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

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.

Surface Charge Properties of Epoxy Composites under DC Voltage Affected by Surface and Bulk Conductivity

“…In general, the surface resistivity is high for dry and clean dielectrics. It becomes lower mainly because there is moisture or impurities adsorbed on the surface [2]. Besides, the effect of surface trap distribution is an important factor in surface electron migration [21].…”

“…With the increased demand of power loads, large-capacity power transmission over long distances has developed rapidly in recent years [1,2]. In the meantime, with advances in technology, DC transmission is getting more and more attention from researchers and engineers.…”

“…In the meantime, with advances in technology, DC transmission is getting more and more attention from researchers and engineers. Especially when the transmission distance is greater than the economic distance, DC transmission shows a clear advantage in the economical way [2]. However, the higher DC voltage imparts longer DC wall bushings.…”

A zero‐sample state evaluation model for valve‐side bushing of UHV converter transformer oriented to digital twin under attribute analysis

“…The valve‐side bushing of the ultra‐high voltage (UHV) converter transformer is the “bridge” and weak link to realize power conversion [2], and its running state stability directly affects the reliability of DC transmission projects. According to statistics, in recent years, power system failures caused by converter valve‐side bushing of converter transformer account for 16.7% of all equipment failures [3], and the forms of failures also show diversity, such as SF6 gas leakage, aging of capacitor core, oil leakage, discharge, and so on [4–7]. At this stage, most of the research on the valve‐side bushing of UHV converter transformers remains in the fault occurrence mechanism, fault analysis, and physical structure optimization [8–10].…”