Aluminum Conductor Steel Reinforced Research Articles

Aluminum Conductor Steel-Supported Conductors for the Sustainable Growth of Power Line Capacity: A Review and Discussion.

Industrial development and population growth have increased the need for higher-capacity power transmission lines. Aluminum conductor steel-supported (ACSS) conductors, a type of high-temperature low-sag (HTLS) conductor, are now widely used in new designs and reconductoring applications. ACSS conductors are preferred over traditional aluminum conductor steel-reinforced (ACSR) conductors due to their high strength, low sag, and excellent thermal stability. These attributes have garnered significant interest from researchers, engineers, and manufacturers. This paper provides a comprehensive review of the structure, properties, testing methods, and environmental behavior of ACSS conductors.

The Test Study on Tension-torsion Coupling Effect of ACSR in Overhead Transmission Lines

In order to analyze the relationship between the tensile and torsional characteristics of the Aluminum Conductor Steel Reinforced (ACSR), test research on the coupling effect of tension and torsion in conductors was carried out. A conductor tension-torsion coupling test device was designed, and selected the JL/G1A-630/45-45/7 ACSR as sample which is commonly used in ultra-high voltage AC engineering. The relationship between conductor tension, torque, and tensile strain, torsional strain was measured. And obtain the stiffness coefficients of conductor tension, torsion, and tension-torsion coupling. The testing results show that the tension and torque of the conductor gradually change from non-linear to linear under the action of tension or torsion deformation; The torsional stiffness Kφφ and tension-torsion coupling stiffness Kεφ when the conductor is turned to the right are greater than the corresponding stiffness when it is turned to the left.

Experimental Study on Torsional Friction of Stringing Blocks on Conductor in Tension Stringing Construction

An experimental study was conducted to analyze the torsional friction effect of stringing blocks on the conductor during tension stringing construction. By analyzing the torsional friction force of stringing blocks on the conductor, the torsional friction experimental device of the stringing blocks on the conductor was designed. The torsional friction torque of the JL/G1A-630/45-45/7 Aluminum Conductor Steel Reinforced (ACSR) under the different tensions and wrap angles passing through the stringing blocks was measured, and then the friction coefficient was obtained. The experimental results show that the torsional friction coefficient of the stringing blocks to the conductor μ decreases with the increase of the tension of the conductor and the wrap angle passing through the stringing blocks. The relationship between the coefficient of friction and the wrap angle and tension of the conductor passing through the stringing blocks is obtained by fitting, and the formula for calculating the torsional frictional torque is obtained.

Research and application of key technology of energy saving and capacity increasing for overhead conductors with carbon fiber composite core reinforced

Aluminum conductor composite core (ACCC) has many excellent comprehensive properties and is gradually popularized and applied in overhead transmission lines. As an energy-saving and environmentally friendly capacitance-increasing conductor, ACCC gives full play to the advantages of carbon fiber materials. This article analyzes the test results of ACCC and compares them with traditional aluminum conductor steel reinforced (ACSR) in terms of mechanical and electrical properties and proposes the development trend of ACCC.

Performance Assessment of Overhead Conductors Subjected to Combined Thermal and Wind Loads

The overhead power conductors carry electricity power from distribution feeders to consumers, providing a necessary service. Aluminium Conductor Steel Reinforced (ACSR) and All Aluminium Conductors (AAC) are widely utilised in the Australian power distribution network. ACSR offers increased strength and conductivity by combining both steel and aluminium strands while AAC offers proper conductivity and lightweight powerlines. Due to factors like current flow, extremely elevated ambient temperatures, direct sunlight exposure, and short circuit currents, these conductors can be subjected to elevated temperature levels. Operating at higher temperatures can alter the mechanical characteristics of the conductor materials. Consequently, the mechanical strength of conductors diminishes when powerlines consistently operate under these conditions. Conductors are set up in various environmental conditions, resulting in different wind load impacts. While the temperature rise can be somewhat offset by these wind variations in terms of cable strength, wind action still introduces additional tensile stress in the conductor. Hence, this research aims to determine the combined effects of thermal and wind factors in the performance of ACSR and AAC cables. The laboratory experimental testing was performed to determine the decrease in the tensile strength of conductors under steady-state elevated temperature scenarios. The Australian standard prediction for wind and thermal conditions is considered for the calculation of the required strength in the conductors. Finally, the long-term safety performance of both ACSR and AAC cables was evaluated by considering the combined effect of temperature and wind effects.

