A method is proposed to measure the process margin of the main steam inlet and outlet pipe of a nuclear power plant by using an industrial photogrammetry system. This method includes steps of preparation,image acquisi...A method is proposed to measure the process margin of the main steam inlet and outlet pipe of a nuclear power plant by using an industrial photogrammetry system. This method includes steps of preparation,image acquisition,image processing,and result analysis,as well as the final processing margin analysis,and so on. In particular,it suggests a specific method for target-point layout and design of shooting network for the main steam inlet and outlet pipe measurement,and then uses a method of sub-section photography and collation to measure the inner and outer surfaces of the nuclear power interface pipe. The machining tolerance analysis shows that the method can effectively test whether the machining tolerance data of the interface pipe's top surface,outer surface and the inner surface reach a critical value,which provides a reliable reference for the next step in this process,and it is a type of machining tolerance detection method worthy of popularisation.展开更多
Energy in its varied forms and applications has become the main driver of today’s modern society. However, recent changes in power demand and climatic changes (decarbonization policy) has awakened the need to rethink...Energy in its varied forms and applications has become the main driver of today’s modern society. However, recent changes in power demand and climatic changes (decarbonization policy) has awakened the need to rethink through the current energy generating and distribution system. This led to the exploration of other energy sources of which renewable energy (like thermal, solar and wind energy) is fast becoming an integral part of most energy system. However, this innovative and promising energy source is highly unreliable in maintaining a constant peak power that matches demand. Energy storage systems have thus been highlighted as a solution in managing such imbalances and maintaining the stability of supply. Energy storage technologies absorb and store energy, and release it on demand. This includes gravitational potential energy (pumped hydroelectric), chemical energy (batteries), kinetic energy (flywheels or compressed air), and energy in the form of electrical (capacitors) and magnetic fields. This paper provides a detailed and comprehensive overview of some of the state-of-the-art energy storage technologies, its evolution, classification, and comparison along with various area of applications. Also highlighted in this paper is a plethora of power electronic Interface technologies that plays a significant role in enabling optimum performance and utilization of energy storage systems in different areas of application.展开更多
A monitoring system is proposed in order to detect the condition changes at abrasive/workpiece interface in abrasive cutoff operation.The system can detect the condition changes from the electric power change consumed...A monitoring system is proposed in order to detect the condition changes at abrasive/workpiece interface in abrasive cutoff operation.The system can detect the condition changes from the electric power change consumed by the driving motor of lapping tool.The electric power is strongly related with the abrasive effectiveness.When the abrasive effectiveness has been kept a normal state,the electric power also has been kept a constant value.The bodily removal of abrasive leads to reduce the electric power monotonously.The piling up of cutting chips leads to a peculiar electric power change;the electric power increased gradually at the beginning and then began to fluctuate periodically.The severe adhesion of cutting chips to the cutting edges leads to the loss of nominal function in the cutting edges and the electric power input was thus descended suddenly at an early stage of lapping.展开更多
In practical power systems,operators generally keep interface flowing under the transient stability constrained with interface real power flow limits(TS-IRPFL)to guarantee transient stability of the system.Many method...In practical power systems,operators generally keep interface flowing under the transient stability constrained with interface real power flow limits(TS-IRPFL)to guarantee transient stability of the system.Many methods of computing TS-IRPFL have been proposed.However,in practice,the method widely used to determine TS-IRPFL is based on selection and analysis of typical scenarios as well as scenario matching.First,typical scenarios are selected and analyzed to obtain accurate limits,then the scenario to be analyzed is matched with a certain typical scenario,whose limit is adopted as the forecast limit.In this paper,following the steps described above,a pragmatic method to determine TS-IRPFL is proposed.The proposed method utilizes data-driven tools to improve the steps of scenario selection and matching.First of all,we formulate a clear model of power system scenario similarity.Based on the similarity model,we develop a typical scenario selector by clustering and a scenario matcher by nearest neighbor algorithm.The proposed method is pragmatic because it does not change the existing procedure.Moreover,it is much more reasonable than the traditional method.Test results verify the validity of the method.展开更多
