The characteristics and distribution law of electromagnetic environment around substations with different levels of voltage were studied,and the main influencing factors were discussed. Meanwhile,a scheme for locating...The characteristics and distribution law of electromagnetic environment around substations with different levels of voltage were studied,and the main influencing factors were discussed. Meanwhile,a scheme for locating monitoring points suitable for an on-line monitoring system of electromagnetic environment was proposed.展开更多
To overcome the disadvantages of conventional DGA (dissolved gas-in-oil)analysis using gas chromatography and other electrochemical sensors, initial researches werecompleted to realize on-line monitoring of dissolved ...To overcome the disadvantages of conventional DGA (dissolved gas-in-oil)analysis using gas chromatography and other electrochemical sensors, initial researches werecompleted to realize on-line monitoring of dissolved gas-in-oil of power transformers using FTIR(Fourier Transform InfraRed) spectroscopy. Gas cell method is used to determine the characteristicabsorption peaks of each diagnostic gas; simple and novel devices and procedures were designed inorder to get measurable samples and spectra of mixed diagnostic gases with known concentration aretaken using long optical path gas cell. The range of wavelength is estimated to be 3.0-13.9 mum fromexperimental spectra data. Hence the corresponding sampling frequency range should be in 536-4288Hz and usable optical materials are suggested. It is concluded that a resolution of 10 cm^(-1) maywell satisfy the monitoring of all diagnostic gases and water content except hydrogen, and thelowest detection limit may be as low as 2Xl0^(-8) to acetylene with a 2.4-meter-long optical length.展开更多
Several industrial computers and a server are combined to set up the on-line monitoring and diagnostic system of turbo-generator sets. The main function of the system is to monitor machine sets' running condition....Several industrial computers and a server are combined to set up the on-line monitoring and diagnostic system of turbo-generator sets. The main function of the system is to monitor machine sets' running condition. Through analyzing running data, technicians can detect whether there exist faults and where they occur. To share and transmit the dynamic information of the turbo-generator sets, a distributed network system is introduced. NetWare network operating system is used in the LAN (Local Area Network) system. The LAN is extended to realize the sharing of data and remote transmission of information. Furthermore, functions of monitoring and diagnostic clients are listed.展开更多
Discusses on-line monitoring of electric parameters, such as dielectric loss, divulging current, equivalent capacitance and running voltage, and presents an on-line monitoring system of insulation quality, based on mo...Discusses on-line monitoring of electric parameters, such as dielectric loss, divulging current, equivalent capacitance and running voltage, and presents an on-line monitoring system of insulation quality, based on monitoring divulging current and dielectric loss of high voltage equipment, and its advantages, such as helping people to discover the hidden problems in a timely manner, to reduce power cut and overhaul and to improve security of power supply.展开更多
Based on the collection of relevant literature and cases,the research and application status of on-line monitoring technology for electromagnetic environment of power transmission and transformation projects at home a...Based on the collection of relevant literature and cases,the research and application status of on-line monitoring technology for electromagnetic environment of power transmission and transformation projects at home and abroad were introduced.Moreover,the problems existing in the on-line monitoring of electromagnetic environment were expounded,and the development prospect was forecasted.展开更多
An on-line monitoring system for partial discharge from high voltage transformer is presented with structure of hardware and principle of software discussed and a new effective method combining DFT with DWT is propose...An on-line monitoring system for partial discharge from high voltage transformer is presented with structure of hardware and principle of software discussed and a new effective method combining DFT with DWT is proposed to get rid of both sinusoidal continuous noise and other external discharges.展开更多
