Electrical Treeing in Power Cable Insulation under Harmonics Superimposed on Unfiltered HVDC Voltages

Fard, Mehrtash Azizian; Farrag, Mohamed Emad; Reid, Alistair; Al-Naemi, Faris

doi:10.3390/en12163113

Cited by 15 publications

(10 citation statements)

References 29 publications

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“…Electrical discharges also produce electromagnetic radiation, covering visible light, UV, and high-energy ionizing radiation [27]. Partial discharges themselves are among the primary sources of electrical insulation degradation [28] which can lead to early insulation failure in power cables [29]. Thus, coronas can produce fast acceleration of the natural aging process of different electrical and electronic systems, having a negative impact on the reliability of some critical electric and electronic systems.…”

Section: Corona Effect and Arc Trackingmentioning

confidence: 99%

Experimental Study of Visual Corona under Aeronautic Pressure Conditions Using Low-Cost Imaging Sensors

Riba

Gómez-Pau

Moreno-Eguilaz

2020

Sensors

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Visual corona tests have been broadly applied for identifying the critical corona points of diverse high-voltage devices, although other approaches based on partial discharge or radio interference voltage measurements are also widely applied to detect corona activity. Nevertheless, these two techniques must be applied in screened laboratories, which are scarce and expensive, require sophisticated instrumentation, and typically do not allow location of the discharge points. This paper describes the detection of the visual corona and location of the critical corona points of a sphere-plane gap configurations under different pressure conditions ranging from 100 to 20 kPa, covering the pressures typically found in aeronautic environments. The corona detection is made with a low-cost CMOS imaging sensor from both the visible and ultraviolet (UV) spectrum, which allows detection of the discharge points and their locations, thus significantly reducing the complexity and costs of the instrumentation required while preserving the sensitivity and accuracy of the measurements. The approach proposed in this paper can be applied in aerospace applications to prevent the arc tracking phenomenon, which can lead to catastrophic consequences since there is not a clear protection solution, due to the low levels of leakage current involved in the pre-arc phenomenon.

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Section: Corona Effect and Arc Trackingmentioning

confidence: 99%

Experimental Study of Visual Corona under Aeronautic Pressure Conditions Using Low-Cost Imaging Sensors

Riba

Gómez-Pau

Moreno-Eguilaz

2020

Sensors

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“…This system has the ability to control the power flow by setting the proper phase angle of the voltage appearing on the inductance ends, which acts as the separation between the grid and converter [1,2]. The high-voltage DC systems provide non-ideal DC voltages, which also contain trace AC harmonics or a DC voltage ripple [3,[5][6][7][8]. The pulsating disturbances imposed on the DC voltage occur during the normal operation of the power converters, and can be transmitted from the AC side of the DC grid.…”

Section: Introductionmentioning

confidence: 99%

“…The pulsating disturbances imposed on the DC voltage occur during the normal operation of the power converters, and can be transmitted from the AC side of the DC grid. These disturbances increase the exposure of high-voltage insulation systems on the strong electric field [5][6][7][8][9][10][11][12][13][14][15][16][17]. The HVDC components can be divided into two groups of devices depending on the exposure type.…”

Section: Introductionmentioning

confidence: 99%

“…The simultaneous, combined AC and DC voltage stresses during the operation of power equipment can lead to increased accumulation of space charge; this was observed in XLPE cable samples [6,19]. The DC voltage harmonic distortions can also impact the power electronics modules; this was observed for modular multilevel converters (MMCs), which are a part of the VSC systems, in which the voltage ripples have an influence on their terminal characteristics [20].…”

Section: Introductionmentioning

confidence: 99%

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Measurements and Analysis of Partial Discharges at HVDC Voltage with AC Components

2022

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This paper presents the methodology for phase-resolved partial discharge measurements in HVDC systems with a DC voltage containing trace AC harmonics or a DC voltage ripple. The measurement result of partial discharges is an indicator of the current condition of the high-voltage power devices’ insulation system. The voltage waveforms in HVDC systems are not ideal DC, because different disturbances occurring naturally in these systems can affect the DC voltage. The AC harmonics related to the AC source voltage, and the voltage ripples provided by the power converter topology, can be found in the HVDC voltage. This paper proposes a novel approach to partial discharge measurement in DC networks. The synchronization to the particular AC harmonics appearing in DC voltage was applied to the PD measurements. The analyses were performed on the model sample containing a void inclusion, which was placed between electrodes fed by the DC voltages with the imposed chosen AC harmonics. Two scenarios were analyzed at a constant DC level: one with a variable AC magnitude and the second with a variable frequency of an AC source adjusted to the harmonics: 50, 150, 300, and 350 Hz. It was observed that the superimposed AC voltage component resulted in an intensification of PDs.

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“…Phenomena occurring in insulation in a strong electric field result in aging and include ionization processes in the dielectric materials. The DC insulation is a crucial element of high voltage power equipment, such as cables, transformer bushings, converter transformers-especially the valve winding, capacitors, including DC capacitors in HVDC modules; wall bushings [1][2][3][4]. The problem of the reliability of electrical power devices refers-in both AC and DC systems-to the possibility of assessing the condition of the insulation systems under the action of operational stresses.…”

Section: Introductionmentioning

confidence: 99%

Influence of Insulating Material Properties on Partial Discharges at DC Voltage

Florkowski

2020

Energies

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Understanding a partial discharge mechanism at direct current (DC) is an actual research topic that requires both modeling, simulations and measurements. This paper describes an influence of insulating material properties on partial discharges at DC voltage. Modifications of the traditional model reflecting the conditions of partial discharges (PD) inception and post discharge processes at DC voltage have been proposed. The aim was to show the partial discharge mechanisms and draw attention to the role of parameters of insulation materials adjacent to the cavity at DC voltage. The investigations were performed on two kinds of dielectric material used in power cables. Various combinations of specimens were designed to reveal the effect of the material resistivity on the PD activity. Key observations referred to the impact of the void adjacent material resistance on the partial discharge inception voltage threshold at DC voltage. The modified PD model was applied to analyze both inception and post discharge recovery stage. The role of dielectric properties of material adjacent to the void was investigated, highlighting its impact during static inception stage and in charging stage. Despite many simplifications introduced in the model, measurement results have confirmed the role of the dielectric material surrounding the void on partial discharge dynamics. The average time interval between PD pulses revealed a systematic relationship with respect to the applied voltage and specimen resistivity. This value can be considered in the future research for diagnostic indicator at DC voltage.

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Electrical Treeing in Power Cable Insulation under Harmonics Superimposed on Unfiltered HVDC Voltages

Cited by 15 publications

References 29 publications

Experimental Study of Visual Corona under Aeronautic Pressure Conditions Using Low-Cost Imaging Sensors

Experimental Study of Visual Corona under Aeronautic Pressure Conditions Using Low-Cost Imaging Sensors

Measurements and Analysis of Partial Discharges at HVDC Voltage with AC Components

Influence of Insulating Material Properties on Partial Discharges at DC Voltage

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