Pressure Dependent Propagation of Positive Streamers in a long Point-Plane Gap in Transformer Oil

Linhjell, D.; Lundgaard, L.E.; Unge, Mikael

doi:10.1109/icdl.2019.8796570

Cited by 7 publications

(5 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thirdly, this paper only simulates the propagation of a single streamer branch instead of streamer with multiple branches due to the limitation of 2D-axisymmetric model and demanding computational resources in 3D model. Although streamer branching may have some shielding effects on the velocity of streamer branches to some extent, the recent results in [11], as is discussed in the introduction, it is indicated that the shielding effects of streamer branching is not the dominant reason to constrain streamer velocity. Therefore, it is acceptable to only simulate a single streamer channel.…”

Section: Discussionmentioning

confidence: 99%

“…The reason of the stable velocity of second mode streamer in macroscopic view was assumed to be the increase of branching extent when applied voltage magnitude is increased [9,10]. However, recent study [11] showed that increasing pressure during streamer propagation, which decreases streamer branching extent, can hardly affect V a . This result indicated that the increase of branching extent from a macroscopic view may not be the underlying mechanism for the stable velocity of second mode streamer.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Modelling of second mode positive streamer in cyclohexane by considering optimized electron saturation velocity

Liu

Wang

2021

J. Phys. D: Appl. Phys.

View full text Add to dashboard Cite

Experimental and modelling study of the pre-breakdown phenomenon in dielectric liquids, generally called ‘streamers’, is vital for the application of liquids in high voltage and power dense devices. Streamer is characterized into four modes by average propagation velocity, among which the second mode streamer is responsible for breakdowns at a wide range of gap distances and voltage levels. The stable propagation velocity of around 2 km s−1 is one of the key characteristics of the second mode streamer. The most recent study found that streamer branching is not the main reason for the stable velocity of second mode streamer as was assumed previously. Besides, one major drawback of the existing charge-drift model of the second mode streamer is the over-estimation of electron velocity, which leads to the much higher streamer propagation velocity in simulation than that observed in experiments. In this paper, restriction of streamer propagaiton velocity by using electron saturation velocity (ESV) is found to be the key reason for the stable propagaiton velocity of the second mode streamer. The charge-drift model is modified by considering different ESVs. It is found that reducing ESV from 30 km s−1 to 2.5 km s−1 in simulation can greatly constrain positive streamer propagation velocity from 4.15 km s−1 to 0.50 km s−1 in cyclohexane. When ESV is set to be 7.5 km s−1 in cyclohexane, the streamer propagation velocity in simulation increases from 1.59 km s−1 at 80 kV (below breakdown voltage) to 1.91 km s−1 at 100 kV (near to acceleration voltage), which closely matches the experimental observations.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Modelling of second mode positive streamer in cyclohexane by considering optimized electron saturation velocity

Liu

Wang

2021

J. Phys. D: Appl. Phys.

View full text Add to dashboard Cite

show abstract

“…• The fact that streamer propagation speed is not influenced by high pressure indicates that processes take place in the liquid phase [6,36].…”

Section: Discussionmentioning

confidence: 99%

Pre-breakdown phenomena in hydrocarbon liquids in a point-plane gap under step voltage. Part 2: behaviour under negative polarity and comparison with positive polarity

et al. 2020

Self Cite

View full text Add to dashboard Cite

This study addresses the dielectric performance of nonpolar hydrocarbon liquids and mineral oils under negative polarity stress. Stopping length for non-breakdown streamers, breakdown voltages and velocities for various pre-breakdown streamer modes have been studied for a selection of model liquids (cyclohexane and white oils), for a gas to liquid oil, and a refined naphthenic transformer oil. Studies of propagation modes were done using an 80 mm point to plane gap and a step voltage with 0.5 μs rise time. Light emission and pre-breakdown currents have been recorded and instantaneous velocities have been derived from images of propagating streamers. Compared to positive polarity, there are less differences in streamer behaviour in the oils examined under negative polarity. Breakdown voltages and acceleration voltages are higher for negative streamers than for positive ones, while their propagation velocities are lower. While propagation modes for positive voltages are quite distinct, the mode changes for negative ones are more gradual. The behaviour of both positive and negative streamers is in line with the hypothesis that the propagation is governed by electron avalanches and quantum chemical properties of liquid components.

show abstract

“…Streamer parameters, such as conductivity of the streamer channel and streamer head radius, need to be reevaluated as well for other liquids. The properties of the streamer channel are also important to simulate the effects of external pressure, which mainly affects processes in the gaseous phase [26].…”

Section: Current Functionality and Future Prospectsmentioning

confidence: 99%

Cerman: Software for simulating streamer propagation in dielectric liquids based on the Townsend-Meek criterion

Madshaven,

Hestad,

Åstrand

2020

Preprint

View full text Add to dashboard Cite

We present a software to simulate the propagation of positive streamers in dielectric liquids. Such liquids are commonly used for electric insulation of high-power equipment. We simulate electrical breakdown in a needle-plane geometry, where the needle and the extremities of the streamer are modeled by hyperboloids, which are used to calculate the electric field in the liquid. If the field is sufficiently high, electrons released from anions in the liquid can turn into electron avalanches, and the streamer propagates if an avalanche meets the Townsend-Meek criterion. The software is written entirely in Python and released under an MIT license. We also present a set of model simulations demonstrating the capability and versatility of the software.

show abstract

Pressure Dependent Propagation of Positive Streamers in a long Point-Plane Gap in Transformer Oil

Cited by 7 publications

References 12 publications

Modelling of second mode positive streamer in cyclohexane by considering optimized electron saturation velocity

Modelling of second mode positive streamer in cyclohexane by considering optimized electron saturation velocity

Pre-breakdown phenomena in hydrocarbon liquids in a point-plane gap under step voltage. Part 2: behaviour under negative polarity and comparison with positive polarity

Cerman: Software for simulating streamer propagation in dielectric liquids based on the Townsend-Meek criterion

Contact Info

Product

Resources

About