On-line measurement for dielectric loss angle can effectively monitor the insulation condition of capacitive equipment in power systems. Synthetic relative measuring methods not only markedly overcome the shortcomings...On-line measurement for dielectric loss angle can effectively monitor the insulation condition of capacitive equipment in power systems. Synthetic relative measuring methods not only markedly overcome the shortcomings of traditional absolute measuring methods but also greatly improve the accuracy of dielectric loss angle measurement. However, synthetic relative measuring methods based on two or three pieces of capacitive equipment do not have the characteristic of generality. In this paper, a principle of synthetic relative measuring method is presented. The example of application for synthetic relative methods based on three and four pieces of capacitive equipment running in the same phase is taken to present the failure judgment matrices for N pieces of equipment. According to these matrices, the fault condition of N pieces of capacitive equipment can be watched, which is more general. Then some problems needing to be concerned along with two diagnostic methods used in diagnostic system are introduced. Finally, two programmable flow charts for the two methods are given and corresponding examples demonstrate their feasibility in practice.展开更多
This study presented an insulation state monitoring method for large generator based on radio frequency (RF) technique. As an on-line condition monitor and the precondition of condition-based maintenance (CBM), the RF...This study presented an insulation state monitoring method for large generator based on radio frequency (RF) technique. As an on-line condition monitor and the precondition of condition-based maintenance (CBM), the RF monitor used the high frequency current mutual inductor to detect the partial discharge signal from neutral wire of stator windings. According to the magnitude of indicative value of RF monitor, a five phase model was also proposed to manage the generator’s running better. The practices show that the proposed method is effective.展开更多
A wireless distributed monitoring terminal was designed with embedded Linux used on the basis of ARM board, and an application program was developed for data collection, processing and transmission. Data were collecte...A wireless distributed monitoring terminal was designed with embedded Linux used on the basis of ARM board, and an application program was developed for data collection, processing and transmission. Data were collected from the surrounding environment and transmitted to a server via WLAN in the form of Extensible Markup Language (XML) stream, so the terminal had good flexibility to be compatible with different sensors, network devices and information systems from multiple manufacturers.展开更多
At present, the on-line monitoring is widely applied to the power line monitoring. In this paper, a new mechanical calculation model is established according to the on-line monitoring. And this model is based on the p...At present, the on-line monitoring is widely applied to the power line monitoring. In this paper, a new mechanical calculation model is established according to the on-line monitoring. And this model is based on the parameters that tension sensors and angle sensors on suspended points detect, and combines with the parameters of the wire itself, and also considers the deflection angel of wires due to wind. In this model, mechanics parameters of wires are turned into the new coordinate plane after deflection angel of wires due to wind, or windage yaw plane. A statics tension balance equation is built in the vertical direction of the new windage yaw plane. According to the theoretical analysis and algorithm, we verify the accuracy of this newly developed mechanical calculation model.展开更多
At present the detecting of ultra high voltage direct current (UHVDC) earth electrode frequently uses manual inspection. This method can't get the real-time operational data of the earth electrodes, and meanwhile,...At present the detecting of ultra high voltage direct current (UHVDC) earth electrode frequently uses manual inspection. This method can't get the real-time operational data of the earth electrodes, and meanwhile, the labor cost is very high. In order to satisfy the security needs of UHVDC, this paper designs an on-line monitoring system for UHVDC earth electrode. By 3G wireless communication-technologies, the system can monitor remotely many kinds of data such as the value of the grounding current, water level of the observation well, soil temperature and humidity near the earth electrode, the micro-climate around the earth electrode site, video data, etc. Through analyzing the datum, the system has broad prospect on fault detection and life evaluation of the UHVDC earth electrode.展开更多
In order to improve an on-line ferrograph, this paper simulates a three-dimensional magnetic field distribution of an electromagnet, builds a sinking motion model of a wear particle, and investigates the motion law of...In order to improve an on-line ferrograph, this paper simulates a three-dimensional magnetic field distribution of an electromagnet, builds a sinking motion model of a wear particle, and investigates the motion law of wear particles under two different conditions. Both numeric results and experimental results show that the on-line ferrograph is capable of monitoring machine wear conditions by measuring the concentration and size distribution of wear particles in lubricating oil.展开更多
