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The transmission line is one of the most crucial electric power system components, demanding special attention since they are subject to failures that can cause disruptions in energy supply. In this scenario, the fault location emerges as a fundamental task, providing an approximate position where the failure occurred in the line. This paper presents a method for fault location using a novel dynamic regressor selection (DRS) framework, in which we introduce embedded normalization, incorporating the data scaling process inside the framework. The DRS aims to select the most accurate models from a pool of regressors to predict the fault distance. Moreover, since there is a lack of a public dataset, this paper presents and makes a new fault dataset available to the scientific community with several features extracted from current and voltage signals of representative failure events. In our experiments, we demonstrate the importance of this embedded normalization as well as the significance in the variation of critical hyperparameters of the DRS strategy, such as the distance metric used to define the region of competence and the criterion to select the best regressors from the pool of predictors. This work also presents the definition of the oracle concept in DRS, which represents the ideal predictor selection scheme. The results demonstrate the effectiveness of the proposed method with a mean error of 0.7086 km ± 0.0068 km, representing 0.1712% ± 0.0016% of the transmission line extension (414 km). [ABSTRACT FROM AUTHOR]

The application of distributed sensors in smart transmission lines to replace traditional inspection methods is an inevitable trend. Currently, the challenge of energy supply for sensors serves as a bottleneck that hinders the intelligent development of transmission lines. This paper focuses on the application of self‐powered inspection technology based on triboelectric and electromagnetic mechanisms in transmission lines. It proposes a self‐powered temperature and vibration monitoring and warning system (STV‐MWS) for multi‐parameter monitoring of transmission line status. This work utilizes the quasi‐zero stiffness structure and center misalignment design to improve the output performance of STV‐MWS at low vibration amplitude, thereby extending its vibration amplitude response range. The STV‐MWS is capable of harvesting and monitoring vibration of 50 µm and above vibration amplitude and 2–700 Hz vibration frequencies, which fully covers the breeze vibration range of transmission lines. Through the split package design, the flexible deployment of STV‐MWS is achieved, further enhancing its engineering application value. This work can effectively ensure that the transmission line inspection can carry out accurate status monitoring and intelligent analysis in the environment characterized by steep terrain, challenging power extraction, and difficult fault judgment, thereby realizing the visualization and intelligence of the transmission line status. [ABSTRACT FROM AUTHOR]

This paper proposes a design scheme for a wireless power transfer (WPT) system based on multi-relay coils to solve the power supply demand of 500 kV transmission line online monitoring equipment. The relationship between the operating frequency and the coil loss is established to analyze the influence of the number of relay coils and the coil distance on the transmission performance. The particle swarm optimization model is established with transmission efficiency as the optimization objective. The distribution spacing between coils, the working frequency, and the number of coils are optimized. Based on the equidistant arrangement of relay coils, an optimization scheme of non-equidistant arrangement is proposed. Under the condition of the same number of relay coils, the transmission efficiency of the system is increased by 20.56% and has been verified by experiments. In addition, finite element analysis software has simulated the surrounding high-voltage field strength of the WPT system added to the insulators. The results show that the insulators still meet the insulation standards. The simulation and experimental results show that the proposed scheme can effectively meet the power demand of high-voltage line monitoring equipment. [ABSTRACT FROM AUTHOR]

This paper analyzes the behavior of an electrical power system when N-1 contingencies occur in the transmission stage, which can be produced by incorrect operation of the protection relays, phenomena of natural origin, or increased loadability, which affect the operation and reliability of the electrical system. The operation output of a transmission line results in the variation of the nominal values of the electrical parameters involved because they disturb the stability of the generation, transmission systems, and the supply of electrical energy to the loads, such as voltages and angles of the nodes and the active and reactive power of the system. The proposed methodology was based on analyzing the different electrical parameters of the power system, quantifying the contingency index in a state of regular operation, and comparing it to operation in contingency N-1, with which the most severe contingency was determined and, therefore, achieved; identifying contingencies that can cause system collapses; improving the contingency index from 23.08555 to 22.9276624 for the L16–19 contingency and to 22.9795235 for the L21–22 contingency, which are the most severe contingencies determined with the proposed methodology. To test the proposed methodology, the IEEE 39 bus-bar test system was considered, and the elements that should be implemented to avoid the vulnerability of the power system to N-1 contingencies were determined. [ABSTRACT FROM AUTHOR]

The electrical power distribution parts include the distribution transformer responsible for reducing high voltage (HV) 11 Kv to low voltage (LV) 416/240 volts, and the power distribution lines (PDLs), which are the source of electrical power supply for residential neighborhoods. Any malfunction of these parts, result in a power outage. Currently, any faults are reported, detected, and alert in a primitive way, and this mechanism certainly takes a lot of time and effort. In this paper, an automatic approach for detection, report and alert has been suggested. This approach process is carried out by continuously checking the status of the three output feeders (power distribution lines), which is the low voltage side of the distribution transformer, when a malfunction occurs in any one or more of these feeders, it will generate an alert signal in the form of a text message using short message service (SMS). The maintenance center is notified by receiving this SMS via SIM900 modem through the global system for mobile (GSM) communications network. The SMS text message includes feeder number, fault type and location address (street number and distribution transformer number). In this design, time and effort are shortened and the maintenance center enables fully automatic monitoring of electric power distribution parts within the sector of responsibility. [ABSTRACT FROM AUTHOR]

Low-voltage distribution lines lack efficient monitoring. With the massive proliferation of distributed energy resource supply, it is necessary to establish an effective monitoring system for low-voltage distribution lines to ensure the electrical safety and continuity of power supply services. This paper proposes monitoring system for low-voltage distribution lines based on the Internet of things (IoT) technology. An IoT based monitoring system contains a large number of low-voltage monitoring terminals, different manufacturers, and different types of terminal equipment to solve the interconnection problem of information interaction. This paper first analyzes the terminal functional communication requirements based on IEC 61850 standards. Further, the information models required by the electrical volume collection and non-electric quantity collection functions are studied. The information modeling for different types of monitoring terminal equipment is presented and thus provide the configuration suggestions. The monitoring terminal based on the information model developed in this paper is applied in a university campus to realize the monitoring of low-voltage lines and distributed power supply. [ABSTRACT FROM AUTHOR]

