Overhead Lines Research Articles

Detection of overhead line glass insulator condition using dual function device and deep learning approach

This paper presents a design of a multifunction smart wireless device for online condition monitoring of transmission line insulators. The proposed device can measure the insulator leakage current and take images of the high-voltage insulation. Yolov5-based models and deep convolutional neural networks (DCCN) are developed to analyze and classify the measured data and estimate the insulator's health condition. We have developed and tested a prototype of the proposed device. The device can issue a real-time warning message when a sudden change takes place in the leakage current value. The control center or smartphones receive the collected data wirelessly. We analyze the transmitted data using the developed methods to detect any anomalies and take appropriate remedial action. The performance and feasibility of the developed device are assessed through extensive experimental analysis. Results attest to the robustness of the proposed device, which is easy to install for existing and future overhead transmission line insulators.

Influence of Cable and Overhead Lines Parameters on the of Transient Recovery Voltages of High-voltage Circuit Breakers

Influence of Cable and Overhead Lines Parameters on the of Transient Recovery Voltages of High-voltage Circuit Breakers

An investigation on NGR failure in Indian smart cities while replacing the existing overhead lines by underground cables

Abstract Nowadays, Indian power distribution companies (PDCs) are implementing smart distribution networks. Older cities are becoming smarter as per the recent government’s policy. Existing overhead distribution lines are being replaced by underground cables as an essential criterion of a smart city. One of the main problems arising in this process is the overheating of the neutral grounding resistor (NGR) in 11 kV distribution systems, even in normal conditions. NGRs, placed inside the substations, are overloading the air conditioning and exhaust systems of the substation. Sometimes failure of the NGR occurs due to overheating. In this paper, a comprehensive investigation has been carried out to reach the roots of this problem. It is observed that long underground cables have a higher ground capacitance than overhead distribution lines. Due to the higher cable capacitance, the third harmonic current circulates through neutral, which overheats the NGR even in normal conditions. The situation becomes worse when the substation runs on diesel generators (DGs) in an isolated state under main grid failure, as a higher amount of third-harmonic current circulates depending on the type of winding and pitch factor of the DGs. Different solutions are proposed, and their advantages and disadvantages are analyzed. Finally, the rating of the NGR is modified, and louvers-cooling fan arrangement is preferred for the running substation.

Nonlinear Analysis and Closed-Form Solution for Overhead Line Magnetic Energy Harvester Behavior

Recently, much attention has been given to the development of various energy harvesting technologies to power remote electronic sensors, data loggers, and communicators that can be installed on smart grid systems. Magnetic energy harvesting is, perhaps, the most straightforward way to capture a significant amount of power from a current-carrying overhead line. Since the harvester is expected to have a small size, the high currents of the distribution system easily saturate its magnetic core. As a result, the operation of the magnetic harvester is highly nonlinear and makes precise analytical modeling difficult. The operation of an overhead line magnetic energy harvester (OLMEH) generating significant DC power output into a constant voltage load was investigated in this paper. The analysis method was based on the Froelich equation to analytically model the nonlinearity of the core’s BH characteristic. The main findings of this piecewise nonlinear analysis include a closed-form solution that accounts for both the core and rectifiers’ nonlinearities and provides an accurate prediction of OLMEH transfer window length, output current, and harvested power. Continuous and discontinuous operational modes are identified and the mode transition boundary is obtained quantitatively. The theoretical investigation was concluded by comparison with a computer simulation and also verified by the experimental results of a laboratory prototype harvester. A good agreement was found.

Failure evaluation of outdoor polymeric insulators based on statistical condition-assessment methods

Field aging of outdoor polymeric insulators results in unscheduled outages in power systems particularly in harsh climate conditions. In this paper, a strategic maintenance framework is proposed in order to prevent overhead line outages. The presented scheme is based on condition assessment of the real aged polymeric insulators. Data of tensile test, hardness test, thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR) are used to extract critical features of the aged samples based on classification of fuzzy c-means clustering. Then, a lifetime prediction analysis is done based on Cox hazards analysis to develop further maintenance strategy. The proposed model is validated through numerical analyses on polymeric insulators for various validation evaluations including pollution severity analysis and hydrophobicity class (HC) measurement. Obtained results verify accuracy of the intelligent model to predict lifetime of the aged polymeric insulators. The presented strategic framework can be effectively applied to online monitoring, condition assessment and preventive maintenance programs of the power system utilities.