Because the melting point of the alkalis is very high and the metal activity is strong, the common pressure sensor can't be used to measure pressure of liquid metal. In this paper, a differential transformer differen...Because the melting point of the alkalis is very high and the metal activity is strong, the common pressure sensor can't be used to measure pressure of liquid metal. In this paper, a differential transformer differential pressure sensor for measuring liquid alkalis pressure is designed, the working principle and specific design plan of the sensor are introduced, the standard current signal ( 4 -20 mA) or digital communication RS485 can be output according to the needs, and the functions of remote monitoring and data optimization can be realized through the LAN interface.展开更多
Transformers are required to demonstrate the ability to withstand short circuit currents.Over currents caused by short circuit can give rise to windings deformation.In this paper,a novel method is proposed to monitor ...Transformers are required to demonstrate the ability to withstand short circuit currents.Over currents caused by short circuit can give rise to windings deformation.In this paper,a novel method is proposed to monitor the state of transformer windings,which is achieved through on-line detecting the leakage inductance of the windings.Specifically,the mathematical model is established for online identifying the leakage inductance of the windings by applying least square algorithm(LSA) to the equivalent circuit equations.The effect of measurement and model inaccuracy on the identification error is analyzed,and the corrected model is also given to decrease these adverse effect on the results.Finally,dynamic test is carried out to verify our method.The test results clearly show that our method is very accurate even under the fluctuation of load or power factor.Therefore,our method can be effectively used to on-line detect the windings deformation.展开更多
Emissions from mobile sources and stationary sources contribute to atmospheric pollution in China,and its components,which include ultrafine particles(UFPs),volatile organic compounds(VOCs),and other reactive gases,su...Emissions from mobile sources and stationary sources contribute to atmospheric pollution in China,and its components,which include ultrafine particles(UFPs),volatile organic compounds(VOCs),and other reactive gases,such as NH3and NOx,are the most harmful to human health.China has released various regulations and standards to address pollution from mobile and stationary sources.Thus,it is urgent to develop online monitoring technology for atmospheric pollution source emissions.This study provides an overview of the main progress in mobile and stationary source monitoring technology in China and describes the comprehensive application of some typical instruments in vital areas in recent years.These instruments have been applied to monitor emissions from motor vehicles,ships,airports,the chemical industry,and electric power generation.Not only has the level of atmospheric environment monitoring technology and equipment been improving,but relevant regulations and standards have also been constantly updated.Meanwhile,the developed instruments can provide scientific assistance for the successful implementation of regulations.According to the potential problem areas in atmospheric pollution in China,some research hotspots and future trends of atmospheric online monitoring technology are summarized.Furthermore,more advanced atmospheric online monitoring technology will contribute to a comprehensive understanding of atmospheric pollution and improve environmental monitoring capacity.展开更多
Using on-line monitoring during the CNC grinding process,the hazard case such as the crushing of grinding wheel and various safety accidents could be avoided,and the optimum time for dressing and replacing grinding wh...Using on-line monitoring during the CNC grinding process,the hazard case such as the crushing of grinding wheel and various safety accidents could be avoided,and the optimum time for dressing and replacing grinding wheel could also be determined,and hence,the service life of the grinding wheel could be prolonged and grinding quality could be improved. To overcome the limitation of some traditional techniques in which some parameters including the grinding power and force,torque and so on were monitored,the acoustic emission (AE) technique,which provides high sensitivity and responding speed,were developed in the present paper. The mechanism of AE during grinding was reviewed. Moreover,a virtual AE monitoring system,which could monitor the grinding state under different working conditions during the grinding,has been developed based on the Virtual Instruments technique. Some experiments were also performed on the internal grinder. The results showed that the AE signals became stronger with increasing the main shaft speed and grinding depth or decreasing the distance between the AE sensor and grinding area.展开更多