In the electricity business, power evacuation from source to load is a challenging task when there is contingency and agencies have to swirl around for solutions in terms of rescheduling generator dispatch, load slashing, adding of network, etc. The more challenging scenario arises when the independent operator wants to re-dispatch a generator during the contingent situation. So, in this paper, we focus on a new generator rescheduling technique with congestion price and transmission security as an intervention. The significant intention of this paper involves restricting the load thereby dispatching a particular generator or a set of generators with low cost and secure transmission line. In addition to this, the network jamming is unpredictable and does not follow any pattern, but power supply in some zones is disrupted due to hidden reasons. Therefore, a macroscopic or holistic approach is adopted for congestion forecasting through demand schedule, gathering, minimum as well as maximum drawls. Here, two significant factors namely the transmission utilization charges as well as transmission congestion charges for predicting the congestion of a transmission line are evaluated. Finally, the experimental analysis to determine transmission utilization charges, transmission congestion charges, cost function and generation supply as well as demand balance with congestion optimization. [ABSTRACT FROM AUTHOR]

The secular increase of load causes the evolving power system to operate near the critical margins. In such attitudes, the probability of cascading line outages, as the major reason for recent blackouts, is much more than expected. As a result, an innovative approach for optimal AC transmission expansion planning (TEP) to minimize the risk of cascading blackouts is presented in this paper. The proposed multi‐objective AC‐TEP problem minimizes the expected energy not supplied due to the total load shedding imposed on the system to mitigate the risk of cascading line outages along with the total investment and operational costs of the new transmission lines planned to be optimally added to the system. This probabilistic procedure is based on self‐organized criticality and considers the actual aspects of the power system such as reactive power and voltage concerns in the planning stage. The obtained Pareto front set provides the opportunity for the planners to choose the most preferred solution. The proposed method is implemented and verified in the IEEE 118‐bus test system and compared with two types of TEP approaches. The first one is a previously reported version of this work which was a simplified DC model of the problem and the second one is the conventional AC‐TEP model. The obtained results show the benefits of the proposed AC model on the mitigation of cascading line outages in a more realistic framework, considering the impact of reactive power and voltage stability concerns. An innovative approach for optimal AC transmission expansion planning (AC‐TEP) to minimize the risk of cascading blackouts is presented in this paper. The proposed multi‐objective AC‐TEP problem minimizes the expected energy not supplied due to the total load shedding imposed on the system to mitigate the risk of cascading line outages along with the total investment and operational costs of the new transmission lines planned to be optimally added to the system. This probabilistic procedure is based on self‐organized criticality and considers the actual aspects of the power system such as reactive power and voltage concerns in the planning stage. [ABSTRACT FROM AUTHOR]

In this paper, a DC power supply is presented that, in addition to a power factor correction, is equipped with an active power filter function. This function enables compensation of both the reactive and the distortion power, generated by an external load, which is connected to the same power line node as the presented device. A tuneable inductive filter is added at the input of the power electronics controlled current source, which constitutes the main block of the power supply. This filter allows for a visible improvement in the quality of the current source control, compared to a similar device with a fixed inductive filter. This improvement depends on extending the "frequency response" of the current source, which facilitates an increase in the dynamics of changes in the input current of the power supply. The actual modification to the presented device is related to its control section, which is equipped with analogue regulators. The main purpose of this work is to present the results from a simulation model of an electrical system with a power supply, especially compared to those from a similar device but with a discrete control. The work represents a continuation of a research cycle on DC power supplies that are equipped with a power compensation function and are based on tuneable magnetic devices. [ABSTRACT FROM AUTHOR]

In recent times, the virtual power plant (VPP) is gaining more attention in power system engineering due to its tremendous potential in enhancing sustainable urbanism, in which, it supplies clean energy from distributed generators. Electricity is deemed a basic requirement for future automotive and ultra-modern technologies. The deficiency of traditional energy resources and their complex generation process make the production cost of electricity increase dramatically. Moreover, traditional power distribution systems are encountering issues in distributing electrical energy to fulfill customer demands. Therefore, this paper proposes a novel power management system named 'the hybrid genetic local binary knowledge (HGLBK) algorithm' to manage power distribution in the transmission lines and to optimize the total operation cost of the network. The hybrid optimization algorithm effectively controls the load by supplying the surplus power load to the adjacent feeders thereby optimally selecting and placing the distributed energy resource (DER). The proposed concept is implemented at Kayathar, Tamil Nadu in India, and their real-time data are utilized for modeling the VPP. The proposed VPP concept is implemented in the IEEE-9 bus system and the performance of VPP is simulated using the MATLAB software. The performance of the proposed HGLBK algorithm is assessed by comparing its effectiveness with the existing approaches. [ABSTRACT FROM AUTHOR]

Vegetation encroachment in power line corridors remains a major challenge for modern energy-dependent societies, as it can cause power outages and lead to significant financial losses. Unmanned Aerial Vehicles (UAVs) have emerged as a promising solution for monitoring infrastructure, owing to their ability to acquire high-resolution overhead images of these areas quickly and affordably. However, accurate segmentation of the vegetation encroachment in this imagery is a challenging task, due to the complexity of the scene and the high pixel imbalance between the power lines, the vegetation and the background classes. In this paper, we propose a deep learning-based approach to tackle this problem caused by the original and different geometry of the objects. Specifically, we use DeepLabV3, U-Net and a modified version of the U-Net architecture with VGG-16 weights to train two separate models. One of them segments the dominant classes, the vegetation from the background, achieving an IoU of 0.77. The other one segments power line corridors from the background, obtaining an IoU of 0.64. Finally, ensembling both models into one creates an "encroachment" zone, where power lines and vegetation are intersected. We train our models using the Vegetation Encroachment in Power Line Corridors dataset (VEPL), which includes RGB orthomosaics and multi-label masks for segmentation. Experimental results demonstrate that our approach outperforms individual networks and original prominent architectures when applied to this specific problem. This approach has the potential to significantly improve the efficiency and accuracy of vegetation encroachment monitoring using UAV, thus helping to ensure the reliability and sustainability of power supply. [ABSTRACT FROM AUTHOR]

