers. At times, conflicts of interests might occur among these contractual subjects requesting civil and commercial claims of the same subject matter based on agreements or legal rights. As for the causes of these conflicts and their solutions, a majority of existing researches still stay at the superficial causes from the perspective of civil and commercial law, and the solution of determining the order of priority of compensation of related rights. Due to the lack of research into deep-seated reasons and solutions from the perspective of economic law, the current legislative and judicial approaches to this kind of problems tend to give more protection to the rights of one subject while lack sufficient attention to other subjects. This paper attempts to carry out analyses and research on the causes and solutions to this kind of conflicts from the perspective of economic law, to achieve integrated protection of diverse interests in real estate development and operation so as to better safeguard the order in real estate development and operation and facilitate the healthy and ordered development of the real estate industry.展开更多
Digital twin is a novel technology that has achieved significant progress in industrial manufactur-ing systems in recent years.In the digital twin envi-ronment,entities in the virtual space collect data from devices i...Digital twin is a novel technology that has achieved significant progress in industrial manufactur-ing systems in recent years.In the digital twin envi-ronment,entities in the virtual space collect data from devices in the physical space to analyze their states.However,since a lot of devices exist in the physical space,the digital twin system needs to aggregate data from multiple devices at the edge gateway.Homomor-phic integrity and confidentiality protections are two important requirements for this data aggregation pro-cess.Unfortunately,existing homomorphic encryp-tion algorithms do not support integrity protection,and existing homomorphic signing algorithms require all signers to use the same signing key,which is not feasible in the digital twin environment.Moreover,for both integrity and confidentiality protections,the homomorphic signing algorithm must be compatible with the aggregation manner of the homomorphic en-cryption algorithm.To address these issues,this paper designs a novel homomorphic aggregation scheme,which allows multiple devices in the physical space to sign different data using different keys and support in-tegrity and confidentiality protections.Finally,the security of the newly designed scheme is analyzed,and its efficiency is evaluated.Experimental results show that our scheme is feasible for real world applications.展开更多
The protection system for traditional Chinese medicine(TCM)varieties,as an important policy tool to promote the development of TCM,has a long history of over 30 years,from the promulgation of the“Regulations on the P...The protection system for traditional Chinese medicine(TCM)varieties,as an important policy tool to promote the development of TCM,has a long history of over 30 years,from the promulgation of the“Regulations on the Protection of Traditional Chinese Medicine Varieties”in 1992 to the comprehensive revision of the draft for soliciting opinions in 2022.The TCM protection system evolves to meet the needs of innovative development of TCM.This paper reviews the policy developments in TCM varieties protection,collates protection data(1993 to 2024),and analyzes enterprises application strategies amid impending regulatory changes.展开更多
Facing the growth of energy demand and the worldwide interests in renewable energy sources,smart grid has been proposed in order to accommodate the needs of power grid development.In China,digital substations have bee...Facing the growth of energy demand and the worldwide interests in renewable energy sources,smart grid has been proposed in order to accommodate the needs of power grid development.In China,digital substations have been widely applied.Moreover,as the worldwide interest and development in smart grid have increased significantly,the digital information availability and communication capability of modern substation have been improved.Different with traditional substation protection configuration based on local information,Integrated Protection(IP)is used to denote the integration of several protective devices for multiple power equipment within the substation into one protective relay,obtaining all the real time information of the substation by communication network.The analysis of sharing information and cooperation among different protection functions helps to realize more reliable and sensitive fault detection.This paper describes several different integrated protection schemes and their respective advantages and disadvantages.The principles and functions applied in integrated protection systems are addressed to provide an overview of the current state of the technology.A new coordinated protection system based on inter-substation information is proposed and simulation study is discussed to verify the improved reliability and sensitivity.展开更多
