Papers by Marek Florkowski
Przegląd Elektrotechniczny, 2024
The reliability and operating time of electrical devices may be limited by phenomena that occur i... more The reliability and operating time of electrical devices may be limited by phenomena that occur in their insulation systems under the
influence of an electric field. One of the methods of particular importance for the assessment of the condition of medium- and high-voltage insulation
systems is the measurement of partial discharges (PD). The article presents the influence of the magnetic field on the dynamics of partial discharges
in high-voltage insulation systems. This problem applies to both insulation systems in the area of power transmission and distribution, industrial
equipment, as well as transportation, e.g. electric vehicles, traction. In all electrically conductive power devices, the magnetic field is superimposed
on the electric field, affecting the partial discharge mechanism. It was observed that the mutual interaction of electric and magnetic fields affects the
dynamics of partial discharges - the article presents examples of parallel and perpendicular mutual orientation of these fields. The applied phaseresolved PD measurement technique allows for determining the influence of the magnetic field in the model electrode system and for quantitative
visualization in the form of diagrams of time sequences of discharge pulses. Simulation of the electron trajectories under conditions of simultaneous
electric and magnetic fields revealed changes in their trajectories in relation to the presence of only the electric field. The presented results of the
experiments may contribute to the development of a methodology for measuring partial discharges with the superposition of electric and magnetic fields, as well as to a better understanding of the basic characteristics of their physical mechanisms. The observed effect of partial discharge dynamics modulation, additionally by the magnetic field, may be important in the diagnostics of insulation systems of power equipment.
Measurement, 2024
In this article, an original measurement methodology is presented for insight into the partial di... more In this article, an original measurement methodology is presented for insight into the partial discharge (PD) mechanismbeing one of the key indicators of high-voltage insulation system integrity. This approach is based on riveting measurements of PD echo (PDE) that are acquired by applying a chopped sequence. The new extension of PDE potential, presented in this paper, refers to the detection and extraction of echo attributes, providing an additional quantitative assessment of the insulation condition. In this way a noninvasive insight into source of defect can be provided, which is not possible by conventional PD measurements. Hence, intension and future development direction of this method is to provide insulation deterioration imaging. The detection of echo discharges occurs during the voltage-less time break between consecutive periods of excitation voltage, therefore the further advantage of PDE is higher immunity to excitation-driven disturbances. The whole measurement sequence can be subdivided in to AC and DC parts. The measurement methodology can be applied to various high-voltage objects and insulation systems. As an example, measurement results obtained on polymeric material that contained an embedded defect are presented. A comparison of PD echo effects on both untreated and aged specimens revealed the dependence of gaseous inclusion surface conditions on the echo pattern. Presented new measurement methodology allowed for extraction and evaluation of PD echo time constant, which yielded distinct values in the cases of new and aged specimens. The echo discharges were attributed to the mechanisms in the dielectric that started in the voltage-less part after the transition point. These effects represent the interplay between the remnant electric field and the decay of the electric field that was accumulated from the previous PDs. The aim of this paper was to show advanced PD measurement approach to investigate the effects of an internal embedded electrical insulation defect on an externally measurable indicator. The paper also presents an attempt to extract additional information from phase-resolved PD images. In this context, further research is needed to provide directions toward a measurement technique and a potential future diagnostic approach.
Energies, 2024
In this article, an extension of a conventional partial discharge (PD) approach called partial di... more In this article, an extension of a conventional partial discharge (PD) approach called partial discharge echo (PDE), which is applied to different classes of electrical insulation systems of power devices, is presented. Currently, high-voltage (HV) electrical insulation is attributed not only to transmission and distribution grids but also to the industrial environment and emerging segments such as transportation electrification, i.e., electric vehicles, more-electric aircraft, and propulsion in maritime vehicles. This novel PDE methodology extends the conventional and established PD-based assessment, which is perceived to be one of the crucial indicators of HV electrical insulation integrity. PD echo may provide additional insight into the surface conditions and charge transport phenomena in a non-invasive way. It offers new diagnostic attributes that expand the evaluation of insulation conditions that are not possible by conventional PD measurements. The effects of partial discharge echo in various segments of insulation systems (such as cross-linked polyethylene [XLPE] power cable sections that contain defects and a twisted-pair helical coil that represents motor-winding insulation) are shown in this paper. The aim is to demonstrate the echo response on representative electrical insulating materials; for example, polyethylene, insulating paper, and Nomex. Comparisons of the PD echo decay times among various insulation systems are depicted, reflecting dielectric surface phenomena. The presented approach offers extended quantitative assessments of the conditions of HV electrical insulation, including its detection, measurement methodology, and interpretation.