In the islanded microgrids, distributed energy sources are responsible for powersharing, and accurate power-sharing is essential among these microgrids. Due to the mismatch of the physical impedance of power lines, poor reactive power-sharing is observed. Therefore, in this paper, the use of virtual impedance in the form of two methods of virtual positive impedance and virtual negative impedance is proposed to improve the accuracy of reactive power-sharing in a conventional droop controlled islanded microgrid. In this paper, in addition to presenting a controller to properly adjust the virtual impedance, the concept of vir'tual negative impedance is used to correct the effective impedance of the power supply line and improve the common bus voltage, and increase tire output power of energy sources. To evaluate the proposed control methods, a test islanded microgrid is simulated inPSCAD/EMTDC software. The results show that both pr'oposed methods have a good effect on the proper reactive power-sharing irr the microgrid. In addition, the results show that the virtual negative iirrpedance method can improve the common bus voltage and increase the output power of the source by reducing the effective line impedance. [ABSTRACT FROM AUTHOR]

Missing insulator caps are the key focus of transmission line inspection work. Insulators with a missing cap will experience decreased insulation and mechanical strength and cause transmission line safety accidents. As missing insulator caps often occur in glass and porcelain insulators, this paper proposes a detection method for missing insulator caps in these materials. First, according to the grayscale and color characteristics of these insulators, similar characteristic regions of the insulators are extracted from inspection images, and candidate boxes are generated based on these characteristic regions. Second, the images captured by these boxes are input into the classifier composed of SVM (Support Vector Machine) to identify and locate the insulators. The accuracy, recall and average accuracy of the classifier are all higher than 90%. Finally, this paper proposes a processing method based on the insulator morphology to determine whether an insulator cap is missing. The proposed method can also detect the number of remaining insulators, which can help power supply enterprises to evaluate the degree of insulator damage. [ABSTRACT FROM AUTHOR]

The power supply of many applications running off the power line is made up of an isolated dc-dc converter powered by a front-end power factor corrector (PFC) stage. The PFC stage ensures compliance with the electromagnetic compatibility regulations but does not usually provide safety isolation since it is typically implemented with a boost converter. Lately, the increase in multi-output power supplies, especially in lighting and USB Power Delivery applications, has raised the need for an isolated PFC at power levels where currently there is not an industry standard solution. This isolated PFC is intended to power one or more non-isolated post-regulators to enable a substantial simplification of the overall architecture and a cost reduction. The usage of an LLC resonant converter as an isolated PFC has been considered and demonstrated only quite recently, raising the industry's attention due to the favorable converter's characteristics that have led to its success as a dc-dc converter. This paper provides two significant contributions. Firstly, it provides a quantitative assessment of the difference in the results obtained by designing an LLC-based PFC converter based on the first harmonic approximation analysis or the time-domain analysis by applying them to the design of the same converter. Secondly, it demonstrates that designing an LLC-based PFC converter to work also in the above-resonance region optimizes its performance by reducing the (magnetizing) reactive current in the resonant tank and, therefore, the rms currents on both the input and the output side and the related power loss. [ABSTRACT FROM AUTHOR]

Transmission line fault detection using drones provides real-time assessment of the operational status of transmission equipment, and therefore it has immense importance in ensuring stable functioning of the transmission lines. Currently, identification of transmission line equipment relies predominantly on manual inspections that are susceptible to the influence of natural surroundings, resulting in sluggishness and a high rate of false detections. In view of this, in this study, we propose an insulator defect recognition algorithm based on a YOLOv5 model with a new lightweight network as the backbone network, combining noise reduction and target detection. First, we propose a new noise reduction algorithm, i.e., the adaptive neighborhood-weighted median filtering (NW-AMF) algorithm. This algorithm employs a weighted summation technique to determine the median value of the pixel point's neighborhood, effectively filtering out noise from the captured aerial images. Consequently, this approach significantly mitigates the adverse effects of varying noise levels on target detection. Subsequently, the RepVGG lightweight network structure is improved to the newly proposed lightweight structure called RcpVGG-YOLOv5. This structure facilitates single-branch inference, multi-branch training, and branch normalization, thereby improving the quantization performance while simultaneously striking a balance between target detection accuracy and speed. Furthermore, we propose a new loss function, i.e., Focal EIOU, to replace the original CIOU loss function. This optimization incorporates a penalty on the edge length of the target frame, which improves the contribution of the high-quality target gradient. This modification effectively addresses the issue of imbalanced positive and negative samples for small targets, suppresses background positive samples, and ultimately enhances the accuracy of detection. Finally, to align more closely with real-world engineering applications, the dataset utilized in this study consists of machine patrol images captured by the Unmanned Aerial Systems (UAS) of the Yunnan Power Supply Bureau Company. The experimental findings demonstrate that the proposed algorithm yields notable improvements in accuracy and inference speed compared to YOLOv5s, YOLOv7, and YOLOv8. Specifically, the improved algorithm achieves a 3.7% increase in accuracy and a 48.2% enhancement in inference speed compared to those of YOLOv5s. Similarly, it achieves a 2.7% accuracy improvement and a 33.5% increase in inference speed compared to those of YOLOv7, as well as a 1.5% accuracy enhancement and a 13.1% improvement in inference speed compared to those of YOLOv8. These results validate the effectiveness of the proposed algorithm through ablation experiments. Consequently, the method presented in this paper exhibits practical applicability in the detection of aerial images of transmission lines within complex environments. In future research endeavors, it is recommended to continue collecting aerial images for continuous iterative training, to optimize the model further, and to conduct in-depth investigations into the challenges associated with detecting small targets. Such endeavors hold significant importance for the advancement of transmission line detection. [ABSTRACT FROM AUTHOR]

The power system on Jeju Island currently faces challenges due to an imbalance between power supply and demand owing to increasing renewable energy (RE) generation. Consequently, the multi-infeed high-voltage direct-current (MIDC) systems are expected to play an important role in reducing RE curtailment and increasing RE penetration. However, despite the balance between power supply and demand, transmission line (TL) overloads on Jeju Island, which has a low permissible rating, may lead to RE curtailment. We propose an operational strategy for the MIDC systems to mitigate TL overloading and RE curtailment. This strategy was aimed at managing the possible congestion of TLs, maintaining a power supply–demand balance, and increasing the penetration level of RE. In this paper, we present a scheme for calculating the operating points of the MIDC systems and allocating RE curtailment using optimization with security constraints to mitigate TL overloading. The proposed optimization model simplifies solving the mathematical equations involved by employing a sensitivity factor called the power transfer distribution factor (PTDF), using which linear programming (LP) optimization can be performed. To verify the feasibility of the operational strategy, case studies are conducted using an actual Jeju Island power system with a power system analysis tool—Power System Simulator for Engineering (PSS/E). The optimization problem was solved using MATLAB. [ABSTRACT FROM AUTHOR]

