Low density polyethylene (LDPE) was melt-compounded with MgO nano-fillers to produce LDPE/MgO nanocomposite. Its partial discharge (PD) resistance was evaluated by using a rod-to-plane electrode system. Erosion depth was measured as an index of PD resistance. Permittivity and tan delta were also measured to investigate interfacial morphological change due to nanostructuration. It was found that LDPE exhibits the increase in its partial PD resistance, if it is filled with the nanofillers by 1 to 10 phr (parts per hundred parts of resins). It should be noted that marked improvement appears in their content even as small as 1 phr. This tendency also appears for the permittivity of the same nanocomposite, i.e. the permittivity seems to show a minimum point, when nanofillers are added by 1 phr. PD resistance and dielectric properties of LDPE/MgO nanocomposite are discussed in terms of a multi-core model

Inter-turn short circuit fault (ITSCF) can be a great threat for the safety and effectiveness of the generator. In this paper, a simulation model with the experimental platform is established to diagnose the ITSCF in stator windings. A simulation model based on the Finite Element Method (FEM) is designed in ANSYS. Stator current is used for calculating the Root-Mean-Square (RMS) value, phase difference, symmetrical components, Park’s vector trajectory’s and Total Harmonic Distortion (THD). It was found that when ITSCF happened, three phase currents in stator is no longer symmetrical. The ratio of negative to positive sequence of current raises from 0.40 to 14.18 in simulation and 0.52 to 19.89 in the experiment from normal condition to 7 turns shorted. The same trend was seen in Park’s vector trajectory analysis where the eccentricity raises from 0.03 to 0.65 in simulation and 0.14 to 0.75 in the experiment. Phase difference of the three phases is at 120° degree deviation as the ITSCF occurs in stator winding. THD also increased with the increase in the fault level. The results show a good consistency of simulation with experimental results. It was found that the analysis performed in this research are major indications for serious fault in DFIG.

Frequency accelerated partial discharge degradation of epoxy nanocomposite with 5 wt % additions of clay (layered silicate) was evaluated by a rod-to-plane electrode system, and investigated in comparison with that of epoxy without clay. Comparisons were made as to erosion depth using a laser surface profilometer. It was found that the change in the erosion depth is far smaller in specimens with clay than those without clay. It was also found that the solubilization method using acid anhydride curing agent seems to give PD resistance characteristics superior to the organic modification method using amine and acid anhydride curing agents and even to the solubilization method using amine curing agent.

Since the early 21st century, nanodielectrics have attracted significant attention. Initially regarded as exotic materials, they have since evolved into widely accessible advanced materials. Research has primarily focused on solid polymer nanocomposites and has recently expanded to include liquid nanocomposites, known as nanofluids. Over the past decade, considerable progress has been made in the field of nanodielectrics. To capture this progress, more than 400 papers published in the IEEE Transactions on DEI and EI Magazine between 2011 and 2023 have been collected and reviewed by theme. The evaluation of host materials, guest nanoparticles, and their combinations has been carried out to identify those that deliver superior performance. Notable advances in microscopic studies of interphases and particle dispersions are highlighted. Applications in high-voltage equipment and power electronics devices are also referenced to promote further research in this area. Additionally, it is important to recognize that machine learning plays a critical role in accelerating the R&D of nanodielectrics and their applications.

Polymer nanocomposites possess promising high performances as engineering materials, if they are prepared and fabricated properly. It was also clarified that they could provide favorable performances as dielectrics and electrical insulation. Comprehensive reviews were given in literatures by the author firstly in 2004 and secondly in 2005. This review is based on the second paper and covers recent significant findings. It also utilizes a recently proposed multi-core model, i.e. a fine structure of "interaction zone" in order to explain various phenomena associated with nanocomposites

Epoxy/fumed and precipitated silica and alumina nanocomposites were evaluated on their dielectric properties and partial discharge (PD) resistance. Dielectric properties, i.e., permittivity and dissipation factor tanδ were measured in the frequency range from 20 Hz to 1 MHz. PD resistance was assessed using a rod-to-plane electrode with an air gap 0.2 mm under 4 kV _rms . A new discovery was made for moisture and chemical residue effects for the dielectric properties. Natural moisture would not affect much permanent dielectric properties. It was elucidated that nano filler addition would enhance PD resistance, as expected. Furthermore, it was found that epoxy/silica nanocomposite is better in PD resistance than epoxy/alumina nanocomposite. Filler preparation methods, i.e., fumed and precipitated, might influence both properties.