An integrated energy service company in an industrial park or commercial building is responsible for managing all energy sources in their local region, including electricity, water, gas, heating, and cooling. To reduc...An integrated energy service company in an industrial park or commercial building is responsible for managing all energy sources in their local region, including electricity, water, gas, heating, and cooling. To reduce energy wastage and increase energy utilization, it is necessary to perform efficiency analyses and diagnoses on integrated energy systems(IESs). However, the integrated energy data necessary for energy efficiency analyses and diagnoses come from a wide variety of instruments, each of which uses different transmission protocols and data formats. This makes it challenging to handle energy-flow data in a unified manner. Thus, we have constructed a unified model for diagnosing energy usage abnormalities in IESs. Using this model, the data are divided into working days and non-working days, and benchmark values are calculated after the data have been weighted to enable unified analysis of several types of energy data. The energy-flow data may then be observed, managed, and compared in all aspects to monitor sudden changes in energy usage and energy wastage. The abnormal data identified and selected by the unified model are then subjected to big-data analysis using technical management tools, enabling the detection of user problems such as abnormalities pertaining to acquisition device, metering, and energy usage. This model facilitates accurate metering of energy data and improves energy efficiency. The study has significant implications in terms of fulfilling the energy saving.展开更多
The arc-suppression coil(ASC)in parallel low resistance(LR)multi-mode grounding is adopted in the mountain wind farm to cope with the phenomenon that is misoperation or refusal of zero-sequence protection in LR ground...The arc-suppression coil(ASC)in parallel low resistance(LR)multi-mode grounding is adopted in the mountain wind farm to cope with the phenomenon that is misoperation or refusal of zero-sequence protection in LR grounding wind farm.If the fault disappears before LR is put into the system,it is judged as an instantaneous fault;while the fault does not disappear after LR is put into the system,it is judged as a permanent fault;the single-phase grounding fault(SLG)protection criterion based on zerosequence power variation is proposed to identify the instantaneous-permanent fault.Firstly,the distribution characteristic of zero-sequence voltage(ZSV)and zero-sequence current(ZSC)are analyzed after SLGfault occurs in multi-mode grounding.Then,according to the characteristics that zero-sequence power variation of non-fault collector line is small,while the zero-sequence power variation of fault collector line can reflect the active power component of fault resistance,the protection criterion based on zero-sequence power variation is constructed.The theoretical analysis and simulation results show that the protection criterion can distinguish the property of fault only by using the single terminal information,which has high reliability.展开更多
Integration of primary and secondary devices are impelled by the development of smart grid. Based on the ideology of primary and secondary device integration, an all-in-one device and its concept, configuration and fu...Integration of primary and secondary devices are impelled by the development of smart grid. Based on the ideology of primary and secondary device integration, an all-in-one device and its concept, configuration and function are proposed. Then, an all-in-one device framework of distributed substation area protection is proposed. Point-topoint model and virtual local area network(VLAN) based network-to-network model are adopted in this framework.The dual redundancy on hardware and software level is realized by modularization and protection information mirroring storage/overwriting. Considering the fact that the sampling, logic judgment and information sharing processes of protection may fail in atrocious conditions, a distributed cooperative all-in-one device cluster based substation area joint defensive protection strategy is proposed. The adaptability of sectional component failure in secondary system is strengthened by reusing module function, setting value mirroring storage and dynamic load balancing computing ability to constitute strong intelligent outdoor secondary device integrated network. Finally, the simulation examples based on EPOCHS which consider various system failure conditions are presented to verify the validity and rationality of the proposed architecture and strategy.展开更多
