Overhead Distribution Research Articles

Fault location algorithms for active distribution systems utilizing two-point synchronized or unsynchronized measurements

This paper introduces two alternative formulations of a fault location algorithm, based on two-point measurements, which is appropriate for unbalanced medium voltage overhead distribution systems of radial configuration with or without distributed generation. The first alternative is solely based on synchronized three-phase voltage signals taken from the two measurement points. The algorithm applies fundamental bus-impedance-matrix-based fault analysis theory and calculates voltage drops to derive a fault location equation set for each fault type. The standard bus impedance matrix theory is also the basis for the second alternative. By combining the expressions correlating unsynchronized voltage and currents measurements from the two points with the elements of a modified bus impedance matrix, the need for synchronization angle is eliminated. Then, a fault location equation set is formed to obtain the fault distance and resistance. A multiple solutions elimination methodology is also proposed which is applicable for both alternative fault location algorithms addressed in this paper Extensive simulation studies demonstrate a good performance for the proposed fault location algorithms under numerous short-circuit conditions with varying pre-fault system loading conditions, fault resistances and measurement errors.

Statistical Safety Factor in Lightning Performance Analysis of Overhead Distribution Lines

This paper introduces a novel machine learning (ML) model for the lightning performance analysis of overhead distribution lines (OHLs), which facilitates a data-centrist and statistical view of the problem. The ML model is a bagging ensemble of support vector machines (SVMs), which introduces two significant features. Firstly, support vectors from the SVMs serve as a scaffolding, and at the same time give rise to the so-called curve of limiting parameters for the line. Secondly, the model itself serves as a foundation for the introduction of the statistical safety factor to the lightning performance analysis of OHLs. Both these aspects bolster an end-to-end statistical approach to the OHL insulation coordination and lightning flashover analysis. Furthermore, the ML paradigm brings the added benefit of learning from a large corpus of data amassed by the lightning location networks and fostering, in the process, a “big data” approach to this important engineering problem. Finally, a relationship between safety factor and risk is elucidated. THe benefits of the proposed approach are demonstrated on a typical medium-voltage OHL.

Practical Schemes on Lightning Energy Suppression in Arresters for Transformers on 10 kV Overhead Distribution Lines

This paper presented an assessment of lightning energy absorption by dedicated surge arresters (SA <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DT</sub> ), which are provided to protect the distribution transformers on 10kV overhead distribution lines (OHLs). A hybrid Partial Element Equivalent Circuit-Multi-conductor Transmission Line (PEEC-MTL) code was applied to evaluate lightning surges on SA <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DT</sub> . This method has the capability of modeling both short and long wires in OHL systems and is verified numerically and experimentally. A Monte Carlo procedure was adopted to assess the fault rate (FR) of SA <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DT</sub> . It is found that the direct lightning strokes to the phase wire are the primary threat to the SA <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DT</sub> , compared with the strokes to the poles as well as indirect strokes to the ground or structure nearby. Several protection schemes are identified, and their performance is evaluated from the aspects of lightning protection and economic cost. The full shielding wire (SW) scheme performs the best, but with the most expensive protection cost. The lightning energy absorption by SA <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DT</sub> can be suppressed significantly by installing extra SAs on the adjacent poles. The scheme of two or four extra SAs together with a partial SW can achieve a balanced performance of protection effect and economic cost for the OHL. The SW for a section of the OHL alone is not enough to the lightning protection for SA <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DT</sub> .

A Review on Characteristics and Assessment Techniques of High Voltage Silicone Rubber Insulator

The usage of polymeric insulators in transmission and distribution overhead lines for the last few decades has increased extensively. Silicone rubber (SiR) material is used enormously to make high voltage (HV) polymeric insulators. The SiR insulator provides insulation protection for overhead HV lines. The life span of the SiR insulators is shortened due to the aging effect. The progressive aging ultimately leads to the failure of the insulation system as well as the power supply. Therefore, a regular condition assessment of SiR insulators can help prevent the power system’s failures. A comprehensive study of the various types of aging processes of SiR insulators is reported in this article. Also, the comparative analysis of SiR insulators’ physical, chemical, and electrical properties under the influence of aging is reported here. The usefulness, limitation, and difficulties confronted in the existing methodologies are also reported in this article. This review article would be helpful to implement in future research for applying the HV overhead line insulator.

