Method for assessing the state and residual life of the insulation based on analysis of the time of discharge of the capacity of electric cables

As of today, the problem of the lack of non-destructive methods for assessing the state and determining the residual life of the insulation of electrical cables is relevant for cable lines in operation, and especially for lines that have exhausted their service life. The research presented in the framework of this article is aimed at creating a non-destructive technique for assessing the state and residual life of electrical cables insulation. The study was carried out using computer simulation methods and using the basic theoretical laws of physics and electrical engineering. A method for assessing the condition and residual life of electrical cable insulation has been developed, which is based on the analysis of the discharge time of the cable capacity. The applicability of the method is determined, instructions are given on its applicability and the analysis of the output data. The obtained results can be used by power grid companies and industrial enterprises to analyze the state of the insulation of electrical cables.

Analysis of XLPE cable parameters subject to thermo aging

Modern marine vessels use electrically driven rudders; cruise liners, gas carriers, tankers are equipped with Azipod systems manufactured by the Swedish-Swiss company ABB. Gondola-type propellers make it possible to break ice when the vessel is moving astern, therefore such vessels are used for work on the Northern Sea Route, in particular, when working on the Yamal LNG project. The 22MW Azipod propulsion system rotates 360° and enables difficult maneuvering without the assistance of tugs. When operating such propellers, powerful diesel generators are installed on the ship. For the transmission of electricity, ship cables are used, which are subject to increased requirements that meet the standard of the International Electrotechnical Commission. Modern marine vessels are equipped with XLPE or EPDM insulated cable lines; industrial production of these cables is carried out in the Russian Federation. In the course of the study, a method for auditing the state of insulation has been considered based on an assessment of the change in the tangent of the angle of dielectric losses in the process of thermal aging of the cable of the PvBPng(A)-HF brand. Measurements of the tangent of the dielectric losses' angle have been carried out with a Tangens-2000 insulation parameter meter.

CAD FOR SOLVING EDUCATIONAL RESEARCH PROBLEMS WHEN DESIGNING MODERN HIGH AND EXTRA HIGH VOLTAGE CABLE LINES

The development of teaching and research version of the computer aided design of cable lines of high and extra-high voltage is at the final stage. For TR CAD CL, software has been developed that allows solving design and research problems for a power cable for a voltage of 35-500 kV with XLPE insulation. The development of the documentary subsystem TR CAD CL, which fully meets the regulatory requirements, has been completed.

Romanenko N. G. Increasing efficiency of ship cables defectation

The ship power supply system is a complex system that supplies electrical energy to various mechanisms and devices using wires and cables. The reliability of power supply largely depends on the technical condition of the cable lines. During operation, cable lines are regularly exposed to mechanical stress, both from external factors and from people. Some of the most common causes of cable damage are: aging insulation, overvoltage, thermal stress, boat vibration, and corrosion and moisture. Leaving the operating state of the cable line can lead to emergencies. A cable with damaged insulation can cause an electric arc with a metal object. If several phases of a cable with damaged insulation, then when they touch, a phase-to-phase short circuit occurs, as a result of which a large amount of heat is released, from which the cable insulation and other nearby combustible materials can ignite. There is considered the principle of operation of DIPCEL (a device for diagnosing ship cables) and shown its main disadvantages in determining the aging and moisture indicators of cable insulation. It is proposed to use the absorption coefficient for increasing the efficiency of measuring the ship’s cable insulation moisture. For insulating materials, in which the absorption current decreases rapidly, resistance measurements should be taken after 15 sec and 60 sec. The absorption coefficient is defined by measuring the ratio of a sixty-second insulation resistance to a fifteen-second resistance. If the value of the obtained coefficient is less than 1.25, then the insulation is unsatisfactory; if the value is within 1.25 - 1.6, than the insulation is normal, if more than 1.6 - the insulation is excellent

Simulation study of 6–10 kV cable lines for transient processes calculation during earth faults

As a rule, researchers do not consider the dependence of the inductance of cable lines on frequency in their scientific papers devoted to the calculation of transient processes during single phase-to-ground fault in 6–10 cable networks. In some cases, it can lead to significant errors in evaluation of current and voltage transient components parameters. Therefore, it is an urgent task to estimate defined errors and the scope of application of frequency-independent equivalent circuits and models of 6–10 kV cable lines during calculation and simulation of transient processes in case of single phase-to-ground fault. The authors applied PSCAD / EMTDC software to study the effect of the frequency dependence of the inductances of 6–10 kV cable lines on the calculation accuracy of transient processes during single phase-to-ground fault. It allows to simulate electric power systems models with the usage of both frequency-dependent and frequency-independent cable line models with round conductors only. To check the adequacy of the frequency-dependent three phase cable model developed in PSCAD software, the authors have used a frequency-dependent model of 6–10 kV three-phase cable with sector-shaped conductors designed in COMSOL Multiphysics software. The authors have developed an approach to develop of 610 kV cable lines models with frequency-dependent and frequency-independent parameters. The authors have obtained error estimation in transient current and voltage parameters during single phase-to-ground fault in cable networks models that do not consider the frequency dependence on inductance (for discharge components the error is 1520 %, for charging components the error is equal to 510 %). It is shown that models with cable line parameters defined according to spreading speed of electromagnetic wave, can be used for approximate calculation of transient current and voltage to solve most of tasks of investigation of transient processes during single phase-to-ground faults. Application of the developed recommendations to determine three phase medium voltage cable lines parameters will increase the calculation accuracy of transient processes during single phase-to-ground faults in 6–10 kV cable networks. Only application of frequency-dependent models of cable lines allows us to provide required accuracy to develop methods of distant earth fault localization in 6–10 kV networks.

