Phase Voltage Research Articles

Study on the Characteristics of Turn-to-Turn Short Circuit Faults in the Primary Windings of the Generator Terminal Voltage Transformer

Turn-to-turn short circuit faults in the primary winding of generator terminal voltage transformers can lead to erroneous operation of stator grounding protection systems. This paper analyzes the fault characteristics associated with such failures and derives formulas for the fault phase current and zero-sequence voltage during a turn-to-turn short circuit in the primary winding. A 3D finite element model of the generator terminal voltage transformer is established by using Altair Flux 3D, and the accuracy of the model is verified. Based on this model, simulation tests were conducted to investigate turn-to-turn short circuits in the primary winding. The results reveal that as the number of shorted turns increases, the voltage of the fault phase decreases continuously while the voltages of the other two phases increase. The current in the short-circuited phase rises significantly, accompanied by an increase in zero-sequence voltage. Visualizations of magnetic field parameters indicate that as the number of shorted turns increases, the magnetic induction magnitude of the fault phase rises steadily and approaches saturation, resulting in heightened magnetic field intensity near the shorted turns. This analysis of fault characteristics through simulation contributes to the advancement of fault diagnosis systems for generator terminal voltage transformers.

RISC Fault of Non‐Salient Wound‐Rotor Synchronous Generator: A Detection Method and Effect Analysis of Insulation

Rotor interturn short circuit (RISC) fault is one of the most prevalent fault types in the non‐salient wound‐rotor synchronous generator (WRSG). In the paper, the theoretical mechanism of the RISC fault is studied in detail. Building upon this understanding, from the fault detection and harm consequences, the further work of this article includes proposing a RISC detection method and analyzing the influence of RISC on the insulation thermal damage. On the one hand, a new detection for RISC fault is first proposed based on the phase voltage. The proposed detection method innovatively allows for accurate determination of both the severity and location of RISC faults. On the other hand, the loss and the temperature of the stator core‐winding system are comprehensively investigated with varied RISC degrees and positions. The thermal responses of the winding insulation are obtained under the joint action of the external magnetic heat source and the internal electric heat source. The study identifies critical points of insulation vulnerability, particularly noting areas prone to noise and connection joints. This research contributes to the timely online identification of RISC faults and supports preventive maintenance strategies for protecting winding insulation. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Design of Small Permanent-Magnet Linear Motors and Drivers for Automation Applications with S-Curve Motion Trajectory Control and Solutions for End Effects and Cogging Force

This paper designs and fabricates a small-type permanent-magnet linear motor and driver for automation applications. It covers structural design, magnetic circuit analysis, control strategies, and hardware development. Magnetic circuit analysis software JMAG is used for flux density distribution, back electromotive force (back-EMF), and electromagnetic force analysis. To address the lack of a complete closed magnetic circuit path at the ends of the linear motor, which causes magnetic field asymmetry, a phenomenon known as end effects, auxiliary core structures are proposed to compensate for the magnetic field at the ends. It successfully utilizes auxiliary cores to achieve the phase voltages of each phase, which are balanced at a phase voltage error of 0.02 V. To address the cogging force caused by variations in the magnetic reluctance of the core, this paper analyzes the relationship between electromagnetic force and mover position, conducting harmonic content analysis to obtain parameters. These parameters are applied to the designed cogging force control compensation strategy. It successfully achieves q-axis current compensation of around 1.05 A based on the mover’s position, ensuring that no jerking caused by cogging force occurs during closed-loop electromagnetic force control. The S-curve motion trajectory control is proposed to replace the traditional trapezoidal acceleration and deceleration, resulting in smoother position control of the linear motor. Simulations using JMAG-RT models in MATLAB/Simulink verified these control strategies. After verification, practical test results showed a maximum position error of approximately 5.0 μm. Practical tests show that the designed small-type permanent-magnet linear motor and its driver provide efficient, stable, and high-precision solutions for automation applications.

