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Electric power substations, as critical components of modern power grids, are increasingly becoming targets for intentional physical attacks, including vandalism, theft, and sabotage. These threats, coupled with the potential for cyber-attacks and the weaponization of technologies, necessitate robust security measures and comprehensive auditing practices. Despite utilities providers' focus on understanding grid vulnerability and implementing physical security upgrades, there is a recognized gap in evaluating the effectiveness and long-term usability of these measures. This paper addresses the need for regular security audits to identify vulnerabilities and ensure the overall resilience of substations against evolving threats. The rationale behind this study is to propose a conventional auditing method that includes an auditing framework, checklists, inspections, and post-inspection suggestions. Through the systematic identification and addressing of vulnerabilities via security auditing, the framework aims to significantly enhance the resilience of substations against physical threats. This paper provides a comprehensive guideline for the physical security auditing procedure, which is essential for the reliable operation of the power grid. [ABSTRACT FROM AUTHOR]

Copyright of EMERG: Energy. Environment. Efficiency. Resources. Globalization is the property of Romanian National Committee of World Energy Council and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In smart electric grid systems, various sensors and Internet of Things (IoT) devices are used to collect electrical data at substations. In a traditional system, a multitude of energy-related data from substations needs to be migrated to central storage, such as Cloud or edge devices, for knowledge extraction that might impose severe data misuse, data manipulation, or privacy leakage. This motivates to propose anomaly detection system to detect threats and Federated Learning to resolve the issues of data silos and privacy of data. In this article, we present a framework to identify anomalies in industrial data that are gathered from the remote terminal devices deployed at the substations in the smart electric grid system. The anomaly detection system is based on Long Short-Term Memory (LSTM) and autoencoders that employs Mean Standard Deviation (MSD) and Median Absolute Deviation (MAD) approaches for detecting anomalies. We deploy Federated Learning (FL) to preserve the privacy of the data generated by the substations. FL enables energy providers to train shared AI models cooperatively without disclosing the data to the server. In order to further enhance the security and privacy properties of the proposed framework, we implemented homomorphic encryption based on the Paillier algorithm for preserving data privacy. The proposed security model performs better with MSD approach using HE-128 bit key providing 97% F1-score and 98% accuracy for K=5 with low computation overhead as compared with HE-256 bit key. [ABSTRACT FROM AUTHOR]

Historically, dense vegetation cover near buildings has caused power disruptions during weather phenomena. These types of severe storms impact the coast of Florida each year. However, challenges exist for obtaining both power outage data and calculating the impact of tree cover. NASA's Nighttime Lights, Black Marble, VNP46 product is utilized to analyze the natural and built environments. One aspect of the built environment that can be mapped with the Black Marble data is the megawatts of electricity used by the electrical power grid based on the magnitude of emitted nighttime light energy. This paper discusses using Black Marble data and other landscape variables within a probabilistic model to examine spatial patterns and map electricity outages with Bayesian networks. The research results indicate a high probability of a significant power outage when dense vegetation is present, but nuances in our natural and built environments like electric substations and land cover type alter the chance of reducing energy emissions. [ABSTRACT FROM AUTHOR]

We could get many helpful information and results from satellite remote sensing images and aerial images, including disaster monitoring, grid hidden danger identification, and electricity consumption management. In the recent years, novel computer vision and deep neural network have got a lot of attention in many fields because of mimicking mammalian cognitive mechanism as much as possible. With the in-depth of mammalian cognitive and motor mechanisms research, people trend to adopt these reliable and efficient methods for power grid management and maintenance.For utilizing computing resources and improving analysing efficiency flexibly, we propose an assessing and verification framework based on bio-inspired perception and understanding, which summarizes the most appropriate image scale in the electric facilities place recognition. The proposed framework consists of different scenes aerial images datasets, several electric facilities place recognition methods, and credible evaluating methods mimicking mammals. Firstly, we gather satellite remote images and aerial images of sufficient electric power facilities in the United States via Google Earth and other public datasets. Then, several typical place recognition methods are adopted to testing recognition ability of multi-scale perception results, like SAD, NetVLAD, and GIST descriptor. To get more reliable result, multi-units and multi-scenes experiments are implemented roundly. After all experiments and evaluations, we could get that the most appropriate image scale is 1000 m size and the highest recognition accuracy of electric power facilities location is 500 m. Conclusion in our article shows the recommended perception form and scale closest to human cognition in the power grid management and maintenance. [ABSTRACT FROM AUTHOR]

