Feeder Currents Research Articles

Simulation of Faults in the Yeywa-Thaphaywa High Voltage Transmission Line using Fuzzy Logic

Faults in transmission networks frequently undermine the reliability and stability of electrical power supply, causing load shedding and posing risks to power system equipment. Effective fault classification is crucial to minimize power outages and ensure timely restoration. This study presents a fault classification method for transmission lines using fuzzy logic. The classification utilizes three-phase feeder currents, neutral current, and phase voltages as inputs to the Fuzzy Inference System (FIS). The proposed method accurately classifies the various types of faults in a high voltage transmission network, including line-to-ground fault, double line-to-ground fault, line-to-line fault, and three-phase faults. Numerous test cases demonstrate the technique's high accuracy. The simulations are carried out in MATLAB/SIMULINK using Sim Power Systems and the Fuzzy Logic Toolbox (MATLAB 2016a).

Assessment of the spectral energy of zero-sequence currents in protected feeders with the presence of single-phase to ground fault in the isolated network

Subject of research: methods of relative measurement of higher harmonics for detecting a faulty feeder with a single-phase ground fault. Purpose of research: evaluation of sensitivity of the methodology of faulty feeder search using wavelet transform. Object of research: distribution networks of 6(10) kV. Main results of research: the level of higher harmonics does not affect the performance of the technique, regardless of the point of the fault and the harmonic composition of the load, the damaged connection is the highest value of the spectrum energy.

Multi-source data driven harmonic spectrum estimation of substation feeder current

With the proliferation of non-linear loads and distributed power resources that connect through power electronic equipment, decentralized harmonic pollution in three-phase symmetric power system becomes increasingly serious. Despite this, monitoring the current harmonic of all substation feeders regardless of cost is unrealistic. To this end, a multi-source data driven method is proposed in this paper, utilizing data from the power quality monitoring system, dispatching system, and market business system, to estimate the harmonic spectrum of substation feeder currents and estimate the harmonic current components of each feeder with monitoring data of bus voltage harmonics and line harmonic currents. The objective function of the harmonic spectrum estimation model is constructed based on the analysis of current harmonic phasor and power relationship on the feeders. An improved particle swarm optimization (PSO) algorithm is proposed to solve the proposed estimation model thereby obtaining the current harmonic content of each feeder and the phase angle difference between the current harmonics of the feeders. The performance of the proposed model and algorithm is validated by numerical simulation with a test system and an actual system.

Load-current demand forecasting in substations of urban railway lines

Load-current forecasting is important in the operation and energy management of urban railway lines. It helps control strategies to manage and distribute energy optimally, thereby saving energy and reducing voltage fluctuations. This paper presents a method to predict the traction current at the busbar of a substation using the supervised machine learning algorithm. Because the traction power load is supplied from both adjacent traction power stations, and the energy exchange process between trains also takes place during work, the input data are selected to combine the value history of busbar currents and feeder currents. Besides, the neural network configuration and the number of training cycles in the estimated model can be adjusted to achieve the desired accuracy. The proposed method was tested and adjusted based on the actual operation data at the Lang traction station on 24 June, 2022. The estimated results compared with measurement data from the supervisory control and data acquisition (SCADA) have proven that the largest absolute error is no more than 5 (A). The maximum relative error is not more than 0.005, and the mean squared error does not exceed 0.01 over the whole operating time of a day from 4h45 to 22h45.

VeHIF current arcing, volatility and vegetation ignition development: An EMD based volatility analysis for earth-fault classification

Vegetation High Impedance Fault (VeHIF) events pose severe risks to public safety, wildlife, and forests. Overcurrent protection schemes generally cannot clear VeHIF events, which have previously resulted in bushfires. This research presents a VeHIF classification method based on the statistical variance analysis of volatility in the empirical mode decomposed feeder current. The author applied the proposed scheme to a dataset of 130 earth-faults with 100 % success rate and a mean classification time of 10 s (standard deviation of 14.32 s). While faster VeHIF fault classification should ideally be achieved, research findings show that faster classification speeds may not always be feasible or necessary. This finding relates to the fact that bushfire risk increases, when charring starts to spread over a branch with a breakout of flames. The present work further validates a positive pairwise correlation between a fault current's volatility and arcing, demonstrating the efficacy of High Frequency (HF) signals as reliable VeHIF volatility signatures.