A microgrid is defined as a local electric power distribution system with diverse DG （distributed generation） units, energy storage systems, and loads, which can operate as a part of the distribution system or when ...A microgrid is defined as a local electric power distribution system with diverse DG （distributed generation） units, energy storage systems, and loads, which can operate as a part of the distribution system or when needed can operate in an islanded mode. Energy storage systems play a key role in improving security, stability, and power quality of the microgrid. During grid-connected mode, these storage units are charged from various DG sources as well as the main grid. During islanded mode, DG sources along with the storage units need to supply the load. Power electronic interfaces between the microgrid buses and the storage units should be able to detect the mode of operation, allow seamless transition between the modes, and allow power flow in both directions, while maintaining stability and power quality. An overview of bidirectional converter topologies relevant to microgrid energy storage application and their control strategies will be presented in this paper.展开更多
Real-time simulation of power electronics has been recognized by the industry as an effective tool for developing power electronic devices and systems.Since there is no energy transfer during the course of the usage,r...Real-time simulation of power electronics has been recognized by the industry as an effective tool for developing power electronic devices and systems.Since there is no energy transfer during the course of the usage,real-time simulation has a lot of advantages in the process of development and experimentation.From the perspective of real-time simulation,this paper focuses on the main problems in modeling accuracy,system bandwidth and stability,limitations on communication interface and energy interface,and the cost of platform construction.Finally,we provide further research directions.展开更多
We demonstrate a broad area（400 μm） high power quantum cascade laser（QCL）. A total peak power of 62 W operating at room temperature is achieved at λ~ 4.7 μm. The temperature dependence of the peak power charact...We demonstrate a broad area（400 μm） high power quantum cascade laser（QCL）. A total peak power of 62 W operating at room temperature is achieved at λ~ 4.7 μm. The temperature dependence of the peak power characteristic is given in the experiment, and also the temperature of the active zone is simulated by a finite-elementmethod（FEM）. We find that the interface roughness of the active core has a great effect on the temperature of the active zone and can be enormously improved using the solid source molecular beam epitaxy（MBE） growth system.展开更多
基金Supported by the National Natural Science Foundation of China(No.41301598)the Open Fund Program of Henan Engineering Laboratory of Pollution Control and Coal Chemical Resource Comprehensive Utilization(No.502002-B07,502002-A-04)
文摘A method is proposed to measure the process margin of the main steam inlet and outlet pipe of a nuclear power plant by using an industrial photogrammetry system. This method includes steps of preparation,image acquisition,image processing,and result analysis,as well as the final processing margin analysis,and so on. In particular,it suggests a specific method for target-point layout and design of shooting network for the main steam inlet and outlet pipe measurement,and then uses a method of sub-section photography and collation to measure the inner and outer surfaces of the nuclear power interface pipe. The machining tolerance analysis shows that the method can effectively test whether the machining tolerance data of the interface pipe's top surface,outer surface and the inner surface reach a critical value,which provides a reliable reference for the next step in this process,and it is a type of machining tolerance detection method worthy of popularisation.
文摘Energy in its varied forms and applications has become the main driver of today’s modern society. However, recent changes in power demand and climatic changes (decarbonization policy) has awakened the need to rethink through the current energy generating and distribution system. This led to the exploration of other energy sources of which renewable energy (like thermal, solar and wind energy) is fast becoming an integral part of most energy system. However, this innovative and promising energy source is highly unreliable in maintaining a constant peak power that matches demand. Energy storage systems have thus been highlighted as a solution in managing such imbalances and maintaining the stability of supply. Energy storage technologies absorb and store energy, and release it on demand. This includes gravitational potential energy (pumped hydroelectric), chemical energy (batteries), kinetic energy (flywheels or compressed air), and energy in the form of electrical (capacitors) and magnetic fields. This paper provides a detailed and comprehensive overview of some of the state-of-the-art energy storage technologies, its evolution, classification, and comparison along with various area of applications. Also highlighted in this paper is a plethora of power electronic Interface technologies that plays a significant role in enabling optimum performance and utilization of energy storage systems in different areas of application.