Geomagnetically induced current (GIC) in utility systems such as electric power grids occurring during extreme geomagnetic storms can exceed the tolerance limit of the systems, which can cause serious system damages. It has therefore been important to evaluate the GIC levels in the utility systems. This study presents the simulation and analysis of GIC levels in the Shandong 500 kV power grid system consisting of 34 substations under a variety of uniform induced geoelectric fields. The line type, substation grounding resistance, and other influencing factors are included in the simulations. The results show that the GIC level varies largely in the 34 substations. In 11 substations, the GIC exceeds 100 A and it reaches up to ∼200 A in two substations for an assumed 1 V/km induced electric field. The changes in the GIC distribution are found consistent with the direction changes of the electric field. Utilizing the directional sensitivity, we calculate the maximum GIC level for the optimum direction for all substations. By combining this information with statistical tools, we propose a method for identifying the key substations which are most vulnerable. The result can provide suggestions for GIC disaster prevention and mitigation, substation site selection, monitoring equipment installation, and so on, in Shandong province. Key Points: Geomagnetically induced current (GIC) levels in the Shandong 500 kV power grid system are simulated and analyzedIt is shown that GIC levels have high sensitivity to the direction of the geoelectric fieldBy calculating the maximum GIC level for the optimum direction for all substations, we propose a method for identifying the vulnerable substations [ABSTRACT FROM AUTHOR]

It is significant to research the impulse characteristics of substation grounding grid for its optimal design and safe and stable operation. In order to obtain the impulse transient characteristics of substation grounding grid under lightning impulse current more accurately, the impulse current field test was done on a real substation grid. By monitoring the impulse grounding impedance, impulse coefficient, longitudinal current, and node potential under different test conditions, impulse characteristics curves and the effect of some influence factors are gotten, then the main zones of current dispersion and voltage drop are proposed, as well as the effective areas under different conditions are proposed combined with simulation analysis. The results show that: the impulse grounding impedance and impulse coefficient are smaller when the current is injected from the central of the grid. The main current dispersion region of the large-scale grounding grid is about 40 m around the injection point. The potential drops about 30% within 20 m around the injection point, and the change of the potential is small in the far distance. The effective area of substation grounding grid is affected by soil resistivity, and its side length is usually only tens of meters. [ABSTRACT FROM AUTHOR]

Very fast transient over voltage (VFTO) is a unique electromagnetic transient phenomenon occurring in Gas Insulated Substation (GIS), which determines the insulation level of the GIS (above 330 kV). Unfortunately, up to the present, there is no standard VFTO waveform to test the high voltage equipment to ensure the safety of power grid. For this reason, this paper focuses on obtaining the standard VFTO waveform through finding a method to fit the curve of VFTO. Hence, a UHV disconnector operation experiment of GIS was carried out on the UHV GIS test platform. The representative waveform of VFTO generated by a single SF6 gas discharge was extracted from the measured data. Furthermore, The Fast Fourier Transformer is applied to analyze the frequency features of VFTO. As one of the switchgear operation voltage, VFTO can be concluded to be a superposition of the power-frequency waveform with the non-periodic impulse waveform. Thus, it is found that The Squares Method is convenient for fitting the expression of VFTO according to its transient characteristics. Then the standard VFTO waveform can be obtained from the fitting expression, which coincides well with the measured waveform. The simulation results using ATP-EMTP software are compared with the calculation results and the measured results. [ABSTRACT FROM AUTHOR]

Resonance or harmonic amplification occurs when the frequency of the harmonics generated by the converter station is near the inherent resonance frequency of the substation. Considering there are six DC projects in the Yunnan power grid, analysing the resonant characteristics of the grid is imperative for safety reasons. This study establishes a simulation platform of the Yunnan power grid based on the Power System Analysis Software Package and formulates the modelling principles and simulation steps. In order to successfully analyse the resonant characteristics of a substation under normal operation mode and put forward any necessary suggestions, the impedance frequency of all 500 kV substations in the power grid are scanned. This is followed by studying, the influence of different operation modes of Yunnan power grid and different operation modes of DC system of Luxi converter station on the resonant characteristics of Yunnan substation. Based on these results, effective measures for resonance suppression are proposed. [ABSTRACT FROM AUTHOR]

