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The hybrid dc circuit breaker is one of the most promising dc circuit breakers (DCCBs). However, its cost is relatively high, and the completion of its fault isolation is significantly delayed because of the large current limiting inductors configured in the multi-terminal dc grid. Besides, due to the utilization of overhead lines, the probability of temporary faults is much increased, which means there is a great possibility that the power supply can be rapidly restored by reclosing DCCBs. However, the temporary faults must be distinguished from the permanent faults before the reclosing operation to avoid damaging the fragile power electronic equipment. Therefore, considering the above issues, a novel multiport hybrid dc circuit breaker (MHCB) is proposed in this paper. The MHCB mainly has three advantages: the reduced implementation cost by sharing the expensive main breaker among multiple lines, the reduced fault isolation time by bypassing the current limiting inductor during energy dissipation, and the ability to reclose softly. Extensive simulations and experiments verify the effectiveness of the device. In addition, the comparison of the new device and existed solutions is presented.

This brief presents SRAM write assist circuit using cell supply voltage self-collapse with bitline charge sharing (SC-BCS) that can lower the minimum operating voltage to the near-threshold voltage (Vth) region while consuming a minimal write energy. The proposed SC-BCS improves the write-ability by utilizing the cell supply voltage (CVDD) self-collapse and the feedback operation through the detection of write failure. Because the amount of CVDD collapse is regulated automatically depending on the write-ability of the selected cell, the write energy of the proposed SC-BCS is effectively reduced. The proposed SC-BCS can achieve a 5σ write-ability yield with a smaller delay overhead than gate-modulated self-collapse and self-collapse write assists in the near-Vth region. In addition, the proposed SC-BCS consumes the lowest write energy with minimal delay overhead or without any delay overhead compared with the strong-bias transient CVDD collapse and pulsed-pMOS transient CVDD collapse. The measurement result of the test chip fabricated using 65-nm CMOS technology indicates that the proposed SC-BCS can operate without any failure up to 0.36 V consuming write power 12.6 μW/MHz.

The integration of overhead lines in future MTDC grids leads to a higher fault rate compared to cables. Most of the faults are con-sidered to be non-permanent, so that the line can be recon-nected after dielectric recovery. The auto-reclosing procedure in HVDC systems reveals new challenges since multiple restrikes are possible within a short period of time. This paper proposes an auxiliary circuit for DC Circuit Breakers (DCCB) which enables to use the DCCB internal capacitor for the line pre-energization. A comprehensive description of the switchgear operations during the pre-energization sequence is provided and the fault property identification method is defined. The method is validated by simulations in a MTDC grid and a sensitivity analysis is carried out using EMTP-RV.

Cable current detection plays a vital role in power grids toward improving transmission efficiency, relieving power congestion, and ensuring grid reliability. However, the sensors in existing current detection systems either are wired with measurement instruments or are wireless yet require batteries, which is inconvenient for monitoring overhead powerlines. Inspired by RF sensing tags, which are widely used for applications such as temperature and humidity measurements, in this article, we propose a distinctive cable current detection system that can avoid the constraint of wires and batteries. By detecting the ambient magnetic field produced by ac current flowing through a cable, the proposed system realizes a minimal measurement range of 5–17.5 A at 50/60 Hz with a maximum wireless distance of 5.2 m. This prototype can detect cable current with an extendable measurement range, providing a promising strategy for passive and wireless current detection.

The hardware security of RSFQ circuits has become an issue of growing importance for prospective exascale computing systems. Hardware security in RSFQ circuits is particularly relevant to large scale data centers operating with sensitive information. The number of fabrication facilities for superconductive niobium-based technology is limited, and the supply chain for distributing fabricated circuits can be compromised. Logic locking is widely used in modern CMOS circuits to enhance security by masking the functionality of the circuit using a secret key. If an attacker possesses a physical circuit secured by logic locking, the attacker would be unable to determine the intended function. In this paper, a novel methodology for logic locking is proposed for SFQ circuits. Mutual inductances are used to apply additional currents to some or all of the logic gates. These currents behave as keys to access the functionality of the SFQ logic elements. In the proposed technique, only after an additional correct current is applied to all of the locked gates will the circuit produce the proper output. By using inductors with a positive and negative mutual inductance connected to the internal inductances of the gates, the range of current required to unlock a secured circuit is greatly narrowed. In this work, the operation of this proposed logic locking technique is demonstrated using modified SFQ OR gates to enable security while maintaining proper functionality. Less than 4% area overhead is achieved.