—The modular multilevel converter (MMC) has proven to be the most advanced voltage source converter (VSC). For long-distance power transfer, high-voltage DC (HVDC) is the best choice. Across the globe, electric power networks are witnessing rapid growth in MMC-HVDC installation to meet the ever-growing power demand. The existing AC transmission lines can be converted to DC lines by adding converters. The MMC-based multi-pole HVDC presents an adequate solution for upgradation. However, more study is required to make it a reality. The present paper attempts to bridge this gap. The proposed study can be divided into two parts. Initially, the concept of symmetrical multi-pole MMC-HVDC is proposed, and its mathematical relations have been derived. The multi-pole has been subdivided into an even and an odd configuration. The half-bridge submodule (HBSM)-based MMC lacks DC fault handling capability. The second part of the study includes controller and fault analysis of the HBSM-based tri-pole MMC HVDC. The study shows the severity of the pole-to-pole faults, leading to a complete shutdown of the transmission line. A controller and an algorithm for the DC fault-ride-through (FRT) have been proposed. The proposed controller has digital switches to temporarily bypass the real-time measurement values with measurements taken under healthy conditions. An impact analysis of the parameters of one MMC on the equilibrium of the entire multi-pole configuration is performed. The performance of the proposed controller has been carried out on a real-time digital simulator (RTDS). The proposed controller and FRT algorithm ensure that the tri-pole HVDC maintains the power supply during all DC faults. In the worst-case scenario, the shutdown is averted with a 50% reduction in power transfer capability. The transients in active and reactive power are minimized and eliminated within a cycle. Further, using the most economical and simplest submodule ensures the configuration without any additional cost. [ABSTRACT FROM AUTHOR]

The electrical energy supply of industrial equipment is provided by electrical power stations with high- (HT), medium- (MV) and low-voltage (LV) busbars. Consumers are connected to either MV or LV busbars. In this paper, a real power station was considered, through which the gasoline extraction from the well gas installation is powered. Electric consumers (electric motors) supplied by a MV busbar have active power of 13.54 MW, and those fed by a LV busbar have active power of 6.4 MW. Since electrical consumers operate in explosive environments, the design and operating conditions are more severe than in the case of electrical installations operating in non-explosive environments. The case of a single phase-to-ground fault occurring on the HV transmission lines feeding the power station has been analysed. First, the mathematical models for the calculation of the phase voltages, the dissymmetry and asymmetry coefficients, the reduction coefficient of the plus sequence component, and the effective values of the phase voltages were established. The influence of the source impedance (the equivalent impedance of the HV transmission lines) and of the neutral point configuration of the HV/MV medium-voltage transformer on the calculated quantities was analysed. Then, the results obtained using the established mathematical models were compared with those obtained experimentally by provoking a single-phase-to-ground fault near the HV busbars of the real power station. This study has shown that the de-symmetrisation of the phase voltages of the MV and LV busbars is lower when using the Y/Δ connection for the HV/MV transformer. As a result, it is recommended the Y/Δ connection be used for this transformer, instead of the Y0/Δ connection. [ABSTRACT FROM AUTHOR]

The unnecessary prolonged operating time of conventional current differential protection under high‐impedance DC line faults is an important issue affecting the continuity of power supply. This issue originates from the extreme differential current fluctuation under fault conditions. This paper presents a reinforced pilot protection algorithm for bipolar CSC‐HVDC transmission lines to achieve a selective and sensitive performance without sacrificing the protection speed. In this regard, the characteristics of low‐frequency transient modal currents are investigated along with the impact of discharging capacitive current under various fault conditions. Based on the features arising from line‐mode compensated currents, it is shown that their opposite changing directions induces a positive high‐value differential current during DC line faults, whereas the compensated line‐mode currents follow the same changing trend under external faults. After detecting internal faults, the faulted pole is detected by utilizing the polarity of ground‐mode components. Compared to other pilot protections, the proposed protection provides more reliability, selectivity, and sensitivity with high operating speed. Moreover, it has robust performance against discharging capacitive current, asynchronous measurement, line parameters uncertainty, and noise. Various simulation tests are performed on a ±500 kV HVDC test system in PSCAD to verify effectiveness of the proposed protection. [ABSTRACT FROM AUTHOR]

• The proposed single-ended fault location framework fully considers the effect of partial coupling, without requiring measurements from the remote ends. • Within the proposed framework, two methods based on impedance line model and fully distributed line model are presented. • The effectiveness of the proposed methods is validated through many simulation analyses. The proposed methods demonstrate some robustness towards measurement noises and parameter errors. Accurate fault location technology can not only speed up fault search but also enhance the power supply reliability. This paper introduces a single-ended fault location framework for single line to ground faults, taking into account the effects of partially coupled lines. The proposed framework relies only on local measurements. Within the proposed framework, the two methods proposed in this paper are based on the impedance line model and the fully distributed parameter line model, respectively. The impedance model based fault location method does not require iteration and has no risk of divergence, while the method based on the fully distributed parameter model has higher accuracy. The estimated results of the impedance-based method can be used as the initial values of the solution of the distributed parameter model based method. The proposed methods are validated through a number of testing cases, encompassing various fault locations, resistances, and coupling ratios. [ABSTRACT FROM AUTHOR]

• This article realizes the simultaneous output of high-voltage high-frequency excitation for transmission line measurement. • The proposed differential linear cascaded amplifier topology breaks through the limitation of gain bandwidth product. • Designing appropriate isolation voltage for cascaded power supply can meet different testing voltage requirements. • The parallel fiber optic isolation cascade method breaks through the kHz limitation of high-voltage amplifiers. In this paper, a high-frequency and high-voltage linear cascaded amplifier based on parallel optical fiber isolation is proposed. The electro-optical synchronous drive of the excitation signal is realized through equal proportional laser splitting, which achieves the same linear gain and output phase shift in each photoelectric conversion unit. The differential linear cascade topology designed in this paper effectively solves the gain bandwidth product limitation and achieves a high-voltage linear output in a high-frequency range. The new amplifier solves the problem that due to the low AC excitation voltage of traditional impedance analyzer, the signal attenuation is severe in long distance and high insulation distributed electrical parameter network. It can be widely used to measure high-frequency dielectric loss and impedance spectrum for dielectric materials and electrical components in industry and laboratory. By cascading n -stage amplifier units, the voltage gain can reach 6n times. Finally, a 16-stage cascade amplifier is built, and the response characteristics are tested with the distributed electrical parameter network loads. The output characteristics show that the expected amplifier gain can be obtained accurately in the high-frequency range of 100 kHz–100 MHz, the output voltage can reach 192Vpp, and the peak current can reach ±500 mA. The maximum of the curve about THD and noise versus frequency could be limited to 0.49 %, which could meet the needs of on-site measurement. [ABSTRACT FROM AUTHOR]