The use of standard HVac disconnectors for bus-transfer switching in future HVdc gas-insulated switchgear (GIS) has been demonstrated successfully in past research through simulation and testing. Prolonged arcing times through reignitions caused by high frequency harmonics as well as the proposed extension of GIS disconnector switching cases, however, create an HVdc-specific demand for more advanced disconnector concepts capable of withstanding higher switching stresses and increased recovery voltages. A spring-loaded disconnector designed for use in HVac mixed technology switchgear was found to shorten the time to first current zero through an accelerated increase of the arcing voltage compared to standard disconnectors. Despite its increased switching performance, the reignition characteristics of this fast-acting disconnector were found to largely follow the previously established extinction criterion, which enables further simulation of similar technologies for HVdc applications. To additionally combat the issue of contamination of HVdc GIS by electrode erosion products, a prototype disconnector was improved using permanent magnets to evoke arc rotation. Erosion tests in air have shown an effective reduction of electrode erosion for long arcing times at currents typical for disconnector switching, whereas bus-transfer tests revealed promising enhancements of the reignition behavior. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Impulse performance of grounding grid is needed for lightning protection design of power system. This paper describes an impulse test facility established for the full-scale grounding grid (50 m long and 52.5 m wide) in a 110 kV substation. Test method is presented, including configuration of current injection and return point, measurement of potential rise and longitudinal current. Impulse test is carried out with 2.6/50 and 8/20  μs current waveform, and the maximum current amplitude is 4 kA. A Current Distribution, Electromagnetic fields, Grounding and Soil structure simulation for the tested grounding grid is also adopted. Impulse performance of full-scale grounding grid is affected by soil ionization and conductor inductance. There is steeper peak on the potential rise waveform near the injection point with shorter wave front current, which leads to more uneven potential rise distribution. Partial soil ionization could increase the current dispersing into the soil at partial area of the grounding grid, and the longitudinal current flowing to the next area decreases. These two factors pose a high potential difference hazard to the secondary equipment via the secondary cable. [ABSTRACT FROM AUTHOR]

The power distribution networks (PDN) are spread in different street and Alley. Furthermore, nowadays, the DG is used in PDN, especially photovoltaic (PV). Therefore, fault location in these PDNs is complex. In this paper, an improved impedance based method has been proposed for fault location in power distribution network with presence of photovoltaic distributed generation resources. According that the PV has an uncertain behavior in different conditions, the proposed method is designed to be robust against PV behavior and upstream feeder changes. In the suggested method, detail equations are derived to prove a new quadratic equation for locating fault in PDNs using recorded voltage and current at the beginning of feeder and DG terminals. According to this proved equation is depended on to just voltage and currents of source or substation terminals, consequently dynamic modeling of PV and substation is not important in the proposed method. Within this method, the π line model is used for improving the accuracy of the suggested method. To evaluate the accuracy of the proposed method, the modified 11 node test Feeder is simulated in the MATLAB software and sensitivity of the suggested method was investigated against the different fault distances fault types, fault resistances and fault inception angles. Furthermore, the proposed method is investigated and tested on the real test feeder in power system simulator of power system and protection Lab. in Persian Gulf University. The results indicate the high accuracy of the algorithm. [ABSTRACT FROM AUTHOR]

The medium-voltage grid is often planned in loops, but operated in a radial structure to allow a robust protection scheme. This allows the reconfiguration of the grid. This paper focuses on reconfiguration after a fault to re-establish the service, also referred to as self-healing. It includes the localization of faults and finds new grid configurations based on the actual status of the grid. The solving of the reconfiguration problem is nonpolynomial difficult. Finding an acceptable solution to resupply nonfaulted grid parts under tight time limits is difficult. The innovative contribution of this paper is an approach that finds new configurations as local as possible to the faulty area, evolvingly increasing the search space. New configurations are generated based on a heuristic method relying on graph theory. An aggregated fitness function is used to evaluate the solutions. For the realization, a distributed control architecture in the form of an advanced substation automation is proposed. [ABSTRACT FROM PUBLISHER]

In recent times, real-time simulation has been used to validate the testing and design of protection, control, and communications systems prior to their commissioning in the field, which has improved the reliability and security of the commissioning processes for electrical systems. This paper reviews the state-of-the-art and future trends in protection, control, and communications testing of electrical grids using real-time simulation. In addition, a summary is presented in which all the works and technologies mentioned are listed with the purpose of identifying new challenges in the proposed topic. Finally, future trends related to the use of real-time simulation for evaluating protection, control, and communications schemes are presented. Real-time simulation is very useful due to the increasing complexity of modern electrical power systems, therefore, it is necessary to use this kind of tool to facilitate field testing, avoid unnecessary work, and reduce costs for clients. [ABSTRACT FROM AUTHOR]