Correlation-based polarity-check algorithm for instrument transformers

A polarity identification is very important for operation of transformers, measurement and protection equipment, where it is useful in analyzing of transformer connections and operation as well as testing of protective systems. Moreover, it’s essential in assessment of power systems performance during both normal and abnormal operation. Ensuring the correct polarity of the primary and secondary windings in voltage and current transformers is of paramount importance for various measurement and protection schemes in power networks. This paper proposes a digital polarity detector and tester using correlation coefficients and nine polarity indices calculated for instrument transformer signals. In order to test the performance of the proposed polarity tester algorithm, MATLAB code is imported to the LABVIEW model, and the numerical data obtained from the synchronous generator terminals via instrument transformers are interfaced with the computer through the Data Acquisition Card (DAC). The experimental system consists of a motor-generator set supplying a three-phase inductive load with instrument transformers connected to measure each phase voltage and current. The obtained results for various operating conditions and different types of abnormal conditions prove that the suggested algorithm is accurate, reliable and applicable to smart grids and substation automation systems. It can be considered as an integrated system incorporated with digital fault recorders, relays and meters.

The Impact of Modulation Techniques on Brushless DC Motor Drive

ABSTRACTThree‐phase brushless DC (BLDC) motors are cost‐effective and are increasingly used in various speed control applications. The phase voltage, DC‐bus utilization, current ripple, and torque ripple are major performance parameters for a BLDC motor drive. Different pulse width modulation (PWM) methods will diversely influence these parameters. This paper presents the phase voltage, current ripple, and DC‐bus utilization analysis of BLDC motor drive for four PWM techniques and provides a comparative analysis. The current ripple of the BLDC drive is evaluated with low and high switching frequency operations. Phase voltage and DC‐bus utilization of a BLDC motor are evaluated using analytical methods and validated experimentally. The investigation provided in this work are significant for PWM selection and implementation for low and high switching frequency operations. Both low‐ and high‐frequency operations are performed by supplying the BLDC drive from a silicon carbide (SiC) based inverter. These PWM techniques are also compared, considering high and low‐speed applications. Experimental results of SiC inverter‐fed BLDC motor drive are provided to substantiate the proposed work.

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).

IoT-Based Control, Monitoring, and Protection System for 3-Phase Induction Motors in Electric Motorcycles

This study investigates the application of the Internet of Things (IoT) for wireless control and monitoring of a 3-phase electric motor using a smartphone. The system integrates PZEM-004T, DS18B20, and Hall Effect sensors to collect data on voltage, current, temperature, and rotational speed using the NodeMCU ESP8266 microcontroller. Measurements are displayed on an LCD and transmitted to the Blynk server for smartphone access. A comparative method evaluates the accuracy of sensor readings against standard measuring instruments. Results obtained an average percentage error of 0.5% for the R phase voltage, 0.2% for the S phase, and 0.1% for the T phase. Current measurements reveal errors of 5% for the R phase, 10.3% for the S phase, and 11.7% for the T phase. The control system’s performance varies with internet speed, with an average delay of 0.99 seconds on a 4G network and 2.51 seconds on 3G. Additionally, the study evaluates three protection mechanisms, demonstrating that the motor stops within 4.03 seconds in the event of a phase failure, while overcurrent and overheating protections activate within 8.47 seconds and 3.64 seconds, respectively. Overall, the findings affirm the viability of IoT in motor monitoring and control, emphasizing accuracy and response times under varying conditions.

Optimal Configuration Model for Large Capacity Synchronous Condenser Considering Transient Voltage Stability in Multiple UHV DC Receiving End Grids

