Actual sea condition testing and inspection and evaluation method research are carried out for tidal energy devices to provide scientific and effective technical support for the ocean high-tech achievement transformat...Actual sea condition testing and inspection and evaluation method research are carried out for tidal energy devices to provide scientific and effective technical support for the ocean high-tech achievement transformation and marine renewable energy development. By analyzing three core indicators, including the power output characteristics of the tidal current device, the generating capacity, energy conversion efficiency, proposed the test contents and evaluation methods of indicators are proposed in this paper; and based on the research of wind farms, power quality testing and assessment methods of offshore tidal energy device are proposed; given the security access to the test contents of tidal current energy device, tidal current energy device running conditions in the testing ground are comprehensively assessed.展开更多
On the basis of analyzing the influencing factors and harmfulness of stray current, and discussing the existing problems of monitoring and prevention system for stray current, the integrated monitoring and prevention ...On the basis of analyzing the influencing factors and harmfulness of stray current, and discussing the existing problems of monitoring and prevention system for stray current, the integrated monitoring and prevention system for stray current in metro was developed. A net system of distributed computers for monitoring was set up. It can monitor the distribution of stray current in metro and the corrosion of the metal structure in the whole line. According to the situation of monitoring it can also control the drainage of its tank to reach the best effect and eliminate the negative effect of polarity drainage. By using the new type unilateral electric device, the problem of burning the rail by electric arc can be avoided. The unilateral electric device can be connected with the monitoring net system directly to realize the monitor in line and improve the reliability of the device.展开更多
In this study, in order to investigate the power consumption of feed drive system, mathematical models for the single-axis experimental apparatus are developed. This apparatus can be driven by either of ball screw or ...In this study, in order to investigate the power consumption of feed drive system, mathematical models for the single-axis experimental apparatus are developed. This apparatus can be driven by either of ball screw or linear motor and it is possible to change the mechanical properties of such as grease viscosity of the table. Then, the power consumption is simulated by proposed method based on the mathematical model of feed drive systems and the simulated results are compared with the measured results of the experimental apparatus to confirm the validity of the proposed method. In addition, it is clarified that the energy usages of the feed drive system. The energy losses of the feed drive system are divided into the loss of each part and these energy losses are calculated by the proposed method. Then, it is investigated that the influence of the velocity and friction to the energy consumption of feed drive system. As the results, it is confirmed that proposed method can accurately predict the power consumption of the ball-screw feed drive system. It is also clarified that the energy usage for both of ball-screw and linear motor drive systems.展开更多
In this paper, a method to calculate the slope of the ratio restraint characteristic of a transformer differential relay protection is proposed. The method allows using some concise but effective means to get the slop...In this paper, a method to calculate the slope of the ratio restraint characteristic of a transformer differential relay protection is proposed. The method allows using some concise but effective means to get the slope. Modulating the argument of current output from ONLLY testing equipment can make the relay protection device operate, thus, the data used for calculation would be obtained naturally after several trails. In order to make sure how effective that method could be, some experiment data is given as well.展开更多
Units and components of the powerful power equipment are exposed to the big static and dynamic load. An example of such equipments is turbines hydraulic power plant and, especially, hydroelectric pumped storage power ...Units and components of the powerful power equipment are exposed to the big static and dynamic load. An example of such equipments is turbines hydraulic power plant and, especially, hydroelectric pumped storage power plant. Existing techniques of control of a vibrating condition do not consider： very wide frequency range of vibrating processes, difficult character of such processes in the form of the sum multiharmonic, random and close to shock processes. Such techniques usually do not consider intervals of start-up and stop, and also work on transitive modes when loadings on a construction are maximum. Available techniques of an estimation of admissible level of vibrating influence and tests for vibration durability are not harmonized enough among themselves. Various known interpretations of communication of vibrating characteristics and durability estimations on mechanical pressure at broadband vibrating influence yield ambiguous result. On the basis of the analysis of the published information, we attempt to formulate the requirement to system of vibrating monitoring of the hydraulic turbine and power motor pumps. System should provide data acquisition and the analysis of the data on a vibrating condition taking into account accumulation of vibrating influences and long term of operation on the basis of estimation methods as low-cycle, and high-cycle （gigacycle） fatigue is made.展开更多