Power supply arm protection scheme of high-speed railway based on wide-area current differential

When fault occurs on cross-coupling autotransformer (AT) power supply traction network, the up-line and down-line feeder circuit breakers in the traction substation trip at the same time without selectivity, which leads to an extended power failure. Based on equivalent circuit and Kirchhoff’s current law, the feeder current characteristic in the substation, AT station and sectioning post when T–R fault, F–R fault, and T–F fault occur are analyzed and their expressions are obtained. When the traction power supply system is equipped with wide-area protection measurement and control system, the feeder protection device in each station collects the feeder currents in other two stations through the wide-area protection channel and a wide-area current differential protection scheme based on the feeder current characteristic is proposed. When a short-circuit fault occurs in the power supply arm, all the feeder protection devices in each station receive the feeder currents with time stamp in other two stations. After data synchronous processing and logic judgment, the fault line of the power supply arm can be identified and isolated quickly. The simulation result based on MATLAB/Simulink shows that the power supply arm protection scheme based on wide-area current differential has good fault discrimination ability under different fault positions, transition resistances, and fault types. The verification of measured data shows that the novel protection scheme will not be affected by the special working conditions of the electrical multiple unit (EMU), and reliability, selectivity, and rapidity of relay protection are all improved.

Waveform Correlation Based Harmonic Voltage Contribution Determination of Iron and Steel Plants Supplied From PCC

This paper presents a new waveform correlation based method which determines the individual harmonic voltage contributions of Electric Arc Furnace (EAF) plants supplied from a point of common coupling (PCC). The method is based on the waveform correlation computations between the PCC voltage and the feeder current at the individual harmonic frequency. PCCs supplying multiple EAF plants usually suffer from high voltage harmonic components due to their operation principles. A relationship between the correlation coefficient of the PCC voltage and the feeder current waveforms, and the harmonic voltage contribution of each plant is derived and this relationship is used to derive the individual contributions to the PCC voltage. The main idea of the method is based on the fact that harmonic voltage at the PCC is a result of the additive effect of voltage drops on the source side impedance of the power system caused by the individual feeder currents. No real-time impedance measurements are required in the proposed method and no need for the measurements of the other feeders to compute the contribution of a specific feeder in contrast to some previously proposed methods for the same problem. The proposed method is further expanded in order to reveal the effects of the compensation systems of the EAF plants, which identifies the harmonic current sinking problem of a victim plant with a powerful compensation system using further correlation computations between the feeder currents and in-plant current measurements. The proposed method can be easily adapted as a real time harmonic contribution detection tool for the already-installed power quality analyzers, most of which employ synchronized voltage and feeder current waveform measurements.

Centralized Protections of Busbars and Electric Motors Connected to Them

Centralized protections have several advantages over autonomous protections; however, incorrect actions of the former can result in more serious consequences. The reliability of their operation can be ensured with the help of majorization principle, but the number of devices with different principles of operation is insufficient so far. Three centralized protections are suggested; one of them allows duplication of current transformers. They all are based on the fact that the electric motors of feeders feed a short-circuit point; as a result, the current in a feeder damaged becomes higher than the current at the power input, and the currents in undamaged feeders change the direction to opposite. The conditions for protection actuation are presented. Operation of the protections in different modes is described in detail.