Power systems are experiencing drastic changes with the introduction of renewables and customer owned resources. These changes introduce new challenges in protection, control, and operation of power systems. In protection, it is necessary to develop new methods that are immune to the new characteristics and they avoid relay misoperations. In particular, any protection system is vulnerable to hidden failures. This paper introduces a new dynamic state estimation-based centralized protection scheme (DSEBCPS) at a substation level. The system supplements dynamic state estimation-based protection for individual zones known as “setting-less relays” to secure their operation against hidden failures. The DSEBCPS communicates with the setting-less relays via the station bus and obtains essential information from each protection zone, such as phasor quantities and breakers/disconnects status. This information is processed by the DSEBCPS to estimate substation topology and states. Specifically, the DSEBCPS performs dynamic state estimation in the quasi dynamic domain once per cycle to detect any abnormality within the substation. Upon detecting abnormalities, the DSEBCPS performs hypothesis testing to identify the source of the abnormality, that is, a fault or a hidden failure. Upon detecting a hidden failure, the DSEBCPS identifies the compromised data, replaces this data with estimated values by using the substation estimated states and model. The corrected data are used by the setting-less relays, enabling self-healing characteristics. The proposed capability to detect hidden failures and correct the effects of these failures in real time makes the setting-less relays secure against misoperations and bridges a critical gap in protection systems. This capability is demonstrated through numerical experiments that include several scenarios of hidden failures. The integration of the proposed scheme with the individual protection zone relays form a resilient protection and control system, which is self-immunized against hidden failures. [ABSTRACT FROM AUTHOR]

In the modern electrical grid, accuracy and speed of fault clearance are the major challenges which need to be addressed. This paper covers a case study of fault location techniques in electrical transmission network, using numeric relay and offline fault locator. Healthiness of electrical transmission line is ensured using line signature analyzer. Comparative study of online and offline fault location in electrical transmission network has been carried out and the inferences are drawn. On the basis data available it can be said that the frequency of occurrence of single line to ground fault is maximum (about 75%) among various types of faults. Data at 220 kV and 132 kV substations has been collected and analyzed, keeping focus on single line to ground fault. Architecture of Substation Automation System (SAS) using single communication technology based on IEC 61850-8 and IEC 61850-9 is explained. Proposed architecture consisting of numeric meter with Java Compilation Unit (JCU) and Ethernet switch standardized as per IEC 61850 is demonstrated. The Java source code to send indications to output port of numeric meter is included. [ABSTRACT FROM AUTHOR]

Modern cyber-physical smart power grids are becoming increasingly dependent on the associated cyber networks for performing various monitoring and control functions, which inevitably leads to increased cyber vulnerabilities. It is thus a pressing task to develop effective methods for comprehensively evaluating the overall adequacy of power systems considering the probable cyber vulnerabilities. This paper is focused on quantifying the impact of substation cyber vulnerabilities on power supply adequacy. The temporal occurrence pattern of cyber attacks is statistically analyzed based on the human dynamics theory. Also, the attack/defense interactions of intelligent attackers and defenders are modeled by static and Markov games in different attack scenarios. A novel power system adequacy evaluation framework is proposed by incorporating both physical failures and cybersecurity risks. Simulation studies are performed on a typical IEEE reliability test system, and the influences of critical factors related to cybersecurity are carefully investigated. These quantitative studies show that implementing effective cyber security measures and making informed decisions about the allocation of limited resources are beneficial to enhancing the overall adequacy of contemporary cyber-physical power systems. [ABSTRACT FROM AUTHOR]

In this paper, the finite-elements method was used to analyze the approximation being typically used in the international standards for the calculation of the touch voltage, appearing at earth faults in power networks. The calculations in this paper were performed on the series of earthing systems applied in practice and the results are compared with the results of the widely accepted approximate method from standards. The origin of discrepancy in the results is analyzed and evaluated. The outcome of this paper is the justification of the application of Thevenin's theorem and the development of the higher accuracy equations for the resistance between feet and remote earth in case of the application of high resistivity additional surface material. [ABSTRACT FROM PUBLISHER]

The leader progression model (LPM) is employed to investigate the shielding system performance of high-voltage substations against direct lightning strokes in the presence of substation instruments. The substation is simulated in detail for high accurate calculation of the shielding failure rate. Almost all of the apparatuses are modeled as fictitious charges in the stepwise simulations of LPM. The charge simulation method is used for finding the electrical field during the lightning movement. The probability of upward leader propagation is considered from all apparatuses. For more practical simulation, the environmental conditions are also included in simulations. The investigations are implemented on a test case and a practical high-voltage substation. The results are compared to those of the electrogeometric model. It is very likely that the results of this paper better simulate reality because lots of parameters have been taken into account. The results reveal that the presence of substation instruments increases the striking distance and the SF since they attract the lightning moving down near the substation. [ABSTRACT FROM PUBLISHER]