Case study of the Geomagnetically Induced Currents (GICs) along a hypothetical overhead Aluminum Conductor Steel Reinforced (ACSR) during active geomagnetic storms in Egypt

Case study of the Geomagnetically Induced Currents (GICs) along a hypothetical overhead Aluminum Conductor Steel Reinforced (ACSR) during active geomagnetic storms in Egypt

Review of Technological Advances in High Temperature Overhead Line Composite Conductors

ACSR (Aluminium Conductor Steel Reinforced) conductors consisting of pure aluminum wires helically stranded around a core of high strength galvanized steel core wires are widely used in overhead transmission line applications. While the steel wires provides the required strength, the outer aluminium serves as electricity conducting member. The thermal rating or ampacity of conductors is the maximum current that a circuit can carry within the temperature limits as dictated by the allowable conductor sag or by the annealing onset temperature of the conductor, whichever is lower. On a continuous basis, ACSR may be operated at temperatures up to 100°C without any significant change in the conductor’s physical properties. Above 100°C, aluminum wires loses tensile strength over time and becomes "fully annealed" giving rise to increased thermal expansion of the conductor; this causes excessive sagging reducing the clearance between the ground and the energized conductors.
 While, the electric utilities are posed with increased challenges of production of additional capacities and building new transmission circuits to meet the ever growing demand and the high cost and environmental restrictions of constructing new lines, methods are being explored to increase their capacity with minimum changes in the existing towers. Replacement of the existing conductor with a advanced high temperature composite (HTC) conductors operating upto temperatures of 200°C with reduced sagging characteristics have been attempted and an increase in capacity of 30-80%, can be achieved through application of these composite conductors.
 The advanced HTC conductors with varied combinations of core material and outer conducting wires are being tried so as to achieve wide ranging properties. In general, HTC conductors features the combinations of either soft aluminum wires with ultra high strength steel or temperature resistant aluminium with or fiber reinforced metal/polymer matrix composites as the core. Both the alumina fiber reinforced temperature resistant aluminium metal matrix composite and the carbon fiber reinforced high temperature polymer resin composite wires as the core material appears to have favorable applications. The comparative performance of the HTC depends on the degree to which both outer aluminum strand and reinforcing core’s physical properties are stable at high temperature and on the elastic, plastic, and thermal elongation of the combined HTC.
 The summary of various developments realized in the area of composite conductors and their relative merits and demerits have been discussed in detail.

An experimental study of rime ice accretion on bundled conductors

The dynamic ice accretion process on bundled electrical power conductors and icing-induced effects on the aerodynamic forces acting on the conductors were examined experimentally. An Icing Research Tunnel was used to generate a typical atmospheric rime icing condition experienced by power transmission cables. Two pieces of Aluminum-Conductor-Steel-Reinforced (ACSR) cables were mounted in the icing wind tunnel with different spacing and angular displacements with respect to the incoming airflow. While ice accretion was found to take place primarily on the frontal surfaces of the bundled conductors, the accreted ice layers resembled well the twisted outer strands of the ACSR conductors. Averaged outer profiles of the iced conductors were elliptical with the semi-minor axis being the radius of the conductors and the semi-major axis passing through the foremost frontal points of the accreted ice layers. The icing process on the windward conductor was almost unaffected by the existence of the leeward conductor. The ice accretion and resultant aerodynamic force acting on the leeward conductor were found to vary significantly, depending on the spacing and angular displacements between the bundled conductors. The windward conductor was found to induce a “shadowing effect” by intercepting airborne supercooled water droplets to prevent them from impinging onto the leeward conductor, resulting in much less ice accretion and smaller aerodynamic drag acting on the leeward conductor. The aerodynamic force measurements were correlated with the acquired ice accretion images and wake flow field around the bundled conductors to elucidate the underlying physics.

Ice monitoring of aluminum conductor steel-reinforced cables using guided waves

Aluminum conductor steel-reinforced (ACSR) cables are commonly used as power transmission conductors. In cold regions, icing of ACSR cables is a common problem. Ice accretion on ACSR cables may cause various problems. Timely ice monitoring is a primary measure for any type of de-icing solution. In this study, a guided wave-based method was proposed to monitor the ice-forming processes on ACSR cables owing to its advantages of high sensitivity and long-range inspection. The dispersion curves were first obtained using the semi-analytical finite element (SAFE) method for the ACSR cross-section geometry, particularly for different ice thicknesses. They could be used to accurately determine the group velocity for each guided wave mode. Subsequently, a series of tests were conducted with different ice thicknesses in the laboratory. Guided waves were excited by an electromagnetic acoustic transducer (EMAT) in ACSR cables. A new method that combined principal component analysis (PCA) and empirical mode decomposition (EMD) was employed to process the original guided wave signals to obtain effective icing indicator. The results obtained by the guided wave-based method were verified using an image-based method. This study indicates that the proposed ultrasonic guided wave combined with the PCA–EMD method is efficient and sensitive for the ice monitoring of ACSR cables.