Inverter-based resources respond differently than synchronous generation sources during power system faults, challenging line protection reliability. To understand the reliability challenges, Sandia National Laboratories and North American Electric Reliability Corporation (NERC) led a collaborative study with four inverter manufacturers (mix of Type 3 Wind, Type 4 Wind, and PV Solar) and two North American protective relay manufacturers. As part of this study, an electromagnetic transients program (EMTP) with “real-code” models representing inverter firmware was used to investigate the protective relay response to faults on the modeled power system with the different inverter types. The currents and voltages obtained from the study were then played back through line relay hardware with settings typical of systems with conventional generation. The protective relays exhibited the expected reliability challenges but provided insight into the behavior of inverter-based resources during power system faults. In this paper, we share some of the challenging cases with the responses of the different line protection schemes. Using insight from the various event records, Part II of this paper shows how relay settings can be modified to obtain a substantial improvement in reliability. [ABSTRACT FROM AUTHOR]

Line loss accounts for most of the energy loss in low-voltage distribution network. Accurate prediction of line loss rate (LLR) is of great significance to eliminate abnormal transmission line faults in time and ensure power supply safety. The existing prediction methods for LLR seldom consider the seasonal trend data that affect it, and there is a hysteresis effect in predicting non-stationary line loss sequences. To solve the above problems, this paper proposes a prediction method based on multi-dimensional information matrix and dimensional attention mechanism-long-and short-term time-series network (DAM-LSTNet). Firstly, the maximum information coefficient (MIC) method is used to screen the distribution network characteristics and seasonal trend parameters. Secondly, the variational mode decomposition (VMD) method optimized by the genetic algorithm is used to decompose the historical line loss data and form a multi-dimensional information matrix with the screened characteristic parameters of the network. Finally, the multi-dimensional information matrix is put into the LSTNet network with dimensional attention mechanism to predict the LLR. The example analysis shows that compared with the existing methods, it has the advantages of sufficient consideration of prediction parameters, adaptive changes of prediction weights, weak hysteresis effect and high prediction accuracy. [ABSTRACT FROM AUTHOR]

Aiming at the difficulty of power supply for online monitoring equipment (OME) of transmission lines and towers, a long-distance high-efficient wireless power transfer (WPT) system based on a new relay structure is designed in this paper. The transmission power and transmission efficiency (TE) are improved, which meets the continuous and stable power supply of OME. Combined with the limitation of 110 kV line on the transmission distance (TD) and size of WPT, the influence of the relative position of relay coil (ReC) on transmission performance is studied and summarized. The optimal position of ReC and the physical size of the magnetic coupling mechanism (MCM) are established. The effects of TD and DC voltage on the transmission performance of typical and new WPT are compared and tested. TE of new WPT is increased by about 20%. The proposed new MCM will provide a reference for the design and application of WPT on OME. [ABSTRACT FROM AUTHOR]

The virtual power plant (VPP) is an important technology for realizing smart grids. VPPs are not limited by geographical location, which greatly aggregates the distributed energy resources. To divide a VPP across regions, we no longer limit it to power lines. This paper proposes a three-stage strategy for the classification of VPPs that includes graph model construction, communication capacity assessment and cross-regional classification. To construct the VPP graph model, complex network theory and communication matrices are used. In addition, a network representation learning and clustering algorithm is used to classify the VPP decision areas. Then, the classification results are evaluated using modularity and network communication sequence entropy to identify VPP boundaries. Finally, the validity of the method is verified by simulating the test network and the real network. [ABSTRACT FROM AUTHOR]

Meeting the customer's power demands is crucial for energy companies, even when unexpected and consecutive failures are present. This task has considerably increased its complexity due to the high integration of renewable energies and their intermittent behaviors. Therefore, it is important to achieve reliable power supply based on a criterion closer to real-life system operations and capable of addressing consecutive failures. The N-1-1 contingency involves the loss of a single transmission line or generation unit, followed by systems adjustments. Afterward, the power system experiences a subsequent loss of an additional generation unit or transmission line. This paper presents a power system unit commitment problem considering the N-1-1 reliability criterion with operations compliance check on economic dispatch and power flows under contingency states and renewable energy integration. Corrective actions are also included to determine the time that the failed components are restored. To address the complexity caused by renewable energy integration, the reliable unit commitment is achieved under the worst-case renewable output. The formulation results in an extremely large-scale adaptive robust mixed-integer linear programming model. For an efficient solution, a variation of the nested column-and-constraint generation algorithm is designed. Besides using the susceptance and phase angles to model the power flow, the linear sensitivity factors are also applied for improving the computational performance. The proposed models and algorithms are evaluated on modified IEEE 6-bus, 14-bus, and 118-bus test systems to confirm their effectiveness. [ABSTRACT FROM AUTHOR]

• The proposed single-ended method uses the extra information brought by the time interval between the operations of the circuit breakers at two line ends; the proposed method also considers distributed line parameters. Therefore, the proposed method has higher fault location accuracy than the existing method. • The proposed formulation of the fault location problem with distributed parameters is subtly simplified by Taylor expansion, and a non-iterative fault location method is proposed. The risk of unconvergence is systematically avoided and the fault location accuracy is ensured at the same time. • The proposed method does not rely on the assumptions of legacy methods (e.g., the fault current and the terminal current are in the same phase, the system is homogeneous, etc.). The proposed method does not require the parameters of the remote power system. Fast and accurate fault location methods can save costs and ensure power supply reliability. This paper proposes a novel noniterative single-ended phasor domain fault location method with distributed parameter model for AC transmission lines. Due to the limitation of information, the legacy impedance-based single-ended fault location methods usually are based on assumptions on the line or system to obtain more information. The method proposed in this paper takes advantage of the additional information brought by the operation mode of circuit breakers. The proposed method only needs the local measurements and does not need the measurements and the equivalent source parameters of the remote system. The proposed method only uses single-ended data and is not affected by communication and synchronization. The proposed method is noniterative and there is no risk of non-convergence. In addition, the method proposed in this paper does not rely on the assumptions of legacy methods and considers the distributed parameters, avoiding the disadvantages of the legacy methods. The effectiveness of the proposed method is verified through a lot of case studies in PSCAD/EMTDC, with different fault types, fault locations and resistances. © 2017 Elsevier Inc. All rights reserved. [ABSTRACT FROM AUTHOR]