This paper focuses on estimating the substation grounding resistance to improve the modeling of geomagnetically induced currents (GICs). Grounding resistances are not included in the standard power flow models, and their approximate values are often used for performing GIC studies. This paper provides an algorithm to estimate the resistances from the GIC measurements. This algorithm calculates the linear sensitivity factors of the GICs around the local grounding resistive components and uses linear regression to solve for the resistances. The effectiveness of the proposed algorithm is demonstrated using both a small test case as well as a 62 500-bus model of the North American Eastern Interconnection. [ABSTRACT FROM PUBLISHER]

Unity power factor (PF) injections through distributed grid-tie inverters reduce net real power demand at distribution substations. This reduces line utilization, but can also result in undesirable PFs within the system. PF constraints, therefore, may limit injection or “load” capability (LC) in circuits with growing distributed resource penetration. Therefore, this work presents a PF-based estimator of LC for distribution systems, which can be appended to existing LC formulations without additional inputs. A solution algorithm is provided, and simulation results are presented for an actual 2556-node distribution system. An increase in distributed photovoltaic injections resulted in reduction of overall system LC due to substation PF constraints. Finally, series acceleration is investigated for LC problems; in the tested cases, the acceleration technique reduced the number of iterations for a current-based LC estimator by an average of 85%. [ABSTRACT FROM AUTHOR]

This paper introduces an efficient methodology to design optimally cable layout of inner grid as well as location of offshore substation. The methodology is composed of two optimizers: one is inner grid layout optimizer, which consists of several algorithms such as the k-clustering-based genetic algorithm, the minimum spanning tree, and the cable selection; the other one is offshore substation location optimizer based on the pattern search method. While performing iteratively two optimizers, alternatives for cable layout and candidates for location of offshore substation are generated and evaluated in the economic and reliability aspects, respectively. Optimal layout of offshore wind farm is determined so as to minimize the total cost which is a sum of construction, power loss, maintenance, and reliability costs. [ABSTRACT FROM AUTHOR]

Presents the table of contents for this issue of the publication. [ABSTRACT FROM PUBLISHER]

The increment of distributed energy resources such as small photovoltaic plants or microcogeneration systems, together with the increase of electric vehicles connected to the grid, is bringing new challenges to distribution system operators (DSOs). In order to support DSOs to face such new challenges, this paper proposes a new solution based on a framework for the implementation of substation automation units. This framework supports the development of smart distribution systems solutions. The monitoring and control functionalities of the proposed solution are decentralized and, therefore, closer to the associated field devices compared to traditional solutions. Thus, the proposed approach allows us to increase performance and to reduce the system complexity by avoiding the concentration of data in one single point. An automation unit placed in the electrical substation is proposed and characterized for automation in distribution networks. Test results in laboratory and real-world environments will show some results of the proposed solution. [ABSTRACT FROM PUBLISHER]

In the traction power supply system (TPSS) of the high-speed railway (HSR), the traction load produces extremely severe load conditions. Therefore, Gas insulated substation (GIS) equipment served in TPSS of HSR suffers from both progressive degradation and random shocks. In this paper, the failure model of GIS equipment is considered as a competing failure mode multiplied by these two failure mechanisms. The degradation process and the shock process are described by gamma process and compound Poisson process, respectively, based on their temporal and spatial randomness. Furthermore, the maintenance strategy for GIS equipment in long-run time span with periodic inspections is developed. Under comprehensive consideration of optimal reliability and economic efficiency, indices associated reliability and maintenance cost are defined to evaluate the maintenance strategy performance in long-run time span for GIS equipment. The analysis results in the case study show that the inspection period and the shock threshold, as two maintenance decision parameters, can be optimized to achieve both high reliability and low maintenance cost. The influences of failure model parameters on optimized maintenance strategy are also revealed. [ABSTRACT FROM PUBLISHER]

The smart substation, revolutionarily changing every aspect of the modern substation, is developing fast in the world and being massively deployed in China quickly. A smart substation is typically implemented with a sophisticated combination of smart primary high-voltage equipment and hierarchically networked secondary devices. Based on the IEC61850 communication protocol, the functionalities, such as the information sharing and interoperability among smart electric equipment, are realized in smart substations. It is regarded as the basis for the development of smart grid and represents the future development trend of substation technologies. This paper reviews the fundamental vision of the smart substation. The state of the art and the challenges encountered in the practice of engineering implementation are presented. Future developments to solve the present challenges and promote the development of smart substations are also described. [ABSTRACT FROM PUBLISHER]

