The paper proposes the analytic modelling of flexible textile shields made of fabrics with insert... more The paper proposes the analytic modelling of flexible textile shields made of fabrics with inserted conductive yarns and metallic plasma coating in order to calculate their electromagnetic shielding effectiveness (EMSE). This manufacturing process is highly innovative, since copper plasma coating improves EMSE on the fabrics with inserted conductive yarns of stainless steel and silver with 10–15 dB in the frequency range of 0.1–1000 MHz, as shown by the measured EMSE values determined according to the standard ASTM ES-07 via the Transverse Electromagnetic (TEM) cell. On the other hand, modelling of EMSE for such conductive flexible shields gives an insight on estimating EMSE in the design phase of manufacturing the shield, based on its geometric and electrical parameters. An analytic model was proposed based on the sum of EMSE of the fabric with inserted conductive yarns and EMSE of the copper coating. The measurement results show close values to the proposed analytic model, especia...
2016 International Conference on Applied and Theoretical Electricity (ICATE), 2016
In the last decades, the interest of researchers and public regarding the effects of electromagne... more In the last decades, the interest of researchers and public regarding the effects of electromagnetic field on living beings and in particular on humans has increased more and more. Scientific studies have sought to establish exposure limits for the general public and workers exposed to intense fields due to occupational environments in which they operate. This paper addresses the problem of power frequency electric and magnetic fields occurring in a substation, in the area of access paths and, in particular, near equipment serviced frequently by the workers. The Low Frequency electric and magnetic fields values measured in a typical configured air insulated substation are in good agreement, when compared, with computed values. The best agreement has been obtained for the magnetic field.
Considerable numbers of glass, ceramic and non-ceramic insulators strings are used on transmissio... more Considerable numbers of glass, ceramic and non-ceramic insulators strings are used on transmission and distribution overhead lines. Defects that commonly occur on this type of high voltage equipment are often associated with the presence of the corona discharges or gap discharges and therefore could be diagnosed using the electromagnetic signature of such phenomena. The paper investigates the correlation of the Radio Interference Voltage (RIV) measured in a standard CISPR circuit to the emitted radio frequency disturbance received by a high frequency electric field isotropic probe, placed in different locations around the insulator string under test. The results show that the radio frequency emission is strongly correlated to the RIV level, i.e. to the disturbing current injected by the discharge in the line conductor, confirming the possibility to develop a remote sensing diagnosis technique based on RF emission.
2015 9th International Symposium on Advanced Topics in Electrical Engineering (ATEE), 2015
Nowadays the economic lamps have replaced, in some countries even by law, the incandescent bulbs.... more Nowadays the economic lamps have replaced, in some countries even by law, the incandescent bulbs. Despite the evident advantages of this type of lamp in terms of energy consumption, many concerns are raised regarding the network's pollution with current harmonics and emission of high frequency radiated fields, during the lamp operation, which could affect the public health. This paper presents and compare, based on measurements, two different methods which could evaluate the radiated fields caused by these lamps.
The paper attempts to identify correlations between radiated disturbances generated by high-volta... more The paper attempts to identify correlations between radiated disturbances generated by high-voltage equipment and the conducted disturbances injected by the same equipment into an overhead line to which it is connected. Nowadays, according to relevant standards, the radio frequency disturbances caused by such an equipment are evaluated by means of a specified voltage across a resistor which simulate the wave impedance of the line although the overall effect is evaluated in the vicinity of the overhead line by means of radiated disturbances. This voltage is measured using an EMI receiver with quasi-peak detector. Rigorous experimental arrangement is described by the standards and measurements must be done in a shielded high voltage laboratory. Because RIV measurement procedure specified above, is relatively complicated, the authors try to determine the correlation between the conducted and radiated disturbances of two insulator sets in order to identify a new method of measuring the ...
