Three cast-resin current transformers with different PD inception voltages of 43kV, 24kV and 12kV... more Three cast-resin current transformers with different PD inception voltages of 43kV, 24kV and 12kV, respectively, are used in accelerated aging tests during which PD information is detected and measured. Lastly, the real measurement results of two cast-resin current transformers are used to examine the feasibility of the proposed determination rules. Our study shows that the slop of the average discharge amount's development trend is more suitable for insulation status determination than other parameters, and said slop's accuracy and practicality is valuable for continuous research in insulation aging.
Journal of the Chinese Institute of Engineers, 1995
ABSTRACT The paper presents a new formulation of harmonic current injection of the 6‐pulse uncont... more ABSTRACT The paper presents a new formulation of harmonic current injection of the 6‐pulse uncontrolled bridge rectifier with commutation impedance. In cooperation with a train simulator developed earlier, the proposed harmonic source model is applied in a harmonic analysis program to comprehensively simulate the harmonic penetration in the Blue Line of Taipei Rapid Transit Systems (TRTS). Both frequency scans and harmonic distortion calculations were performed for various system component models. Simulation results indicated that both the voltage and current harmonic distortions in the Blue Line of TRTS were improved by use of 24‐pulse rectifiers. The application of further harmonic suppression schemes in traction networks to alleviate the harmonic distortions can be achieved using the simulated results.
... Since the analysis of inverter operation does not differ from that of controlled rectificatio... more ... Since the analysis of inverter operation does not differ from that of controlled rectification, equations presented above are ... 3. 2) Harmonic Current Injection Modeling: The ... 7]. To facilitate the convergence property of power flows of transit systems, a unified NewtonRaphson ac/dc ...
With their vast amount of joints, underground cable systems are expensive to maintain; therefore,... more With their vast amount of joints, underground cable systems are expensive to maintain; therefore, measurement equip- ment must be cost-effective. This study proposes the long-term placement of partial-discharge (PD) monitoring units at cable joints. The unit consists of a peak detect circuit and a digital signal processor for acquiring and converting the sensors' PD signals into discharge sequence data, whose
ABSTRACT Because of lower voltage levels and smaller power ratings, the R/X ratio of commutation ... more ABSTRACT Because of lower voltage levels and smaller power ratings, the R/X ratio of commutation impedance in industrial AC/DC distribution systems is usually higher than that in HVDC transmission systems. Considerable discrepancies may therefore occur in industrial AC/DC power flow results, especially the reactive power consumption of converters, if the commutation resistances of the converters are neglected. To describe the effects of commutation impedance on converter operations and to precisely relate the fundamental line current and DC output current of the converter, a detailed model of the bridge converter with commutation impedance for use of Newton-Raphson power flow studies in industrial AC/DC power systems is derived in this paper. A coal mine power system and a DC electrified transit railway system with regenerative braking function, a part of Taipei Rapid Transit Systems under planning, have been analyzed to show the improved accuracy and good convergence characteristics of the developed Newton-Raphson power flow formulation with the proposed converter model
Parallel operation of two 6-n prepulse uncontrolled bridge rectifiers, to obtain a 12-pulse recti... more Parallel operation of two 6-n prepulse uncontrolled bridge rectifiers, to obtain a 12-pulse rectification, without an interphase transformer connected on the DC sides is investigated in this paper. The mechanism of interactions between the two six-pulse bridges is analyzed. As the load current varies from no-load to the complete short-circuit value, seven modes of operation are recognized. Equations describing the mean output voltage and various operating angles of the rectifier circuit are given in terms of a reactance factor. Voltage regulation and variations of the ignition angle and the commutation overlap angle for rectifiers with and without an interphase transformer are also compared
IEEE Transactions on Dielectrics and Electrical Insulation, 2000
This paper aims to address the problem of equipment fault prevention by preventive diagnosis of i... more This paper aims to address the problem of equipment fault prevention by preventive diagnosis of its insulation. Preventive diagnosis, as the name implies, means the accurate judgment made in advance on when power equipment can be replaced from on-site service before its breakdown. The experimentation, via voltage-stress aging tests and partial-discharge (PD) measurements, investigates the degree to which the insulation
This paper presents a systematical evaluation experience on the performance and economic studies ... more This paper presents a systematical evaluation experience on the performance and economic studies of line arresters for a 69 kV transmission system in Taiwan. The transient over-voltage phenomenon in high voltage transmission lines under lightning by using the Electro-Magnetic Transients Program (EMTP) package is well modeled and analyzed. The modeling for the simulated system including lightning, transmission line, transmission tower and line arrester are all considered to have more practical results. The cost and benefit evaluation for line arresters installation is then conducted to provide a reasonable suggestion for lightning protection. The performance of line arresters is evaluated by considering different installation schemes and lightning currents. Finally, a Taiwan�s experience is illustrated from both of the cost and benefit points of view.