Reliable planning of electricity networks is a crucial challenge to maintain the continuous power supply. This can be ensured through careful planning which requires a number of parameters as inputs such as electricity demand, generation capacity, fuel price, renewable intermittent generation, among others. The uncertain behaviors of such parameters have been well studied in literature. Another important parameter which is a vital requirement for reliable planning is the resistance of overhead transmission lines. Traditionally, the current models ignore to consider the resistance variations due to Joule heating and ambient temperature changes in transmission expansion planning (TEP) problem. In this sense, this paper presents an adaptive robust optimization (ARO) framework for TEP to model the uncertain resistance through ellipsoidal uncertainty set. Moreover, a data-driven selection of the ellipsoidal uncertainty set is proposed. In this regard, Khachiyan's algorithm (KA) is used to identify the minimum-volume covering ellipsoid (MVCE) that contains all uncertain parameters. A case study based on IEEE 118-bus power system is presented to demonstrate the effectiveness of the proposed method. Simulation results show that resistance uncertainty is of serious concern in the TEP problem since the solutions are highly sensitive to fluctuations in the line resistances. [ABSTRACT FROM AUTHOR]

The power penetration line of high-speed railway adopts all-cable lines, and its failure will seriously affect the safety and reliability of railway transportation. The accurate location of the fault will greatly reduce the range of finding the cable fault point and the workload of cable fault repair, shorten the maintenance time, and improve the reliability of high-speed railway power supply. This paper introduces the current situation of power line fault location, analyzes various traveling wave location principles and the traveling wave transmission and attenuation characteristics of all-cable penetration lines, and analyzes the adaptability of the traditional traveling wave location technology in all-cable penetration line fault location. It is proposed that the distributed traveling wave location method can greatly reduce the transmission distance of fault traveling waves and can effectively reduce the influence of attenuation and distortion in the traveling wave transmission process. For different types of fault traveling waves, different fault transition resistances, and different positions of fault points, the method can achieve the accurate location. The practical application case shows that the technology has high location accuracy and meets the requirements of a precise location. [ABSTRACT FROM AUTHOR]

• A cooperative energy trading mechanism for MGs is proposed. • Coalitions are formed amongst MGs on the basis of distance. • Analyses of power losses and energy trading cost with and without ESS are performed. Over the past few years, Micro Grids (MGs) have gained much popularity due to two-way communication in the power network with special emphasis on Distributed Energy Resources (DERs), which comprise of both Renewable Energy Sources (RESs) and Nonrenewable Energy Sources (NRESs). Currently, the main focus of researchers is to deal with the intermittent nature of RESs, which lead to the fluctuations in power production and dispatch. In this paper, direct energy trading among MGs is considered as an assuring solution for improving the grid stability, reducing power line losses and minimizing energy trading cost. The focus of this work is on energy transactions amongst multiple MGs within the same geographic region. In the proposed method, coalitions among MGs are made on the basis of the distance between them for energy transaction. Furthermore, an Energy Transaction Algorithm (ETA) is proposed for energy trading among MGs in the coalitions. Energy Storage System (ESS) is also integrated, which stores energy when an MG has surplus energy and utilizes the stored energy if it becomes energy deficient. Simulations are performed and the results demonstrate that energy transactions among MGs in the proposed method minimize the power line losses and energy trading cost up to 34.6% and 14%, respectively as compared to the existing method. [ABSTRACT FROM AUTHOR]

Globally, around 1.1 billion people do not have access to electricity and 84% of the population who do not have modern energy access are living in rural and remote areas of developing countries. Since the loads are far from the grid and providing the connection by extending from the main grid requires a high investment associated with long and costly transmission and distribution lines, addressing the problem requires innovative solutions. Therefore, off-grid microgrid systems, using solar photovoltaic and storage systems, integrated with very high-efficiency lighting appliances, are a promising solution to supply energy for rural and remote location in areas which lack access to the electric grid. This paper presents an overview on the existing solar photovoltaic technologies for off-grid systems including the most recent plug and play solutions. A characterization of the most common strategies used for control, communication and metering of microgrids is presented, as well as the recent evolution of the associated component technologies. The security and protection systems used to protect the system against theft or robbery of the systems itself or energy theft in remote areas are also addressed. Additionally, a resumed characterization of the sociologic profile and motivation of people to damage off-grid systems is presented. An overview on the main off-grid appliance market evolution and efficiency trends, in terms of energy efficiency, is also addressed in this paper. Finally, a set of recommendations to promote cost-effective systems is made, considering the market evolution path and the large growth potential of off-grid systems. There is an urgent need to reduce the total system costs, namely the soft costs of new microgrid systems in order to further accelerate the market growth, as well as widely accepted open standards to regulate and develop the market. [ABSTRACT FROM AUTHOR]

This paper analyses the electrical performance of power supply cables in operation by investigating previous faults and forecasting faults using the Easyfit Professional 5.6 software program. The calculation of the maximum operating time until the first fault occurs is based on an algorithm for estimating the parameters entered in the application, respectively the intervals of good operation time between two successive faults. The case study presented in the paper analyses the probability of failure of a medium voltage power line, under the administration of a distribution operator, based on information collected during maintenance work on medium and low voltage installations in the analysed area. [ABSTRACT FROM AUTHOR]

As one of the most important diagnostics of field reversed plasma, the single-flux loop around the vacuum chamber is usually used to measure the magnetic flux to deduce the plasma size. In the theta-pinch process, the power supply will drive a large current through the coil in a short time to generate a high magnetic field, which will cause the magnetic flux in the vacuum chamber to rise sharply. Therefore, the induced voltage on the single-flux loop may be very strong and have high-frequency components. A voltage divider must be used to reduce the induced voltage to the range that the transmission line can withstand. According to the high-frequency characteristics of the measured signal, this paper designs a capacitor voltage divider single-flux loop with reference to the capacitive voltage divider in the industry. After theoretical derivation of parameter selection and then in the preliminary experimental test with and without plasma, the effectiveness of the distributed capacitor flux loop is verified. [ABSTRACT FROM AUTHOR]