Control of power converter used for electric vehicle DC charging station with the capability of balancing distribution currents and reactive power compensation

The global interest in electric cars aims to achieve sustainability in the transportation sector and reduce dependence on conventional cars that mainly depend on fossil fuels, the main source of emissions polluting the environment. However, the electric cars required electric fast chargers to charge the batteries with high currents in order to make the electric cars competitive with conventional cars that required a short time for filling fuel. Single-phase electric chargers make the distribution feeders with unbalanced currents as the single-phase loads and single-phase PV inverters. In the case of the unbalanced operation, one of the three phases may reach its maximum limit before other phases which leads to disconnect the transformer and thereby inefficient and unreliable system operation. This paper presents a control scheme for a three-phase, four-leg power converter that can be used as a fast charger for electric cars. Moreover, it can be used for balancing grid currents and for reactive power compensation. This will avoid frequent interruptions of distribution transformers due to unbalanced operation and reactive power loads. The distribution feeder considered to evaluate the control scheme consists of single-phase loads and inverters in addition to the proposed converter. The converter controls the charging power effectively and balancing the feeder currents. Moreover, during off charging time which is a possible manner for the charging station when the EV battery is fully charged the converter is effectively used for unbalanced mitigation and reactive power compensation. The simulated results show the effectiveness of the proposed control scheme.

Evaluation of central tendency measures in relation to the parameters of contact network feeders controlled by relay protection

The paper considers the importance of possible input values of standby stages of remote protection of contact network feeders from the point of view of their influence on the reliability of protection. The measures of the central tendency of parameters controlled by relay protection of contact network feeders were evaluated based on the theory of statistics, using the example of the Trans-Baikal Railway for 2018-2019. In total, 14 parameters were measured according to GOST 32144-2013. Electric power. Electromagnetic compatibility of technical facilities. Standards for the quality of electric energy in general-purpose power supply systems, in 2020 on the feeder of the contact network of the Sokhondo traction substation of the Trans-Baikal Railway against 88965290 obtained values, which made it possible to select significant values from all possible parameters on the basis of mathematical analysis. Statistical data on the following parameters were considered and analyzed: effective voltage value, effective current, peak voltage amplitude factor, peak current amplitude factor, harmonic voltage distortion factor, harmonic current distortion factor, phase shift factor, load resistance, angle between the first voltage harmonic on substation buses and feeder current. The reasonable selection of significant parameters proposed by the authors allows improving the operation of standby stages of remote protections of contact system feeders in heavy traffic conditions and increasing their selectivity.

Estimate the Probability Distribution of Imbalance-Induced Energy Loss With Minimal Data

Imbalance-induced energy loss accounts for a significant part of energy loss in low-voltage distribution networks. However, due to the prohibitive cost of full monitoring, high-resolution time-series data of low-voltage feeder currents are usually absent for accurate energy loss computation. This letter presents a novel method to estimate the probability distribution of imbalance-induced energy loss. In the proposed method, only the line resistance and statistical data (mean and covariance) of the phase currents are required to estimate imbalanced networks' energy loss. Furthermore, a Bayesian statistics-based data-driven method is also proposed to get the mean and covariance value of phase current with minimal measurements. Numerical tests on a real three-phase imbalanced circuit show the proposed approach obtains the probability distribution of imbalance-induced energy loss with a low estimating error and low field measurement frequency.

Deep Belief Network Based Faulty Feeder Detection of Single-Phase Ground Fault

This paper proposes a faulty feeder detection method based on Deep Belief Network (DBN) of deep learning theory for the neutral non-effectively grounded systems. It consists of two steps: firstly, a DBN-based faulty feeder detection model is built with feeder current, power and power factor as input feature parameters. Then, the input feature data are obtained during the single-phase ground fault from the master station of power dispatching system, which will construct a training set. By unsupervised pre-training and supervised fine-tuning, the proposed model obtains the mapping relationship between raw data and fault characteristics and realizes the faulty feeder detection. The advantage of the proposed method is using millisecond-level data in power dispatching system directly. Moreover, the sampling device does not need to install, which significantly reduces the construction costs and is of strong adaptability. The analyzed result using the ground fault data of an actual substation for more than two years shows that the proposed method has a better performance than SVM and BP neural network, and the accuracy is up to 94.7%. The proposed method has been implemented in Lipu Power Grid, Guangxi, China with excellent application effect and extensive application prospects.