The traditional“three defense lines”for power systems are based on local information and static protection&control strategy,which are not suitable to modern large-scale power systems.In order to improve the secu...The traditional“three defense lines”for power systems are based on local information and static protection&control strategy,which are not suitable to modern large-scale power systems.In order to improve the security of UHV hybrid power grids,the Integrated Wide Area Protection&Control(IWAPC)is proposed in this paper by applying the new technologies of synchronized high-speed communication,which integrates“three defense lines”and promotes existing wide area protection only for security control.The IWAPC is the hierarchical protection and control system which provides the protection and control for wide area power networks to improve their reliability and security.It is divided into three levels,the local bay level,the substation integrated protection level and the wide area protection level.The wide area real-time protection and control information platform is the most important part of the IWAPC,which is based on a synchronized wide area communication network.The key technologies and new development trends include network topology analysis,wide area backup protection,wide area intelligent reclosing,wide area load shedding,wide area auto-switching,overload cutoff and transfer,transmission section protection,intelligent system splitting and dynamic stability control.It cannot only integrate three lines of defense for power system protection and control,but also improve security of the power grid.展开更多
This series of papers report on relay protection strategies that satisfy the demands of a strong smart grid.These strategies include ultra-high-speed transient-based fault discrimination,new co-ordination principles o...This series of papers report on relay protection strategies that satisfy the demands of a strong smart grid.These strategies include ultra-high-speed transient-based fault discrimination,new co-ordination principles of main and back-up protection to suit the diversification of the power network,optimal co-ordination between relay protection and auto-reclosure to enhance robustness of the power network.There are also new development in protection early warning and tripping functions of protection based on wide area information.In this paper the principles,algorithms and techniques of single-ended,transient-based and ultra-high-speed protection for EHV transmission lines,buses,DC transmission lines and faulty line selection for non-solid earthed networks are presented.Tests show that the methods presented can determine fault characteristics with ultra-high-speed(5 ms)and that the new principles of fault discrimination can satisfy the demand of EHV systems within a smart grid.展开更多
Half-wavelength AC Transmission(HWACT)can improve capability of AC transmission significantly.According to the basic principle of HWACT,the electromagnetic transient model of HWACT is built to analyze the fault transi...Half-wavelength AC Transmission(HWACT)can improve capability of AC transmission significantly.According to the basic principle of HWACT,the electromagnetic transient model of HWACT is built to analyze the fault transient process of transmission line.Based on fault characteristics of HWACT,the adaptability of traditional protections for transmission lines is analyzed briefly,such as current differential protection,distance protection and over current protection.In order to solve the problems of conventional protection caused by HWACT,a novel integrated protection based on multi-frequency domain information is proposed in this paper,which uses both the power frequency information and transient information.The integrated protection based on multi-frequency domain information takes advantages of power frequency and transient protections,which can not only improve the performance of traditional protection of AC transmission line but also realize fast fault judgment by transient travelling wave protection.展开更多
基金supported by National Key Research and Development Program of China (No.2017YFB903304)the State Grid Science and Technology Program (Hybrid Simnlation Key Technology for Integrated Energy System and Platform Construction)
文摘An integrated energy service company in an industrial park or commercial building is responsible for managing all energy sources in their local region, including electricity, water, gas, heating, and cooling. To reduce energy wastage and increase energy utilization, it is necessary to perform efficiency analyses and diagnoses on integrated energy systems(IESs). However, the integrated energy data necessary for energy efficiency analyses and diagnoses come from a wide variety of instruments, each of which uses different transmission protocols and data formats. This makes it challenging to handle energy-flow data in a unified manner. Thus, we have constructed a unified model for diagnosing energy usage abnormalities in IESs. Using this model, the data are divided into working days and non-working days, and benchmark values are calculated after the data have been weighted to enable unified analysis of several types of energy data. The energy-flow data may then be observed, managed, and compared in all aspects to monitor sudden changes in energy usage and energy wastage. The abnormal data identified and selected by the unified model are then subjected to big-data analysis using technical management tools, enabling the detection of user problems such as abnormalities pertaining to acquisition device, metering, and energy usage. This model facilitates accurate metering of energy data and improves energy efficiency. The study has significant implications in terms of fulfilling the energy saving.
基金This paper is supported in part by the National Natural Science Foundations of China,and the Major Science and Technology Projects in Yunnan Province under Grant Nos.51667010,51807085,and 202002AF080001.
