Basalt fiber (BF) has a high mechanical strength, excellent temperature resistance, good chemical stability, low energy consumption, and an environmentally friendly production process. In addition, BF-reinforced polymers (BFRPs) have good corrosion resistance and designability; thus, they meet the application requirements of electrical equipment, such as new conductors, insulating pull rods, and composite cross-arms. However, there are still a series of technical issues in the mass production of BF, and the stability of the products needs to be further improved. Therefore, the research on the production, modification, and application of BF is necessary. This paper discusses the chemical composition and production technology of BF, describes the morphology and properties of BF, summarizes the interface problems and modification methods of composites, and finally, introduces the application prospects of BF in the field of electrical materials, which is expected to provide a reference for the application and promotion of BFRP in the future.

Basalt fiber (BF) has high mechanical strength, good insulation performance and low cost. It is suitable to be used as reinforcement material in the manufacture of electrical equipment. However, the large surface inertia of basalt fiber makes it difficult to combine with the matrix material, which seriously limits its service life and application scenarios. In addition, the serious vacancy in the research of insulation properties also limits its production and application in the electrical field. Therefore, in order to solve the problem of difficult bonding between basalt fiber and resin matrix and make up for the research blank of basalt fiber composites in insulation performance, this paper provides a basalt fiber modification method—SiO₂ coating, and tests the insulation and mechanical properties of the modified composite. We used nano-SiO₂ coating solution to modify basalt fiber, and manufactured BF/resin composite (BFRP) by hand lay-up and hot-pressing technology, and experimentally analyzed the influence of nano-SiO₂ content on the mechanical and insulation properties of the modified composite. Fourier transform infrared spectrum and scanning electron microscope analysis showed that nano-SiO₂ was successfully coated on basalt fibers. Through the microdroplet debonding test, it was found that the IFSS of fiber/resin was improved by 35.15%, 72.97 and 18.9%, respectively, after the modification of the coating solution with SiO₂ concentration of 0.5%, 1% and 1.5%, showing better interface properties; the single fiber tensile test found that the tensile strength of the modified fiber increased slightly. Among all composites, 1 wt% SiO₂ coating modified composites showed the best comprehensive properties. The surface flashover voltage and breakdown field strength reached 13.12 kV and 33 kV/mm, respectively, which were 34.6% and 83% higher than unmodified composite. The dielectric loss is reduced to 1.43%, which is 33.8% lower than the dielectric loss (2.16%) of the untreated composite, showing better insulation ability; the tensile strength, bending strength and interlaminar shear strength were increased to 618.22 MPa, 834.74 MPa and 16.29 MPa, respectively, which were increased by 53%, 42.4% and 59.7%, compared with untreated composites. DMA and glass transition temperature showed that the modified composite had better heat resistance. TGA experiments showed that the resin content of the modified composite increased, and the internal structure of the composite became denser.

As basalt fiber has better mechanical properties and stability than glass fiber, cross arms made of continuous basalt-fiber-reinforced epoxy matrix composites are capable of meeting the mechanical requirements in the event of typhoons and broken lines in coastal areas, mountainous areas and other special areas. In this paper, continuous basalt-fiber-reinforced epoxy matrix composites were used to fabricate the core rods and composite cross arms. The results verified that basalt fiber composite cross arms can meet the strict requirements of transmission lines in terms of quality and reliability. In addition to high electrical insulation performance, the flexural modulus and the flexural strength of basalt fiber core rods are 1.8 and 1.06 times those of glass fiber core rods, respectively. Basalt fiber core rods were found to be much better load-bearing components compared to glass fiber core rods. However, the leakage current and the result of scanning electron microscopy (SEM) analysis reveal that the interface bonding strength between basalt fibers and the matrix resin is weak. A 3D reconstruction of micro-CT indicates that the volume of pores inside basalt fiber core rods accounts for 0.0048% of the total volume, which is greater than the 0.0042% of glass fiber rods. Therefore, improving the interface bond between basalt fibers and the resin can further improve the properties of basalt fiber core rods.