MHPPs （micro hydro power plants） have become prominent in hydropower plants as a solution to provide the energy demands of the grid. In this study, a new hybrid renewable energy based DC excitation system for synchr...MHPPs （micro hydro power plants） have become prominent in hydropower plants as a solution to provide the energy demands of the grid. In this study, a new hybrid renewable energy based DC excitation system for synchronous generator in the developed MHPP system is introduced. Proposed hybrid DC excitation system consists of solar ＆ hydrogen energy based power generating systems. Hybrid renewable energy based system is used for the excitation of the synchronous generator in the MHPP test system. The renewables are used as a secondary energy source to provide the excitation current to a synchronous generator that generates energy in MHPP. A PV （photovoltaic） array is used as the main source of excitation, and a FC （fuel cell） stack is used for DC excitation in the lack of sunshine. In the experimental setup, an electrical control card is developed, and a microcontroller is used to perform the proposed excitation system. All experimental results obtained from 5 kW rated power MHHP test system. Experimental results show that, the proposed method provides the continuous excitation current, and the operation of the synchronous generator is uninterrupted. The proposed method is also practical and easily implemented for MHPP systems.展开更多
This paperdescribes the development and applications of a fiber-optic electric current sensing technique with the stable properties and compact, simple, and flexible structure of the sensing device. The special charac...This paperdescribes the development and applications of a fiber-optic electric current sensing technique with the stable properties and compact, simple, and flexible structure of the sensing device. The special characteristics of the sensors were achieved by use of the special low birefringence fiber as the Faraday-effect sensing element and were also achieved with creation of sensing schemes which matched with the features of the fiber. Making use of the excellent features of the sensing technique, various current monitoring devices and systems were developed and applied practically for the control and maintenance in the electric power facility. In this paper, the design and performance of the sensing devices are introduced first. After that, examples of the application systems practically applied are also introduced, including fault section/point location systems for power transmission cable lines.展开更多
There has not been an effective method to measure the resistivity of small-size sample of mineral and solid insulating material until now.According to the Chinese National Standard(GB/T1410-2006) and features of digit...There has not been an effective method to measure the resistivity of small-size sample of mineral and solid insulating material until now.According to the Chinese National Standard(GB/T1410-2006) and features of digital high resistance meter,a small electrode experimental installation was developed;it can work with current high resistance meter;the sample decreases to 18 mm from standard size 100 mm in diameter and reduces by 30.86 times in area.A three-electrode system is supported and precisely positioned by two insulating bases whose diameter is 60 mm and height is 20 mm,which ensures accuracy of device structure and reliability of measuring results.The key technological parameters are as follows:diameter of high voltage electrode is 18mm;diameter of measuring electrode is 14.6 mm;internal diameter and external diameter of guard electrode are 16 and 18 mm,respectively;the gap between guard electrode and measuring electrode is set at 0.6 mm.These parameters are adequate for the measurement of flat specimen of mineral and solid insulating material whose diameter is 18 mm.According to the confirmatory experiment on the volume resistivity and surface resistivity,the measuring results are almost the same,using a small electrode experimental installation and a standard electrode.展开更多
基金supported by the Implementation Programs for Marine Renewable Energy Special Funds (GHME2012ZC02)
文摘Actual sea condition testing and inspection and evaluation method research are carried out for tidal energy devices to provide scientific and effective technical support for the ocean high-tech achievement transformation and marine renewable energy development. By analyzing three core indicators, including the power output characteristics of the tidal current device, the generating capacity, energy conversion efficiency, proposed the test contents and evaluation methods of indicators are proposed in this paper; and based on the research of wind farms, power quality testing and assessment methods of offshore tidal energy device are proposed; given the security access to the test contents of tidal current energy device, tidal current energy device running conditions in the testing ground are comprehensively assessed.
文摘On the basis of analyzing the influencing factors and harmfulness of stray current, and discussing the existing problems of monitoring and prevention system for stray current, the integrated monitoring and prevention system for stray current in metro was developed. A net system of distributed computers for monitoring was set up. It can monitor the distribution of stray current in metro and the corrosion of the metal structure in the whole line. According to the situation of monitoring it can also control the drainage of its tank to reach the best effect and eliminate the negative effect of polarity drainage. By using the new type unilateral electric device, the problem of burning the rail by electric arc can be avoided. The unilateral electric device can be connected with the monitoring net system directly to realize the monitor in line and improve the reliability of the device.
文摘In this study, in order to investigate the power consumption of feed drive system, mathematical models for the single-axis experimental apparatus are developed. This apparatus can be driven by either of ball screw or linear motor and it is possible to change the mechanical properties of such as grease viscosity of the table. Then, the power consumption is simulated by proposed method based on the mathematical model of feed drive systems and the simulated results are compared with the measured results of the experimental apparatus to confirm the validity of the proposed method. In addition, it is clarified that the energy usages of the feed drive system. The energy losses of the feed drive system are divided into the loss of each part and these energy losses are calculated by the proposed method. Then, it is investigated that the influence of the velocity and friction to the energy consumption of feed drive system. As the results, it is confirmed that proposed method can accurately predict the power consumption of the ball-screw feed drive system. It is also clarified that the energy usage for both of ball-screw and linear motor drive systems.