This paper describes hands-on modeling and simulation experience for designing substation ground grids. The grounding studies enable an optimized ground grid design to protect utility personnel and the public. These optimized ground grids meet the IEEE-80 standard [1] for safety and have been simulated and designed using more accurate transient and steady-state fault current calculations. The SI and MI methods are used to simulate the actual fault locations and fault currents at a small station and a large extremely high-voltage station, respectively. The simulations primarily focus on substation specific data for the application rather than utilizing predetermined split-factor curves and the decrement-factor table in IEEE-80. In addition, the new clearing time analysis and grounding study safety assessment strategy will be implemented instead of using the widely applied longest clearing time and its corresponding threshold calculation, which could further optimize the ground grid. With AEP's research and applications, the authors hope it can benefit similar industrial substation design projects. [ABSTRACT FROM AUTHOR]

The power networkswith reliable transmission and distribution systems require high voltage substations with effective ground grid systems. Therefore, this study aimed to analyze the effects of overvoltage on ground grid systems within high voltage substations in two cases, including a single substation and the two neighboring substations, by using ATP/EMTP and ANSYS softwares. The simulations were performed to show both plotting graphs and 3D results when the fault current flowed into the ground grids of substations at various positions. In case of the single highvoltage substation, the overvoltage was highest when the fault current was injected at the corner of ground grid. However, in case of two neighboring high voltage substations, the levels of overvoltage were similar between that caused by injecting the fault current at the center and at the corner of ground grid. The simulation showed that overvoltage which occurring at the ground grid of high voltage substation A could permeate to the ground grid of nearby high voltage substation B, which nevertheless depending on the how the fault current was injected at different spots. The data from these simulations and analysis can be useful for future designs of ground grid systems with high reliability. [ABSTRACT FROM AUTHOR]

Demand response (DR) is an important component for the establishment of smart electricity grids. It can decrease the system peaks through load shedding or shifting and optimize the utilization of the existing grid assets, which delays the need for costly upgrades. DR can also enable the integration of intermittent and distributed energy resources (DER) into the existing electricity grid. Fast DR from aggregated flexible loads can provide ancillary services (AS) to absorb grid disruptions and may replace the expensive fast-ramping reserve generation units. This study presents a methodology for load aggregation based on the prioritization of loads according to their flexibility. Different flexible load types are categorized as thermostatically controlled loads (TCL), urgent non-TCL, non-urgent non-TCL, and battery-based loads. Models based on their physical behaviour are developed and simulations performed to apply the proposed aggregation and control algorithm. Results show that the loads during peak hours can be shed off without rebound demand spikes after the DR event commonly seen in other types of DR programs. The algorithm also automatically adjusts the power demand according to the output of the distributed renewable generation, mitigating disruptions due to variations of the DER output. Additionally, the algorithm is able to adjust the load demand dynamically according to the fluctuations of electricity price. [ABSTRACT FROM AUTHOR]

The analyses for overcoming problems arising in basic grid substation buses and equipment are of essential importance to the Brazilian electric sector in view of the constant expansion of this system. These analyses are not simple tasks because they involve an evaluation of the impacts caused by installations arising from new connections and because they always include various studies. This paper presents examples of necessary investigations into the causes of the rated characteristic violations of basic grid installation components. An overview of the proposed electrical system that will be evaluated in conjunction with a new thermal generator plant connection to an existing system substation system is presented. [ABSTRACT FROM AUTHOR]

Power grid facilities can be vulnerable with respect to malicious physical attacks. An advanced system to monitor physical security of substations and other facilities is essential to maintain system integrity. This paper describes a substation physical security monitoring (SPSM) system for remote monitoring of power substations. The proposed methodology consists of video surveillance for outdoors, motion detectors for indoors, and the classification of intrusion events. An important feature of the proposed method is the ability to determine the response to a threat based on the result of physical security monitoring. In addition, industry experience from two transmission system operators (TSOs) is incorporated in the development of the methodology. To validate the proposed SPSM system, an experiment was performed at a critical substation involving two physical intrusion scenarios. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper presents an investigation of utilizing dc links to merge heavily meshed urban distribution networks in dense-load areas to increase reliability and expand operational flexibility. It provides a cost-benefit evaluation of utilizing dc-link technology to interconnect three segments of New York City electric distribution networks with complex grid configurations. The outcome of this work highlights the advantages provided by dc links, such as increased reliability and power quality, improved voltage support, and demand relief for feeders at or above capacity limitations. Furthermore, the study shows that dc links may provide a better alternative to transformer installations, feeder upgrades, and/or capacitor additions, and offer the opportunity to postpone large capital investments for system upgrades (such as building a new substation) due to demand increase. The study was carried out with power-flow simulations using field-validated power-flow data. [ABSTRACT FROM AUTHOR]

