Alexander A. Yurov

Analysis of partial discharges (PDs) in solid dielectric systems improves the quality of cable line insulation diagnostics by identifying installation defects, aging, and other destructive factors. However, known ABC models and single-line equivalent circuits provide an approximate description of discharges, and the distribution of amplitude-phase (APD) and amplitude-frequency (AFC) characteristics of PDs does not sufficiently agree with experiments reflecting the stochastic nature of PD-related voltage pulses recorded at the sensor output. This paper proposes a block-hierarchical approach to PD modeling in a three-phase power cable line (PCL) in LTspice. The model is based on a multilevel equivalent circuit with distributed parameters (MRLCG), supplemented by an ABC defect model. The hybrid MRLCG+ABC model takes into account the mutual influence of conductors and the sheath, the sheath grounding scheme, laying geometry, wave attenuation, distributed defects, conductor-to-conductor and conductor-to-sheath mutual inductance, the proximity effect, and the skin effect. A stochastic set of PDs is obtained using the Monte Carlo method, which reproduces the nature of the discharge process and provides stable statistical estimates. The novelty lies in the comprehensive consideration of electromagnetic and topological factors within a unified hierarchical scheme. Verification on a 10 kV cable showed convergence between numerical and physical APD/AFC according to statistical criteria: a Pearson correlation coefficient of r ≥ 0.93, an average amplitude discrepancy of ≤ 15% (over 1000 cycles), and a peak-to-peak amplitude discrepancy of single pulses of ΔU = 2–3%. This improves diagnostic quality and provides a basis for future studies on predicting the residual life of insulation.

The aim of the work is to search for the possibility of an in-depth study of the dynamics of wave processes and phenomena in solid dielectric systems of high-voltage cables associated with changes in the insulating properties of the material, namely, to determine the influence of design and operational features of power cable lines (SCL) on the amplitude-frequency characteristics (frequency response). One of the ways to achieve this goal is to develop a refined simulation (computer) model of the line that takes into account the design features of the SCL elements, in particular frequency-dependent specific parameters and mutual induction of the current-carrying parts of a three-phase cable, as well as the presence of a defect(s) in the solid insulation of the SCL. To achieve this goal, the authors conducted a statis-tical study of accidents based on a six-year analysis from 2018 to 2024, covering more than 1,669 damages to insulation materials on existing lines, resulting in technological disruptions to 6-10 kV cable distribution networks of Southern Russian electric grid companies in an area of over 340 thousand km2. The conducted research indicates the imperfection of methods and technical means of monitoring the technical condition of cable lines, resulting in a large number of accidents and, as a result, significant material damage. The method of numerical modeling of wave processes and phenomena in the insulating materials of cable lines will allow for an in-depth analysis to establish the relationship between defects in the line and its residual life and to carry out an accurate assessment of the technical condition of the cable line. The results of numerical simulation do not contradict the results obtained by the experimental method and correspond to generally accepted concepts of discharge processes in cable insulation. The results of the investigation of the frequency response of discharges in cable insulation by the method of oscillatory and partial discharge make it possible to contribute to the development of new or improvement of existing scientific and technical solutions in the field of cable line diagnostics, to reduce the time and volume of repair and emergency work in 6-20 kV distribution networks.

Crosslinked polyethylene (XLPE) has been the cornerstone material in the power industry for insulating high-voltage cables due to its exceptional properties, including reduced dielectric loss, high dielectric constant and thermal conductivity, and excellent resistance to electrical stress. In the current study, in order to further enhance the electrical and mechanical properties of XLPE’s various types of nanofillers such as metal oxides, boron nitride nanosheets of nanosilica and graphene oxide are incorporated into the XLPE matrix. These nanoparticles promote the occurrence of numerous trap sites, even at modest concentrations, due to their extensive interfacial regions, which affect crucial characteristics including breakdown voltage strength, electrical tree growth, structural defects, space charge accumulation, and thermal aging. The present review summarizes the effects of nanoparticles on the dielectric performance of XLPE. At the same time, the current advancements in the development of a new generation of recyclable insulation materials are briefly discussed.

The article considers an electrical device designed for diagnostic work in distribution networks of 6-10 kV, namely, the determination of damage zones in case of failure of insulating materials of cable lines during high-voltage diagnostics with a rectified voltage of negative polarity. The novelty of the developed device is its ability to connect directly to a high-voltage cable line without additional matching devices. The device is capable of detecting damage zones in lines up to 10 km remotely with an error of up to 0.2% of the cable length. The prefix allows you to fix any variants of damage to single-phase and three-phase cable lines with high transient resistance at the site of damage without the operation of “burning” insulation, which significantly reduces the time of repair work at the controlled facility.