This paper presents an integrated protection technique for power distribution systems. A novel integrated protection scheme based on overcurrent protection technique for distribution system is described, in which a sp...This paper presents an integrated protection technique for power distribution systems. A novel integrated protection scheme based on overcurrent protection technique for distribution system is described, in which a specially designed protection relay is installed at each substation of a network and responsible for the protection of every line sections connected to the substation busbar The conventional directional overcurrent and the new adaptive accelerated protection algorithms with multiple settings are implemented into the relay to cover all the protected line sections. The paper includes studies of a typical multi section distribution network to demonstrate the principle of the scheme. Studies show that the new scheme not only offer the new protection features for individual power line section, but also provide the characteristics of integrated protection.展开更多
Phaeocystis globosa Scherffel is one of the common harmful algae species in coastal waters of the southeastern China.In this study,sandwich hybridization integrated with nuclease protection assay(NPA-SH)was used to qu...Phaeocystis globosa Scherffel is one of the common harmful algae species in coastal waters of the southeastern China.In this study,sandwich hybridization integrated with nuclease protection assay(NPA-SH)was used to qualitatively and quantitatively detect P. globosa.Results showed that this method had good applicability and validity in analyzing the samples from laboratory cultures and from fields.The linear regression equation for P.globosa was obtained,and the lowest detection number of cells was 1.8×104 c...展开更多
Prorocentrum donghaiense is an important harmful algae bloom （HAB） causing creature in China＇s seas, and the conventional visual detection can not cope with long-term monitoring and highthroughput sampling projects...Prorocentrum donghaiense is an important harmful algae bloom （HAB） causing creature in China＇s seas, and the conventional visual detection can not cope with long-term monitoring and highthroughput sampling projects. An assay for P. donghaiense with sandwich hybridization integrated with nuclease protection assay （NPA-SH） was established. Tests with mixed samples and spiked field ones confirmed its good specificity and sensitivity. The cell number of P. donghaiense correlated well with the optical density, and the regression equation is y=4× 10^- 6x＋ 0.694 9, in which x is the cell number, and y is the optical density, with r2=0.953 5. These results show that the NPA-SH method has good feasibility in the detection of P. donghaiense. Results of NPA-SH and microscopy are excellent for each sample. The NPA-SH method was a simple way in quantitative detection of P. donghaiense, and the whole process could be finished in about six hours, which provided a new approach in high-throughput sampling and long-term monitoring of P. donghaiense.展开更多
To explore new light-weight integrated thermal protection system panel configuration and gain good insight into the responses mechanism,heat transfer and structural field analysis for one single-layer and four double-...To explore new light-weight integrated thermal protection system panel configuration and gain good insight into the responses mechanism,heat transfer and structural field analysis for one single-layer and four double-layer corrugated core panels were performed. The obtained the temperature,buckling,stress and deflection responses were compared,and the deflection and stress distributions as well as thermal buckling mode at the time were discussed for the considered configurations when the temperature difference between the top and bottom face sheet was maximum. The results demonstrated that the non-orthogonal and hat-stiffened double-layer structures provide superior performance to resist thermal buckling deformation in comparison with other configurations. The useful information is provided for the forthcoming optimization in which thermal buckling is considered as critical design driver.展开更多
Antenna Group Delay Variation(AGDV)is a hardware error source that affects the performance of Dual-Frequency Multi-Constellation(DFMC)Ground-based Augmentation System(GBAS),and these errors are difficult to distinguis...Antenna Group Delay Variation(AGDV)is a hardware error source that affects the performance of Dual-Frequency Multi-Constellation(DFMC)Ground-based Augmentation System(GBAS),and these errors are difficult to distinguish from multipath errors.Currently,AGDV is usually modeled as a part of the multipath error,which is called the multipath-AGDV model.However,because of the inconsistency of AGDV and multipath when switching among different positioning modes of GBAS,and because the traditional model does not consider the impact of the azimuth on AGDV,using the traditional multipath-AGDV model will cause the protection levels to be inaccurately calculated.In this paper,azimuth-based modeling of AGDV is conducted by using anechoic chamber measurements.The biases and standard deviations of AGDV based on azimuths are analyzed and modeled,and the calculation method for the DFMC GBAS protection level is optimized.The results show that the azimuth-based AGDV model and protection level optimization algorithm can better avoid the error exceeding the protection level than the multipath-AGDV model.Compared with AGDV elevation model,the VPLs of the B1C signal are increased by 0.24 m and 0.06 m,and the VPLs of the B2a signal are reduced by 0.01 m and 0.16 m using the 100 s and 600 s DFree filtering positioning modes,respectively.The changes in the B1C and B2a protection levels reflect the changes in AGDV corresponding to the azimuth for the respective frequencies,further ensuring the integrity of airborne users,especially when they turn near the airport.展开更多