Introduction: Correct adjustment of dry weight after hemodialysis (HD) with no signs of hypervolemia is important. Intradialytic hypotension (IDH) is the most common complication during HD. IDH occurs in 15% to 30% an...Introduction: Correct adjustment of dry weight after hemodialysis (HD) with no signs of hypervolemia is important. Intradialytic hypotension (IDH) is the most common complication during HD. IDH occurs in 15% to 30% and possibly in up to 50% of dialysis sessions. IDH augments mortality essentially due to chronic overhydration and the inability to reach the proper dry weight. On-line hemodiafiltration (ol-HDF) has been reported to reduce the frequency of IDH. The aim of this study was to assess the effect of ol-HDF on hemodynamic stability and dry weight adjustment compared with low-flux HD. Methods: IDH-prone HD patients at our center were enrolled. This study was designed as a crossover trial with two phases (A arm: low-flux HD for 8 weeks followed by ol-HDF for 8 weeks vs. B arm: ol-HDF for 8 weeks followed by low-flux HD for 8 weeks) and two treatment arms (ol-HDF vs. low-flux HD), each phase lasting 8 weeks. We measured the proportion of body water using a body composition monitor (BCM). Results: In a comparison of the systolic blood pressure (SBP) and diastolic blood pressure (DBP) reductions from the baseline blood pressure between the HD and ol-HDF groups, statistically significant differences were observed only in the SBP of the B arm (SBP: HD vs. HDF, -9.83 ± 6.64 vs. -4.62 ± 1.61 mmHg, p = 0.036;DBP: HD vs. HDF, -3.29 ± 4.05 vs. -1.86 ± 1.49 mmHg, p = 0.261). Neither the mean of the interdialytic body weight gains nor the frequency of IDH was different between the A and B arms (p = 0.817 and p = 0.562, respectively). In terms of dialysis modality, there were no significant differences in the amount of overhydration between the conventional HD and ol-HDF groups during the two study phases, as measured by the BCM (A arm: p = 0.875, B arm: p = 0.655). Conclusion: Our study did not show a better benefit of ol-HDF to reach the dry weight compared with low-flux HD in IDH-prone patients.展开更多
基金Supported by the Open Project of Jiangsu Key Laboratory of Environmental Engineering(ZX2017005)
文摘The characteristics and distribution law of electromagnetic environment around substations with different levels of voltage were studied,and the main influencing factors were discussed. Meanwhile,a scheme for locating monitoring points suitable for an on-line monitoring system of electromagnetic environment was proposed.
文摘To overcome the disadvantages of conventional DGA (dissolved gas-in-oil)analysis using gas chromatography and other electrochemical sensors, initial researches werecompleted to realize on-line monitoring of dissolved gas-in-oil of power transformers using FTIR(Fourier Transform InfraRed) spectroscopy. Gas cell method is used to determine the characteristicabsorption peaks of each diagnostic gas; simple and novel devices and procedures were designed inorder to get measurable samples and spectra of mixed diagnostic gases with known concentration aretaken using long optical path gas cell. The range of wavelength is estimated to be 3.0-13.9 mum fromexperimental spectra data. Hence the corresponding sampling frequency range should be in 536-4288Hz and usable optical materials are suggested. It is concluded that a resolution of 10 cm^(-1) maywell satisfy the monitoring of all diagnostic gases and water content except hydrogen, and thelowest detection limit may be as low as 2Xl0^(-8) to acetylene with a 2.4-meter-long optical length.
文摘Several industrial computers and a server are combined to set up the on-line monitoring and diagnostic system of turbo-generator sets. The main function of the system is to monitor machine sets' running condition. Through analyzing running data, technicians can detect whether there exist faults and where they occur. To share and transmit the dynamic information of the turbo-generator sets, a distributed network system is introduced. NetWare network operating system is used in the LAN (Local Area Network) system. The LAN is extended to realize the sharing of data and remote transmission of information. Furthermore, functions of monitoring and diagnostic clients are listed.
文摘Discusses on-line monitoring of electric parameters, such as dielectric loss, divulging current, equivalent capacitance and running voltage, and presents an on-line monitoring system of insulation quality, based on monitoring divulging current and dielectric loss of high voltage equipment, and its advantages, such as helping people to discover the hidden problems in a timely manner, to reduce power cut and overhaul and to improve security of power supply.
基金Supported by the Open Project of Jiangsu Key Laboratory of Environmental Engineering(ZX2017005)
文摘Based on the collection of relevant literature and cases,the research and application status of on-line monitoring technology for electromagnetic environment of power transmission and transformation projects at home and abroad were introduced.Moreover,the problems existing in the on-line monitoring of electromagnetic environment were expounded,and the development prospect was forecasted.
文摘An on-line monitoring system for partial discharge from high voltage transformer is presented with structure of hardware and principle of software discussed and a new effective method combining DFT with DWT is proposed to get rid of both sinusoidal continuous noise and other external discharges.
