Three-phase Circuit Research Articles

Research on Series Arc Fault Detection and Phase Selection Feature Extraction Method

Series arc fault is one of the important causes of electrical fire in industrial and mining enterprises. It is of great significance to study the series arc fault detection and phase selection feature extraction method to ensure safe and stable operation of electrical equipment and to guide line maintenance. Arc fault experiments under different current and circuit conditions with a three-phase motor and inverter load were carried out. A new arc fault detection and phase selection method based on single-phase current was proposed. First, wavelet threshold noise reduction, piecewise linear fitting, and first-order difference processing were performed on single-phase current signals to filter out noise interference and highlight fault features. Second, fractional Fourier transform (FRFT) was applied to the first-order differential signal to construct the amplitude matrix of the signal from the time domain to the frequency domain. The local features of the amplitude matrix were effectively extracted, and the feature vector of arc fault with lower dimension was established by combining the two-level block singular value decomposition (SVD) method. Finally, an arc fault detection and phase selection model was established using a support vector machine (SVM) optimized by grid search (GS) and particle swarm optimization (PSO) algorithm. The applicability of the model in single-phase multiload was analyzed. The results showed that the proposed method could realize series arc fault detection and phase selection in three-phase motor and inverter circuits, and it can also be used to single-phase multiload circuits.

Measuring the Voltage of a Three-Phase Circuit in a Generator Set Control System

Measuring the Voltage of a Three-Phase Circuit in a Generator Set Control System

DEVELOPMENT OF A MATHEMATICAL MODEL OF TRANSITIONAL PROCESSES IN THE ELECTRICAL NETWORK IN PHASE COORDINATES

Distribution electrical networks of great length are characterized by a high order of the system of equations of electromagnetic transients. To improve the efficiency of modelling such networks, it is necessary to develop formalized procedures that provide automation of both the solution and the formation of systems of equations using modern computer technology. To simplify the development of mathematical models, transformations are used to move from a real three-phase network to other coordinate systems, but this is achieved at the expense of additional restrictions. To solve the problems of choosing and increasing the efficiency of means for limiting currents and overvoltages during transient processes in electrical networks, it is necessary to have a model reflecting a number of features, both of the networks themselves, and of the transient processes occurring in them. This is implemented in a model based on the representation of network elements not by single-phase equivalents, but by equations in phase coordinates. These equations contain the parameters of the network elements (active resistances, own and mutual inductances and capacitances) and the parameters of its mode (currents, voltages, phase powers), corresponding to the real physical parameters of electrical systems. A mathematical model of electromagnetic transient processes in an electrical network in phase coordinates has been developed. Calculation of the transient process when using the implicit method and representing the three-phase elements at the integration step by discrete models makes it possible to reduce the solution of a system of differential equations to multiple formation and solution of a system of equations. The diakoptic method for studying complex systems was developed, which was used to develop a mathematical model of electromagnetic transient processes in a three-phase electrical network. The proposed form of representation of discrete models of three-phase multipoles allows one to formalize both the solution procedure and the procedure for drawing up equations of transient processes for three-phase circuits of electrical networks of arbitrary configuration. Prospects for further research are computational experiments to study electromagnetic transient processes during ground faults in electrical networks of arbitrary configuration with various neutral modes and means of limiting currents and overvoltages.

Sheath losses correction factor for cross‐bonded cable systems with unknown minor section lengths: Analytical expressions

The IEC Standard 60287-1-1 contains the formulae for the calculation of the sheath and armour loss factors of a three-phase cable circuit where sheath circulating current losses are computed for single-, multiple- or cross-bonded systems. For cross-bonded systems, the standard gives a formula allowing calculation of the circulating current losses when the lengths of the minor sections are known. When the lengths of the minor sections are not known, the standard suggests using a correction factor of 0.004, which multiplies the circulating current loss factor computed for a multi-point bonded system. Previous studies by the authors have shown that this assumption may lead to a significant error in the evaluation of the sheath loss factor for some combinations of the minor section lengths. This paper provides analytical formulae for the correction factor in the cross-bonded system with unknown section lengths with the aim of improving the accuracy of the IEC 60287-1-1. Several numerical examples illustrate the applicability and accuracy of the proposed approach.