ALLOYING ELEMENTS EFFECTS ON ELECTRICAL CONDUCTIVITY AND MECHANICAL PROPERTIES OF NEWLY FABRICATED AL BASED ALLOYS PRODUCED BY CONVENTIONAL CASTING PROCESS

The present investigation deals with a comprehensive study on the production of aluminum based alloys with the incorporation of different alloying elements and their effect on its electrical conductivity and mechanical properties. Casting of pure aluminum with different concentration and combinations of alloying additives such as cupper (Cu), magnesium (Mg) and silver (Ag) were carried out using a graphite crucible. The as-cast microstructure was modified by hot rolling followed by different heat-treated conditions viz., annealing, normalizing, quenching, and age hardening. The mechanical properties and electrical conductivity of the produced heat-treated alloys sheets under various processing conditions were carried out using tensile testing, hardness, and electrical resistivity measurements. It was found that by increasing the alloying elements content, yield strength results increased significantly by more than 250% and 500% for the as rolled and 8 h aged Al-Cu-Mg alloy, respectively. On the other hand, the electrical conductivity reduces slightly with −14.6% and −16.57% for the as rolled and 8 h aged of the same Al-Cu-Mg alloy, respectively. From the last four decades, due to the increase in demand from the electricity transmission lines, copper is being replaced by Al because of its light weight and relatively low cost. In addition, among the engineering conductor materials, aluminum has a very good electrical conductivity due to lower specific gravity (almost in the second rank after copper). The replacing of copper by aluminum for electricity transmission by overhead ACSR (aluminum conductor steel-reinforced) conductors, power cables, etc. has increased all over the world. Moreover, substitution of copper by aluminum also takes place in countries which have enough resources from copper, since it shows a good economical advantage as serious competitor against copper. Practically, by adding alloying elements to pure aluminum, aluminum’s strength can be significantly improved. However, on the other hand a great reduction in the electrical conductivity takes place due to the solute atoms and impurities generated by substitution of alloying elements. Another process affecting the electrical conductivity of aluminum is the heat treatment process, since elements in the solid solution phase represent a higher resistance than non-dissolved elements. That is why it is a great challenge to play with the strength of the pure aluminum in such a way that the decrease in its electrical conductivity will be still acceptable and valid for the selected application.

Economic analysis of aluminium conductor composite core and conventional aluminium conductor steel reinforced conductors in overhead ultra‐high voltage transmission lines

AbstractThe application potential of aluminium conductor composite core (ACCC) conductors in the 1000‐kV power transmission line project deserves to be investigated. Its economic evaluation is a contentious issue. This paper proposes a method for selecting the type of conductors based on the life cycle cost (LCC) of a transmission line, which includes the initial investments, operation costs, maintenance costs, failure costs, and discard costs. The mathematical model of electromagnetic loss differs due to the various operational circumstances surrounding a transmission line; therefore, a novel three‐dimensional electromagnetic–fluid–thermal coupling model based on the finite element method (FEM) was proposed. The simulation error of ACCC and aluminium conductor steel reinforced (ACSR) conductors is 2.56% and 0.5%, respectively, compared to the experimental value. Subsequently, the LCC model is applied in the economic analysis of a 1000‐kV transmission line, and the costs of ACCC conductors and ACSR conductors under different annual power load utilization hours are calculated. The results indicate that the overhead power transmission line with ACCC conductors saves at least 2 × 106 ¥/km compared with ACSR when annual utilization hours reach 3500 h; meanwhile, energy saving benefits are achieved.

An experimental study of dynamic icing process on an Aluminum-Conductor-Steel-Reinforced power cable with twisted outer strands

An experimental campaign was conducted to investigate the dynamic icing process on an Aluminum-Conductor-Steel-Reinforced (ACSR) power cable with twisted outer strands and characterize the resultant wind loads experienced by the power cable under both dry rime and wet glaze icing conditions. In addition to recording the dynamic icing process over the cable surface with a high-resolution imaging system, the three-dimensional (3D) shapes of the ice layers accreted on the cable model were also quantified by using a novel 3D profile scanning system. While the evolution of the wake flow behind the iced ACSR cable was quantified with a Particle Image Velocimetry (PIV) system, the variation of the wind loads experienced by the cable model was also examined based on the measurements of force/moment transducers. Under the dry rime icing condition, opaque, grainy ice was found to accrete only within the impinging zone of airborne water droplets over the cable frontal surface without any noticeable water runback flow over the cable surface. In comparison, substantial unfrozen water was observed to run back over the cable surface under the wet glaze icing condition, causing the formation of transparent, glazy ice layer over a much wider area over the cable surface. Correlating with the formation of more complicated glazy ice humps/horns over the ACSR cable surface, the accumulated ice mass was found to grow much faster during glaze icing process, in comparison to that of rime icing case. While the resultant wind loads acting on the iced ACSR cable was found to decrease gradually with the increasing icing time under the rime icing condition, the corresponding values were found to increase continuously under the glaze icing condition.