With the continuous progress of the comprehensive implementation of the rural revitalization strategy, the protection of famous historical and cultural cities, towns and villages has received great attention from the ...With the continuous progress of the comprehensive implementation of the rural revitalization strategy, the protection of famous historical and cultural cities, towns and villages has received great attention from the state and society. With the continuous improvement of the level of economic development and the further advancement of industrialization and urbanization, the current historical and cultural environment and ecological environment are increasingly eroded and destroyed. From the perspective of cultural ecology, based on exploring the cultural ecological characteristics of Sanggan River Basin, this paper classified and analyzed the historical and cultural cities, towns and villages in the basin according to three levels: natural ecological elements, historical functions of towns and historical function forms of villages, and further explored their overall protection methods, hoping to provide some reference for the protection of other famous historical and cultural cities, towns and villages in China.展开更多
The microgrid has shown to be a promising solution for the integration and management of intermittent renewable energy generation.This paper looks at critical issues surrounding microgrid control and protection.It pro...The microgrid has shown to be a promising solution for the integration and management of intermittent renewable energy generation.This paper looks at critical issues surrounding microgrid control and protection.It proposes an integrated control and protection system with a hierarchical coordination control strategy consisting of a stand-alone operation mode,a grid-connected operation mode,and transitions between these two modes for a microgrid.To enhance the fault ride-through capability of the system,a comprehensive three-layer hierarchical protection system is also proposed,which fully adopts different protection schemes,such as relay protection,a hybrid energy storage system(HESS)regulation,and an emergency control.The effectiveness,feasibility,and practicality of the proposed systems are validated on a practical photovoltaic(PV)microgrid.This study is expected to provide some theoretical guidance and engineering construction experience for microgrids in general.展开更多
To eliminate anomalies and improve the performance of a space station remote manipulator(SSRM) used in a dynamically changeable thermal environment, we analyze the thermodynamic behavior of an SSRM that considers an i...To eliminate anomalies and improve the performance of a space station remote manipulator(SSRM) used in a dynamically changeable thermal environment, we analyze the thermodynamic behavior of an SSRM that considers an integrated thermal protection system(ITPS). Solar radiative heat gain and loss become equally significant as conductive heat transfers through the interior of the SSRM on orbit. A thermodynamic model of the SSRM with a sandwich ITPS structure is established on the coupling between harmonic drive and changeable thermal environment. A motion precision is proposed to evaluate thermodynamic behavior under continuously changeable thermal circumstances. Simulation results indicate that the ITPS with a corrugated sandwich structure reduces the maximum amplitude of angular position errors to 41.6%, which helps improve the motion precision of the SSRM. The feasible regions for the SSRM in the Low Earth Orbit(LEO) and Geostationary Earth Orbit(GEO) are analyzed, which shows that the proportion of feasible region in LEO is significantly larger than that in GEO.展开更多
Synchronized wide area communication has become a mature technology,which makes the real-time interaction between the substations and the wide area protection and control system possible.However,the present protection...Synchronized wide area communication has become a mature technology,which makes the real-time interaction between the substations and the wide area protection and control system possible.However,the present protection and control system to handle this real-time data has been recognized to be deficient.This paper begins by reviewing the development history of power system protection,with special attention paid to the recent development in the field of wide-area and integrated protections,in order to look into the future development of protection and control systems.Then the concept of integrated wide area protection and control is introduced,where it can be shown that a hierarchical protection and control system provides the protection and control for wide area or regional power substations/plants and their associated power networks.The system is mainly divided into three levels:the local,the substation/plant,and the wide area/regional.The integrated functions at each level are described in details with an aim to develop an optimal coordination mechanism between each level.The key element in the proposed system is the wide area real-time protection and control information platform,which not only enables the merger of three lines of defence for power system protection and control,but also provides a perfect tool for the application of cloud computing in substations and power networks.展开更多