A neural network model for predicting the temperature of insulated overhead lines

In this work, we develop a neural network model based on experimental heating and cooling curves of insulated wires of overhead lines under changes in wind speed and its direction relative to the wire axis. Insulated SIP-3 wire used in overhead lines was investigated. A multilayer perceptron neural network was employed to model the process of heating and cooling of insulated wire under changes in wind speed and its direction. The average absolute error was taken as a criterion for evaluating the prediction accuracy of wire core and insulation temperatures. The main parameters of the developed neural network model include the number of hidden layers and neurons in each hidden layer, the degree of regulation, and the regulatory rigidity of the model. The modelled heating and cooling curves of insulated wire were compared with those obtained experimentally. The average absolute error was equal to 1.74 and –4.08°C for the predicted core and insulation temperatures, respectively. The difference between the heating curves at low wind speeds was found to range within 9°C. It was shown that an increase in wind speed leads to a decrease in the difference between the curves. Our analysis showed that neural network models used for predicting variations in the temperature of insulated overhead lines should be trained using a larger number of input parameters. This is the main prerequisite for high prediction accuracy of such models, when the difference between the simulated and experimental data does not exceed 5%.

Methodology for selecting optimal wire grade and cross-section based on an integrated technical and economic criterion

The aim was to develop a methodology for selecting an optimal wire grade and cross-section for overhead power lines with a voltage of above 1 kV under intensive development of power grid systems. This aim was solved using the authors’ previously developed methods: selection of an optimal wire grade based on hierarchy analysis and selection of an optimal wire cross-section by optimizing the specific discounted costs during the entire period of construction and operation of overhead power lines. In the present study, these methods are integrated into a single methodology. It is proposed to implement wire inspections prior to the stage of technical and economic calculations, since the necessary data has already been taken into account during the selection of a wire grade and its cross-section. The proposed methodology was tested on a typical example of reconstruction of the Zapadnaya– Davydovka 110 kV overhead line, which creates limitations in the power supply of Primorsky Krai due to insufficient wire capacity and its operation beyond the normative period. SENILEK AT3/C 150/24 wire was selected as a solution for the example under consideration. The application of this wire grade allows not only the overhead line capacity to be increased by 151% without replacing the existing supports, but also active and reactive power losses in the electric network to be reduced by 18.9 and 2.5%, respectively. The proposed methodology enables selection of an optimal grade and cross-section of any wire design, taking the dynamically changing operational conditions of power grid systems into account. The solutions found by the proposed methodology may contribute to a more efficient operation of power lines due to increasing their transmission capacity, reducing the number of used supports, replacing the line wire without replacing supports, decreasing ice formation on wires, and reducing power losses.

Impact of atmospheric conditions on the flash-over voltage of the transmission line insulators using central composite design

The insulators of overhead power lines play a crucial role in maintaining the reliability of transmission and distribution networks. Because they are exposed to harsh and dynamic environmental conditions, it is essential to investigate the impact of environmental parameters such as pollution, inclined angle with the cross arm, and temperature on the dielectric performance of the insulators of overhead lines. Conventionally, the effect of such parameters can be investigated through experimental measurements of the insulator flashover voltage. However, this approach is costly and time-consuming and calls for the isolation of the lines to conduct the test, causing interruption to the entire grid. As such, there is an essential need to develop a new methodology to quantify the flashover voltage of overhead insulators operating under various environmental conditions, which is the main aim of this paper. The Central Composite Design is employed to develop a mathematical correlation between the insulator flash over voltage as a dependent variable and three environmental parameters: pollution level, inclined angle, and temperature as independent variables. The robustness of the developed equation is validated through extensive experimental measurements of the insulator’s flash overvoltage under various conditions. Results reveal a good agreement between the actual and predicted flashover voltage using the developed correlation, as the absolute error for all investigated samples is less than 6%.