1,500 ㎾ 유도발전기를 배전선로에 연결할 때 발생하는 전압강하에 대한 분석

Induction generators, like induction motors, have a disadvantage in that a voltage drop occurs due to a high current during starting. Induction generators are often connected to the ends of distribution lines. When the induction generator is started and connected to the distribution line through the generated transformer, a voltage drop occurs in the distribution line as well as the transformer terminals. When an induction generator is applied to a hydroelectric power plant, it is necessary to accurately consider substations, distribution lines, loads, transformers for generators, and induction generators to know whether the voltage drop allowed by the system is satisfied.BRIn this paper, we analyzed the application of induction generators with accurate data on substations, underground and overhead distribution lines, customer loads, transformers, and generators for power plants currently installed and operating in Korea. As a result of the analysis, the voltage drop was high in the premises of the power plant, but the voltage drop was low in the distribution line, confirming that it is possible to apply the induction generator to the distribution line.

Lightning Protection of Electric Power Overhead Distribution Lines by Long-Flashover Arresters in Russia

A simple and effective method for lightning protection of power overhead distribution lines by long flashover arresters (LFAs) is presented. Even large lightning currents do not pose any threat to these arresters because the discharge develops in the air and not inside the device. LFAs, which are based on the creeping discharge effect, increase the lightning flashover length significantly and thus eliminate Power Arc Follow (PAF). To protect a line against induced overvoltages, a single arrester should be mounted on a pole. To protect a line against direct lightning strokes, LFA-M arresters should be mounted in parallel with each insulator. For covered-conductor overhead lines (CCL) using conductors with three-layer insulation a new lightning protection approach is suggested, involving use of antenna-type long flashover arresters whose essential component is the protected conductor itself. The essence of antennatype long flashover arresters (LFA-A) is that the arrester which is connected to the antenna gets flashed over well before the lightning leader comes in immediate contact with the line. The toroid-shaped antenna made of a metal tube is mounted on the covered conductor’s surface midway between the protector’s edge and the piercing clamp with the help of the toroid fixation unit. As the lightning leader progresses from a thunderstorm cloud to the CCL a high potential gets induced on the LFA antenna. A voltage drop that develops between the electrode and the zero-potential conductor core gives rise to development of a creeping discharge. Even before the lightning leader hits the line the creeping discharge channel flashes over the covered conductor’s surface Thereby the conductor insulation get bypassed by the discharge channel and thus protected against puncture. LFA’s main applications and field experience are presented.

Attenuation of Lightning-Induced Effects on Overhead Distribution Systems in Urban Areas

Overhead distribution systems can be strongly affected and damaged by indirect lightning. The induced voltages are usually computed neglecting the surrounding geometry and the presence of buildings in urban areas. Buildings can strongly change the behavior of the measured lighting-induced electromagnetic (EM) fields in the proximity of the point of impact. As a consequence, induced voltages can deviate from what would be measured in the absence of buildings. This work proposes an analysis of the main variables, which affect the deviation of the EM fields and of the consequent induced voltages along an overhead distribution line due to the presence of a building. Different distances between the line and the building and different building heights are considered.

Multi-objective integrated BES-CFD co-simulation approach towards pandemic proof buildings