文摘A monitoring system is proposed in order to detect the condition changes at abrasive/workpiece interface in abrasive cutoff operation.The system can detect the condition changes from the electric power change consumed by the driving motor of lapping tool.The electric power is strongly related with the abrasive effectiveness.When the abrasive effectiveness has been kept a normal state,the electric power also has been kept a constant value.The bodily removal of abrasive leads to reduce the electric power monotonously.The piling up of cutting chips leads to a peculiar electric power change;the electric power increased gradually at the beginning and then began to fluctuate periodically.The severe adhesion of cutting chips to the cutting edges leads to the loss of nominal function in the cutting edges and the electric power input was thus descended suddenly at an early stage of lapping.
基金This work was supported by National Key R&D Program of China(2018YFB0904500)and State Grid Corporation of China。
文摘In practical power systems,operators generally keep interface flowing under the transient stability constrained with interface real power flow limits(TS-IRPFL)to guarantee transient stability of the system.Many methods of computing TS-IRPFL have been proposed.However,in practice,the method widely used to determine TS-IRPFL is based on selection and analysis of typical scenarios as well as scenario matching.First,typical scenarios are selected and analyzed to obtain accurate limits,then the scenario to be analyzed is matched with a certain typical scenario,whose limit is adopted as the forecast limit.In this paper,following the steps described above,a pragmatic method to determine TS-IRPFL is proposed.The proposed method utilizes data-driven tools to improve the steps of scenario selection and matching.First of all,we formulate a clear model of power system scenario similarity.Based on the similarity model,we develop a typical scenario selector by clustering and a scenario matcher by nearest neighbor algorithm.The proposed method is pragmatic because it does not change the existing procedure.Moreover,it is much more reasonable than the traditional method.Test results verify the validity of the method.
文摘A microgrid is defined as a local electric power distribution system with diverse DG （distributed generation） units, energy storage systems, and loads, which can operate as a part of the distribution system or when needed can operate in an islanded mode. Energy storage systems play a key role in improving security, stability, and power quality of the microgrid. During grid-connected mode, these storage units are charged from various DG sources as well as the main grid. During islanded mode, DG sources along with the storage units need to supply the load. Power electronic interfaces between the microgrid buses and the storage units should be able to detect the mode of operation, allow seamless transition between the modes, and allow power flow in both directions, while maintaining stability and power quality. An overview of bidirectional converter topologies relevant to microgrid energy storage application and their control strategies will be presented in this paper.
基金supported by the National Natural Science Foundation of China(No.51707053)the Anhui Provincial Natural Science Foundation(No.1808085QE155)the Fundamental Research Funds for the Central Universities(No.JZ2019HGTB0080)
文摘Real-time simulation of power electronics has been recognized by the industry as an effective tool for developing power electronic devices and systems.Since there is no energy transfer during the course of the usage,real-time simulation has a lot of advantages in the process of development and experimentation.From the perspective of real-time simulation,this paper focuses on the main problems in modeling accuracy,system bandwidth and stability,limitations on communication interface and energy interface,and the cost of platform construction.Finally,we provide further research directions.
基金Project supported by the National Basic Research Program of China(No.2013CB632801)the National Key Research and Development Program(No.2016YFB0402303)+2 种基金the National Natural Science Foundation of China(Nos.61435014,61627822,61574136,61306058,61404131)the Key Projects of Chinese Academy of Sciences(No.ZDRW-XH-20164)the Beijing Natural Science Foundation(No.4162060)
文摘We demonstrate a broad area（400 μm） high power quantum cascade laser（QCL）. A total peak power of 62 W operating at room temperature is achieved at λ~ 4.7 μm. The temperature dependence of the peak power characteristic is given in the experiment, and also the temperature of the active zone is simulated by a finite-elementmethod（FEM）. We find that the interface roughness of the active core has a great effect on the temperature of the active zone and can be enormously improved using the solid source molecular beam epitaxy（MBE） growth system.