文摘On-line measurement for dielectric loss angle can effectively monitor the insulation condition of capacitive equipment in power systems. Synthetic relative measuring methods not only markedly overcome the shortcomings of traditional absolute measuring methods but also greatly improve the accuracy of dielectric loss angle measurement. However, synthetic relative measuring methods based on two or three pieces of capacitive equipment do not have the characteristic of generality. In this paper, a principle of synthetic relative measuring method is presented. The example of application for synthetic relative methods based on three and four pieces of capacitive equipment running in the same phase is taken to present the failure judgment matrices for N pieces of equipment. According to these matrices, the fault condition of N pieces of capacitive equipment can be watched, which is more general. Then some problems needing to be concerned along with two diagnostic methods used in diagnostic system are introduced. Finally, two programmable flow charts for the two methods are given and corresponding examples demonstrate their feasibility in practice.
文摘This study presented an insulation state monitoring method for large generator based on radio frequency (RF) technique. As an on-line condition monitor and the precondition of condition-based maintenance (CBM), the RF monitor used the high frequency current mutual inductor to detect the partial discharge signal from neutral wire of stator windings. According to the magnitude of indicative value of RF monitor, a five phase model was also proposed to manage the generator’s running better. The practices show that the proposed method is effective.
文摘A wireless distributed monitoring terminal was designed with embedded Linux used on the basis of ARM board, and an application program was developed for data collection, processing and transmission. Data were collected from the surrounding environment and transmitted to a server via WLAN in the form of Extensible Markup Language (XML) stream, so the terminal had good flexibility to be compatible with different sensors, network devices and information systems from multiple manufacturers.
文摘At present, the on-line monitoring is widely applied to the power line monitoring. In this paper, a new mechanical calculation model is established according to the on-line monitoring. And this model is based on the parameters that tension sensors and angle sensors on suspended points detect, and combines with the parameters of the wire itself, and also considers the deflection angel of wires due to wind. In this model, mechanics parameters of wires are turned into the new coordinate plane after deflection angel of wires due to wind, or windage yaw plane. A statics tension balance equation is built in the vertical direction of the new windage yaw plane. According to the theoretical analysis and algorithm, we verify the accuracy of this newly developed mechanical calculation model.
文摘At present the detecting of ultra high voltage direct current (UHVDC) earth electrode frequently uses manual inspection. This method can't get the real-time operational data of the earth electrodes, and meanwhile, the labor cost is very high. In order to satisfy the security needs of UHVDC, this paper designs an on-line monitoring system for UHVDC earth electrode. By 3G wireless communication-technologies, the system can monitor remotely many kinds of data such as the value of the grounding current, water level of the observation well, soil temperature and humidity near the earth electrode, the micro-climate around the earth electrode site, video data, etc. Through analyzing the datum, the system has broad prospect on fault detection and life evaluation of the UHVDC earth electrode.
文摘In order to improve an on-line ferrograph, this paper simulates a three-dimensional magnetic field distribution of an electromagnet, builds a sinking motion model of a wear particle, and investigates the motion law of wear particles under two different conditions. Both numeric results and experimental results show that the on-line ferrograph is capable of monitoring machine wear conditions by measuring the concentration and size distribution of wear particles in lubricating oil.
文摘Because the melting point of the alkalis is very high and the metal activity is strong, the common pressure sensor can't be used to measure pressure of liquid metal. In this paper, a differential transformer differential pressure sensor for measuring liquid alkalis pressure is designed, the working principle and specific design plan of the sensor are introduced, the standard current signal ( 4 -20 mA) or digital communication RS485 can be output according to the needs, and the functions of remote monitoring and data optimization can be realized through the LAN interface.
基金This work was supported in part by National Natural Science Foundation of China(No.50577050).
文摘Transformers are required to demonstrate the ability to withstand short circuit currents.Over currents caused by short circuit can give rise to windings deformation.In this paper,a novel method is proposed to monitor the state of transformer windings,which is achieved through on-line detecting the leakage inductance of the windings.Specifically,the mathematical model is established for online identifying the leakage inductance of the windings by applying least square algorithm(LSA) to the equivalent circuit equations.The effect of measurement and model inaccuracy on the identification error is analyzed,and the corrected model is also given to decrease these adverse effect on the results.Finally,dynamic test is carried out to verify our method.The test results clearly show that our method is very accurate even under the fluctuation of load or power factor.Therefore,our method can be effectively used to on-line detect the windings deformation.