Today, Ukraine and the world face important issues related to solving the problems of the energy sector, including electricity. In networks of different voltages of power systems the level of short-circuit currents is constantly growing, while the requirements for electrical devices, live parts, power transformers and switchgear designs are becoming more stringent. There is a problem of optimal coordination in the dynamics of electrical equipment parameters and power system requirements or coordination of electrical equipment parameters with existing short-circuits current levels. The growth of short-circuit currents in electrical networks of all voltage classes makes it important to develop new effective methods and devices designed to reduce them. The article considers the issues of comparing the current of single-phase and three-phase short-circuit, average regional power system, the integrated parameters of electrical networks of such a system. Limitations of currents of single-phase short-circuits are analyzed in detail in problem nodes where autotransformers are installed. The conducted researches allowed to recommend the improved methods of calculations of electric devices and current-carrying parts on electrodynamic and thermal stability at short-circuit, including at single-phase. Recommendations for creating a mathematical model for calculating a nonlinear system in the presence of flexible conductors are given, because most of the damage (in the form of short-circuit) on high-voltage overhead power lines and switchgear is accompanied by an electric arc with parameters that change over time. In addition, significant short-circuit currents cause mechanical displacements of flexible wires in space, which leads to changes in the phase distances and inductive resistances of overhead lines of forward and reverse sequences. All these listed factors have a mutual influence during s.c. In addition, when operating electrical installations, an important factor is the switching life of switches, which affects the reliability of the installation and its technical and economic performance. The criterion for decommissioning the circuit breaker may be the residual life of the circuit breaker at the level of one tripping of the full tripping current of the circuit breaker. The analysis showed that it is necessary to take into account when calculating the short-circuit currents additional thermal action of various energy sources and the power system as a whole, synchronous generators and compensators, synchronous and asynchronous motors.

This study aims to investigate the structural behavior of steel transmission towers used for large river crossings. Design standards usually applied to analyze these structures don’t consider situations in which the transmission towers are used in river crossings. In Brazil, due to the fact that it is necessary to cross large areas owing to the rivers’ size, these towers assume great heights. It should be noted that the towers can weigh up to 24,500kN and exceed 300m in height. The current study develops an analysis that surpasses the existing standard methodologies, aiming for a structural optimization compatible with vast crossings and new materials, aiming to resolve this design challenge regarding power transmission lines. To do this, a river crossing spanning 2,300m, situated in the northern region of Brazil, was studied based on the use of three different conductor configurations, electrically equivalent, commonly used wind design standards, and structural solutions utilizing tubular and angle profiles.

In this article the research results of application of back-to-back HVDC system in the Tomsk electric power system are presented. Historically, power transmission between the South to the North parts of the Tomsk electric power system is realized via the long double-circuit 220 kV overhead transmission line. However, due to electrical load increasing and growing complexity of the grid, as well as the length (about 800 km) and low transfer capacity of this transit, it cannot be used as a reliable link for parallel operation of these parts, as a consequence, there is an operational section at this transit. To solve this task, the back-to-back HVDC system is proposed to provide an asynchronous link for parallel operation of these parts. Therefore, appropriate studies and calculations were performed, in particular the optimal location and sizing of back-to-back HVDC system were defined. Extra researches of back-to-back HVDC’s impact on emergency scenarios of Tomsk electric power system power are conducted. It is shown, that its installation decreases the level of short-circuit current and oscillations in electric power system, and as a result increases the stability of load operation, especially motor load.

In this article, we analyze mixed electrified areas where there is a combination of ac/dc electrification. The grounding strategy is completely different, as dc electrification aims to have the rail isolated from the ground, and ac usually has the rail and other metallic parts, such as structures and overhead catenary system (OCS) poles, connected to the ground. At certain locations, it is practically impossible to effectively separate both grounding schemes. This enables the corrosion of the elements directly connected to the ground, namely, structure foundations, grounding rods, or even the rails. This mixed environment presents challenges for both safety and corrosion management. Although it would be a good anticorrosion practice to limit the number of directly grounded elements and connect them all by an aerial ground wire, it must be verified that the touch voltages are safe and compliant with the standards (namely, EN 50122).

Las líneas aéreas de transmisión de energía eléctrica presentan un régimen de operación constante y deben soportar esfuerzos mecánicos debido a posibles descargas atmosféricas, en este sentido es importante realizar una adecuada selección de sus conductores de fase y de guarda. Para soportar los esfuerzos mecánicos los conductores de guarda tienen un componente de acero que presenta características eléctricas variables en función de la corriente circulante por el mismo, por otra parte, esta corriente puede determinarse si se conocen los parámetros eléctricos del cable de guarda.En este contexto, el presente documento detalla dos métodos para determinar la distribución de la corriente entre la tierra y el cable de guarda en condiciones de desbalance, con el cual es posible seleccionar los parámetros eléctricos para la modelación adecuada de una línea de transmisión.Los resultados de estos métodos, aplicados en cuatro casos de estudio, se verifican en su respectiva simulación en el software Alternative Transients Program (ATP).

In this paper, we present a battery management technique that significantly increases the battery lifetime of event-based devices that are predominantly in standby mode without requiring off or on chip large power switches. The proposed technique uses a novel battery management technique to remove Wake-Up Receiver (WUR) Low Drop-Out (LDO) unit, while causing minimal change to the system’s power supply configuration. This technique manages the system so that it can wake up to a normal battery configuration while sleeping in a different battery set-up. This, as a result, drops standby power consumption significantly, making the proposed technique suitable for IoT sensors and, in general, event-based devices. Battery management comprises of voltage level detector, switches for changing battery configuration, and voltage level shifters. The design was applied to an active Radio Frequency Identification (RFID) tag with an embedded WUR and fabricated using TSMC 180nm technology. Measurements on the test chip showed that the proposed architecture and design leads to 80% standby energy saving, prolonging overall (active plus standby) battery’s lifetime by 2.5 times while having negligible area overhead. The advantages and disadvantages of the proposed technique are also presented and discussed.