文摘In this paper, a method to calculate the slope of the ratio restraint characteristic of a transformer differential relay protection is proposed. The method allows using some concise but effective means to get the slope. Modulating the argument of current output from ONLLY testing equipment can make the relay protection device operate, thus, the data used for calculation would be obtained naturally after several trails. In order to make sure how effective that method could be, some experiment data is given as well.
文摘Units and components of the powerful power equipment are exposed to the big static and dynamic load. An example of such equipments is turbines hydraulic power plant and, especially, hydroelectric pumped storage power plant. Existing techniques of control of a vibrating condition do not consider： very wide frequency range of vibrating processes, difficult character of such processes in the form of the sum multiharmonic, random and close to shock processes. Such techniques usually do not consider intervals of start-up and stop, and also work on transitive modes when loadings on a construction are maximum. Available techniques of an estimation of admissible level of vibrating influence and tests for vibration durability are not harmonized enough among themselves. Various known interpretations of communication of vibrating characteristics and durability estimations on mechanical pressure at broadband vibrating influence yield ambiguous result. On the basis of the analysis of the published information, we attempt to formulate the requirement to system of vibrating monitoring of the hydraulic turbine and power motor pumps. System should provide data acquisition and the analysis of the data on a vibrating condition taking into account accumulation of vibrating influences and long term of operation on the basis of estimation methods as low-cycle, and high-cycle （gigacycle） fatigue is made.
文摘MHPPs （micro hydro power plants） have become prominent in hydropower plants as a solution to provide the energy demands of the grid. In this study, a new hybrid renewable energy based DC excitation system for synchronous generator in the developed MHPP system is introduced. Proposed hybrid DC excitation system consists of solar ＆ hydrogen energy based power generating systems. Hybrid renewable energy based system is used for the excitation of the synchronous generator in the MHPP test system. The renewables are used as a secondary energy source to provide the excitation current to a synchronous generator that generates energy in MHPP. A PV （photovoltaic） array is used as the main source of excitation, and a FC （fuel cell） stack is used for DC excitation in the lack of sunshine. In the experimental setup, an electrical control card is developed, and a microcontroller is used to perform the proposed excitation system. All experimental results obtained from 5 kW rated power MHHP test system. Experimental results show that, the proposed method provides the continuous excitation current, and the operation of the synchronous generator is uninterrupted. The proposed method is also practical and easily implemented for MHPP systems.
文摘This paperdescribes the development and applications of a fiber-optic electric current sensing technique with the stable properties and compact, simple, and flexible structure of the sensing device. The special characteristics of the sensors were achieved by use of the special low birefringence fiber as the Faraday-effect sensing element and were also achieved with creation of sensing schemes which matched with the features of the fiber. Making use of the excellent features of the sensing technique, various current monitoring devices and systems were developed and applied practically for the control and maintenance in the electric power facility. In this paper, the design and performance of the sensing devices are introduced first. After that, examples of the application systems practically applied are also introduced, including fault section/point location systems for power transmission cable lines.
基金supported by the National Natural Science Foundation of China (Grant No. 50974025)the National Key Technologies R & D Program of China (Grant No. 2004BA810B02)+2 种基金the Applied Foundation of Basic Research in Sichuan Province (Grant No. 07JY029-029)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20095122110015)the Scientific Research Foundation of the Education Ministry for Returned Chinese Scholars, China (Grant No. 2010-32)
文摘There has not been an effective method to measure the resistivity of small-size sample of mineral and solid insulating material until now.According to the Chinese National Standard(GB/T1410-2006) and features of digital high resistance meter,a small electrode experimental installation was developed;it can work with current high resistance meter;the sample decreases to 18 mm from standard size 100 mm in diameter and reduces by 30.86 times in area.A three-electrode system is supported and precisely positioned by two insulating bases whose diameter is 60 mm and height is 20 mm,which ensures accuracy of device structure and reliability of measuring results.The key technological parameters are as follows:diameter of high voltage electrode is 18mm;diameter of measuring electrode is 14.6 mm;internal diameter and external diameter of guard electrode are 16 and 18 mm,respectively;the gap between guard electrode and measuring electrode is set at 0.6 mm.These parameters are adequate for the measurement of flat specimen of mineral and solid insulating material whose diameter is 18 mm.According to the confirmatory experiment on the volume resistivity and surface resistivity,the measuring results are almost the same,using a small electrode experimental installation and a standard electrode.