Characterization of a 3.3-kV Si-SiC Hybrid Power Module in Half-Bridge Topology for Traction Inverter Application

A state-of-the-art 3.3-kV/450-A hybrid power module for the next generation traction inverter of rolling stock is reported in this paper, combining the silicon (Si) insulated-gate bipolar transistor (IGBT) and silicon carbide Schottky barrier diodes (SBDs) chips. Compared with the existing hybrid technology at the same voltage level, this module is characterized by a half-bridge topology, in which 6 IGBT and 12 SBD chips are integrated in each switch. The outnumbering of the diodes represents a promising mitigation to the low availability of SBDs at this voltage level. Both static and dynamic test of this module and an equivalent Si-based module are carried out comparatively. Apart from describing the features of compactness, low-inductance, and good current distribution among chips, this module is characterized by low turn-ON current overshooting and turn-ON loss of IGBTs, negligible diode reverse recovery time and loss, as well as flexible allowance of IGBT turnON current rising rate dI/dt. A parameterized study is carried out to benchmark the advantage of this new topology. Based on the experimental results, the performance of the hybrid module in a three-phase traction inverter circuit is also evaluated by means of electro-thermal simulation. The hybrid module distinguishes itself by describing much lower power loss and junction temperature than its Si-based counterpart.

Research on the Topology of Wireless V2G for Electric Vehicle

Based on the circuit topology for the electric vehicle wireless V2G power transmission system, the boost circuit, wireless resonance circuit and grid-connected inverter circuit of the system were studied. According to the characteristics of the boost converter, a voltage feedback closed-loop control model based on PID and PWM was established. Since the excitation and magnetic leakage of the wireless transmission coil could not be ignored, the maximum transmission power model of the wireless resonance circuit was derived. Starting from the operation mode of the three-phase grid-connected inverter circuit, the control rules of the three-phase bridge arm that sent electrical energy back to the grid in a steady state were obtained. The simulation results showed that the maximum transmission power of the electric vehicle wireless V2G power transmission system was affected by the leakage magnetic field of the wireless transmission coil, and the maximum transmission power was inversely proportional to the leakage magnetic field. In addition, the boost circuit and grid-connected inverter circuit in the system were sources of harmonics, and a large amount of harmonic energy was sent to the grid during the operation process of the electric vehicle wireless V2G circuit.

Energy modes of a three-section inductor for heating aluminum

The article proposes a method for single-phase power supply of a three-section induction heater for aluminum ingots before extrusion. The solution allows you to flexibly control the heating mode of each section. The peculiarity of the synthesized mode is to increase the uniformity of heating the methodical load at the joints of the sections when replacing the three-phase winding circuit with a single-phase one. Changing the circuitry reduces the phase shifts of currents in adjacent sections. Uneven power distribution between the coils is proposed to be realized by local resonances in the windings. The resulting power factor of the inductor, close to unity, is provided by a common capacitor bank. The set of established modes of an induction heater was investigated using a simulation system built on the basis of a hybrid analysis. The numerical experiment was carried out in a specialized software environment based on a macromodel created using controlled sources. The achieved positive result from the modification of the device is evaluated by comparing the vector diagrams of the operating parameters for the initial and corrected states.

Clarke Transformation Solution of Asymmetrical Transients in Three-Phase Circuits