Degradation of Steel Wires in Bimetallic Aluminum–Steel Conductors Exposed to Severe Corrosion Conditions

High-voltage electrical cables are prone to saline corrosion, mostly in coastal environments. Steel wires are a crucial element in withstanding the mechanical solicitations of commonly used aluminum conductor steel reinforced (ACSR) cables. An experimental accelerated corrosion test was made, using salt spray tests on greased and ungreased ACSR cables and individual galvanized steel wires. The corrosion mechanism occurring on the specimens was observed by optical microscopy for several durations of corrosion, to determine the evolution of the galvanic layer and steel substrate degradation. This study was completed by an SEM (Scanning Electron Microscopy) and Raman spectroscopy analysis to characterize the corrosion products occurring on the galvanized steel wires. An estimation of the evolution of the mean zinc thickness loss is also given, for each type of specimen. It is shown that the loss rate of the zinc layer is significantly reduced by the presence of aluminum layers around the steel wires and by the effect of the grease. Tensile tests were made on the exposed galvanized steel wires which led to fracture surface observations to assess the effect of corrosion on the evolution of mechanical properties.

A New Detection Method Based on Magnetic Leakage Theory and BP Neural Network for Broken Steel Strands in ACSR Conductor

Aluminum conductor steel-reinforced (ACSR) conductor is characterized by inner tensile body of steel core and outer twisted aluminum wire strands, which is obviously different from common steel wire ropes (SWRs) or cables. However, the existing studies are mainly focused on the magnetic flux leakage (MFL) testing of the SWR defects, few or not related to broken steel strands in ACSR conductors. Thus, the leakage magnetic field distributions of SWR and ACSR defects are compared and analyzed by the theoretical and numerical calculations. By considering the nonconductivity characteristics of aluminum wire strands, the steel-air model is established to calculate the effects of fracture width and the number of broken steel strands on the MFL signal for ACSR conductors. Based on the spatial distribution characteristics of ACSR leakage field with low intensity, weak lifting-off effect, and weak circumferential correlation, a single-channel signal processing method with time–frequency domain coupling is proposed. Multiple sets of characteristic values of MFL signal both in time and time–frequency domains are extracted to construct a back propagation (BP) neural network for broken steel strand identification. The results have shown that the improved single-channel time–frequency analysis method has higher accuracy in identifying the ACSR fracture width and the number of broken steel strands compared to the image processing method with multichannel leakage data fusion. With the improved method, the detection error of the fracture width is less than 2 mm, and the accuracy of the number of broken strands can reach 91.67%.

Technical Research on New Transmission Conductor in Medium Ice Area

In this paper, aluminum conductor steel reinforced(ACSR), high conductivity aluminum conductor steel reinforced, heat-resisting aluminum alloy conductor steel reinforced, and all aluminum alloy conductor are compared and analyzed in detail from the electrical characteristics, mechanical characteristics, and annual cost. Finally, combined with factors such as production process and construction technology, the transmission line conductor that is most suitable for a 15mm medium ice area is recommended. It provides a reference for the selection of transmission lines in future design.

Comparison of Structural, Microstructural, Elastic, and Microplastic Properties of the AAAC (A50) and ACSR (AC50/8) Cables after Various Operation Periods in Power Transmission Lines

In modern economic infrastructure, Al cables of overhead power transmission lines are used both without and with a steel core (respectively, all aluminum alloy conductor (AAAC) and aluminum conductor steel reinforced (ACSR) cables). In this article, the changes in structural, microstructural, and elastic-microplastic properties have been analyzed for the outer wires of the AAAC (A50) and ACSR cables (AC50/8 cables with a steel core of ~8 mm2 cross-section, hereinafter referred to as AC50) with the cross-section of the stranded conductor of ~50 mm2, which were in operation for 0–20 years in the Volgograd region of Russia. Using the techniques of X-ray diffraction, electron backscattered diffraction, densitometry, and the acoustic method, the structural and microstructural features of the wires have been compared and found to be correlated with their elastic-microplastic properties. It has been ascertained that the presence of a steel core in AC50 leads to a decrease in the defectiveness of the near-surface layer of their aluminum wires. Compared with A50 cables, the development of void defects in the near-surface layer of Al-wires of AC50 cables slows down (by ~1 year with a service life of ~10 years and by ~3 years with a service life of ~20 years).