Protection of Converter-Interfaced Microgrids Using Modified Short-Time Correlation Transform

The limited and bidirectional fault current of inverter interfaced islanded microgrids make the fault detection and faulty feeder identification the major challenges for conventional overcurrent-based protection systems. To address the first challenge, this article proposes a fault detection strategy based on the modified short-time correlation transform (MSTCT) of feeder current. Using the superimposed component of MSTCT, a new directional element is defined to address the second challenge. The developed strategy relies on an intelligent electronic device in each feeder, making it a cost-effective scheme. The proposed scheme is effective for all types of fault and can differentiate normal switching events from the fault conditions. Also, it properly operates in the presence of nonlinear loads and measurement noises. The reliable performance of the proposed protection scheme is assessed on the MATLAB/Simulink simulation model of the CIGRE benchmark low-voltage microgrid network.

A Robust CIM Based Control Approach for PVECS Interfaced to Local Distribution Network

This article presents a distribution feeder supported single-stage photovoltaic (PV) energy conversion system (PVECS), in which, a voltage source converter is used. It serves for harnessing maximum power from a PV source as well as to inject that harnessed power from PVECS into the distribution feeder with enhanced power quality. The harmonics reduction, distribution feeder currents balancing, power factor correction, compensation of load currents are additional attributes provided by this PVECS as compared to a traditional PV inverter. Moreover, this system also works well in weak distribution network during sag or swell in the grid voltages. The robust correntropy induced metric based normalized least mean fourth algorithm is used here to extract the real power portion of load currents. Besides, this PV contribution is added to distribution feeder currents to improve the dynamic response during varying environmental conditions. Additionally, when solar power is not available, this system serves for power quality enhancement at the distribution network, which makes the system cost effective, because its power converter is utilized up to its extreme level. This control approach is tested at different ambience conditions through a developed prototype in the laboratory either in available solar generation or in absence of it.

A Modeling Study of an Atmospheric Bore Associated With a Nocturnal Convective System Over China

AbstractBores have been shown to play a role in the initiation and maintenance of mesoscale convective systems (MCSs), particularly during the night after the boundary layer stabilizes. To date, the generation, evolution, and structure of bores over China has received little attention. This study utilizes observations and simulations with the WRF‐ARW model to investigate the generation and evolution of an atmospheric bore observed over Yangtze‐Huai Plains of China. The bore was associated with a nocturnal MCS that first formed over elevated terrain. The bore was observed ahead of the MCS with a maximum lateral extension of ~100 km. The feature lasted for over 90 mins and propagated at a speed of ~13 m/s, slightly faster than the MCS. In the simulation, the bore evolved from the separating “head” of the convectively generated gravity current. The bore then continued to propagate ahead of the MCS, even after the dissipation of the feeder current, and took on the appearance of an undular bore. The bore lifted a layer of convectively unstable air above the nocturnal surface inversion, initiating new convection ahead of the MCS to help maintain the MCS. The Scorer parameter ahead of the bore revealed a low‐level wind profile with curvature of the vertical profile of horizontal wind, favoring the trapping of wave energy and the persistence of the bore. These results are generally consistent with the role of bores in the maintenance of nocturnal MCSs and emphasize the need for future studies into the relationship between bores and nocturnal MCSs over China.