This work deals with the use of the Clarke transformation for the theoretical derivation of circuit models for the analysis of asymmetrical transients in three-phase circuits. Asymmetrical transients occur when only one or two phases of a three-phase power system are involved in a switch operation. Such a condition is critical from a theoretical viewpoint since the Clarke transformation is based on the assumption of circuit symmetry between the three phases. If the symmetry assumption is not met, the equivalent circuits in the transformed variables α, β, and 0 are not uncoupled. The literature concerning numerical approaches for asymmetrical transient analysis is very rich, but a comprehensive and rigorous analytical investigation of circuit models within the framework of the Clarke transformation is still lacking. Contrary to numerical approaches, analytical solutions provide deeper insight into the phenomenon and allow for theoretical interpretation and better understanding of the transient behavior. The proposed circuit models show that the β variables are always uncoupled with α and 0 variables, whereas coupling between α and 0 variables can be properly represented by an ideal transformer. Moreover, in the case of single-line switching, the β variables have no transient, i.e., they keep the steady-state behavior. Transient properties can be readily and effectively observed by representing the trajectory of the space vector on the complex plane. All the analytical results have been checked numerically through the Simulink (Matlab R2020a, The MathWorks, Inc., Natick, MA, USA) implementation of a specific three-phase circuit introduced to illustrate the main theoretical issues.

Research on a Fundamental and Harmonic Detection Method Based on D-Q Rotating

The widespread use of power electronics in power systems has led to increasingly serious power quality problems in power systems. Active power filters play an important role in governing the harmonics of power systems. The fast and accurate detection of fundamental and harmonic currents in power systems is one of the key aspects of power filters to manage harmonics. In this paper, a new detection method for the fundamental or the nth harmonic component of the fundamental by presetting the frequency of the d-q conversion matrix is proposed. Analysis of simulation results shows that the detection method is not affected by the voltage distortion or asymmetry of the three-phase circuit, and that the results for fundamental and harmonic detection. The ability to accurately reflect changes in frequency and amplitude excursions.

Symulacja wyladowan atmosferycznych na linii elektroenergetycznej

Modelling electrical circuits by application of schemes containing elements with distributed parameters such as transmission lines has been applied in this research. Functions approximating voltage or current atmospheric discharges have been presented together with frequency spectra of these functions. The results of computer simulations obtained with the help of PSpice software have been presented for a simplified three-phase circuit subject to such discharge.

Fast Detection Using PID Pre-Interpolation Algorithm for Magnetic Particle Testing

The current tracing scheme is based on a silicon-controlled rectifier (SCR) with phase shift triggering, which is utilized in traditional magnetic particle testing. In industrial applications, the popularization and implementation of magnetic particle flaw detection technology could be degraded by various problems such as poor real-time performance of current tracing, the significant error of current tracing, and low precision of flaw detection. In this work, the magnetization current waveforms under different control angles of the SCR are studied to obtain a real-time magnetization current tracking in less than 0.5 s and a current tracking error smaller than 5%. A fast three-phase electric zero detection circuit is designed in which the current tracking method is optimized by combining a high-speed analog to digital (AD) converter with a true root-mean-square (true-rms) device. Moreover, a Newton interpolation-based fast proportional integral derivative (PID) algorithm is proposed to achieve a precise real-time current tracking. The experimental results show that the real-time magnetic particle flaw detection for current tracking is performed in less than 0.2 s with a current tracking error below 2%, which meets the technical requirements of magnetic particle flaw detection. The fast three-phase electric zero detection method using the PID algorithm can improve the real-time performance and accuracy of current tracking in magnetic particle flaw detection.

A Harmonic Detection Method of UPQC Based on LSL Algorithm in Photovoltaic Microgrids

Photovoltaic microgrids have discontinuity and intermittency issues that affect the load current amplitude and frequency, and this leads to disturbances. The unified power quality conditioner (UPQC) combines a series active power filter (SAPF) and a parallel active power filter (PAPF), and therefore, it has the advantages of SAPF and PAPF to treat power quality problems. Considering detection precision and response speed, and to meet the fast speed and accuracy of PAPF harmonic detection, the algorithm principle of adaptation and least-squares lattice (LSL) is analyzed. A new harmonic detection method of three-phase circuit based on LSL adaptive algorithm is proposed. The two other harmonic detection methods between least mean square and instantaneous power theory based are compared using the Simulink simulation platform. The compensation effect of LSL is more stable and better than the two other methods. The experimental results also indicate that the new method based on LSL can accurately detect and compensate the harmonic component in photovoltaic microgrids in real time. Therefore, this harmonic detection method based on LSL can be used in the practical engineering applications, and it provides a new method for harmonic detection of UPQC PAPF.

