Study on Surface Charge Accumulation Characteristics of Resin Impregnated Paper Wall Bushing Core Under Positive DC Voltage

Chen Chen,Liang Liang,Zhao Zhao,Tang Tang,Liu Liu

doi:10.3390/en12234420

Chen Chen, Liang Liang + Show 3 more

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https://doi.org/10.3390/en12234420

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Abstract

As a critical component of a high-voltage direct current (HVDC) transmission system, resin impregnated paper (RIP) wall bushing has become a weak point because of its surface charge accumulation. This paper studies a model RIP wall bushing core designed by the equal capacitance method. The stationary resistive field along the gas–solid interface of the RIP wall bushing core is investigated theoretically by a gas model, which considers the non-linearly field-dependent volume conductivity. The results show that the gas conductivity along the core surface tends to be an arched distribution from the high-voltage conductor to the end shielding screen. The surface charge mainly accumulates at the turning point of the radius, which may threaten the core’s insulation. Then, the surface charge is obtained through a measurement system, where the experimental results are highly consistent with the simulation results. Considering the time constant of charge dissipation is nearly 15 min, it would be better to measure the surface charge on one axial direction of RIP wall bushing core after each voltage application. The simulation and experimental results of this paper can guide the design of a RIP wall bushing core.

Highlights

The operation safety of the AC/DC hybrid power grid strongly depends on the resin impregnated paper (RIP) wall bushings [2]
Operation experiences show that RIP wall bushings with voltage grades higher than 400 kV currently have a high failure rate, resulting in single-pole lockout at the high-voltage direct current (HVDC) converter stations, which has a large negative impact on the AC-DC
When flashing along the core surface, the large current makes the lead between the end shielding screen and the grounding flange disconnected, and the grounding flange becomes the channel for current conduction, resulting in a more obvious flashover trace from the grounding flange to the high-voltage conductor

Summary

Introduction

Operation experiences show that RIP wall bushings with voltage grades higher than 400 kV currently have a high failure rate (five year average failure rate is about 1.2%), resulting in single-pole lockout at the HVDC converter stations, which has a large negative impact on the AC-DC transmission system [3,4]. The surface discharge begins to develop toward the high-voltage conductor, resulting in flashover along the core surface. When flashing along the core surface, the large current makes the lead between the end shielding screen and the grounding flange disconnected, and the grounding flange becomes the channel for current conduction, resulting in a more obvious flashover trace from the grounding flange to the high-voltage conductor. Under AC voltage, the electric field distribution depends on the permittivity

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