The paper presents the results of experimental tests performed with impulse voltage with short ta... more The paper presents the results of experimental tests performed with impulse voltage with short tail (STLI: 1.2/4 mus) on composite insulators in use in the MV distribution lines and electric traction lines. The voltage-time to breakdown characteristics under 1.2/4 mus waves are presented and compared with the characteristics under standard lightning impulse (LI: 1.2/50 mus). Models based on the disruptive
2013 8TH INTERNATIONAL SYMPOSIUM ON ADVANCED TOPICS IN ELECTRICAL ENGINEERING (ATEE), 2013
ABSTRACT The paper presents an approach to predict corona power losses under rain based on numeri... more ABSTRACT The paper presents an approach to predict corona power losses under rain based on numerical weather forecasting combined with geographic information system mapping of the overhead lines assets, and the day ahead horary forecast of the power flow, extracted from power flow analysis performed by the system operator for the entire network.
... δ + δ + = T T R Z s, j1 sinh j1 0 dif . ... [3] Imposimato, C. Hoeffelman, J. Eriksson, A. sa... more ... δ + δ + = T T R Z s, j1 sinh j1 0 dif . ... [3] Imposimato, C. Hoeffelman, J. Eriksson, A. sa, EMI characterization of HVAC substations – updated ... T. - Experience of Numerical Protective Relays Operating in an Environment With High-Frequency Switching Surge in Japan, IEEE Trans. ...
2013 8TH INTERNATIONAL SYMPOSIUM ON ADVANCED TOPICS IN ELECTRICAL ENGINEERING (ATEE), 2013
ABSTRACT This paper addresses the problem of recording those fast voltage variations with feature... more ABSTRACT This paper addresses the problem of recording those fast voltage variations with features that do not meet the conditions required by conventional trigger systems. It is about transients, with amplitudes below the minimum trigger level that is usually set higher than the maximum amplitude of the rated voltage. For this purpose, it is used a Butterworth numeric type filter, implemented on an field programmable gate array (FPGA) processor in order to obtain a trigger command at a slope variation of the traced signal.
In many papers, the good behavior in operation and benefits offered by a certain type of insulato... more In many papers, the good behavior in operation and benefits offered by a certain type of insulator, classic (toughened glass or porcelain) or composite (fiberglass core and silicone rubber) for overhead lines, is often exaggerated and compared only with the disadvantageous characteristics of the other type of insulator. This paper present both the advantages and disadvantages of each of the two types of insulators, and also some results of tests performed mainly in the last 15 years in the High Voltage Laboratory of Polytechnic University of Bucharest and conclusions based on theirs data processing.
2021 12th International Symposium on Advanced Topics in Electrical Engineering (ATEE), 2021
Knowing how insulating strings behave to different types of electrical stresses is useful in seve... more Knowing how insulating strings behave to different types of electrical stresses is useful in several situations including: designing the overhead transmission line and choosing the protection devices or the right interpretation of the records generated by the SCADA system. The integrity of the insulating strings is tested at commissioning and it can periodically be verified using laboratory tests involving standardized voltage forms. As a result, their behavior is well documented at lightning and switching impulse voltage, without insisting on other random voltage forms. Considering that during normal operation the electric stresses do not have standardized forms, we propose a numerical model in ATPEMTP that approximates the behavior of the insulator strings to any impulse voltage variation for different geometries and different weather conditions using the results obtained during standardized laboratory tests.
The generation of high voltage steep-front impulses has always been a concern of researchers in t... more The generation of high voltage steep-front impulses has always been a concern of researchers in the field of high voltage engineering and electromagnetic compatibility. Obtaining such voltage impulses was imposed by the necessity to simulate real stresses of insulation in electrical installations or electromagnetic disturbances having such characteristics (high altitude nuclear electromagnetic pulse, electrostatic discharges or certain switching operations). For the necessity of electromagnetic immunity tests of civil equipment, the amplitudes of these pulses are usually limited to a few kV, and the circuits that produce them are based on power electronics. However, for insulation tests, they are of the order of hundreds of kV. The paper presents three methods to obtain steep high voltage pulses required for testing high voltage insulations. Their advantages and disadvantages (limitations) are discussed for each of them.