This paper presents a two-stage stochastic planning model for transmission systems and distributed energy resources (DERs) considering power system resiliency. The model takes into account both normal and emergency conditions as well as the duration of each condition. The proposed model is formulated as a mixed-integer linear program to minimize the total investment cost of transmission lines and DERs, expected values of generators’ operation cost in normal and emergency situations, and load shedding cost in emergency condition. The emergency scenarios are considered as moderate, severe, and complete damage states, which have different recovery times for transmission assets. The Benders decomposition technique is utilized to solve the optimization problem. Numerical results are demonstrated based on the IEEE 118-bus test system. [ABSTRACT FROM AUTHOR]

Electroencephalogram (EEG) is a biomedical technique for capturing the human brain's electrical information to process its activities and actions. EEG is one of the main methods commonly used in neuroscience, from clinical analysis to the design of brain–computer interfaces. The first one of the many challenges in an EEG system design regards the ultra-low amplitude of signals (i.e., of the order of 20 μ V ) and their susceptibility to several kinds of interferences. Electromagnetic interference (EMI) omnidirectionally irradiated by the power line supplies disturbs the EEG instrumentation system with a noise power mostly concentrated from 50 to 60 Hz . Our paper investigates the energy efficiency of adaptive filtering (AF) techniques based on the least mean square (LMS), normalized LMS, and set-membership (SM) families for meeting the protection against EMI in EEG systems. The results demonstrate that the LMS algorithm presents an unstable behavior with unsatisfactory results against the normalized LMS filters when subject to noisy scenarios. Therefore, we herein explore dedicated VLSI hardware architectures for the following filters: (a) normalized LMS (NLMS), (b) SM-NLMS, (c) partial update NLMS (PU-NLMS), and (d) SM bi-normalized LMS (SM-BNLMS). PU-NLMS architecture offers the best trade-off between the capability of eliminating the EMI versus its power dissipation, circuit area, and maximum clock frequency. PU-NLMS provides an artifact reduction level of up to 8.8 dB , with low energy consumption of 0.62 nJ/operation and just 1.41 % larger circuit area than the NLMS architecture. [ABSTRACT FROM AUTHOR]

Integration of distributed energy resources has been significantly increasing in the electric power grid. One of the predominant renewable energy sources, wind energy, possess a significant challenge for grid operations, due to its intermittency, uncertainity, and variability. In changing operating conditions with wind uncertainity, part of wind may need to be curtailed for the safe utilization of the transmission system. In order to minimize the wind power curtailment and to keep the power flow on a transmission line under limits, a cyber resilient distributed remedial action scheme (DRAS) is developed in this paper. The remedial action scheme (RAS) is formulated as an optimization problem, considering the real-power flow constraints of the transmission lines and given wind variability. In this paper, DRAS is developed to operate even with failures in the computing nodes to make it cyber-resilient. Distributed simplex algorithm is used for optimization in the distributed RAS. The DRAS is implemented in a decentralized platform called Resilient Information Architecture Platform for Smart Grid to enable cyber resiliency of DRAS. The effectiveness of the proposed approach is validated through offline simulations of the New England 39-bus system and online simulations of IEEE 14-bus test system. A cyber–physical testbed utilizing real time digital simulator, phasor measurement units, and BeagleBones has been used for the online simulation and validation of the developed cyber-resilient RAS. [ABSTRACT FROM AUTHOR]

• This paper provides a comprehensive review on sub synchronous oscillation (SSO) in large asynchronous machines connected to high voltage transmission lines with thyristor controlled series capacitor (TCSC). • The SSO occurrence is analysed on the simulation of a 250 MW DFIM based on a hydropower system with a series-compensated transmission line. • To validate the simulation results, a scaled-down laboratory prototype has experimented with a 2.2 kW DFIG system. • Further, the state-of-the-art SSO reduction methods are discussed with their benefits and drawbacks. Hydropower is a leading energy resource amongst the world's renewable energy capacities. According to the International Hydropower Association Status Report 2018, hydropower contributes 16.4% of total electricity production. To achieve proficient generation in the arena of the hydropower sector, a widespread design with recent trends and developments in technology is obligatory. Asynchronous machines are now extensively used in non-conventional energy resources due to their reduced cost and size, ruggedness in performance, ease of maintenance, partly rated power converter interface, and intrinsic short-circuit and overload protection. Asynchronous machines of large capacity (e.g. 250 MW) need further research to address redundancy in converter control circuits and also to identify the amount of compensation in transmission lines in view of variable speed of operation. This paper provides a comprehensive review on Sub Synchronous Oscillation (SSO) in large asynchronous machines connected to high voltage transmission lines with Thyristor Controlled Series Capacitor (TCSC). Methodologies used for SSO analysis are discussed. A simulation of a 250 MW doubly fed induction machine (DFIM) based on a hydropower system with a series-compensated transmission line is carried out in MATLAB/Simulink. A hardware prototype of a 2.2 kW DFIM system is used to test the results. Further, the state-of-the-art SSO reduction methods are discussed with their benefits and drawbacks. [ABSTRACT FROM AUTHOR]

• Based on the heat transfer theory and Thermal-Electric module, a simple method for quickly predicting the maximum temperature of water-cooled busbar with connector is proposed, which is convenient for engineering application. • Compared with V-T method and experimental results, the simple method in this paper has the advantages of global temperature distribution analysis and better temperature prediction accuracy, and can be used for the design of the same type of transmission lines. • The relationship among cooling water flow rate, contact resistance and maximum temperature of CRAFT busbar under rated working condition is determined, which can provide reliable guidance for actual operation of busbar. Due to the shortcomings of time-consuming and complicated operation of traditional fluid software simulation, a simple temperature prediction method that can quickly determine the reasonable working parameters of water-cooled busbar with connector is needed in the design of fusion power supplies. In this paper, considering the influence of contact resistance, the connector maximum temperature under same working conditions is studied by two kind of methods (combination method of heat transfer theory and Thermal-Electric module in ANSYS, Contact Voltage-Temperature (V-T) method), respectively. The comparison between simulation and experimental results shows that this method has the advantage of analyzing the global temperature distribution and predicting the maximum value more accurately than the latter. Based on this method, the relationship among contact resistance, water flow rate, and maximum temperature of the busbar connector used in Comprehensive Research Facility for Fusion Technology (CRAFT) is determined. This method can be applied to the rapid temperature analysis of fusion power busbar connector, which greatly reduces the design cycle. [ABSTRACT FROM AUTHOR]