文摘The arc-suppression coil(ASC)in parallel low resistance(LR)multi-mode grounding is adopted in the mountain wind farm to cope with the phenomenon that is misoperation or refusal of zero-sequence protection in LR grounding wind farm.If the fault disappears before LR is put into the system,it is judged as an instantaneous fault;while the fault does not disappear after LR is put into the system,it is judged as a permanent fault;the single-phase grounding fault(SLG)protection criterion based on zerosequence power variation is proposed to identify the instantaneous-permanent fault.Firstly,the distribution characteristic of zero-sequence voltage(ZSV)and zero-sequence current(ZSC)are analyzed after SLGfault occurs in multi-mode grounding.Then,according to the characteristics that zero-sequence power variation of non-fault collector line is small,while the zero-sequence power variation of fault collector line can reflect the active power component of fault resistance,the protection criterion based on zero-sequence power variation is constructed.The theoretical analysis and simulation results show that the protection criterion can distinguish the property of fault only by using the single terminal information,which has high reliability.
基金supported by the Science and Technology Project of State Grid Corporation of China(research and development of novel framework based protection adaptive to the evolution of substation and power grid)
文摘Integration of primary and secondary devices are impelled by the development of smart grid. Based on the ideology of primary and secondary device integration, an all-in-one device and its concept, configuration and function are proposed. Then, an all-in-one device framework of distributed substation area protection is proposed. Point-topoint model and virtual local area network(VLAN) based network-to-network model are adopted in this framework.The dual redundancy on hardware and software level is realized by modularization and protection information mirroring storage/overwriting. Considering the fact that the sampling, logic judgment and information sharing processes of protection may fail in atrocious conditions, a distributed cooperative all-in-one device cluster based substation area joint defensive protection strategy is proposed. The adaptability of sectional component failure in secondary system is strengthened by reusing module function, setting value mirroring storage and dynamic load balancing computing ability to constitute strong intelligent outdoor secondary device integrated network. Finally, the simulation examples based on EPOCHS which consider various system failure conditions are presented to verify the validity and rationality of the proposed architecture and strategy.
文摘The traditional“three defense lines”for power systems are based on local information and static protection&control strategy,which are not suitable to modern large-scale power systems.In order to improve the security of UHV hybrid power grids,the Integrated Wide Area Protection&Control(IWAPC)is proposed in this paper by applying the new technologies of synchronized high-speed communication,which integrates“three defense lines”and promotes existing wide area protection only for security control.The IWAPC is the hierarchical protection and control system which provides the protection and control for wide area power networks to improve their reliability and security.It is divided into three levels,the local bay level,the substation integrated protection level and the wide area protection level.The wide area real-time protection and control information platform is the most important part of the IWAPC,which is based on a synchronized wide area communication network.The key technologies and new development trends include network topology analysis,wide area backup protection,wide area intelligent reclosing,wide area load shedding,wide area auto-switching,overload cutoff and transfer,transmission section protection,intelligent system splitting and dynamic stability control.It cannot only integrate three lines of defense for power system protection and control,but also improve security of the power grid.
文摘This series of papers report on relay protection strategies that satisfy the demands of a strong smart grid.These strategies include ultra-high-speed transient-based fault discrimination,new co-ordination principles of main and back-up protection to suit the diversification of the power network,optimal co-ordination between relay protection and auto-reclosure to enhance robustness of the power network.There are also new development in protection early warning and tripping functions of protection based on wide area information.In this paper the principles,algorithms and techniques of single-ended,transient-based and ultra-high-speed protection for EHV transmission lines,buses,DC transmission lines and faulty line selection for non-solid earthed networks are presented.Tests show that the methods presented can determine fault characteristics with ultra-high-speed(5 ms)and that the new principles of fault discrimination can satisfy the demand of EHV systems within a smart grid.
文摘Half-wavelength AC Transmission(HWACT)can improve capability of AC transmission significantly.According to the basic principle of HWACT,the electromagnetic transient model of HWACT is built to analyze the fault transient process of transmission line.Based on fault characteristics of HWACT,the adaptability of traditional protections for transmission lines is analyzed briefly,such as current differential protection,distance protection and over current protection.In order to solve the problems of conventional protection caused by HWACT,a novel integrated protection based on multi-frequency domain information is proposed in this paper,which uses both the power frequency information and transient information.The integrated protection based on multi-frequency domain information takes advantages of power frequency and transient protections,which can not only improve the performance of traditional protection of AC transmission line but also realize fast fault judgment by transient travelling wave protection.