Wide area monitoring(WAM) offers many opportunities to improve the performance of power system protection. This paper presents some of these opportunities and the motivation for their development. This methods include...Wide area monitoring(WAM) offers many opportunities to improve the performance of power system protection. This paper presents some of these opportunities and the motivation for their development. This methods include monitoring the suitability of relay characteristics,supervisory control of backup protection, more adaptive and intelligent system protection and the creation of novel system integrity protection scheme. The speed of response required for primary protection means that the role WAM in enhancing protection is limited to backup and system protection. The opportunities offered by WAM for enhancing protection are attractive because of the emerging challenges faced by the modern power system protection. The increasingly variable operating conditions of power systems are making it ever more difficult to select relay characteristics that will be a suitable compromise for all loading conditions and contingencies. The maloperation of relays has contributed to the inception and evolution of 70 % of blackouts,thus the supervision of the backup protection may prove a valuable tool for preventing or limiting the scale of blackouts. The increasing interconnection and complexity of modern power systems has made them more vulnerable to wide area disturbances and this has contributed to several recent blackouts. The proper management of these wide area disturbances is beyond the scope of most of the existing protection and new, adaptive system integrity protection schemes are needed to protect power system security.展开更多
Power system faults can often result in excessively high currents.If sustained for a long time,such high currents can damage system equipment.Thus,it is desirable to operate the relays in the minimum possible time.In ...Power system faults can often result in excessively high currents.If sustained for a long time,such high currents can damage system equipment.Thus,it is desirable to operate the relays in the minimum possible time.In this paper,a busbar splitting approach is used for adaptive relay setting and co-ordination purposes for a system integrity protec-tion scheme(SIPS).Whenever a fault occurs,the busbar splitting scheme splits a bus to convert a loop into a radial structure.The splitting schemes are chosen such that the net fault current is also reduced.Busbar splitting elimi-nates the dependency upon minimum breakpoints set(MBPS)and reduces the relay operating time,thus making it adaptive.The proposed methodology is incorporated into the IEEE 14-bus and IEEE 30-bus systems with single and multiple fault conditions.The modeling and simulation carried out in ETAP,and the results of the proposed busbar splitting-based relay co-ordination are compared with the MBPS splitting-based relay co-ordination.展开更多
Electric power grids are critical infrastructure for delivering energy from generation stations to load centers. To maximize utilization of assets, it is desirable to increase the power transferred over transmission s...Electric power grids are critical infrastructure for delivering energy from generation stations to load centers. To maximize utilization of assets, it is desirable to increase the power transferred over transmission systems. Reliable protection of transmission systems is essential for safeguarding the integrity and reliability of the power grid. Distance protection is the most widely used scheme for protecting transmission lines. Most existing protection systems use local measurements to make a decision while pilot protection is used in some circumstances. Distance protection may fail under stressed operating conditions, which could lead to cascading faults. This paper proposes a system integrity protection scheme by utilizing wide area measurements. The scheme partitions the system into subnetworks or protection zones and employs current measurements to derive a fault identification vector indicating the faulted zone. Then the fault location is pinpointed based on wide area measurements and network data. The proposed method is able to deal with multiple, simultaneous faults, and is applicable to both transposed and untransposed lines. Evaluation studies based on simulation studies are presented.展开更多
Over the past decade,China has undertaken substation intellectualization of more than 2000 substation operations in three stages.Much experience has been achieved during this developmental period.In this paper,the sta...Over the past decade,China has undertaken substation intellectualization of more than 2000 substation operations in three stages.Much experience has been achieved during this developmental period.In this paper,the status of smart substation development in China is systematically presented,as well as future directions of the smart substation,such as adoption of the hierarchical protection and control system.展开更多
基金National Natural Science Foundation of China(No.50677003).
文摘This paper proposes an advanced substation integrated protection communication system based on the latest development in power system.The integrated protection communication system within a substation comprises a number of major components such as the merging unit, communication network and integrated protection unit.The design and capability evaluation of the communication network based on IEC61850 are focused on.Results show that huge information from 4 merging units can be transmitted real-time via adopting 100 Mbit/s optical fiber in a substation,and the proposed communication network is able to achieve required performance.