In a multi-fed DC environment, the UHV DC recipient grid faces significant challenges related to DC phase shift failure and voltage instability due to the high AC/DC coupling strength and low system inertia level. While the new large-capacity synchronous condensers (SCs) can provide effective transient reactive power support, the associated investment and operation costs are high. Therefore, it is valuable to investigate the optimization of SC configuration at key nodes in the recipient grid in a scientific and rational manner. This study begins by qualitatively and quantitatively analyzing the dynamic characteristics of DC reactive power and induction motors under AC faults. The sub-transient and transient reactive power output model is established to describe the SC output characteristics, elucidating the coupling relationship between the SC’s reactive power output and the DC reactive power demand at different time scales. Subsequently, a critical stabilized voltage index for dynamic loads is defined, and the SC’s reactive power compensation target is quantitatively calculated across different time scales, revealing the impact of transient changes in DC reactive power on the transient voltage stability of the multi-fed DC environment with dynamic load integration. Finally, an optimal configuration model for the large-capacity SC is proposed under the critical stability constraint of dynamic loads to maximize the SC’s reactive power support capability at the lowest economic cost. The proposed model is validated in a multi-fed DC area, demonstrating that the optimal configuration scheme effectively addresses issues related to DC phase shift failures and voltage instability resulting from AC bus voltage drops.

Analysis Of Load Balance In 20 Kv Distribution Systems On Power Losses

Load balancing is one of the things that must be considered by reducing the value of voltage drops or power losses that occur in distribution channels. It is necessary to know the characteristics of the load in an area or area with a balanced supply so that each phase is burdened evenly. Calculating the voltage drop on the distribution network conductors, the voltage drop on the KBN09 Slawi feeder was calculated. What will be calculated here is from the line to the transformer furthest from the GI, namely from the three-phase 20 kV main line, single-phase branching. The results of power calculations from GI Kebasen Tegal show differences between R, S and T phases with three 20 kV phases in pre-balance and post-balance conditions. As written, the value for R wire is 82661.52 W, for S 52613 W, while for the T phase the value is 60127.06 W. Meanwhile, the calculation of power losses from GI Kebasen Tegal shows differences between the R, S and T phases with 1 phase voltage in the conditions before balance and after balanced. On the 3-phase line for the R wire, the power loss decreases from 34,198 W to 17,0425 W, for S it increases from 11,540 W to 19,077 W, while for the T phase the value remains 15,274 W.

A machine learning based fault location method for power distribution systems using wavelet scattering networks

This paper proposes a novel machine learning based method for localizing single-line-to-ground faults in modern power distribution systems using single-end measurements. The challenge of identifying the faulty lateral is formulated as a support vector machine model-based classification problem, where a class represents a different part of the distribution network. The challenge of finding the exact fault distance is formulated as an ensemble model-based regression problem. Both models are trained with scattering coefficients extracted from the application of a wavelet scattering network on the captured faulty phase voltage signal. The performance of the proposed fault location method is evaluated with a comprehensive simulation study, conducted for the IEEE 34-bus test distribution system. The results demonstrate the efficacy of the proposed method in terms of fault location accuracy, as well as its sufficient insensitivity against several influencing factors, such as load, DG, external system strength, and network topology variations. Comparison of the proposed method with other well-established machine learning based fault location methods for power distribution systems reveals its great performance.

Performance analysis of mono-stage three-phase DC-AC converter with reduced logic power supply circuits

This paper presents the performance analysis of a mono-stage three-phase DC-AC converter with reduced logic power supply circuits. The power DC-AC power converter of the proposed system is formed by arrangement of one inductor, two power switches, and one capacitor in an opener-like configuration to yield each leg of the inverter. During the inversion process, the number of capacitor elements that charges up (builds electrical energy) or discharges across the power switches will be equal to the number of inductors that discharges or builds up magnetic energy that terminates in between the power switches and vice versa. Under this condition, the proposed system, boosts and converts DC power to AC power and at the same time maintains energy balance in the system in one stage power conversion phenomenon unlike conventional power inverters. The logic power supply circuit used in the proposed system has fewer component counts and performs optical isolation unlike its conventional counterparts which have larger component counts and isolate by electromagnetic induction. The proposed system achieved the following results: lower and cheaper logic power supply circuits, simulated phase voltages of 327.8 V and 326.6 V and 329.8 V at THDs of 0.09879 %, 0.2569 % and 0.2905 % and average phase currents of 6.30A, 6.32A and 6.26A, respectively, and experimented: scaled down phase-A, B, and C average voltages of 66.95 V, 65.6 V and 68.93 V at phase angles of 0°, 120°, and -120° respectively. The performance analysis of the mono-stage three-phase DC-AC converter with reduced logic power supply circuits can be used in home appliances, hospital equipment, communication-based power stations, and drive systems such as electric vehicles.