The overhead distribution transformer is one of the most important and expensive equipment in the distribution grid. Without the proper monitoring of its performance, it can become very difficult to detect possible failures or adverse situations of equipment operation. This article describes a system designed for real-time monitoring and protection of transformers in overhead distribution lines via motorized circuit breakers, installed on the low voltage side. The remote control of the circuit breaker and the calculations of the hot spot temperature and the load of the transformer on the low voltage side will be performed by edge computing. The proposed solution aims to provide protection in the low voltage of the distribution grid and provides more information about the main asset of the utility in the distribution grid. The study is part of an innovation project by Enel Distribuicao Sao Paulo, called “Urban Futurability”. This project is located in an area with a diversity of grid types, from underground grids with high load density to overhead grids of medium load density. The application of the proposed solution in this article will be carried out in part of the overhead grid of the project region, in the city of Sao Paulo, Brazil.

Body-coupled powering (BCP) via the human body channel has demonstrated improved pathloss and body-area coverage over conventional approaches. This work focuses on dynamic optimization of the transmitter (hub-side) output power and frequency, to avoid power overdraw for prolonged transmitter (hub) lifetime. Power evaluation and feedback allow for the transmitter to dynamically adapt its power and frequency, based on the node-specific channel and power condition, with only ~90nW overhead. This saves the overall TX power by 7×. Moreover, HV driver with simplified driving circuits is proposed in standard CMOS process, which allows for 20× improved power delivery (at 105cm) while saving 23% of the TX power consumption. The 40nm CMOS body-coupled power transceiver (TRX) ICs delivers up to 1.1mW and 22µW power to the receiver located at 20cm and 105cm away on the body.

Single-phase short circuit is the most common failure in a 110 kV network of any power supply system. At the same time, the detection and elimination of such a malfunction is a laborious process. This is especially difficult for overhead power lines with polymer insulators, where the damage cannot be seen without climbing to the top of the tower. Therefore, special software is needed for modeling the power system, calculating the parameters of steady-state and emergency modes, as well as remote detection of single-phase faults. The problem of remote localization of single-phase faults imposes certain requirements on the accuracy of the mathematical model of the overhead power transmission line. This is the introduction of the actual distance between the phase conductors. Now it is relevant for industrial power supply systems, where 110 kV power lines can be made with conductors designed for 220 kV. Such wires have reference data calculated for a geometric mean distance between phases of 15 m, which is almost twice as much as the phase-to-phase distance in a 110 kV system. The most convenient and accurate way to model overhead power lines is to use phase coordinates. But using this method is not always justified. The authors of the article have developed a combined equivalent circuit, in which the overhead line is modeled in phase coordinates, and the rest of the circuit elements are modeled in symmetric components.

For the near-distance railway applications, DC feeding is suitable whose demand is on the rise. In DC traction power supply systems, the overhead lines or the third rails are energized from rectifier stations at certain intervals. The breaking of DC current results in a powerful arc since there is no zero crossing in this case. It makes the task of DC supply more challenging and use of power electronic components feasible [1]. To extinguish the generated arc, rectifier stations are equipped with DC circuit breakers. In mechanical DC circuit breakers, the arc burning between the contacts moves into the arc quenching chamber due to its own thermal action. This process takes time while the fault currents continue to increase. Eventually, there is high wear and tear with a great deal of maintenance work. To get rid of these problems, a hybrid DC circuit breaker, otherwise known as the high-speed switching module (SSM), based on principle of power electronics, is used. This paper deals with the simulation of power circuit of SSM using ANSYS Twin Builder.

Energy harvesting has shown to be an effective technology to power wireless sensors and devices for Internet of the Things and Smart City related applications. In this paper, we propose a new design of a free-standing magnetic energy harvester around overhead power lines. The I-shaped core with a pair of magnetic collector plates at both ends can significantly increase the effective permeability and output power of the energy harvester.

Superconducting qubits based on Josephson junctions are one of the leading candidates for building a largescale quantum information processor. There have been significant advances in the performance of superconducting qubits over the past decade and there is currently rapid progress in the development of systems with up to tens of qubits. In order to build to yet larger systems, new techniques will need to be developed to address the overhead requirements for room-temperature electronics hardware and cryostat wiring for controlling and reading out large numbers of qubits. One approach to this challenge involves implementing more of the qubit control and readout in the low-temperature environment. I will describe our efforts on integrating superconducting classical digital circuitry with superconducting qubits for coherent control and readout.