The Simultaneous Impact of EV Charging and PV Inverter Reactive Power on the Hosting Distribution System’s Performance: A Case Study in Kuwait

Recently, electric vehicles (EVs) have become an increasingly important topic in the field of sustainable transportation research, alongside distributed generation, reactive power compensation, charging optimization, and control. The process of loading on existing power system infrastructures with increasing demand requires appropriate impact indices to be analyzed. This paper studies the impact of integrating electric vehicle charging stations (EVCSs) into a residential distribution network. An actual case study is modeled to acquire nodal voltages and feeder currents. The model obtains the optimal integration of solar photovoltaic (PV) panels with charging stations while considering reactive power compensation. The impact of EV integration for the case study results in two peaks, which show a 6.4% and 17% increase. Varying the inverter to the PV ratio from 1.1 to 2 decreases system losses by 34% to 41%. The type of charging is dependent on the maximum penetration of EVCSs that the network can install without system upgrades. Increasing the number of EVCSs can cause an increase in power system losses, which is dependent on the network architecture. Installing PV reduces the load peak by 21%, and the installation of PV with consideration of reactive power control increases system efficiency and power delivery.

Performance Analysis of Skewness Methods for Asymmetry Detection in High Impedance Faults

Skewness can be used to identify the asymmetry introduced into a current stream by a High Impedance Fault (HIF). This letter introduces relative skewness as a superior computational approach for detecting HIF induced asymmetry changes in the feeder current. Relative skewness is defined as a measure of asymmetry in the stream with respect to the stream itself. The key highlight is the analysis of four different methods for detecting HIF induced asymmetry changes for HIF currents as low as 0.5 Amps. The work confirms Pearson's moment coefficient of skewness as the most efficient method in producing the highest asymmetry separability in the post fault average skewness. The letter concludes by proposing a technique in discriminating HIF induced skewness changes from those by other likely disturbances.

Probabilistic distribution planning: Including the interactions between chance constraints and renewable energy

Abstract Integration of renewable energy resources introduces several uncertainties for planning of distribution networks, requiring the consideration of random variables. This paper proposes a chance-constrained distribution network planning to deal with the long-term uncertainties related to load power, wind power, and solar power using probability density functions under a pseudo-dynamic approach. The model is constructed through linearized load flow equations which are combined with probability density functions using convolution. The optimization problem is then solved by integer genetic algorithm; minimizing the installation and maintenance costs of substations, feeders, and renewable generators and the expected cost for purchased energy from the upper grid. The chance constraints are formulated for voltage limits, feeder currents’ limits, and substation limits in order to control the satisfaction level of power system parameters. The proposed method, which is computationally efficient, is applied to the 24-nodes and 34-nodes test networks to compare the obtained results with Monte Carlo Simulation along with the full AC load flow and the results show the importance of considering chance constraints and penetration level of renewable energy in terms of investment variables through case studies.

Optimized bandpass admittance criteria for earth fault protection of MV distribution networks

This paper is concerned with the new method of earth fault detecting in MV distribution networks. The goal of investigations was to enhance protection sensitivity to low resistance faults resulting in small increase of voltage and residual currents in protected feeders. The earth fault detection criteria for three earthing methods and details of the criteria optimization algorithm are presented. The multi-option protection criteria optimization was based on relaying signals obtained from MV distribution network modelling in EMTP. The reliability of the protection algorithm for sustained and intermittent arcing earth faults is discussed.

Slowing of Caribbean through-flow

Trends in near-surface currents passing through the southeastern Caribbean are described using ocean reanalysis and a coupled model projection. The decline of Caribbean through-flow is linked with tropical and polar forcing. In the upstream zone, the North Brazil Current shows increasing retroflection as the southern Hadley Cell expands across the equatorial Atlantic. This inhibits northwestward transport next to the Amazon River plume. In the downstream zone, the Labrador Current feeds low saline Arctic waters into the Gulf Stream, inducing an equatorward shift and reduced flow.Evidence is growing for spin-down of the North Atlantic gyre and its feeder currents, that inhibit poleward heat exchange and contribute to climatic shifts. Eastward trends of winds and currents in the equatorial Atlantic is projected to bring a drier climate to the lower Amazon basin and southeastern Caribbean, hence greater salinity with knock-on effects for regional sea temperatures.