Energy efficiency of a hybrid cable yarding system: A case study in the North-Eastern Italian Alps under real working conditions

In order to reduce greenhouse gas emissions, low emission or zero-emission technologies have been applied to light and heavyduty vehicles by adopting electric propulsion systems and battery energy storage. Hybrid cable yarders and electrical slack-pulling carriages could represent an opportunity to increase the energy efficiency of forestry operations leading to lower impact timber harvesting and economic savings thanks to reduced fuel consumption. However, given the limited experience with hybrid-electric systems applied to cable yarding operations, these assumptions remain uncertain. This study assessed an uphill cable yarding operation using a hybrid cable yarder and an active slack-pulling electric power carriage over thirty working days. A total of 915 work cycles on four different cable lines were analysed. Longterm monitoring using Can-BUS data and direct field observations were used to evaluate the total energy efficiency, total energy efficiency (%), and fuel consumption per unit of timber extracted (L/m3). The use of the electric-hybrid system with a 700 V supercapacitor to store the recovered energy made it possible to reduce the running time of the engine by about 38% of the total working time. However, only 35% to 41% of the Diesel-based mechanical energy was consumed by the mainline and haulback winches. Indeed, the remaining energy was consumed by the other winches of the cable line system (skyline, strawline winches and carriage recharging or breaking during outhaul) or dissipated by the system (e.g., by the haulback blocks). With reference to all work cycles, the highest net energy consumption occurred during the inhaulunload work element with a maximum of 1.15 kWh, consuming 70% of total net energy consumption to complete a work cycle. In contrast, lower energy consumption was recorded for lateral skid and outhaul, recording a maximum of 23% and 32% of the total net energy consumption, respectively. The estimated recovered energy, on average between the four cable lines, was 2.56 kWh. Therefore, the reduced fuel need was assessed to be approximately 730 L of fuel in the 212.5 PMH15 of observation, for a total emissions reduction of 1907 kg CO2 eq, 2.08 kg CO2 eq for each work cycle.

Interval Waktu Pemeliharaan Berdasarkan Reliability Centered Maintanance (RCM) Pada Kinerja Saluran Udara Tegangan Menengah (SUTM) Perusahaan Listrik Negara

The State Electricity Company (PLN) serves all Indonesian people from Sabang to Merauke with overhead lines and cable lines. The frequency of blackouts in an area due to disturbances in the channel. PLN seeks to suppress disturbances by carrying out maintenance, namely turning it off or without being extinguished. Medium Voltage Air Lines (SUTM) are more frequent disturbances. The worst damage happened to the conductors, Jumpers, and insulators. Damage will often occur if it is not predictable. In order to find out when damage occurs, a method based on Predictive Maintenance is used, namely maintenance based on historical disturbance data statistics. Predictive Maintenance can be realized by using Reliability Centered Maintenance (RCM). From the results of RCM calculations and statistical data on one PLN unit, there is a new value for predictive maintenance time intervals, for conductors maintenance schedule must be carried out every 2 days, Jumpers every 12 days, and isolators every 16 days before serious damage occurs and widespread blackout Perusahaan Listrik Negara (PLN) melayani seluruh masyarakat Indonesia dari Sabang sampai Merauke dengan saluran udara dan saluran kabel. Frekuensi terjadi pemadaman pada suatu wilayah karena adanya gangguan pada saluran tersebut. PLN berupaya untuk menekan gangguan dengan melakukan pemeliharaan, yaitu dipadamkan atau tanpa dipadamkan. Saluran Udara Tegangan Menengah (SUTM) lebih sering terjadi gangguan. Kerusakan terparah ternyata terjadi pada konduktor, Jumper dan isolator. Kerusakan akan sering terjadi apabila tidak mampu diprediksi. Untuk dapat mengetahui kapan akan terjadi kerusakan digunakan metode berbasis Predictive Maintanance, yaitu pemeliharaan berdasarkan statistik data historis gangguan. Predictive Maintenance dapat terwujud dengan menggunakan Relliability Centered Maintanance (RCM). Dari hasil perhitungan RCM dan data statsik pada salah satu unit PLN, maka terdapat nilai baru intuk interval waktu pemeliharaan secara predictive, untuk konduktor harus dilakukan penjadwalan pemeliharaan setiap 2 hari, Jumper setiap 12 hari, dan Isolator setiap 16 hari sebelum terjadi kerusakan yang parah dan pemadaman meluas.

Evaluation of the Influence of Lightning Overvoltage Propagation on Wind Turbine and “Mix” Overhead-Cable Lines

Due to the growing demand for new and renewable energies and a favorable geographical position, Vietnam is constructing many wind farms. Besides the advantages of being environmentally friendly and the primary endless source of materials, wind farms have disadvantages, for example, high-structured wind towers are usually built in high, empty places and the resistivity of large soil is vulnerable to lightning damage. In this research, we investigate the effects of overvoltage due to lightning strikes on the wings of wind turbines and propagation causing overvoltage on the insulation of cable in the control cable and mixed-lines. The paper also considers the overvoltage protection measures propagated into the insulation equipment and cable insulation using EMTP-RV simulation software