The lightning overvoltage characteristics and lightning withstand level of 35kV overhead lines are further studied. The grounding resistance has a greater impact on the counterattack overvoltage, but less on the shielding overvoltage; the lightning conductor has a greater impact on the counterattack overvoltage, shielding overvoltage and induced overvoltage the results show that the amplitude of lightning current, the location of lightning point and the height of line have great influence on induced overvoltage.

Electromagnetic (EM) radiations are emitted by almost all electrically energized devices such as laptops, smartphones, wireless routers, Wi-Fi, etc. The radiations emitted from the antennas of these electrically charged bodies, when exposed to human tissue without any electromagnetic compatibility protection, can cause severe damage. The presence of electrically charged components is nevertheless increasing day by day and, in turn, increasing the presence of electromagnetic radiation. In present days, electromagnetic radiations consist of radio waves in higher percentages and are present abundantly everywhere. These electromagnetic radiations to be a source of renewable source of energy. The primary aim of this work is to fabricate an electromagnetic collector to energize a battery by absorbing surrounding natural radiation. The gatherer should assemble free power from pretty much anything, including PCs, cell phones, overhead electrical cables, iceboxes, or even the outflows from Wi-Fi or cell phone. This is achieved by the process of wireless power transfer (WPT). One harvester might not be useful, but several such harvesters put together with power electronic converters can generate high output power. A case study is carried out, and the same is demonstrated using a simulation study on the MATLAB/Simulink platform.

Using a continuous dynamic matching circuit in an RF energy harvester ensures the desired output voltage is achieved over the input power range. However, the minimum harvestable power level is limited by the power overhead of the continuous dynamic matching circuit. In order to reduce this power overhead, the processing and actuating block of the control system are duty-cycled. In addition, reducing the granularity or the number of the matching circuit sets lessens the power overhead needed for sensing, processing, and actuating. The RF energy harvester was implemented using an intermittent dynamic matching circuit to improve its input power sensitivity. By reducing the power overhead of the dynamic matching circuit, the RF energy harvester’s lower input power limit was extended from -7dBm to -20dBm.

As the continuous improvement of the level of urban construction in China, more and more overhead lines are replaced by power cables in the distribution network. Therefore, it is particularly important for power enterprises to master and manage the basic data of cables, and cable identification technology is an important basic technology in cable survey and management. The traditional cable identification mostly adopts the amplitude identification technology, there are some problems of low identification accuracy and hidden danger in the actual field application. A research idea of using phase angle identification technology is put forward, and a phase angle cable identification instrument is developed successfully. The principle of electromagnetic induction is used to identify the different phases of the coupling signal through the calculation and analysis of the instrument, and the electrification identification of power cable is realized.

With downscaling of process technology, conventional memories encounter challenges, such as soaring static power, low reliability, and charge sharing effect induced by radiation effects. Magnetic random access memory (MRAM) is considered as an outstanding candidate for addressing these challenges. In particular, emerging spin–orbit torque (SOT) MRAMs have shown ultra-fast switching and read-disturbance immunity compared with spin-transfer torque MRAMs. However, the write operation of the SOT-MRAM is more vulnerable to single-event upsets (SEUs) as its ultra-short write pulse is comparable to the radiation current pulse. In addition, its read circuit can also be disturbed by SEUs or even double-node upsets (DNUs) induced by the charge sharing effect. In this paper, we investigate radiation effects on read/write circuits of the SOT-MRAM. Then, we propose novel radiation hardening designs for SOT-MRAM. The hardening technique is first studied at the write circuit by adding six PMOS transistors as a feedback structure to charge/discharge. Afterwards, we propose a radiation hardening read circuit addressing the issue of SEUs and DNUs, which uses redundant six transistors and two feedback connections as the hardening structure. Based on a physics-based SOT magnetic tunnel junction model and a 65-nm complementary metal–oxide–semiconductor design kit, simulation results indicate that radiation-induced soft errors can be corrected at sensitive nodes. Moreover, the error rate of the proposed read circuit is $40\times $ smaller than the previous work, and restoring time is reduced by 30.6% with negligible area overhead.

Transmission of electrical energy is the most important component of an electric power system. Optimization, modernization of the electric power transport system, increasing the capacity, as well as variability of connection arrangements, while maintaining the required level of reliability and safety, is regarded today as an urgent task for the energy industry as a whole. The article is devoted to the problem of determining the efficiency of the circuit design solution for a double-circuit three-phase power transmission line with an additional mode of operation — «with a split back-up phase» and determining its main reliability indicators. A circuit design solution for a double-circuit power transmission line with expansion of operating modes is presented in detail. The functional redundancy of the transmission line in accordance with the circuit design solution is based on switching of a conventional double-circuit power transmission line in the emergency mode to the single-circuit split-phase mode, which is the second working circuit. The ways of increasing the natural power of a double-circuit power transmission line are considered. The results of calculation of the capacity of a line with a split back-up phase and a comparison of the main parameters of overhead transmission lines with an additional mode of operation — with a split back-up phase — and power lines in conventional modes of operation, are presented. The results of calculations of reliability indicators are presented, such as the probable relative number of hours of interruption of power supply and the undersupply of electrical energy. A comparison of options have shown that the probable relative under-supply of the electric power of a double-circuit overhead transmission line with an additional operating mode — with a split back-up phase, is lower by approximately 13% than that of a conventional double-circuit power line, which will positively affect the maneuverability and reliability of the entire system.