COVID-19 has posed an extraordinary burden to those professionals responsible for properly operating and safely maintaining facilities throughout this disaster. Considering this global pandemic, the common spaces in buildings must be reconsidered to accommodate a future in-presence existence. Governments address human health and safety as the most vital considerations worldwide; thus, Heating, Ventilation, and Air Conditioning (HVAC) designs, airflow patterns, and temperature distribution must all be reconsidered to achieve such healthy circumstances. Based on this, a Building Energy Simulation-Computational Fluid Dynamics (BES-CFD) validated model has been analysed in terms of various HVAC designs. The simulations assessed the proposed solutions in terms of energy-saving, operational CO2 emissions, thermal comfort enhancement, and infection control. The results were closely examined and showed that the Underfloor Air Distribution (UFAD) system generates approximately laminar vertical airflow, reducing the likelihood of indoor infections and viral transmission. Supply air is delivered to the inhabitants’ zone without sacrificing mixing efficiency, ensuring long-term indoor environmental quality. Moreover, the UFAD model proved to be more cost-efficient compared to the Conventional Overhead Distribution (COHD) and has a lower carbon footprint and energy consumption. In terms of thermal comfort, the dynamic simulations showed a noticeable enhancement in PMV. Additionally, the UFAD provides a vertical temperature gradient profile that is sufficiently uniform. Moreover, the integrated DOAS-UFAD systems’ effectiveness was proved through a techno-economic analysis with a Return on Investment of 8.25% and a Payback period of 7.3 years.

Resiliency-Driven Multi-Step Critical Load Restoration Strategy Integrating On-Call Electric Vehicle Fleet Management Services

In order to enhance the restoration capability of the distribution system during emergency conditions, a resiliency-driven critical load restoration strategy is propounded in this paper. Electric vehicles (EVs) are considered for the grid-support services to deal with challenges on such occasions, in order to maintain the power supply continuity of critical loads by reducing the number of outage periods. The collaboration between fleet operator and distribution system operator is considered in the proposed scheme, making it possible to direct available EVs to the damaged areas. The random characteristic of the seismic event is captured by generating numerous hazard scenarios using a probabilistic approach with the Monte Carlo Simulation (MCS) technique. Afterwards, the unavailability of overhead distribution branches is determined within the fragility curve concept. Besides, the uncertainties caused by EV mobility are considered by performing learning-based analyses for forecasting the location and amount of EVs in the related zone. The obtained data is processed as input parameters in a mixed-integer linear programming (MILP) framework-based stochastic model. Besides, the conceptually developed interfaces for all stakeholders in the proposed scheme are described in detail for bridging the gap between the theoretical background of the concept and practical real-world implementation.

High-impedance fault detection on downed conductor in overhead distribution networks

High impedance faults (HIF) may occur in the medium voltage distribution systems and constitute a danger to human beings. Many cases of HIF are caused due to downed power cables in the distribution network. These cables in contact with the ground generate a great risk to the population, animals and fire risk. In this paper, a methodology for detecting HIF, generated by cable breakage, is presented. The algorithm is based on the analysis of the harmonic and symmetrical components of the current. The method aims to gain reliability in HIF detection, where the detection of conductor breakage incorporated into the method allows a better distinction of HIF from other events. A distribution network based on a Brazilian real feeder was implemented, as well as two well know HIF models. The method is validated using real-time digital simulations and hardware implementation, or HIL (hardware-in-the-loop) concept with OPAL-RT real-time simulator. A comparison with other methods is also performed in order to evaluate the performance of the method. The results show that the proposed methodology has presented a better performance under different types of HIF, models of HIF, and achieved a general accuracy of 90% and security of 100% for the tests performed.

Optimal Design of Distribution Overhead Powerlines Using Genetic Algorithms

As the design of distribution overhead power lines becomes increasingly standardized in the 21st century, the reduced search space of its design parameters allows for increasing opportunities to automate the design process. It involves specifying the distribution utility pole heights and classes, pole-top attachments, and conductor span tensions. A successful algorithm must be able of generating designs that are compliant with applicable codes and utility standards, achieve construction labour and material costs that are commensurate to that of a human-created design, and require a reasonable computation time. A design automation algorithm is created for ATCO Electricity, Alberta, Canada. Based on provided requirements and constraints, it uses the genetic algorithm to optimize the design parameters, including a completed design staking list, material loading file, and relevant calculation reports for use by the design department. Evaluation of the developed tool is based on five samples of real design scenarios. Within a reasonable amount of computation time, the tool produces results free from major design errors, comparable in material and construction costs to those of human-created designs. Furthermore, the design automation tool makes rigorous use of design decisions that result in small cost savings but that are not commonly found in human-created designs.