2017 10th International Symposium on Advanced Topics in Electrical Engineering (ATEE), 2017
The paper aims to assess side effects which occur as a result of measures adopted to reduce the e... more The paper aims to assess side effects which occur as a result of measures adopted to reduce the electromagnetic field in the vicinity of overhead power lines, respectively using the phases' transposition for double circuit transmission lines. Practical considerations about the accuracy of magnetic field calculation were discussed considering the real positions of conductors, the optimal phasing in the case of double-circuit lines and the losses which appear in ground wire(s) in different configuration of phases.
2017 5th International Symposium on Electrical and Electronics Engineering (ISEEE), 2017
The paper will present the first results of an extended analysis based on synchronously recorded ... more The paper will present the first results of an extended analysis based on synchronously recorded electrical and weather data, aimed to numerically evaluate the stochastic variation of transmission power losses measured on a given 400 kV line, in correlation with different environmental influence factors such as air temperature and pressure, dew point, wind speed and direction, type and amount of precipitation reported at 14 meteorological stations.
2021 12th International Symposium on Advanced Topics in Electrical Engineering (ATEE), 2021
The paper presents a short analysis of benefits and disadvantages of multi-circuit overhead lines... more The paper presents a short analysis of benefits and disadvantages of multi-circuit overhead lines operation. Nowadays, the problem to build a new overhead line is a very difficult one because of land cost and different properties crossed by it, environmental impact, opposition of large public etc. Therefore, the solution to use same tower to support many circuits, with same or different rated voltage, also for AC and DC systems is very attractive. The main advantage is that of use of a narrow corridor to transmit a large amount of power. But other problems must be solved in order to make this type of line working properly, from solving the mutual influence of the circuits to lightning protection and up to the low frequency electromagnetic fields profile recorded near to ground.
The paper proposes the analytic modelling of flexible textile shields made of fabrics with insert... more The paper proposes the analytic modelling of flexible textile shields made of fabrics with inserted conductive yarns and metallic plasma coating in order to calculate their electromagnetic shielding effectiveness (EMSE). This manufacturing process is highly innovative, since copper plasma coating improves EMSE on the fabrics with inserted conductive yarns of stainless steel and silver with 10–15 dB in the frequency range of 0.1–1000 MHz, as shown by the measured EMSE values determined according to the standard ASTM ES-07 via the Transverse Electromagnetic (TEM) cell. On the other hand, modelling of EMSE for such conductive flexible shields gives an insight on estimating EMSE in the design phase of manufacturing the shield, based on its geometric and electrical parameters. An analytic model was proposed based on the sum of EMSE of the fabric with inserted conductive yarns and EMSE of the copper coating. The measurement results show close values to the proposed analytic model, especia...
2016 International Conference on Applied and Theoretical Electricity (ICATE), 2016
In the last decades, the interest of researchers and public regarding the effects of electromagne... more In the last decades, the interest of researchers and public regarding the effects of electromagnetic field on living beings and in particular on humans has increased more and more. Scientific studies have sought to establish exposure limits for the general public and workers exposed to intense fields due to occupational environments in which they operate. This paper addresses the problem of power frequency electric and magnetic fields occurring in a substation, in the area of access paths and, in particular, near equipment serviced frequently by the workers. The Low Frequency electric and magnetic fields values measured in a typical configured air insulated substation are in good agreement, when compared, with computed values. The best agreement has been obtained for the magnetic field.