On-Line Core Losses Determination in ACSR Conductors for DLR Applications.

Dynamic line rating (DLR) is a method that focuses on dynamically determining the maximum allowable current of power lines, while ensuring they operate within safe limits. DLR needs to monitor the temperature and current of the line in real-time, as well as the weather variables in the surroundings of the power line. DLR approaches also require determining the AC resistance of the power line conductors, which is a key parameter that enables it to determine Joule and core losses. This paper presents an approach for an on-line alternating current (AC) resistance estimation of aluminum conductor steel-reinforced (ACSR) conductors to determine the DLR capability of such conductors from real-time conductor and meteorological parameter measurements. For this purpose, conductors with one, two and three layers of aluminum strands are analyzed in detail. Based on the experimental results presented in this paper, two possible approaches are proposed.

Analysis of ACCC failure of composite core glass transition temperature reduction due to brittle damage

The failure analysis of the Aluminum Conductor Steel Reinforced (ACSR) was often based on conventional failure methods such as strength and fracture, and the failure analysis of the Aluminum Conductor Composite Core (ACCC) usually followed the analysis methods of the ACSR. This research proposed a new ACCC failure mode based on the glass transition temperature (Tg) of composite materials. In this paper, a fracture accident of a 500 kV overhead transmission line was discussed. Firstly, impact test found that composite core of the ACCC was more brittle than steel core of the ACSR, and the brittle damage of the composite core was inferred as the cause of the accident in combination with fracture analysis. Then, thermal-structural coupling analysis showed that the axial stress of aluminum wires increased to 33 MPa after the brittle damage of the composite core. Subsequently, thermoelectric coupling analysis showed that the operating temperature (T) of conductor was raised to 151 °C after the increment of the axial stress of the aluminum wires. Finally, in dynamic mechanical analysis, it was shown that the Tg of faulty composite core was reduced to 146.3 °C. According to investigation, the T of conductor was greater than the Tg of epoxy resin in the faulty composite core, resulting in a decrease in the tensile strength of the composite core, which eventually led to the ACCC failure. The failure mechanism proposed in this paper can provide a reference for the prevention and maintenance of ACCC lines in power grid system.

Advanced Composite Materials: A Panacea for Improved Electricity Transmission

The demand for electricity has increased drastically due to population explosion globally. Unfortunately, supply does not meet the demand. Consequently, the transmission grid becomes overloaded, culminating in frequent power outages. Worse still, the transmission grid lacks adequate maintenance, and this has led to energy crisis in Africa and some parts of Asia. In this review, studies on the strength and weaknesses of existing transmission conductors were conducted. Further studied were natural and artificial phenomena that attack the overhead transmission networks. It was observed that besides inherent conductor defects, overloading, bush fire, short-circuit, harsh weather, and lightning were the factors that ravage the transmission grid. Hence, there is the need to develop more robust conductor materials that can withstand these challenges. The conventional conductors such as all aluminum conductor (AAC) and aluminum conductor steel reinforced (ACSR) are challenged by low operating temperatures, among others. High-temperature low-sag (HTLS) conductors that were invented to tackle these shortcomings certainly have higher ampacity and better thermal rating than the conventional conductors. However, some challenges still devastate them. So, from the study conducted, it was discovered that developing advanced nano-based Al-composite conductor would help in ameliorating the challenges prevalent in the transmission grid. Such an Al-nanocomposite conductor would possess higher ampacity and better thermal stability and would be more durable and cost effective.

Detecting Broken Strands in Transmission Lines Based on Pulsed Eddy Current

High-voltage transmission lines are the main facilities for power transmission, and they are mainly composed of aluminum conductor steel-reinforced (ACSR). Over long-term outdoor use, overhead transmission lines will encounter lightning strikes, chemical pollutant corrosion, deicing, wind vibration, and other external forces. This often results in a series of potential failures, such as breakage, for the strands. In order to ensure the safe operation of the power grid and avoid fatal accidents, such as line breaks, it is necessary to identify and repair line faults. Among them, the main basis for the regular detection and replacement of high-voltage transmission lines is whether a broken strand defect appears. In this paper, a type of pulsed eddy current (PEC) sensor is developed to detect the broken strand defect in transmission lines. The simulation and experimental results showed that the designed PEC sensor could effectively and accurately identify the fault.