СИСТЕМА "АЛЬТРА" ДІАГНОСТУВАННЯ СТАНУ ІЗОЛЯЦІЇ ЕЛЕКТРИЧНОЇ МЕРЕЖІ ТА ЗАХИС-ТУ ЇЇ ВІД ОДНОФАЗНИХ ЗАМИКАНЬ

One of the problems in an electrical network with an isolated (compensated) neutral is the selective determina-tion of a damaged element during a single-phase earth fault. Taking into account the negative impact of single-phase earth faults on the equipment of electrical networks with an isolated or compensated neutral, as well as improving the electrical safety conditions of people and animals, it is necessary to install selective protections with the of turning off of damaged element. Selective operation of protections against such damage can be en-sured on the basis of the analysis of zero-sequence currents, phase voltages and zero-sequence voltage of the bus section from which these feeders are powered. As operational experience has shown, selective operation of pro-tection against single-phase earth faults in such networks can be ensured only with the use of digital devices. The work considers the "Altra" system, designed for diagnosing the state of insulation, protecting feeders of 6-35 kV from single-phase earth fault, recording analog and binary signals of electrical installations. Altra digital protec-tion simultaneously covers up to 28 feeders, which provides comprehensive protection against single-phase earth faults of all substation feeders. The working algorithm of the developed protection against single-phase earth faults is based on the analysis of the transient process immediately after the occurrence of damage, which provides selective identification of the damaged feeder both in networks with an isolated neutral and in networks with a compensated. The system organizes the recording of oscillograms of emergency processes and infor-mation about damage by "Altra" devices, followed by their transfer to the dispatcher's automated workplace. This makes it possible to carry out a detailed analysis of accidents and diagnose the insulation of the electrical net-work.

Motor Fault Diagnosis and Detection with Convolutional Autoencoder (CAE) Based on Analysis of Electrical Energy Data

This study develops a Convolutional Autoencoder (CAE) and deep neural network (DNN)-based model optimized for real-time signal processing and high accuracy in motor fault diagnosis. This model learns complex patterns from voltage and current data and precisely analyzes them in combination with DNN through latent space representation. Traditional diagnostic methods relied on vibration and current sensors, empirical knowledge, or harmonic and threshold-based monitoring, but they had limitations in recognizing complex patterns and providing accurate diagnoses. Our model significantly enhances the accuracy of power data analysis and fault diagnosis by mapping each phase (R, S, and T) of the electrical system to the red, green, and blue (RGB) channels of image processing and applying various signal processing techniques. Optimized for real-time data streaming, this model demonstrated high practicality and effectiveness in an actual industrial environment, achieving 99.9% accuracy, 99.8% recall, and 99.9% precision. Specifically, it was able to more accurately diagnose motor efficiency and fault risks by utilizing power system analysis indicators such as phase voltage, total harmonic distortion (THD), and voltage unbalance. This integrated approach significantly enhances the real-time applicability of electric motor fault diagnosis and is expected to provide a crucial foundation for various industrial applications in the future.

Study of the State Primary Measurement Standard of the Unit of Phase Shift Angle Between Two Voltages