Partial discharge of the dielectric is an important problem in fault detection of transmission line systems. It has gained gigantic attention to understand the breakdown characteristics of partial discharge. In this paper, the needle–plate discharge experiment is carried out by using the needle–plate defect discharge device and high voltage pulse power supply under atmospheric pressure. The breakdown characteristics are measured and analyzed by changing the needle plate clearance distance and using the step-up method. Finally, a simulation model of the needle plate was established to calculate the electric field intensity when the needle plate gap with different spacing was broken down, and the relationship between the maximum electric field intensity and the needle plate spacing was obtained. It is found that the breakdown voltage increases with the increase in the spacing between the needle and plate. The measured value is only slightly larger than the theoretical value of the breakdown voltage without the influence of harmonics. The simulation found that the larger the spacing between the needle and plate was, the smaller the maximum electric field intensity was during the breakdown, which was different from the theory. [ABSTRACT FROM AUTHOR]

Due to a lack of high and stable power supplies for large-scale online monitoring devices, the intelligent development of high voltage transmission lines has always been restricted. This paper presents a method for capacitive power tapping from an insulated shield wire of overhead high voltage transmission lines with tuning. A general equivalent model, which considers the influence of line sag and landform on the equivalent circuit parameters, is established. The calculated equivalent circuit parameters show good agreement with the field measured data obtained by a 220 kV single-circuit transmission line. In order to maximize the tap-off power, a nonlinear tuning method is proposed since linear tuning can cause an overvoltage problem, and a tuned reactor is developed. Based on the measured equivalent circuit parameters, an experiment platform is built in the laboratory to measure the tap-off power under different resistive loads. The experimental results indicate that the maximum power is about 900 W, which represents an improvement of 80% compared with the maximum power without tuning. Additionally, the tuned reactor shows good robustness to the perturbation of equivalent circuit parameters, which validates the effectiveness of the proposed power tapping method. [ABSTRACT FROM AUTHOR]

This paper deals with nonlinear control and optimal management of wind energy conversion systems connected to HVDC transmission lines. Specifically, the energy system under study consists of a wind turbine driving a permanent magnet synchronous generator, the latter supplies energy to a power grid through a Vienna rectifier and a DC link. To compensate for intermittent nature of wind power and load demand variations, we design a voltage controller as well as a novel energy management strategy that accounts for the available wind power and DC load demands. In the considered management, distinction is made between two operation modes: i) the maximum power point tracking mode using an intelligent adaptive optimizer, where only electrical parameter measurements are used to ensure maximum power extraction; ii) the adaptive power point tracking mode employing demand-driven production. In both modes, the power factor requirement is ensured, regardless the weather conditions and load demand variations, enhancing thus the aerogenerator's efficiency. One more novelty of the proposed control and management system is the online estimation of the DC voltage, avoiding thus the use of a physical sensor. The performances of the control and management system are highlighted by several simulations, showing the achievement all control objectives. • SVPWM applied to the Vienna rectifier. • WECS recursive backstepping nonlinear control design. • ANFIS algorithm-based speed optimizer. • Adaptive high gain observer for HVDC transmission lines. [ABSTRACT FROM AUTHOR]

• The quantitative expression of the current phase difference between both sides of the PV transmission line for faults with transition resistance is analyzed. • A Dice similarity coefficient-based pilot protection method for 500 kV transmission lines is proposed, considering the angle difference and magnitude difference between currents on both sides of the line. • The proposed method has a higher sensitivity than existing protection methods and performs better to transition resistance. • The effectiveness and accuracy of the proposed method under different fault locations, fault types, transition resistances, fault inception angles, line lengths, PV power supply capacities, have been verified by simulation and field data tests. Due to the shortage of fossil fuel resources and energy transformation efforts, the installed capacity of photovoltaic (PV) power supplies has been steadily increasing, resulting in the problem of low sensitivity for PV transmission line segregated-phase current ratio differential protection. Furthermore, there are increasing cases of large-scale gigawatt-level PV power supply integrated into the 500kV grid, bringing new challenges to the security and stability of the grid. In this paper, according to the fault characteristics of photovoltaic power supply, the current phase characteristics on both sides of the line are quantitatively analyzed during internal faults with transition resistance, and then the phase and amplitude differences of the currents on both sides of the line are used to propose a Dice similarity coefficient-based pilot protection method for photovoltaic transmission lines. PSCAD/EMTDC simulation and field data test results show the proposed method can accurately identify internal faults under the conditions of different fault locations, fault types, transition resistances, fault inception angles, line lengths, PV power supply capacity, and levels of noise. The method also performs well with CT saturation, simultaneous faults, evolving faults, and channel asymmetry. Additionally, the proposed method has a fast operation speed and a great performance to transition resistance. [ABSTRACT FROM AUTHOR]

The peer-to-peer (P2P) energy management in the buildings is modeled and studied by this paper. In the proposed P2P home energy management, the buildings share their energy resources with each other to supply their demands. Three individual buildings are considered, two buildings are equipped with solar panels and the other building is equipped with hydrogen storage unit. The buildings are connected to each other by power lines for P2P operation. The uncertainty of loads and solar energy are incorporated and the model minimizes the cost of solar unit, power lines, fuel-cell, electrolyzer, and storage tank. The optimization problem finds optimal power of solar system, power lines, fuel-cell, electrolyzer; optimal capacity of hydrogen storage tank; and optimal operation pattern (charging-discharging regime) of hydrogen storage system. The results demonstrate that P2P operation helps the buildings to benefit from their energy resources. • Peer-to-peer home energy management is presented to minimize the costs. • Buildings are equipped with solar units and hydrogen storage system. • Buildings share their energy resources with each other as peer-to-peer operation. • Uncertainty of load and solar energy is handled by stochastic programming. • Optimal sizing and operation are found for hydrogen storage and solar systems. [ABSTRACT FROM AUTHOR]