基金National Natural Science Foundation of China(No.50077011 and 50377019)National Basic Research Project("973"Project No.2004CB217906).
文摘This paper presents an integrated relay and its associated protection scheme for power transmission lines.The concept of integrated protection is firstly introduced,in which a centralized protection system or relay provides the protection for multiple power plants or a substation.A novel integrated protection relay based on the combination of a number of protection principles is described.In the proposed scheme,the specially designed protection relays are installed at each substation of a network and are responsible for the protection of every line section connected to the substation busbar.The combined algorithms with multiple settings are implemented into the relay to cover all the protected line sections.Simulation studies show that the proposed protection scheme is able to produce desirable performance and may offer many advantages over the existing one and great potential for future applications.
文摘In the development and operation of real estate, real estate development enterprises as the principal subject would often establish contractual relationships with subjects of diverse interests including removed households, banks, construction project contractors, and buyers. At times, conflicts of interests might occur among these contractual subjects requesting civil and commercial claims of the same subject matter based on agreements or legal rights. As for the causes of these conflicts and their solutions, a majority of existing researches still stay at the superficial causes from the perspective of civil and commercial law, and the solution of determining the order of priority of compensation of related rights. Due to the lack of research into deep-seated reasons and solutions from the perspective of economic law, the current legislative and judicial approaches to this kind of problems tend to give more protection to the rights of one subject while lack sufficient attention to other subjects. This paper attempts to carry out analyses and research on the causes and solutions to this kind of conflicts from the perspective of economic law, to achieve integrated protection of diverse interests in real estate development and operation so as to better safeguard the order in real estate development and operation and facilitate the healthy and ordered development of the real estate industry.
基金supported by ZTE Industry-University-Institute Cooperation Funds under Grant No.IA20230628015the State Key Laboratory of Particle Detection and Electronics under Grant No.SKLPDE-KF-202314.
文摘Digital twin is a novel technology that has achieved significant progress in industrial manufactur-ing systems in recent years.In the digital twin envi-ronment,entities in the virtual space collect data from devices in the physical space to analyze their states.However,since a lot of devices exist in the physical space,the digital twin system needs to aggregate data from multiple devices at the edge gateway.Homomor-phic integrity and confidentiality protections are two important requirements for this data aggregation pro-cess.Unfortunately,existing homomorphic encryp-tion algorithms do not support integrity protection,and existing homomorphic signing algorithms require all signers to use the same signing key,which is not feasible in the digital twin environment.Moreover,for both integrity and confidentiality protections,the homomorphic signing algorithm must be compatible with the aggregation manner of the homomorphic en-cryption algorithm.To address these issues,this paper designs a novel homomorphic aggregation scheme,which allows multiple devices in the physical space to sign different data using different keys and support in-tegrity and confidentiality protections.Finally,the security of the newly designed scheme is analyzed,and its efficiency is evaluated.Experimental results show that our scheme is feasible for real world applications.
文摘The protection system for traditional Chinese medicine(TCM)varieties,as an important policy tool to promote the development of TCM,has a long history of over 30 years,from the promulgation of the“Regulations on the Protection of Traditional Chinese Medicine Varieties”in 1992 to the comprehensive revision of the draft for soliciting opinions in 2022.The TCM protection system evolves to meet the needs of innovative development of TCM.This paper reviews the policy developments in TCM varieties protection,collates protection data(1993 to 2024),and analyzes enterprises application strategies amid impending regulatory changes.
基金supported by the National Natural Science Foundation of China under Grant 51277009,and the Application Technology Research and Engineering Demonstration Program of National Energy Administration under Grant NY20150302.