Overvoltage phenomenon initiated by breakdown during on-site withstand voltage tests of GIL and GIS: Mechanisms and consequences

An overvoltage was observed in the withstand voltage tests of GIL and GIS projects in China in recent years. The overvoltage may result in insulation damage and secondary breakdown where there is no defect. The analysis shows that the reason for the overvoltage is the wave impedance discontinuity between the pipeline and the overhead line. It results in the superposition of the reflected and refracted waves, and thus the overvoltage is generated. In fact, in addition to the structural change, the branches in the structure can also form wave impedance discontinuities. For example, unlike GIL, there are many branches in GIS that can also cause the overvoltage. The overvoltage is actually a universal phenomenon. The analyses based on an actual GIS structure show that in on-site withstand voltage tests, the overvoltage may exceed the peak value of the rated lighting impulse voltage, and even the insulation limits of GIS. These analyses are verified by simulation and experiment results. This universal phenomenon seriously endangers the safety of GIL and GIS during the withstand voltage test, because of the possible secondary breakdowns. The GIS will even become more vulnerable. Therefore, the on-site test structures or voltages should be revisited.© 2017 Elsevier Inc. All rights reserved.

Flexible DC transmission line fault type identification scheme based on Pearson correlation coefficient

Abstract Faults occurring on the DC side of the line are very harmful to the MMC-MTDC system, and with the popularization of flexible DC transmission technology based on overhead lines, how to discriminate the type of fault is the difficulty of MTDC DC line protection. This paper gives a fault kind identification approach based totally on the Pearson correlation coefficient, which discriminates the fault kind with the aid of calculating the Pearson correlation coefficient of the line voltage at each pole after the fault.

Plug-in charging or electric roads? Powering U.S. long-haul heavy-duty trucks in 2050

Abstract Pervasive plug-in fast chargers and/or electrified roadways (eRoads) might address the limited range, long recharging times, and reliance on greenhouse gas (GHG)-intensive, costly, and heavy batteries associated with electrifying long-haul heavy-duty trucks (HDTs). While these large-scale interventions shift environmental and cost burdens onto infrastructure, there is a lack of studies investigating how eRoads affect system-level GHG emissions, costs, material use, and peak electric grid power demands. We compare these aspects for the case of electrifying U.S long-haul HDTs (Class 8) in 2050 powered by combinations of plug-in fast chargers and eRoads. Our model accounts for battery downsizing, energy consumption, and truck operation patterns in quantifying life cycle impacts of batteries, plug-in chargers, eRoads, and hourly truck electricity demand. We find that plug-in fast chargers and eRoads reduce annualized 2050 HDT life cycle GHG emissions by 8% to 14% compared to using long-range batteries, which in turn have at least 50% lower emissions than diesel trucks. Conductive rails, overhead lines, and wireless eRoads (amortized across light- and heavy-duty vehicles) have lower system-wide costs than long-range batteries, plug-in fast chargers, or diesel trucks. Cost savings from smaller batteries, lower energy use and avoided recharging time offset high eRoads capital costs. While eRoads can reduce both system-level GHG and costs compared to diesel trucks, these reductions are sensitive to eRoads capital costs and losses from wireless power transfer and air resistance. eRoads require less lithium (87%) and copper (67%) than long-range batteries but increase regional peak power demands by up to 32%. Efficient wireless power transfer and aerodynamic pantographs enhance eRoads’ GHG and cost advantages, which may diminish if future batteries are more energy-dense, cheaper, or less GHG intensive. If successfully deployed, eRoads present opportunities for tighter integration between the transportation and electricity infrastructure systems, enabling optimized charging strategies to lower GHG emissions and costs.

LAND PROCUREMENT IN ORDER TO SUPPORT THE DEVELOPMENT REVIEWED FROM THE ASPECTS OF LEGAL CERTAINTY

Article 5 of the Basic Agrarian Law of Indonesia establishes that the earth, water, space, and their natural resources are under the control of the state, with the aim of achieving public prosperity in a just society. In developing the electricity system, as per Law No. 30 of 2009 on Electricity, land use necessitates compensation for land rights holders in accordance with Law No. 2 of 2012 on Land Acquisition for Public Interest and related regulations. Regulation of the Minister of Energy and Mineral Resources No. 13 of 2023 addresses spatial planning, minimum distance for electric transmission networks, and compensation for land and buildings under these networks. However, land beneath the Extra High Voltage Overhead Line (SUTET) only receives compensation for land value, not for the use of the space beneath the line, leading to reduced land productivity and economic value. This research employs normative juridical research with statutory and case approaches, analyzing primary legal materials such as relevant laws and regulations. It utilizes legal theories including legal certainty, justice, and state welfare. The research finds that the current practice of not compensating land under SUTET, but only compensating for land value, results in economic disadvantage and lacks fairness. To promote legal certainty and justice, it is recommended that compensation provisions be explicitly regulated by law to address these issues comprehensively.