Side-channel attacks (SCA) pose significant threats to the hardware security of embedded devices. Various logical and circuit-level countermeasures propose security, but they all come with different power, performance, and area overhead. Besides countermeasures cannot guarantee security, if the adversaries have enough time and computing power in hacking. Thus, highly accurate, real-time attack detection techniques are needed. This paper proposes a switched-capacitor circuit that can detect power SCAs by intrusion detection of a current sense resistor in the external power supply line. A pulsed current is pulled on the supply line to introduce a voltage difference proportional to the IR drop. This IR drop is then amplified through a parasitic- insensitive switched-capacitor amplifier and compared against a pre-determined threshold. The circuit achieved a 4.01us typical detection time and better than 72% accuracy, consuming 2.97 mW in 65-nm CMOS. This work is the first mixed-signal IC implementation for power SCA detection. Compared to prior approaches that monitor the entire on-chip power grid, this circuit is more computation- and energy-efficient. It uses a single sensor with no need for data mining or machine learning classification.

In modern integrated circuits design, security is a significant concern due to power analysis based side-channel attacks. Various countermeasures such as hiding and masking have limitations, for example, performance degradation, power consumption, low scalability, and area overhead. Besides, these countermeasures cannot detect attacks and alert users to take protective steps against attack. A power side-channel attack (P- SCA) detection system is proposed in this paper through battery impedance monitoring. Due to malicious probing, a non-typical impedance change occurs in the battery. Therefore, our system monitors the battery impedance change to detect such attacks. The detection circuit consists of a 10 bit ADC, an S8050 NPN transistor, a 1N4007 diode, and sense resistors (10 Ω, 50 Ω, 1k Ω). The detection system is designed in an Arduino. Measurements show that the system can detect a P-SCA in 22.020 ms, which is well within the desired detection window. The desired detection windows for different sense resistor values are measured as well. The accuracy and power consumption of implementation are also analyzed.

IoT devices operating on harvested energy from the environment need to deal with the variability of the available energy and consequently adapt the application workload. To support this adaptivity, this paper presents a fully-digital multi-level voltage monitor, operating from an unregulated supply voltage down to sub-threshold. The proposed fully-digital voltage monitor eliminates the overhead of analog components and additional power supplies. The proposed design is based on frequency variation with supply voltage of two specifically designed ring oscillators leveraging the dynamic leakage suppression logic. Simulation results of process variations including corners and random mismatch show a maximum standard deviation of 30mV over a supply voltage range from 0.3 V to 0. 9V after one-point calibration. The simulation results also indicate a maximum of 0.3%/°C relative voltage deviation over a temperature range from 0°C to 90°C. The total power consumption of the proposed voltage monitor is 7nW at 0. 5V, designed in a 28-nm FDSOI technology. The designed digital voltage monitor results in the smallest chip area of 293 $\mu m^{2}$, as compared to the state-of-the-art.

The development of smart and efficient power grid is an inevitable trend in the future [1]. Smart grid needs a flexible, stable and secure energy network, but also needs real-time measurement and dynamic adjustment of power grid state quantities, so as to realize smart sense of information and intelligent self-healing of faults in power grid [2]. Voltage is one of the most important state quantities in power grid. At present, potential transformers commonly used in power grid have many disadvantages, such as large volume, heavy weight, high cost and single function, which make it difficult to meet the requirements of digitalization, miniaturization, and low cost for sensors in smart grid [3]. In recent years, new voltage measurement technologies and electric field sense materials have developed rapidly. There are plenty of researches on electric field sense chip based on piezoelectric material, which is suitable for voltage measurement in smart grid [4]. A voltage measurement method for overhead line based on electric field sense chip is proposed in this paper. The voltage value can be calculated without any contact with the overhead line by applying this method, which requires no high voltage insulation, and no magnetic core and coil neither. This method lays a theoretical foundation for the development of micro smart voltage sensor. Simulation models of two different scenes were established and analyzed to verify the accuracy and efficiency of the proposed method.

An overhead line is usually used in electric power transmission and distribution system to transmit electrical energy along with large distances. The overhead lines are replaced by underground cables in some areas due to their advantages like less power outage and safety. With the introduction of underground cables, Ring Main Unit (RMU) came into existence. It is a compact, enclosed switchgear used for medium voltage power distribution. This paper mainly focuses on monitoring of the RMU. A monitoring system for RMU is necessary to minimize the time taken to find the fault. The present RMUs installed in HUBBALLI do not have a monitoring system. Hence, there is a requirement for a device that continuously monitors the status of the relay and circuit breaker present inside the RMUs. This paper proposes a device that overcomes the problems faced by unmonitored RMUs. This device checks the status of each feeder of the RMU and intimates to the concerned officers if any change occurs. This change is also reflected in the panel installed in the section office of HESCOM. This device minimizes the time taken to detect the fault in the feeders by reflecting the changes immediately which will in turn reduce the outage of the power supply.