Power devices intended for high-voltage systems must be tested according to international standards, which includes the short-time withstand current test and peak withstand current test. However, these tests require very special facilities which consume huge amounts of electrical power. Therefore, mathematical tools to simulate such tests are highly appealing since they allow reproducing the electromagnetic and thermal behavior of the test object in a fast and economical manner. In this paper, a three-dimensional finite element method (3D-FEM) approach to simulate the transient thermal behavior of substation connectors is presented and validated against experimental data. To this end, a multiphysics 3D-FEM method is proposed, which considers both the connector and the reference power conductors. The transient and steady-state temperature profiles of both the conductors and connector provided by the 3D-FEM method prove its suitability and accuracy as compared to experimental data provided by short-circuit tests conducted in two high-current laboratories. The proposed simulation tool, which was proven to be accurate and realistic, may be particularly useful during the design and optimization phases of substation connectors since it allows anticipating the results of mandatory laboratory tests. [ABSTRACT FROM AUTHOR]

The topology of grounding grid is important for diagnosing its status, which plays a critical role in the safety of personnel and stable operation of power system. The electromagnetic field method and derivative of surface magnetic flux density on the line has been used to measure the branch position in case the grid is parallel to the plane of earth surface that in practice is unknown while the node points and connections were not discussed. This paper introduces a method that uses derivative of surface flux density on circles and lines in a systematic order to find the position of the grid in the plane of the earth surface and connecting the nodes to measure the full topology. This method even identifies any angled branch present in the mesh of a grid. Software simulations and experimental tests verify that the method is feasible and can be applied to identify the topology of a grounding grid. [ABSTRACT FROM AUTHOR]

Electric power distribution systems can be represented with mathematical graphs in which the hub nodes are substations receiving electric power from the transmission system and delivering it to the consumers via feeders consisting of transformers, junctions, cables and power lines. High-quality diagrams depicting these systems are key elements of efficient monitoring and control. Existing automatic diagram generation solutions are usually limited to drawing single feeders or contain significant simplifications of the underlying distribution system e.g., visualize multiple feeders with their interconnections removed. The goal of this research was to develop an algorithm capable of generating visually-pleasing diagrams of substation areas consisting of a single hub node and a complex network of thousands of interconnected elements. The resulting algorithm was defined as a sequence of transformations which takes a mathematical graph as input and generates a one-line diagram as output. Multiple novel approaches are incorporated to optimize the algorithm thereby allowing it to run efficiently on regular desktop computers. Also, a novel diagram quality evaluation procedure was developed to automatically measure and compare the usability of each generated diagram. The algorithm was tested on 2510 different substation areas of various complexity extracted from the network models of real-life, European distribution systems. The quality of the generated diagrams was measured with the novel evaluation procedure and verified with a human domain experts on a subset of the resulting diagrams. Based on these analyses, it was concluded that the generated diagrams are usable in newly built supervisory and control systems with minimum human intervention. • Electric power systems are monitored and controlled via one-line diagrams. • The algorithm generates diagrams of weakly-meshed distribution substation areas. • Includes a rich data set of 2500+ real-life substation areas as graph adjacency lists. • Proposes a quality assessment formula for qualifying any substation area diagram. • Less error prone and automates the manual labor of expert one-line diagram editors. [ABSTRACT FROM AUTHOR]

This paper presents the study of a measurement technique for touch and step voltages. In essence, we elaborate an approach which is very similar to the measurement of the grounding system impedance. In addition, the main focus is on the measurements at energized substation where different types of coupling between the test leads, grounding grids, sheats of underground cables and overhead ground wires affect the precise measurement. In order to avoid the measurement difficulties, we use low magnitude variable frequency AC test current (so called Frequency Shift Method – FSM). We compare FSM measurement results with the corresponding results obtained by well-known Test Current Reversal Method. The field tests were conducted in two quite different substations. Experimental results demonstrate the validity and usability of this approach. [ABSTRACT FROM AUTHOR]

Utilization of existing grounding systems for the expansions and upgrades of substations offers unique challenges. The identification of current conditions of grounding systems is crucial for safety and for the proper design of their expansions and/or upgrades, which may include the interconnection of an existing grid to a new one. It is also important to note that the evaluation of the conditions of existing substation ground grids may require personal protective equipment to be worn, as well as appropriate safety precautions. In this paper, the authors provide procedures to evaluate the prospective performance of existing grounding systems based upon measurements, as-built and/or contract drawings, site inspections, and examination of key grid points utilizing nonintrusive methods. Safety solutions that can be utilized during the construction phase of the project are also illustrated. A case study that addresses the upgrade of an existing grid is discussed. This paper seeks to clarify for practitioner engineers the problems and variables introduced by the work to be performed on older substation grounding systems. Readers will be provided with tools in compliance with applicable technical standards, which can assist in ensuring continued operation of the substation grounding system during construction. [ABSTRACT FROM PUBLISHER]