文摘Facing the growth of energy demand and the worldwide interests in renewable energy sources,smart grid has been proposed in order to accommodate the needs of power grid development.In China,digital substations have been widely applied.Moreover,as the worldwide interest and development in smart grid have increased significantly,the digital information availability and communication capability of modern substation have been improved.Different with traditional substation protection configuration based on local information,Integrated Protection(IP)is used to denote the integration of several protective devices for multiple power equipment within the substation into one protective relay,obtaining all the real time information of the substation by communication network.The analysis of sharing information and cooperation among different protection functions helps to realize more reliable and sensitive fault detection.This paper describes several different integrated protection schemes and their respective advantages and disadvantages.The principles and functions applied in integrated protection systems are addressed to provide an overview of the current state of the technology.A new coordinated protection system based on inter-substation information is proposed and simulation study is discussed to verify the improved reliability and sensitivity.
文摘This paper presents an integrated protection technique for power distribution systems. A novel integrated protection scheme based on overcurrent protection technique for distribution system is described, in which a specially designed protection relay is installed at each substation of a network and responsible for the protection of every line sections connected to the substation busbar The conventional directional overcurrent and the new adaptive accelerated protection algorithms with multiple settings are implemented into the relay to cover all the protected line sections. The paper includes studies of a typical multi section distribution network to demonstrate the principle of the scheme. Studies show that the new scheme not only offer the new protection features for individual power line section, but also provide the characteristics of integrated protection.
基金supported by the National Hi-Tech Research and Development Program(863)of China(No.2006AA09Z178,2001AA635090)the National Nat-ural Science Foundation of China(No.40706044)
文摘Phaeocystis globosa Scherffel is one of the common harmful algae species in coastal waters of the southeastern China.In this study,sandwich hybridization integrated with nuclease protection assay(NPA-SH)was used to qualitatively and quantitatively detect P. globosa.Results showed that this method had good applicability and validity in analyzing the samples from laboratory cultures and from fields.The linear regression equation for P.globosa was obtained,and the lowest detection number of cells was 1.8×104 c...
基金The National High Technology Research and Development Program ("863" Program) of China under contract No 2006AA09Z178 the National Natural Science Foundation of China under contract No 40706044
文摘Prorocentrum donghaiense is an important harmful algae bloom （HAB） causing creature in China＇s seas, and the conventional visual detection can not cope with long-term monitoring and highthroughput sampling projects. An assay for P. donghaiense with sandwich hybridization integrated with nuclease protection assay （NPA-SH） was established. Tests with mixed samples and spiked field ones confirmed its good specificity and sensitivity. The cell number of P. donghaiense correlated well with the optical density, and the regression equation is y=4× 10^- 6x＋ 0.694 9, in which x is the cell number, and y is the optical density, with r2=0.953 5. These results show that the NPA-SH method has good feasibility in the detection of P. donghaiense. Results of NPA-SH and microscopy are excellent for each sample. The NPA-SH method was a simple way in quantitative detection of P. donghaiense, and the whole process could be finished in about six hours, which provided a new approach in high-throughput sampling and long-term monitoring of P. donghaiense.
基金Sponsored by the National Natural Science Foundation of China(Grant No.11102054)Postdoctoral Science-research Developmental Foundation of Heilongjiang Province(Grant No.LBH-Q12101)the Fundamental Research Funds for the Central Universities(Grant No.HIT.NSRIF.2014026)
文摘To explore new light-weight integrated thermal protection system panel configuration and gain good insight into the responses mechanism,heat transfer and structural field analysis for one single-layer and four double-layer corrugated core panels were performed. The obtained the temperature,buckling,stress and deflection responses were compared,and the deflection and stress distributions as well as thermal buckling mode at the time were discussed for the considered configurations when the temperature difference between the top and bottom face sheet was maximum. The results demonstrated that the non-orthogonal and hat-stiffened double-layer structures provide superior performance to resist thermal buckling deformation in comparison with other configurations. The useful information is provided for the forthcoming optimization in which thermal buckling is considered as critical design driver.
基金the National Key Research and Development Program of China(No.2023YFB3907001)the financial support from the National Natural Science Foundation of China(Nos.62371029,U2233217 and 62101019)the Civil Aviation Security Capacity Building Fund Project of China(Nos.CAAC Contract 2021(77)and CAAC Contract 2022(110)).