High voltage direct current (HVDC) overhead transmission lines produce ion flow and space charge which lead to serious contamination than that of high voltage alternating current (HVAC). Corona and contamination of HVDC may be restrained by covering conductors with insulation layer. In the paper, model of HVDC overhead transmission lines with covered conductors is presented. Electric field is calculated. Results show that covered conductors can restrain ion flow field obviously.

The paper presents a short analysis of benefits and disadvantages of multi-circuit overhead lines operation. Nowadays, the problem to build a new overhead line is a very difficult one because of land cost and different properties crossed by it, environmental impact, opposition of large public etc. Therefore, the solution to use same tower to support many circuits, with same or different rated voltage, also for AC and DC systems is very attractive. The main advantage is that of use of a narrow corridor to transmit a large amount of power. But other problems must be solved in order to make this type of line working properly, from solving the mutual influence of the circuits to lightning protection and up to the low frequency electromagnetic fields profile recorded near to ground.

Ground faults are the most common type of fault in a distribution network. The current seen by the protection relay during a ground fault event largely depends on the impedance of the fault circuit and applied system grounding principle. Therefore, detecting a ground fault effectively and accurately becomes challenging under certain circumstances. A small percentage of ground faults have a very large impedance. They are comparable to load impedance and consequently have very little fault current. These high-impedance faults do not pose imminent danger to power system equipment. However, they are a substantial threat to human beings and properties; people can touch or get close to conductors carrying large amounts of energy. Such ‘wire down’ faults have resulted in causing wild forest fires in some parts of the world with large scale devastation of vegetation and property.There are various technologies available, which can limit the amount of energy released when a ground fault occurs and thus reduce the risk of fire ignition. This paper studies the properties of resonant grounding, also known as compensated networks, which is the prevailing technology globally to limit ground fault current magnitude. The paper also discusses a unique approach to detect ground faults based on Multifrequency admittance principle (67YN). 67YN provides selective directional ground fault protection for any high-impedance grounded networks, that is, for compensated, ungrounded and high resistance grounded systems. It can be applied for the ground fault protection of overhead lines and underground cables. The operation of 67YN is based on novel multi-frequency neutral admittance measurement utilizing Cumulative Phasor Summing (CPS) technique. This concept provides extremely secure, dependable and selective ground fault protection in compensated networks.

A neutral section is a phase break that is used on the Transnet freight rail system to separate the single-phase supply from the 25kV three-phase overhead traction supply. The 25kV is a stepped-down voltage from an 88kV three-phase supply coming from the national grid. Electric locomotives operate only on a single-phase supply and require a separation of supplies as the trains traverse from one phase to the other; consequently, electric locomotives are required to switch off at the neutral sections. The most common automated schemes that have been implemented in switching electric locomotives are ground, on-board, and pole switching systems; one downside to these types of schemes is their relatively large investment and infrastructure costs. This paper proposes a new automated scheme that employs the use of computer vision and image processing methods. The system uses two unique markers that are externally situated along the railway tracks and used to trigger either the opening or closing of the electric locomotive vacuum circuit breakers as the trains traverse through the neutral sections. The two markers were designed in accordance with Transnet guidelines and the system employs shape detection algorithms, including a circular Hough transform (CHT), to locate the markers, and histogram of oriented gradient (HOG) for feature extraction and training of the classifier. The model has an accuracy of approximately 72%.

Capacitive current switching is energization or de-energization of no-load cables/overhead lines, capacitor banks, or filters in ac circuits at distribution or transmission voltages. The switching process may involve high voltage and high current transients. Capacitor banks are widely used for the compensation of reactive power in the power system; The capacitor banks are switched frequently, perhaps once or twice a day.

The demand for electrical power is now increasingly growing day by day, which results in the transition of enormous power by increasing the ability of the transmission line from one location to another. As a result of the development of the structure of the power grid, detecting power system transmission line faults every year becomes a challenging task as the system becomes more complicated. Controlling and monitoring of power systems are inevitable due to the constant growth of the power system network. In order to find the correct decision, to search for any possible problems and fault conditions in a broad interconnected network, modeling and analysis of the power system have become significant. On the overhead transmission line, a fault will rise while the two or more of transmission lines touch each other. Generally, the faults in overhead transmission lines can be categorized as the line to ground fault, the line to line fault, double line to ground fault and three-phase faults. Single line ground faults mostly occur in the distribution network. The main purpose of this work is to study or explore the single line to ground fault and recognize the impact of the transmission line fault along with the industrial load under different loading conditions that is joined with transmission line according to the distance variation using Typhoon HIL.

High voltage direct current () is an economic alternative to alternating current () transmission to transmit power over long overhead lines when the transmission distance exceeds 500 – 1000 km. It is practically the only solution for transmitting power with long underground/submarine cables or to connect two nonsynchronous systems.