Semi-supervised Clustering Based Feature Selection with Multiobjective Genomic Search Class-based Classification Method for NIDPS

Objectives: The purpose of semi-supervised clustering-based feature selection with the multiobjective genomic search class based classification process is to extract the intrusion features from the content of the unbalanced class field and structures in the dataset. Method: A class-based taxonomy with Multiobjective Genomic Search Method (SCMGSM) is semi-supervised Clustering Based Feature Selection designed to avoid inappropriate classification and to generate class based efficient authenticity for detecting intrusions. The proposed SCMGSM operates on a cluster class basis to reduce the overhead distribution by utilizing the subset classifications based on labelling process. For cluster class based feature selection there is not necessary to retain the interconnected features, so the proposed taxonomy to detect the attack features for each subset classification improves the performance. SCMGSM protects the data source using the potential blocking and minimizes the hassle of unauthorized users from changing features. Findings: The experiments focused on a set of data to identify and classify features based on each class. The proposed SCMGSM handles enhanced classification accuracy with 5.37% normal class completeness, reduces false positive rate to 2.78%, improves detection rate to 6.75% and reduces the backup issue by 10.65% compared to overhead classification. Novelty: SCMGSM operates based on multi objective genomic search based cluster class taxonomy and offers high degree of accuracy, classification and low false-positive rating compared to the detection of exploitation, Fuzzers, Generic and Renaissances attack classes with in a specific subset or a group of features. Keywords: Classification; Cluster; Feature selection; Intrusion detection; Network attacks

Assessment of the Lightning Performance of overhead distribution lines based on Lightning Location Systems data

This article presents the Lightning Performance (LP) assessment of a realistic portion of the Italian distribution network with the use of probability distributions for lightning parameters inferred from local data recorded by a Lightning Location System (LLS). The procedure considers downward negative first, negative subsequent, and positive return strokes, taking into account the number of strokes per flash (flash multiplicity) and the distance among return stroke impact points within the same flash (stroke terminations distance). The analysis of the effect produced using LLS data on the estimated number of flashovers per year on the test line is achieved by replacing one by one the standard distributions and parameters typically adopted in the literature, with those inferred from the LLS, when they can be considered reliable. Results show that adopting LLS-inferred parameters and distributions produces significant (positive or negative) variations in the estimated number of flashovers with respect to values computed with the standard approach.

Key Points of Comprehensive Treatment of 10kV Distribution Overhead Lines

Key Points of Comprehensive Treatment of 10kV Distribution Overhead Lines

Application of the Transfer Matrix Approach to Direct Lightning Studies of Overhead Power Lines With Underbuilt Shield Wires—Part I: Theory

This work is devoted to the analysis of voltages produced on overhead distribution lines hit by direct lightning. We will consider arbitrary terminations at both line ends and, also, arbitrary positioning of the pole being struck. We will deal with lines protected by shield wires, placed either above or below the phase conductors. The analytical tools chosen to deal with such complex system are the transfer matrix method and the theory of multiconductor transmission lines with periodic grounding. The innovation of an artificial symmetrical unit cell has been introduced to eliminate the need of two characteristic wave impedance matrices and to ease computation flow.

Lightning protection of overhead distribution lines installed on high resistivity soil

The paper presents a comprehensive study on the lightning performance of overhead distribution lines located on high resistivity soil considering both indirect and direct strokes. An evaluation of the effect of high grounding resistance values of the neutral conductor, shielding wires and surge arresters is presented. A lightning induced voltage calculation methodology is presented and validated. The estimated performance results for distribution lines placed at high resistivity soils, with and without neutral conductor and surge arresters, are presented together with a discussion on the induced voltage problem. Additionally, the protection of distribution lines against direct strokes is analyzed and an innovative solution to reduce the number of arrester failures is proposed. The new solution is compared with the classical one, which uses a shielding wire to protect the arresters, followed by a discussion on the line lightning performance against direct strokes. The results point to different alternatives to improve the distribution lines lightning performance considering direct and indirect strokes together.