МАТЕМАТИЧНІ МОДЕЛІ МОНІТОРИНГУ ВІДКЛАДЕНЬ ОЖЕЛЕДІ ТА ЗМІНИ СТРІЛИ ПРОВИСАННЯ ПРОВОДІВ ПОВІТРЯНИХ ЛІНІЙ ЕЛЕКТРОПЕРЕДАВАННЯ

The paper presents the results of studing the problem of monitoring the condition of an overhead power line wire. The known approaches to the formation of a device for monitoring the sagging boom and ice-coating on the line wires are analysed. It is shown that one of the most promising approaches is based on measuring the angle of inclination of the wire sagging curve near the point of its fixation on the support. It is shown that an unambiguous correlation between the slope angle of the sagging curve and the wire sagging arrow allows for an indirect measurement of the operating temperature of the wire in the absence of ice deposits. It has been shown that equipping the monitoring device with a temperature sensor will allow monitoring the weight of ice-coating and, if necessary, issuing a signal for organising anti-icing measures. Modification of the device with a three-axis gyroscopic sensor allows for additional monitoring of wind pressure on overhead line wires. The paper presents mathematical models for solving these problems of monitor-ing the condition of the wire.

Research Progress on Power Visual Detection of Overhead Line Bolt Defects Based on UAV Images

Research Progress on Power Visual Detection of Overhead Line Bolt Defects Based on UAV Images

Characteristics and Simulation of Icing Thickness of Overhead Transmission Lines across Various Micro-Terrains

The hazard of ice accretion on overhead power circuits is significant, yet predicting it is very difficult. The key reason lies in the shortage of sufficient observational data on ice thickness, and previous studies have also rarely taken into account micro-terrain and micro-meteorological conditions. In response to the challenge of simulating overhead line icing, this study introduces a new icing simulation technique that fully considers the effects of micro-terrain and micro-meteorology. For this technique, typical micro-terrains of overhead line areas are first identified by using high-resolution elevation data, and the icing thickness characteristics in different micro-terrains are analyzed. Subsequently, icing thickness simulations for different micro-terrains are conducted. The results indicate that during the icing process, the icing thickness ranges from 5 mm to 8 mm under three types of micro-terrain, namely, “uplift type”, “alpine drainage divide type” and “canyon wind channel type”, whereas the icing thickness is less than 5 mm in the “flat type” of micro-terrain. This finding suggests that the first three micro-terrain types facilitate icing on overhead transmission lines due to the condensation and uplifting effects of water vapor caused by terrain. However, flat terrain lacks the conditions necessary for water vapor accumulation and thus is not easy to form icing. The results are advantageous for the deployment of overhead power lines in intricate terrain. It is advisable to steer clear of regions susceptible to icing, and endeavor to install circuits in level territories whenever feasible. In addition, the simulated icing thickness under different terrains is in good agreement with the observations. Specifically, the correlation coefficient between simulated and observed icing thickness is significant at the 0.99 confidence level, and the deviations between them are within 0.5 mm. This signifies that the forecasting methodologies employed are dependable and possess significant implications as a reference for disaster prevention and mitigation efforts.

Design and research of high-frequency electromagnetic wave detection antenna for discharge of transmission lines

Abstract Overhead lines have a wide range of applications in power systems. When early insulation faults occur in the long-term operation of overhead lines, corona discharge may occur. Timely detection of corona discharge can guide maintenance personnel to discover and eliminate faults in a timely manner. The height and distribution of overhead lines are relatively high, and close-range detection cannot quickly locate the discharge area. Using radio frequency antennas to measure the electromagnetic wave signals generated by corona discharge can achieve long-distance positioning detection of corona discharge. This article uses a log-periodic antenna as the detection antenna and simulates the antenna structure to prove that its directionality, gain, and measurement frequency band meet the design requirements. Finally, the discharge detection performance of the antenna is verified through experiments.