Gas-insulated mental enclosed transmission Line(GIL) as an overhead transmission mode or a supplementary transmission technology with limited transmission point of cable, has the advantages of large capacity, less space, flexible layout and high reliability. In view of the operating characteristics of UHV GIL, in order to ensure its safe and stable operation, an arc fault monitoring system is deployed inside the GIL tube corridor. The energy acquisition mode of the arc fault monitoring system is mainly studied in this paper. Based on the angle of high and low potential isolation, security and practicality, a scheme of laser optical fiber power supply and communication for UHV GIL arc fault monitoring is proposed, which provides stable and reliable energy supply and communication guarantee for arc fault location and monitoring equipment, and provides support technology for safe and stable operation of UHV GIL.

International audience; This paper describes two fully-integrated transfer switches designed for in-situ reflectometers and Built-In Self-Test applications (BIST) in the 140 to 220 GHz band (G-band). The proposed switches were designed in the STMicroelectronics 55-nm BiCMOS technology using the Single-Shunt and the Double-Shunt topology, respectively. In the 140 to 195 GHz frequency range, the Double-Shunt Transfer Switch shows an isolation between 27 and 46 dB, and an insertion loss between 5 and 7 dB. Compared to the Single-Shunt Transfer Switch, the double shunt switch presents a much better isolation while having a quite comparable insertion loss and area overhead. To the best of our knowledge, the proposed switches are the first fully integrated transfer switches in BiCMOS or CMOS technologies.

Operations with circuit breakers and switches in power system causes switching surges. Switching surges due to closing and reclosing operations with breakers could be dangerous for equipment in substations. Determining overvoltage level for the equipment is important for power system reliability. These representative overvoltages are useful for insulation coordination procedure. Due to the nature of the overvoltages statistical distribution of overvoltages for more than one switching operation is needed. This paper present statistical analysis of energization and re-energization overvoltages in overhead transmission line 220 kV due to circuit breaker operation in substation 220 kV. The model study is done with ATP/EMTP software.

Power system is exposed to overvoltages due to different reasons. Switching overvoltages are one of common causes of outages and damages in the system. Switching overvoltages are caused by circuit breaker operations. These operations are classified as closing and reclosing. Overhead line energization and de-energization causes switching surges. These surges under certain conditions can be dangerous for the facilities in the power substations. Therefore the knowledge of overvoltage levels and the factors affecting them is important for power system reliability. In this paper switching overvoltages due to closing and re-closing operations of overhead power line 220 kV are investigated through model study. ATP-EMTP software is used for power system modeling. Case studies without using surge arresters and with surge arresters are reviewed in the paper. Overvoltages in different location on overhead line are shown.

This paper gives results of the performance evaluation of noninvasive sensors that are used to estimate current by sensing the magnetic field produced surrounding the overhead power conductors in transmission and distribution of power generated by smart grids. The objective of the research is to replace the conventional instrument transformers to bring more ease of operation and maintenance in addition to save the space in the switchgear as well as substation. The experiment is performed in the laboratory on an alternating current. The sensors work on the principle of Giant Magnetoresistance (GMR) and Tunnel Magnetoresistance (TMR) effect.

This paper describes a simulation and an example of remote control of the process of melting ice with reactive currents on overhead power lines without disconnecting consumers from the network, as well as without adding duplicate or bypass wires and complicating the power line. Modeling of the method clearly shows the possibility of increasing the current to the current of melting ice on this section of the circuit. The device consists of a remotemounted choke and capacitor, which are activated by remotely controlled thyristors.

As the supply voltage decreases, there is a need for a high-speed negative charge pump circuit, for example, to produce the back-bias voltage (VBB) with high pumping efficiency at a low supply voltage (VDD). Beyond the basic negative charge pump circuit with the small area overhead, advanced schemes such as hybrid pump circuit (HCP) and cross-coupled hybrid pump circuits (CHPC) were introduced to improve the pumping efficiency and pump down speed. However, they still suffer from pumping efficiency degradation, low level |VBB|, and small pumping currents at very low VDD. A novel negative charge pump using an enhanced pumping clock is proposed. The proposed cross-coupled charge pump consists of the enhanced pumping clock generator (ECG) having a pair of inverters and PMOS latch circuit to produce an enhanced control signal with a greater amplitude, thereby working efficiently especially at low supply voltages. The proposed scheme is validated with a HSPICE simulation using the TSMC 180 nm process. The proposed scheme can be operated down to VDD = 0.4 V, and |VBB|/VDD is obtained to be 86.1% at VDD = 0.5 V and Cload = 20 nF. Compared to the state-of-the-art CHPC scheme, the pumping efficiency is larger by 35% at VDD = 0.6 V and RL = 10 KΩ, and the pumping current is 2.17 times greater at VDD = 1.2 V and VBB = 0 V, making the circuit suitable for very low supply voltage applications in DRAMs.

The characteristic of the problem, relevance of the paper. At the present time in electric power industry a concept of intelligent electrical power system is realized. A key component of this system is a digital substation. One of the main tasks of digital substation equipment is realization of effective relay protection and network automation devices. Relatively new phenomenon in this field is relay protection devices, which are based on travelling wave parameters measurement. A very important characteristic of relay protection devices (especially for extra-high voltage transmission lines of 330-750 kV) is their speed-of-response. The usage of travelling wave-based principle will allow to limit speed-of-response only by travelling wave propagation time along a protected transmission line.