Phase measurements are necessary for determining main parameters of the oscillatory process in complex electrical networks. Most often, it is precisely the phase shift angle (PSA) between two oscillatory processes of the same frequency that is measured. An essential indicator of the quality of electrical energy is the coefficient of asymmetry in a three-phase electrical network, which depends on the load of consumers in this network. This indicator is affected by a short circuit between two phase voltages. Phase measurement standards, phase meters, and phase converters are included in the measuring equipment for phase measurements. They are widely used in such fields as radiolocation, radio navigation, non-destructive testing, radio engineering, telecommunications, acoustics, metallurgy, machine and aircraft industry, space industry, as well as in scientific research and defence. The State Measurement Standard of Ukraine of the PSA unit between two voltages in the frequency range from 0.01 Hz to 10 MHz is maintained at the State Enterprise “UKRMETRTESTSTANDARD”, Kyiv. It provides metrological traceability of phases measured in the country. The main components of the standard were calibrated at the PTB, the National Metrology Institute of Germany. In Ukraine, numerous measurement standards and measurement instruments for phase measurements (more than 500.000 units) are used, in particular, phase calibrators, phase meters, phase shifters, synchronoscopes etc. Regular study of metrological characteristics of the DETU 09-07-11 measurement standard is conducted both in the main (from 5 Hz to 200 kHz) and in the extended (from 0.01 Hz to 10 MHz) frequency range. The PSA values obtained as a result of the research in the main frequency range do not exceed 0.001° (which is maximum according to measurements at all calibration points 0.00015°), and in the extended frequency range – 0.01° (which is maximum according to measurements at all calibration points 0.0053°). To eliminate the systematic measurement uncertainty component of the phase measurement standard, a special calibration is regularly performed using a set of resistive and capacitive phase bridges.

Exploring and evaluating the relationship between Saccharomyces cerevisiae biofilm maturation on carbon felt anodes and microbial fuel cell performance

Microbial fuel cells (MFCs) hold great promise as sustainable bioenergy sources, with their performance intricately linked to the formation and characteristics of biofilms. This study delves into the bio-electrochemical perspective of biofilms in MFCs, aiming to elucidate their pivotal role in MFC functionality. The investigation focused on a yeast-based MFC operated through 48 h per cycle, with cycle 5 marking the maturation stage of biofilm formation. During this phase, voltage stability was observed, with a stationary phase voltage of 38.9±2.6 mV. Notably, cycle 5 exhibited a significant boost in power density, reaching 8.82 mW m-2, accom­panied by the lowest internal resistance of 100 Ω. Furthermore, the electron transfer rate constant from cycle 5 is 1.14±0.02 s-1, 57 times higher than the initial, underscoring biofilm's catalytic potential. Additionally, cyclic voltammetry unveiled non-linear relationships between redox reaction peak current and scan rate, with a consistent DEp of ~219 mV at 100 mV s-1. Importantly, elemental analysis disclosed incorporating diverse elements (Na, Al, Si, P, S, Cl, K, Ca, Cr, and Fe) into the carbon felt, signifying their association with biofilm development. These findings offer critical insights into optimizing MFC performance through biofilm modulation, advancing sustainable bioenergy technologies.

M3D‐DPWM strategy for three‐phase four‐leg inverter with higher harmonic suppression capability

AbstractThree‐phase four‐leg inverters are widely used in power systems due to their inherent ability to handle unbalanced loads. However, with conventional 3D space vector pulse width modulation (3D‐SVPWM), high harmonics of large amplitude exist in the output voltage around the switching frequency and its integer multiples leading to noise in the load motor and limiting the application range of the inverter system. The passband amplification of conventional sinusoidal filters and their cutoff frequency vary with the load, so it is particularly important to investigate the regulation strategy with harmonic suppression. In this study, an improved 3D discontinuous pulse width modulation (M3D‐DPWM) strategy is proposed based on 3D‐SVPWM. By reducing the conventional 3D‐SVPWM switching segments and changing the vector synthesis sequence of the last half switching cycle, the output phase voltage period is reduced to half of the original one, which achieves the purpose of suppressing the output voltage at the switching frequency and its odd multiple high harmonics without changing the fundamental characteristics and adding additional circuits. In contrast, the conventional 3D‐SVPWM switching frequency is increased to 20 kHz to achieve similar performance. Finally, the effectiveness of the proposed strategy is verified by simulation and experiment.

Observation of Young’s double-slit phenomenon in anti-PT-symmetric electrical circuits

Abstract In the last few decades, interference has been extensively studied in both the quantum and classical fields, which reveals light volatility and is widely used for high-precision measurements. We have put forward the phenomenon in which the discrete diffraction and interference phenomena, presented by the time-varying voltage of a Su-Schrieffer-Heeger (SSH) circuit model with an anti-PT (APT) symmetry. To demonstrate Young’s double-slit phenomenon in an APT circuit, we initially explore the coupled mode theory (CMT) of voltage in the broken phase, observe discrete diffraction under single excitation and interference under double excitations. Furthermore, we design a phase-shifting circuit to observe the effects of phase difference and distance on discrete interference. Our work combines the effects in optics with condensed matter physics, show the Young’s double-slit phenomenon in electrical circuits theoretically and experimentally.