In order to promote the application of composite insulators in coastal areas with high temperature, high humidity and high salt, it is of great importance to develop matrix resin with salt corrosion resistance for composite core rods. In this study, bisphenol A epoxy resin was modified by blending with alicyclic epoxy resin (2021P). Three different proportions of 2021P/DGEBA blend resins (0% 2021P/DGEBA, 10% 2021P/DGEBA and 20% 2021P/DGEBA) were prepared, and the high salt medium corrosion test was carried out. The physicochemical (FTIR, DMA, TGA) and electrical properties (dielectric loss, leakage current and breakdown field strength) of the blend resin before and after aging were tested and analyzed, and the optimal blend proportion was determined. The results showed that after salt aging, the Tg of 0% 2021P/DGEBA decreased to 122.99 °C, while the Tg of 10% 2021P/DGEBA reached 134.89 °C; The leakage current of 0% 2021P/DGEBA increased to 48.994 μA, while that of 10% 2021P/DGEBA only increased to 44.549 μA; The breakdown field strength of 0% 2021P/DGEBA dropped to 40.36 kv/mm, while that of 10% 2021P/DGEBA only dropped to 43.63 kv/mm. The introduction of 2021P enhanced the salt corrosion resistance of the blend resin, which could hinder the penetration, diffusion and erosion of external media (such as Na⁺, Cl⁻, H₂O, etc.) to the matrix resin. The comprehensive properties of 10% 2021P/DGEBA blend system reached the best, which was better than other blending resins, showing great application potential.

With the application of the composite cross-arm in power systems, comprehensive anti-aging performance is a key factor to determine whether it can operate safely. In order to study the influence of the operating environment on the external insulation characteristics of composite cross-arms of distribution networks, various aging conditions such as voltage, rain, temperature, humidity, salt fog and ultraviolet light were simulated in a climate chamber based on the real operation conditions of the 10-kV composite cross-arm. A multi-factor aging test of composite cross-arms with two kinds of cross-section shapes (T-shaped and square) was carried out for 5000 h. The change trends of leakage current and flashover voltage of the composite cross-arms before and after aging were analyzed. Finally, the aging mechanism of the silicone rubber sheaths was analyzed to further explain the reasons for the change of external insulation performance of composite cross-arms. The results show that the leakage current rising rate of T-shaped and square composite cross-arms after aging increases significantly, and the minimum flashover voltage decreases to 58.3 kV and 49.502 kV, respectively. The results of FTIR, SEM and hydrophobic angle tests show that, after aging, the performance of the silicone rubber outer sheath material decreases in varying degrees. In general, UV aging has the greatest influence on the external insulation characteristics of composite cross arms. Generally speaking, after 5000 h of multi factor aging, although the external insulation characteristics of the 10-kV composite cross-arm decreases to a certain extent, there is still enough margin to meet the normal operation.

With the digital transformation of the grid, partial discharge (PD) recognition using deep learning (DL) and big data has become essential for intelligent transformer upgrades. However, labeling on-site PD data poses challenges, even necessitating the removal of covers for internal examination, which makes it difficult to train DL models. To reduce the reliance of DL models on labeled PD data, this study proposes a semi-supervised approach for PD fault recognition by combining the graph convolutional network (GCN) and virtual adversarial training (VAT). The approach introduces a novel PD graph signal to effectively utilize phase-resolved partial discharge (PRPD) information by integrating numerical data and region correlations of PRPD. Then, GCN autonomously extracts features from PD graph signals and identifies fault types, while VAT learns from unlabeled PD samples and improves the robustness during training. The approach is validated using test and on-site data. The results show that the approach significantly reduces the demand for labeled samples and that its PD recognition rates have increased by 6.14% to 14.72% compared with traditional approaches, which helps to reduce the time and labor costs of manually labeling on-site PD faults.