文摘Antenna Group Delay Variation(AGDV)is a hardware error source that affects the performance of Dual-Frequency Multi-Constellation(DFMC)Ground-based Augmentation System(GBAS),and these errors are difficult to distinguish from multipath errors.Currently,AGDV is usually modeled as a part of the multipath error,which is called the multipath-AGDV model.However,because of the inconsistency of AGDV and multipath when switching among different positioning modes of GBAS,and because the traditional model does not consider the impact of the azimuth on AGDV,using the traditional multipath-AGDV model will cause the protection levels to be inaccurately calculated.In this paper,azimuth-based modeling of AGDV is conducted by using anechoic chamber measurements.The biases and standard deviations of AGDV based on azimuths are analyzed and modeled,and the calculation method for the DFMC GBAS protection level is optimized.The results show that the azimuth-based AGDV model and protection level optimization algorithm can better avoid the error exceeding the protection level than the multipath-AGDV model.Compared with AGDV elevation model,the VPLs of the B1C signal are increased by 0.24 m and 0.06 m,and the VPLs of the B2a signal are reduced by 0.01 m and 0.16 m using the 100 s and 600 s DFree filtering positioning modes,respectively.The changes in the B1C and B2a protection levels reflect the changes in AGDV corresponding to the azimuth for the respective frequencies,further ensuring the integrity of airborne users,especially when they turn near the airport.
文摘With the continuous progress of the comprehensive implementation of the rural revitalization strategy, the protection of famous historical and cultural cities, towns and villages has received great attention from the state and society. With the continuous improvement of the level of economic development and the further advancement of industrialization and urbanization, the current historical and cultural environment and ecological environment are increasingly eroded and destroyed. From the perspective of cultural ecology, based on exploring the cultural ecological characteristics of Sanggan River Basin, this paper classified and analyzed the historical and cultural cities, towns and villages in the basin according to three levels: natural ecological elements, historical functions of towns and historical function forms of villages, and further explored their overall protection methods, hoping to provide some reference for the protection of other famous historical and cultural cities, towns and villages in China.
基金supported by the National High Technology Research and Development of China 863 Program under Grant 2012AAOS0204,Chinathe National Natural Science Foundation of China under Grant S132100S,S1207076.
文摘The microgrid has shown to be a promising solution for the integration and management of intermittent renewable energy generation.This paper looks at critical issues surrounding microgrid control and protection.It proposes an integrated control and protection system with a hierarchical coordination control strategy consisting of a stand-alone operation mode,a grid-connected operation mode,and transitions between these two modes for a microgrid.To enhance the fault ride-through capability of the system,a comprehensive three-layer hierarchical protection system is also proposed,which fully adopts different protection schemes,such as relay protection,a hybrid energy storage system(HESS)regulation,and an emergency control.The effectiveness,feasibility,and practicality of the proposed systems are validated on a practical photovoltaic(PV)microgrid.This study is expected to provide some theoretical guidance and engineering construction experience for microgrids in general.
基金supported by the National Natural Science Foundation of China(Grant No.11272171)Education Ministry Doctoral Fund of China(Grant No.20120002110070)
文摘To eliminate anomalies and improve the performance of a space station remote manipulator(SSRM) used in a dynamically changeable thermal environment, we analyze the thermodynamic behavior of an SSRM that considers an integrated thermal protection system(ITPS). Solar radiative heat gain and loss become equally significant as conductive heat transfers through the interior of the SSRM on orbit. A thermodynamic model of the SSRM with a sandwich ITPS structure is established on the coupling between harmonic drive and changeable thermal environment. A motion precision is proposed to evaluate thermodynamic behavior under continuously changeable thermal circumstances. Simulation results indicate that the ITPS with a corrugated sandwich structure reduces the maximum amplitude of angular position errors to 41.6%, which helps improve the motion precision of the SSRM. The feasible regions for the SSRM in the Low Earth Orbit(LEO) and Geostationary Earth Orbit(GEO) are analyzed, which shows that the proportion of feasible region in LEO is significantly larger than that in GEO.