Prediction of amplitude of fault generated travelling wave in medium-voltage grids for fault type classification

This paper proposes a new solution for the classification of short-circuits in medium-voltage distribution grids. The solution requires the measurements of the phase voltages at the time of the short-circuit and the voltage amplitudes of the short-circuit wave resulting from the fault. The values of the voltage before the short-circuit are used to calculate the expected values of the short-circuit wave amplitudes for the different types of short circuits. These calculations are based on an analysis of the charge flow between the capacitances of the power line due to the disturbance. The short-time matrix pencil method was used to detect the incoming short-circuit waves. Tests of the algorithm were carried out on the IEEE 34-bus Feeder model, taking into account the influence of voltage sensors on the measured signal values. The classification algorithm uses only non-zero components due to their relatively low attenuation. Despite that, it achieves high performance in the classification of single- and two-phase short-circuits.

Enhancing off-grid wind energy systems with controlled inverter integration for improved power quality

Introduction. Off-grid wind energy systems play a pivotal role in providing clean and sustainable power to remote areas. However, the intermittent nature of wind and the absence of grid connectivity pose significant challenges to maintaining consistent power quality. The wind energy conversion system plays a central role in tapping renewable energy from wind sources. Operational parameters such as rotor and stator currents, output voltages of rectifiers and converters, and grid phase voltage variations are crucial for stable power generation and grid integration. Additionally, optimizing power conversion output through voltage gain analysis in boost converters is essential. Moreover, ensuring electricity quality via total harmonic distortion reduction in inverters is vital for grid compatibility. Goal. Enhancing the power quality of grid-integrated wind energy conversion systems. Methods. The proposed topology is implemented in MATLAB/Simulink with optimized control strategies for enhancing power quality in off-grid wind energy systems. Results. Control strategies with a grid-connected wind energy conversion system yields substantial improvements in power quality. This includes effectively mitigating voltage fluctuations and harmonics, resulting in smoother operation and reduced disturbances on the grid. Practical value. The proposed topology has proven to be extremely useful for off grid-integrated wind system. References 18, table 1, figures 11.

Dspace implementation of real-time selective harmonics elimination technique using modified carrier on three phase inverter

Introduction. In the contemporary world, alternative electrical energy has become an integral part of our daily existence, with the majority of our electrical materials, electronic devices, and industrial equipment relying on this energy source. Consequently, ensuring the quality of the electrical signal obtained is of paramount importance in the process of converting and distributing electrical energy. The improvement of the output voltage inverter can be achieved through adjustments to the inverter structure or by refining the control strategy. The novelty of the presented research lies in an innovative approach that employs real-time modulation for efficient control over the reduction of harmonics, alongside managing the fundamental component. This approach is applicable to both bipolar and unipolar configurations, featuring quarter-wave and half-wave symmetries. Purpose. Employing this modulation strategy aims to enhance the durability of the switching components and enhance the voltage output of the inverter. Methods. The methodology is founded on a sine-sine modulation as its foundational model. It constitutes an inventive pulse width modulation technique in which a reference sinusoidal waveform, operating at the desired signal frequency, is compared to a modified carrier signal with an identical time period as the reference signal. Results. This paper introduces a broader and more comprehensive approach, alongside specific solutions, for the control and mitigation of harmonics in three phase voltage source inverters. The proposed method offers precise control over the reduction of harmonics and the fundamental component, and it can be implemented in extensive power electronic converters. Practical value. To assess the effectiveness of the given control approach, we conducted simulations as well as real-time implementation employing Dspace DS1104 controller board. The outcomes were highly favorable, confirming the effectiveness and validity of the suggested control algorithm. References 15, tables 4, figures 7.