High-voltage substations are fed by transmission lines with the earthing system solidly bonded to the substation earth grid. Under substation fault, both the substation earth grid and the pole grid resistance are exposed to voltage rise. This voltage rise could reach unacceptable and dangerous levels. Earthing system design ensures safety compliance for both the substation and transmission lines under fault conditions. This article analyses the relation between the substation earth potential rise and the transmission pole earth potential rises. The analysis shows that the poles located within the finite length from the substation form a solid input to the substation earth potential rise. The article reviews the existing literature and develops the formulas to assist the designer to compute the substation earth potential rise from the pole earth potential rise and vice versa. The article proposes modifications to IEEE earthing design block diagram. This modification ensures that the transmission line earthing system is always compliant to allowable safety limits under substation fault. Furthermore, the article shows the method to estimate the substation earth potential rise by measuring the pole earth potential rise with a case study. [ABSTRACT FROM PUBLISHER]

This paper addresses one of the fundamental steps in automatic waveform analysis: transient segmentation. We present a new approach which incorporates the advantages of a multilevel wavelet decomposition and the representation of the support vector data description. Real data from a monitoring system developed for lightning overvoltage detection in overhead distribution power lines was used for comparison and validation of segmentation performance. The experiments involve the proposed segmentation approach and usual segmentation methods, such as Kalman filtering, autoregressive models, and standard discrete wavelet transform. The results show that the proposed segmentation method based on DWT+SVDD yields better overall accuracy for transient segmentation when compared to currently used methods, demonstrating the potential for applications in oscillographic recorders for smart distribution networks, where identification, characterization, and mitigation of events are critical for network operation and maintenance. [ABSTRACT FROM AUTHOR]

Purpose. Definition of the direction for further research to improve accuracy of the calculation of rated parameters of ground grids based on the analysis of statistical databases of electrophysical characteristics of the soil. Methodology. To solve this problem we compiled the statistical base of soil of Ukraine in the location of electrical substation, we performed the statistical analysis for the number of layers of geoelectric structure, and electrical characteristics. In the experiments implemented the comparing of accuracy calculation of the most typical three-layer soil in the Ukraine, by the new three-layer model of ground grids and the equivalent two-layer model, which used previously. Results. On the results of analysis the ranges of the electrical resistivity and statistical distribution for electro-physical characteristics of the soil are determined. The resulting distributions allow to develop criteria for instruments, installations and means of interpretation during the sounding of soil, as well as the requirements for mathematical models of ground grids. It was found that the most typical for places of locations the electrical substations in Ukraine are three-layer geoelectric structures. In the paper the statistical distribution for three-layer soil by type (Q, K, H, A) are described. The results of numerical experiments show that the use of methods to simplify of the multilayers soil does not allow the calculation of grounding grids with high accuracy. In the work recommendations for applicability the method equivalenting depending on the type of geoelectric structure are developed. Originality. For the first time, we obtained the statistical distribution of stratification of the soil in the location of power plant in Ukraine, determined the accuracy of the method to simplify a multi-layer soil in determining the rated parameters of grounding grids. In the paper the necessity to develop a mathematical model of the grounding device located in the three-layer soil is shown, as well as a new installation of soil sounding, which allows to increase the depth of sounding and new means of interpreting the results of sounding Wenner installing a four-layers geoelectric structure. Practical value The resulting recommendations for the applicability of equivalenting of multilayer soil, as well as research in specific work areas would help to reduce costs on materials and labours during the modernization and upgrade of grounding devices, moreover it will increase the electrical safety and reliable operation of electrical substation. [ABSTRACT FROM AUTHOR]

The configuration of grounding grids which are used to earth electrical substations could be equally or unequally spaced. Unequally spaced grids were introduced to improve the requirements of the grids such as grounding grid resistance ( R g ), ground potential rise (GPR), maximum touch voltage ( E t ) and maximum step voltage ( E s ) values. Also, unequal spacing can reduce the cost of the grids and enhance the level of safety for people and equipments. In this paper two different approaches were used to determine the best possible configuration of grounding grid. These approaches based on sequential multiplicative and sequential power techniques. [ABSTRACT FROM AUTHOR]