Research and application of composite insulator overheat identification method based on improved case segmentation

Abstract How to quickly and accurately locate the heat of power components is one of the problems that need to be discussed frequently in the power field. At the same time, due to the diverse types of equipment in the power industry and the complex environment, if the heating position of the components cannot be located in time and further safety measures are taken, it will greatly affect whether the line can run stably. Based on infrared images, the device can be detected at a distance, and the problem can be found without interrupting its working state, which is more efficient in the process of equipment inspection. At present, some algorithms are based on infrared image research, but the positioning is not accurate, and some problems such as the temperature extracted by the algorithm and the temperature deviation between the actual parts caused by environmental factors, have not been a perfect solution. With regard to these problems, this paper presents a new method for overheating identification of composite insulators. First, the external profile of composite insulators is identified in infrared images through the YOLOV5 instance segmentation algorithm, and the rod core position of composite insulators is located based on this external profile. Then, the temperature matrix of the rod core position is obtained through the original heat matrix in infrared images. By comparing the temperature of the temperature matrix, we can determine whether the temperature is abnormal. In the actual production environment, the accuracy rate of the proposed method is 0.84, the error detection ratio is 0.2, and the total time of the algorithm is 216 ms. The results show that the proposed method has a good component positioning effect and can filter most of the temperature identification errors caused by environmental factors. It provides a new solution to solve the problem of temperature anomaly identification of overhead line power equipment in different scenarios.

Knowledge-assisted differential evolution based non-contact voltage measurement for multiconductor systems in smart grid

Multiconductor systems, such as overhead lines and multicore cables, are widely used in smart grids for their reliable power transmission capabilities. However, measuring the voltage of individual conductors in these systems has been challenging despite their promising applications. This paper proposes a novel framework to address this issue by utilizing a low-cost electric field (EF) sensor array and a knowledge-assisted differential evolution algorithm. The framework involves designing an annular EF sensor array to capture EF information around the multiconductor systems while ensuring its anti-interference capabilities through grounding and balanced electrodes. Furthermore, an optimization problem is formulated to reflect the model accuracy, and a knowledge-assisted differential evolution algorithm is proposed to optimize the voltage values and conductor positions by leveraging knowledge about the conductor positions and EF distribution. The use of this knowledge is expected to generate promising initial solutions for accelerating the optimization process. The proposed framework is experimentally validated, and the results demonstrate the robustness and accuracy of the EF sensor array and algorithm in obtaining the voltage of individual conductors in multiconductor systems.

An overhead line virtual test track for the assessment of railway catenary pantograph interaction

This paper presents the infrastructure geometry of a virtual test track for investigating the dynamic performance of train pantographs and overhead line systems with discrete features including height transitions and overlaps. This has been developed to support cascade of legacy fleets to new regions of the rail network and to better understand how legacy electrification infrastructure can support more modern fleets. The geometry is developed as an ‘obstacle course’ representative of overhead line fitted to legacy routes which have been electrified after their initial construction and is reusable across overhead line equipment types and modelling packages. A range of demonstration results are presented to illustrate application of three pantograph models. The virtual test track geometry and dynamic modelling can be used to assess the performance of catenary/pantograph combinations for overhead line geometries with discrete features and large height variations that are not currently covered by validation methods such as described in BS EN50318. The approach is applicable as a planning tool to establish safe working speeds across a range of overhead line features when full overhead line geometry is not available, or will be too costly to obtain, in the context of extending the utilisation of legacy assets.

Evaluation of the backflashover performance of 150 kV and 400 kV double-circuit overhead transmission lines as affected by lightning attachment models and peak current distributions

The evaluation of the backflashover performance of overhead transmission lines requires the adoption of a lightning attachment model and a peak current distribution. These affect the estimated backflashover rate, BFR, of the lines. The present study aims to quantify the influence of lightning attachment model and peak current distribution on the BFR of double-circuit overhead lines. This is achieved by evaluating typical 150 kV and 400 kV lines. ATP-EMTP simulations are conducted to obtain the critical currents causing backflashover of line insulation. Then, the critical currents are used in lightning incidence computations to obtain BFR. The influencing parameters taken into account in this work are the low current and low frequency tower ground resistance, the location of lightning strike to the shield wire along the span, and the AC voltage phase angle, all affecting the critical backflashover current. Several lightning attachment models and peak current distributions are evaluated. Their influence on BFR is found to be considerable, especially for lower tower ground resistance values. The lightning peak current distributions yield more pronounced effects on BFR. The results of this study stress the need for computing BFR using a more accurate expression than the simplified one based on CIGRE TB 63.