Considerable numbers of glass, ceramic and non-ceramic insulators strings are used on transmissio... more Considerable numbers of glass, ceramic and non-ceramic insulators strings are used on transmission and distribution overhead lines. Defects that commonly occur on this type of high voltage equipment are often associated with the presence of the corona discharges or gap discharges and therefore could be diagnosed using the electromagnetic signature of such phenomena. The paper investigates the correlation of the Radio Interference Voltage (RIV) measured in a standard CISPR circuit to the emitted radio frequency disturbance received by a high frequency electric field isotropic probe, placed in different locations around the insulator string under test. The results show that the radio frequency emission is strongly correlated to the RIV level, i.e. to the disturbing current injected by the discharge in the line conductor, confirming the possibility to develop a remote sensing diagnosis technique based on RF emission.
2015 9th International Symposium on Advanced Topics in Electrical Engineering (ATEE), 2015
Nowadays the economic lamps have replaced, in some countries even by law, the incandescent bulbs.... more Nowadays the economic lamps have replaced, in some countries even by law, the incandescent bulbs. Despite the evident advantages of this type of lamp in terms of energy consumption, many concerns are raised regarding the network's pollution with current harmonics and emission of high frequency radiated fields, during the lamp operation, which could affect the public health. This paper presents and compare, based on measurements, two different methods which could evaluate the radiated fields caused by these lamps.
The paper attempts to identify correlations between radiated disturbances generated by high-volta... more The paper attempts to identify correlations between radiated disturbances generated by high-voltage equipment and the conducted disturbances injected by the same equipment into an overhead line to which it is connected. Nowadays, according to relevant standards, the radio frequency disturbances caused by such an equipment are evaluated by means of a specified voltage across a resistor which simulate the wave impedance of the line although the overall effect is evaluated in the vicinity of the overhead line by means of radiated disturbances. This voltage is measured using an EMI receiver with quasi-peak detector. Rigorous experimental arrangement is described by the standards and measurements must be done in a shielded high voltage laboratory. Because RIV measurement procedure specified above, is relatively complicated, the authors try to determine the correlation between the conducted and radiated disturbances of two insulator sets in order to identify a new method of measuring the ...
The paper presents the results of experimental tests performed with impulse voltage with short ta... more The paper presents the results of experimental tests performed with impulse voltage with short tail (STLI: 1.2/4 mus) on composite insulators in use in the MV distribution lines and electric traction lines. The voltage-time to breakdown characteristics under 1.2/4 mus waves are presented and compared with the characteristics under standard lightning impulse (LI: 1.2/50 mus). Models based on the disruptive
2013 8TH INTERNATIONAL SYMPOSIUM ON ADVANCED TOPICS IN ELECTRICAL ENGINEERING (ATEE), 2013
ABSTRACT The paper presents an approach to predict corona power losses under rain based on numeri... more ABSTRACT The paper presents an approach to predict corona power losses under rain based on numerical weather forecasting combined with geographic information system mapping of the overhead lines assets, and the day ahead horary forecast of the power flow, extracted from power flow analysis performed by the system operator for the entire network.
... δ + δ + = T T R Z s, j1 sinh j1 0 dif . ... [3] Imposimato, C. Hoeffelman, J. Eriksson, A. sa... more ... δ + δ + = T T R Z s, j1 sinh j1 0 dif . ... [3] Imposimato, C. Hoeffelman, J. Eriksson, A. sa, EMI characterization of HVAC substations – updated ... T. - Experience of Numerical Protective Relays Operating in an Environment With High-Frequency Switching Surge in Japan, IEEE Trans. ...
2013 8TH INTERNATIONAL SYMPOSIUM ON ADVANCED TOPICS IN ELECTRICAL ENGINEERING (ATEE), 2013
ABSTRACT This paper addresses the problem of recording those fast voltage variations with feature... more ABSTRACT This paper addresses the problem of recording those fast voltage variations with features that do not meet the conditions required by conventional trigger systems. It is about transients, with amplitudes below the minimum trigger level that is usually set higher than the maximum amplitude of the rated voltage. For this purpose, it is used a Butterworth numeric type filter, implemented on an field programmable gate array (FPGA) processor in order to obtain a trigger command at a slope variation of the traced signal.