文摘Synchronized wide area communication has become a mature technology,which makes the real-time interaction between the substations and the wide area protection and control system possible.However,the present protection and control system to handle this real-time data has been recognized to be deficient.This paper begins by reviewing the development history of power system protection,with special attention paid to the recent development in the field of wide-area and integrated protections,in order to look into the future development of protection and control systems.Then the concept of integrated wide area protection and control is introduced,where it can be shown that a hierarchical protection and control system provides the protection and control for wide area or regional power substations/plants and their associated power networks.The system is mainly divided into three levels:the local,the substation/plant,and the wide area/regional.The integrated functions at each level are described in details with an aim to develop an optimal coordination mechanism between each level.The key element in the proposed system is the wide area real-time protection and control information platform,which not only enables the merger of three lines of defence for power system protection and control,but also provides a perfect tool for the application of cloud computing in substations and power networks.
文摘Wide area monitoring(WAM) offers many opportunities to improve the performance of power system protection. This paper presents some of these opportunities and the motivation for their development. This methods include monitoring the suitability of relay characteristics,supervisory control of backup protection, more adaptive and intelligent system protection and the creation of novel system integrity protection scheme. The speed of response required for primary protection means that the role WAM in enhancing protection is limited to backup and system protection. The opportunities offered by WAM for enhancing protection are attractive because of the emerging challenges faced by the modern power system protection. The increasingly variable operating conditions of power systems are making it ever more difficult to select relay characteristics that will be a suitable compromise for all loading conditions and contingencies. The maloperation of relays has contributed to the inception and evolution of 70 % of blackouts,thus the supervision of the backup protection may prove a valuable tool for preventing or limiting the scale of blackouts. The increasing interconnection and complexity of modern power systems has made them more vulnerable to wide area disturbances and this has contributed to several recent blackouts. The proper management of these wide area disturbances is beyond the scope of most of the existing protection and new, adaptive system integrity protection schemes are needed to protect power system security.
文摘Power system faults can often result in excessively high currents.If sustained for a long time,such high currents can damage system equipment.Thus,it is desirable to operate the relays in the minimum possible time.In this paper,a busbar splitting approach is used for adaptive relay setting and co-ordination purposes for a system integrity protec-tion scheme(SIPS).Whenever a fault occurs,the busbar splitting scheme splits a bus to convert a loop into a radial structure.The splitting schemes are chosen such that the net fault current is also reduced.Busbar splitting elimi-nates the dependency upon minimum breakpoints set(MBPS)and reduces the relay operating time,thus making it adaptive.The proposed methodology is incorporated into the IEEE 14-bus and IEEE 30-bus systems with single and multiple fault conditions.The modeling and simulation carried out in ETAP,and the results of the proposed busbar splitting-based relay co-ordination are compared with the MBPS splitting-based relay co-ordination.
文摘Electric power grids are critical infrastructure for delivering energy from generation stations to load centers. To maximize utilization of assets, it is desirable to increase the power transferred over transmission systems. Reliable protection of transmission systems is essential for safeguarding the integrity and reliability of the power grid. Distance protection is the most widely used scheme for protecting transmission lines. Most existing protection systems use local measurements to make a decision while pilot protection is used in some circumstances. Distance protection may fail under stressed operating conditions, which could lead to cascading faults. This paper proposes a system integrity protection scheme by utilizing wide area measurements. The scheme partitions the system into subnetworks or protection zones and employs current measurements to derive a fault identification vector indicating the faulted zone. Then the fault location is pinpointed based on wide area measurements and network data. The proposed method is able to deal with multiple, simultaneous faults, and is applicable to both transposed and untransposed lines. Evaluation studies based on simulation studies are presented.
基金National Natural Science Foundation of China under Grant 51120175001Key Project of Smart Grid Technology and Equipment of National Key Research and Development Plan of China under Grant 2016YFB0900600Science and Technology Project of State Grid Corporation of China under Grant GWKJ2013-005.
文摘Over the past decade,China has undertaken substation intellectualization of more than 2000 substation operations in three stages.Much experience has been achieved during this developmental period.In this paper,the status of smart substation development in China is systematically presented,as well as future directions of the smart substation,such as adoption of the hierarchical protection and control system.