Three cast-resin current transformers with different PD inception voltages of 43kV, 24kV and 12kV... more Three cast-resin current transformers with different PD inception voltages of 43kV, 24kV and 12kV, respectively, are used in accelerated aging tests during which PD information is detected and measured. Lastly, the real measurement results of two cast-resin current transformers are used to examine the feasibility of the proposed determination rules. Our study shows that the slop of the average discharge amount's development trend is more suitable for insulation status determination than other parameters, and said slop's accuracy and practicality is valuable for continuous research in insulation aging.
Journal of the Chinese Institute of Engineers, 1995
ABSTRACT The paper presents a new formulation of harmonic current injection of the 6‐pulse uncont... more ABSTRACT The paper presents a new formulation of harmonic current injection of the 6‐pulse uncontrolled bridge rectifier with commutation impedance. In cooperation with a train simulator developed earlier, the proposed harmonic source model is applied in a harmonic analysis program to comprehensively simulate the harmonic penetration in the Blue Line of Taipei Rapid Transit Systems (TRTS). Both frequency scans and harmonic distortion calculations were performed for various system component models. Simulation results indicated that both the voltage and current harmonic distortions in the Blue Line of TRTS were improved by use of 24‐pulse rectifiers. The application of further harmonic suppression schemes in traction networks to alleviate the harmonic distortions can be achieved using the simulated results.
... Since the analysis of inverter operation does not differ from that of controlled rectificatio... more ... Since the analysis of inverter operation does not differ from that of controlled rectification, equations presented above are ... 3. 2) Harmonic Current Injection Modeling: The ... 7]. To facilitate the convergence property of power flows of transit systems, a unified NewtonRaphson ac/dc ...
With their vast amount of joints, underground cable systems are expensive to maintain; therefore,... more With their vast amount of joints, underground cable systems are expensive to maintain; therefore, measurement equip- ment must be cost-effective. This study proposes the long-term placement of partial-discharge (PD) monitoring units at cable joints. The unit consists of a peak detect circuit and a digital signal processor for acquiring and converting the sensors' PD signals into discharge sequence data, whose
ABSTRACT Because of lower voltage levels and smaller power ratings, the R/X ratio of commutation ... more ABSTRACT Because of lower voltage levels and smaller power ratings, the R/X ratio of commutation impedance in industrial AC/DC distribution systems is usually higher than that in HVDC transmission systems. Considerable discrepancies may therefore occur in industrial AC/DC power flow results, especially the reactive power consumption of converters, if the commutation resistances of the converters are neglected. To describe the effects of commutation impedance on converter operations and to precisely relate the fundamental line current and DC output current of the converter, a detailed model of the bridge converter with commutation impedance for use of Newton-Raphson power flow studies in industrial AC/DC power systems is derived in this paper. A coal mine power system and a DC electrified transit railway system with regenerative braking function, a part of Taipei Rapid Transit Systems under planning, have been analyzed to show the improved accuracy and good convergence characteristics of the developed Newton-Raphson power flow formulation with the proposed converter model
Parallel operation of two 6-n prepulse uncontrolled bridge rectifiers, to obtain a 12-pulse recti... more Parallel operation of two 6-n prepulse uncontrolled bridge rectifiers, to obtain a 12-pulse rectification, without an interphase transformer connected on the DC sides is investigated in this paper. The mechanism of interactions between the two six-pulse bridges is analyzed. As the load current varies from no-load to the complete short-circuit value, seven modes of operation are recognized. Equations describing the mean output voltage and various operating angles of the rectifier circuit are given in terms of a reactance factor. Voltage regulation and variations of the ignition angle and the commutation overlap angle for rectifiers with and without an interphase transformer are also compared
IEEE Transactions on Dielectrics and Electrical Insulation, 2000
This paper aims to address the problem of equipment fault prevention by preventive diagnosis of i... more This paper aims to address the problem of equipment fault prevention by preventive diagnosis of its insulation. Preventive diagnosis, as the name implies, means the accurate judgment made in advance on when power equipment can be replaced from on-site service before its breakdown. The experimentation, via voltage-stress aging tests and partial-discharge (PD) measurements, investigates the degree to which the insulation
This paper presents a systematical evaluation experience on the performance and economic studies ... more This paper presents a systematical evaluation experience on the performance and economic studies of line arresters for a 69 kV transmission system in Taiwan. The transient over-voltage phenomenon in high voltage transmission lines under lightning by using the Electro-Magnetic Transients Program (EMTP) package is well modeled and analyzed. The modeling for the simulated system including lightning, transmission line, transmission tower and line arrester are all considered to have more practical results. The cost and benefit evaluation for line arresters installation is then conducted to provide a reasonable suggestion for lightning protection. The performance of line arresters is evaluated by considering different installation schemes and lightning currents. Finally, a Taiwan�s experience is illustrated from both of the cost and benefit points of view.
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