Study on Nano-Modified Mineral Oil Surface Discharge Partial Discharge Signal Characteristics for High Voltage Transformer Applications

摘要

In a high voltage electric power transmission system, transformer plays a vital role in maintaining the reliability of the network. High voltage transformers are generally designed with oil filled insulation. Degradation of oil insulation leads to failure of expensive transformers.Many research works are being carried out in enhancing the performance of conventionally used mineral oil insulation. Recent developments in nanotechnology have exposed the prospects for the growth of nano-modified mineral oil insulation with improved dielectric and thermal properties. Partialdischarge (PD) activities inside the transformer are a major source of degradation of oil insulation. Hence in recent times, researchers are focusing more towards understanding PD characteristics of transformers. However, very few information is available on PD signal characteristics of nano-modifiedmineral oil. Hence this paper makes an effort to understand the surface discharge PD characteristics of SiO₂ nanofiller added mineral oil at various %wt concentrations of nano-filler material. Rod-plane electrode configuration was used to simulate surface discharge PD in the laboratoryand wide band PD detection system was used to measure the PD signals. The PD characteristics namely inception voltage, PD amplitude, stable PD formation voltage and PD signal frequency spectrum was evaluated. From the results, it is understood that adding SiO₂ nano-filler materialto base mineral oil improves the partial discharge characteristics of mineral oil. The computed results will be highly useful for electrical utilities for implementing effective PD based condition monitoring system for transformers.