In many papers, the good behavior in operation and benefits offered by a certain type of insulato... more In many papers, the good behavior in operation and benefits offered by a certain type of insulator, classic (toughened glass or porcelain) or composite (fiberglass core and silicone rubber) for overhead lines, is often exaggerated and compared only with the disadvantageous characteristics of the other type of insulator. This paper present both the advantages and disadvantages of each of the two types of insulators, and also some results of tests performed mainly in the last 15 years in the High Voltage Laboratory of Polytechnic University of Bucharest and conclusions based on theirs data processing.
2021 12th International Symposium on Advanced Topics in Electrical Engineering (ATEE), 2021
Knowing how insulating strings behave to different types of electrical stresses is useful in seve... more Knowing how insulating strings behave to different types of electrical stresses is useful in several situations including: designing the overhead transmission line and choosing the protection devices or the right interpretation of the records generated by the SCADA system. The integrity of the insulating strings is tested at commissioning and it can periodically be verified using laboratory tests involving standardized voltage forms. As a result, their behavior is well documented at lightning and switching impulse voltage, without insisting on other random voltage forms. Considering that during normal operation the electric stresses do not have standardized forms, we propose a numerical model in ATPEMTP that approximates the behavior of the insulator strings to any impulse voltage variation for different geometries and different weather conditions using the results obtained during standardized laboratory tests.
The generation of high voltage steep-front impulses has always been a concern of researchers in t... more The generation of high voltage steep-front impulses has always been a concern of researchers in the field of high voltage engineering and electromagnetic compatibility. Obtaining such voltage impulses was imposed by the necessity to simulate real stresses of insulation in electrical installations or electromagnetic disturbances having such characteristics (high altitude nuclear electromagnetic pulse, electrostatic discharges or certain switching operations). For the necessity of electromagnetic immunity tests of civil equipment, the amplitudes of these pulses are usually limited to a few kV, and the circuits that produce them are based on power electronics. However, for insulation tests, they are of the order of hundreds of kV. The paper presents three methods to obtain steep high voltage pulses required for testing high voltage insulations. Their advantages and disadvantages (limitations) are discussed for each of them.
2017 10th International Symposium on Advanced Topics in Electrical Engineering (ATEE), 2017
The paper aims to assess side effects which occur as a result of measures adopted to reduce the e... more The paper aims to assess side effects which occur as a result of measures adopted to reduce the electromagnetic field in the vicinity of overhead power lines, respectively using the phases' transposition for double circuit transmission lines. Practical considerations about the accuracy of magnetic field calculation were discussed considering the real positions of conductors, the optimal phasing in the case of double-circuit lines and the losses which appear in ground wire(s) in different configuration of phases.
2017 5th International Symposium on Electrical and Electronics Engineering (ISEEE), 2017
The paper will present the first results of an extended analysis based on synchronously recorded ... more The paper will present the first results of an extended analysis based on synchronously recorded electrical and weather data, aimed to numerically evaluate the stochastic variation of transmission power losses measured on a given 400 kV line, in correlation with different environmental influence factors such as air temperature and pressure, dew point, wind speed and direction, type and amount of precipitation reported at 14 meteorological stations.
2021 12th International Symposium on Advanced Topics in Electrical Engineering (ATEE), 2021
The paper presents a short analysis of benefits and disadvantages of multi-circuit overhead lines... more The paper presents a short analysis of benefits and disadvantages of multi-circuit overhead lines operation. Nowadays, the problem to build a new overhead line is a very difficult one because of land cost and different properties crossed by it, environmental impact, opposition of large public etc. Therefore, the solution to use same tower to support many circuits, with same or different rated voltage, also for AC and DC systems is very attractive. The main advantage is that of use of a narrow corridor to transmit a large amount of power. But other problems must be solved in order to make this type of line working properly, from solving the mutual influence of the circuits to lightning protection and up to the low frequency electromagnetic fields profile recorded near to ground.
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