基金supported by the National Key Research and Development Program of China(Nos.2016YFC0201000 and 2016YFC0201100)the Plan for Anhui Major Provincial Science&Technology Project(Nos.202203a07020004 and 202003a07020005)+1 种基金the National Natural Science Foundation of China(Nos.U2133212 and 42005108)the Science and Technological Fund of Anhui Province for Outstanding Youth(No.1808085J19)。
文摘Emissions from mobile sources and stationary sources contribute to atmospheric pollution in China,and its components,which include ultrafine particles(UFPs),volatile organic compounds(VOCs),and other reactive gases,such as NH3and NOx,are the most harmful to human health.China has released various regulations and standards to address pollution from mobile and stationary sources.Thus,it is urgent to develop online monitoring technology for atmospheric pollution source emissions.This study provides an overview of the main progress in mobile and stationary source monitoring technology in China and describes the comprehensive application of some typical instruments in vital areas in recent years.These instruments have been applied to monitor emissions from motor vehicles,ships,airports,the chemical industry,and electric power generation.Not only has the level of atmospheric environment monitoring technology and equipment been improving,but relevant regulations and standards have also been constantly updated.Meanwhile,the developed instruments can provide scientific assistance for the successful implementation of regulations.According to the potential problem areas in atmospheric pollution in China,some research hotspots and future trends of atmospheric online monitoring technology are summarized.Furthermore,more advanced atmospheric online monitoring technology will contribute to a comprehensive understanding of atmospheric pollution and improve environmental monitoring capacity.
基金Supported by fund of National Key Laboratory for Remanufacturing(9140C85030106JS9102)
文摘Using on-line monitoring during the CNC grinding process,the hazard case such as the crushing of grinding wheel and various safety accidents could be avoided,and the optimum time for dressing and replacing grinding wheel could also be determined,and hence,the service life of the grinding wheel could be prolonged and grinding quality could be improved. To overcome the limitation of some traditional techniques in which some parameters including the grinding power and force,torque and so on were monitored,the acoustic emission (AE) technique,which provides high sensitivity and responding speed,were developed in the present paper. The mechanism of AE during grinding was reviewed. Moreover,a virtual AE monitoring system,which could monitor the grinding state under different working conditions during the grinding,has been developed based on the Virtual Instruments technique. Some experiments were also performed on the internal grinder. The results showed that the AE signals became stronger with increasing the main shaft speed and grinding depth or decreasing the distance between the AE sensor and grinding area.
文摘Introduction: Correct adjustment of dry weight after hemodialysis (HD) with no signs of hypervolemia is important. Intradialytic hypotension (IDH) is the most common complication during HD. IDH occurs in 15% to 30% and possibly in up to 50% of dialysis sessions. IDH augments mortality essentially due to chronic overhydration and the inability to reach the proper dry weight. On-line hemodiafiltration (ol-HDF) has been reported to reduce the frequency of IDH. The aim of this study was to assess the effect of ol-HDF on hemodynamic stability and dry weight adjustment compared with low-flux HD. Methods: IDH-prone HD patients at our center were enrolled. This study was designed as a crossover trial with two phases (A arm: low-flux HD for 8 weeks followed by ol-HDF for 8 weeks vs. B arm: ol-HDF for 8 weeks followed by low-flux HD for 8 weeks) and two treatment arms (ol-HDF vs. low-flux HD), each phase lasting 8 weeks. We measured the proportion of body water using a body composition monitor (BCM). Results: In a comparison of the systolic blood pressure (SBP) and diastolic blood pressure (DBP) reductions from the baseline blood pressure between the HD and ol-HDF groups, statistically significant differences were observed only in the SBP of the B arm (SBP: HD vs. HDF, -9.83 ± 6.64 vs. -4.62 ± 1.61 mmHg, p = 0.036;DBP: HD vs. HDF, -3.29 ± 4.05 vs. -1.86 ± 1.49 mmHg, p = 0.261). Neither the mean of the interdialytic body weight gains nor the frequency of IDH was different between the A and B arms (p = 0.817 and p = 0.562, respectively). In terms of dialysis modality, there were no significant differences in the amount of overhydration between the conventional HD and ol-HDF groups during the two study phases, as measured by the BCM (A arm: p = 0.875, B arm: p = 0.655). Conclusion: Our study did not show a better benefit of ol-HDF to reach the dry weight compared with low-flux HD in IDH-prone patients.