Covered conductors represents an alternative to the reinforced aluminum conductors. The E.ON Distribuce company aims to replace some of the reinforced aluminum conductors in its overhead distribution network with covered conductors. To make this distribution network as reliable as possible, the overhead powerlines will be equipped with online insulation fault detector. Problematic insulation fault detection is one of the biggest disadvantages of medium voltage covered conductors, because of the very low fault current. But during this type of faults, partial discharges activity is usually presented. Based on this knowledge, on-line partial discharges monitor was deigned at VSB – TUO to detect such insulation faults on medium voltage overhead power lines. This article describes the testing of various covered conductors from the point of partial discharge activity during high impedance faults.

A 25 kV AC electric railway is a completely asymmetrical network using rails as the return wire. However, part of the return current from the rails flows into the ground. This circumstance leads to an increase in the voltage induced on de-energized overhead power lines and other extended communications located near. The calculation of possible values of the induced voltages on the repaired line, taking into account maximum loads in the contact network, is of great importance to ensure the safe conduct of remedial work on de-energized power lines. The article describes a program complex for estimation of the inducted voltage level on de-energized power lines exposed to the electromagnetic influence of overhead contact system. The results of calculations of the induced voltage on the overhead power lines, made taking into account the experimental data of currents in the traction network are presented. The theoretical and experimental data of the induced voltage were compared.

Single-core X-linked polyethylene (XLPE) cables are widely dispersed in 110–500 kV grids and supposed to replace traditional overhead lines due to different advantages, such as higher operating temperature, its compactness, etc. However, the construction of XLPE cable lines is complex, which defines many difficulties in calculation of its zero-sequence impedance, especially in the case of a group of several cable lines laid in one trench. The number of cable lines laying in one trench may vary from 4 to 6, and several cable lines may be placed in less than one meter between each other. In this case, the mutual inductance may take significant values and should be taken into account in the zero-sequence impedance calculation. This paper outlines a practical approach allowing for the calculation of the zero-sequence impedance precisely. This approach is based on matrix transformations.

Disturbances resulting from switching operations, failures, lightning strikes or loads variations can cause abnormal currents and voltages dangerous for the equipment and the analysis and evaluation of the latter is essential for the reliability of the system [1], [2]. The conventional HV networks are built mainly as overhead, but the progressive increase in the share of cable lines leads to significant topological and parametric changes in the network, and hence its behaviour during transients. Ensuring the reliable and safe operation of the equipment requires the study of the current and the phenomena encountered during transients in networks with a large share of cables. This paper presents a study and analysis of some phenomena caused by switching operations in a real HV electrical network, part of the electric power system. For the purposes of comparison, the paper also represents some transient phenomena typical for overhead lines (OHL) although they are widely studied. The studies were performed in ATP-EMTP.

The 500kV overhead transmission line induction power supply technology can provide stable and reliable power for high-voltage line online equipment and inspection robots. Since the magnitude of the induced current induced in the ground wire is small, in order to make full use of the induced energy, the principle of impedance matching can be used according to the topology of the circuit to increase the power drawn from the induction. This article focuses on the operating environment of 500kV overhead transmission lines, and designs a typical induction power circuit structure consisting of a power coil, a rectifier filter circuit, and a two-level DC-DC converter circuit. Based on this simplified equivalent circuit model, this paper designs the controller of the two-level DC-DC converter circuit, and realizes the maximum power point tracking (MPPT) control of inductive power draw by changing its duty cycle. Finally, the simulation results on the Simulink platform verify the accuracy of the simplified circuit model and the effectiveness of the maximum power point tracking control method.

This paper presents a study concerning the transmission line uprating method by injection of third harmonic voltage (THV). The method has been recently employed as a more economically feasible proposal to raise the transmission voltage level without the requirement for changes in the structural elements of overhead lines. The superposition of a third harmonic voltage component with the fundamental component at the sending and receiving ends of the line increases the amplitude of the fundamental voltage component without exceeding the electrical insulation tolerance limits, which results in a rising of the power transfer capability. This workshows a study on the behavior of the voltage profile of several OHTLs, represented by Bergeron's model, which were uprated by the THV technique. The results have shown that THV technique is a feasible option for OHTLs of up to 200-km length. For OHTLs longer than 200 km, phase voltages may exceed safety levels which imposes a limitation in the uprating of the long lines by this technique.

Power cables are mainly used for power transmission and distribution purposes where it is practically difficult or not safe to use overhead transmission lines. This paper describes the development of a laboratory size model of an actual power cable of 30Km, 4000MVA(SIL) and 500KV, scaled down to 20Amp and 230Volts. A high voltage cable is represented by six π-sections each of 5Km connected in series to represents 30Km long cable. Simulation of cable model has been performed in MATLAB SIMULINK and hardware was tested to analysis the characteristics of power cable.