IEEE Transactions on Transportation Electrification, 2025
One of the mostly applied assessments of electrical insulation’s condition is based on the measur... more One of the mostly applied assessments of electrical insulation’s condition is based on the measurement of partial discharges (PDs). In addition to conventional PD measurements on motor insulation, a novel approach called PD echo (PDE) is described in this article. This can be applied to various excitation-voltage waveshapes [such as sinusoidal, pulse wave modulated (PWM), etc.] that form chopped sequences. The PDE methodology may extract information about the condition of the insulation—especially depicting its surface effects. Since it operates in the voltageless part of a chopped sequence, it is more immune to excitation-driven disturbances. This article presents the results that were obtained on twisted pair (TP) specimens that were the representative of electrical-machine insulation that is untreated and degraded by hot-air streaming. A comparison of the experimental results based on the PDE time constant revealed distinct echo patterns (especially the accelerated decay of the PDE pulse magnitude) in cases of deteriorated TP samples. The echo discharges were attributed to the mechanisms that occurred on the enameled wire surface in the air gap between the turns. The aim of this article was to provide quantitative insight into the winding interturn insulation in the form of PDE attributes. It also provides an attempt to extract additional insulation degradation-related information from phase-resolved PD images. The PDE phenomenon may open new opportunities for evaluating electrical insulation and providing directions toward potential diagnostic applications in motors.
Energies, 2025
Currently, zero-emission targets require future global energy concepts to be based on renewable e... more Currently, zero-emission targets require future global energy concepts to be based on renewable energy sources; therefore, huge investments are being made in bulky offshore wind parks worldwide. In this context, there is ongoing and enormous development and a need for HVDC submarine cables (both static and dynamic) to connect offshore wind farms. One of the basic problems when analyzing the operating conditions of HVDC cables is assessing the effects of the load current, which generates thermal and electric fields on the insulation systems in these cables. This article considers the problem of the influence of the thermal effect and space charges-the field effect-on the electrical conductivity of polymeric insulating materials and, thus, on the distribution of the electric field intensity in the cable insulation. An analytical methodology for joint analysis of the thermal-effect-and space-charge-related influence is presented. The critical value of the electric field intensity at which the electrical conductivity is significantly modified under coupled thermal-electric exposure is determined. Special focus is placed on the analysis of the coefficient representing the dependence of the electrical conductivity on the temperature in a much broader range than typically assumed. Hence, the intention of this paper is to highlight the limit values of the electric field strength under the simultaneous action of the space charge and temperature gradient. Recognizing the changes in the electric field intensity value in the insulation is of fundamental importance from the point of view of HVDC cable technology and construction.
IEEE Transactions on Power Electronics, 2024
This article depicts an original measurement methodology and detection approach for determining t... more This article depicts an original measurement methodology and detection approach for determining the influence of a magnetic field on partial discharge (PD) dynamics in electrical insulation while subjected to pulsewidth modulated (PWM) excitation. Unlike conventional PD measurements that are only carried out in an electric field, it was demonstrated that the interplay of electric and magnetic fields enhances a PD's intensity. The quantitative effect of a magnetic field was captured by phase-resolved acquisition and visualization on time-sequence intensity diagrams. The increase in the PWM carrier frequency resulted in enhanced intensity and was also elevated by the effect of the magnetic field. The influence of the magnetic field on the PDs was associated with the elongation of the charged particle trajectory and effects that were caused by the Lorentz force. The presented study may contribute to PD measurement methodology in the power electronic environment in both electric and magnetic fields as well as a better understanding of the underlying physical mechanisms. Since the endurance and reliability of electrical insulation that is subjected to fast switching, PWM-modulated power electronic-based excitation is an actual topic in many segments, such as power grids, industry, and transportation; the awareness of PD-intensity modulation that originates from the presence of a magnetic field should be raised and investigated.
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Papers by Marek Florkowski
influence of an electric field. One of the methods of particular importance for the assessment of the condition of medium- and high-voltage insulation
systems is the measurement of partial discharges (PD). The article presents the influence of the magnetic field on the dynamics of partial discharges
in high-voltage insulation systems. This problem applies to both insulation systems in the area of power transmission and distribution, industrial
equipment, as well as transportation, e.g. electric vehicles, traction. In all electrically conductive power devices, the magnetic field is superimposed
on the electric field, affecting the partial discharge mechanism. It was observed that the mutual interaction of electric and magnetic fields affects the
dynamics of partial discharges - the article presents examples of parallel and perpendicular mutual orientation of these fields. The applied phaseresolved PD measurement technique allows for determining the influence of the magnetic field in the model electrode system and for quantitative
visualization in the form of diagrams of time sequences of discharge pulses. Simulation of the electron trajectories under conditions of simultaneous
electric and magnetic fields revealed changes in their trajectories in relation to the presence of only the electric field. The presented results of the
experiments may contribute to the development of a methodology for measuring partial discharges with the superposition of electric and magnetic fields, as well as to a better understanding of the basic characteristics of their physical mechanisms. The observed effect of partial discharge dynamics modulation, additionally by the magnetic field, may be important in the diagnostics of insulation systems of power equipment.