A New Detection Method for Load Side Broken Conductor Fault Based on Negative to Positive Current Sequence

Faults in distribution overhead lines occur due to various reasons, such as rain, strong winds, lightning, and other natural causes. The protection from the load side broken conductor (LSBC) faults has been one of the biggest challenges in the power distribution network. The small current generated by the LSBC fault makes the traditional protection system unable to detect this type of fault. The danger of LSBC fault is still enormous; besides, the available works of literature addressing this issue face difficulties when applying it to the real power system. This paper proposes a new method for detecting LSBC fault using single-ended measurements to the overhead distribution lines. The detection method is based on the constant ratio of negative to positive sequence current measured at the feeder end. The proposed study is performed using MATLAB software to implement a real network as a case study and verified by mathematical analysis. According to obtained results, we demonstrated that the fault in the electrical network had been detected with 100% of feeder protection. The proposed method has the benefit of being applicable and compatible with the existing measurement equipment, even when used in conjunction with overcurrent and earth fault relay in the electrical substation. Therefore, the negative to positive sequence currents are powerful in aiding fault detection. The benefit of this approach is providing a suitable LSBC protection solution for utilities while also opening new prospects in fault detection techniques in the distribution system.

Handfan: A flexible peer-to-peer service discovery system for internet of things applications

The Internet of Things (IoT) can be defined as an extensive network of interconnected devices that enables any physical object to be part of the worldwide network. The opportunity of everything being interconnected to the internet leads to many other challenges, such as many devices, the exponentially generated data, and the limited resources capacity of such devices (in terms of storage capacity, processing, energy, and accessibility). Decentralized systems and more particularly Peer-to-Peer (P2P) systems can meet the requirements of IoT applications. Peer-to-Peer DHT-Based approaches enable an effective search within a logarithmic cost. However, two issues need to be addressed to suit efficiently resource-constrained IoT systems. The first technical gap is that DHT-Based approaches do not handle network scalability and resources allocation, so they assume both nodes and keys must be in the same space, therefore, they are exclusively determined by the output of the hashing function. The second gap is that service discovery in such approaches is independent of the node’s resources capacity, which makes it ineffective and unsuitable for resource-constrained IoT systems. To cope with such limitations, our approach fundamentally addresses the previous technical gaps in existing DHT-based approaches by the following: Firstly, it deals with the first issue by adopting a novel mapping mechanism for both keys and identifiers based on geometric angles, the same mechanism is applied for nodes auto-configuration. Secondly, it introduces a customized routing mechanism that factors in nodes' processing capacity. We consider the number of hops, routing table size, configuration overhead, and load distribution as performance metrics. The proposed protocol's implementation and simulation with multiple experimentations confirm our approach's out-performance and effectiveness against competing IoT application approaches.

Research on Motion Path Planning Method of Live Working Robot Manipulator Based on Reverse Splitting Calculation

In the dual manipulator motion planning of live working robot, the traditional motion planning algorithm has the problems of too many turning points and non-smoothness. Therefore, this paper proposes a method of reverse splitting and local interpolation to remove redundant path nodes and optimize the motion trajectory. The working scene of overhead distribution line live working robot is simulated in MATLAB robot toolbox. The model includes manipulator R, manipulator L and overhead conductor to verify the effect of the method proposed in this paper. The results show that, the proposed method ensures that the redundant path nodes are removed on the premise of no collision between the two manipulators, which significantly improves the quality of the path.

Inspection based risk management of electric distribution overhead lines

This paper introduces a comprehensive process based on inspection for determination of medium voltage (MV) overhead line condition and it was tried that all factors influencing the outage of distribution network integrated into one index that called condition index. A condition based failure rate model has been proposed and its unknown parameters are calculated based on historical data. Shortest path problem (SPP) model has been proposed for the long term scheduling of maintenance and reinvestment. Objective function includes sum of the reinvestment, maintenance costs, failure costs and energy not supplied (ENS) costs with considering budget and labor constraints. Finally, as a result of this research, optimal combination of various actions such as reinvestment, preventive maintenance (PM) and tree trimming and it’s scheduling has been determined over the ten and five-year horizon. Results confirmed acceptable performance of proposed method because of compliance with actual condition and engineering judgment.