Parasitic Effects Analysis of Bonding Wires Bonding Parameter of Intelligent Power Modules for Three-Phase Motor Control Applications

Parasitic parameter analysis is the focus of intelligent power module switch performance research. This paper will utilize the model of 600V/30A intelligent power module and extract the part of circuit layout bonding wires parasitic parameter by Ansys Q3D Extractor, expedition the relationship between physical bonding parameter and parasitic parameter in the intelligent power module circuit. An exact three-phase circuit module of high voltage intelligent power module and bonding wires package module is established. Through Ansys Q3D Extractor, test a series of bonding parameters from the three-phase circuit layout module and extract the parasitic parameters of the bonding wires. The experimental results of the parasitic parameters are analysed and compared, and the influence degree of the bonding parameters on the parasitic parameters is discussed. An improved solution is proposed for the bonding wires of the intelligent power module to reduce the voltage spike that the MOSFET chip during the turn-off process.

Cascaded single-phase, PWM multilevel inverter with boosted output voltage

Splitting of a dc voltage source with two capacitors has been the approach in generating 5-level output voltage with single- and three-phase full-bridge circuits and added bidirectional switch. Associated with this configuration is the problem of voltage imbalance between the splitting capacitors. In addition, the inverter output voltage magnitude is obviously limited to the value of the split input voltage source. Presented in this paper is a unit topology for single-phase 5-level multilevel inverter, MLI. It simply consists of a full-bridge circuit, a capacitor, charge-discharge unit and a dc source. The charge-discharge unit with the capacitor is the interface between the full-bridge and the dc source. The proposed unit cell can generate a 5-level output voltage waveform whose peak value is twice the input voltage value. For higher output voltage level, a cascaded structure of the developed unit cell is presented. Comparing the proposed inverter with CHB inverter and some recent developed MLI topologies, it is found that the proposed inverter configuration generates higher output voltage value, at reduced component-count, than other topologies, for a specified number of dc input voltages. For two cascaded modules, simulation and experimental verifications are carried out on the proposed inverter topology for an R-L load.
 Keywords: Cascaded multilevel, Inverter, total harmonic distortion, topologies, waveform

Non-isolated H10 three-phase inverter for leakage current suppression

In recent years, an increasing amount of attention has been paid to non-isolated photovoltaic power generation systems, where leakage current suppression is one of the key issues to be addressed. In view of this problem, this paper proposes a novel ten-switch three-phase circuit that is referred to as an H10 inverter. This circuit is obtained by adding two isolating switches and a clamping circuit to the traditional three-phase inverter (H6 inverter). The working principle of the proposed system is analyzed. On the basis of the logic relationship between the common-mode voltage (CMV) and the switching states, a control strategy combining carrier modulation and logic operation is proposed. With this proposed control strategy, the H10 inverter can effectively reduce the variation of the CMV and improve the leakage current suppression. Finally, simulation and experimental platforms are built for the inverter system, and the obtained results are compared with those of a traditional three-phase inverter to verify the correctness of the theoretical analysis.

Fault Diagnosis Method of Power Electronic Converter Based on Broad Learning

In order to realize the unsupervised extraction and identification of fault features in power electronic circuits, we proposed a fault diagnosis method based on sparse autoencoder (SAE) and broad learning system (BLS). Firstly, the feature is extracted by the sparse autoencoder, and the fault samples and feature vectors are combined as the input of the broad learning system. The broad learning system is trained based on the error precision step update method, and the system is used to the fault type identification. The simulation results of the thyristor fault diagnosis of the three-phase bridge rectifier circuit show that the method is effective and has better performance than other traditional methods.

Analysis of autoparametric oscillations in three-phase electro-ferromagnetic circuits

The paper presents mathematical models for the analysis of autoparametric oscillations at the frequency of subharmonic oscillations in three-phase electro-ferromagnetic circuits, which are developed taking into account the main factors and conditions for obtaining subharmonic oscillations in which the process under consideration occurs. With an increase in the degree of adequacy of the mathematical model, its form and algorithmization of problems on PC become more complicated.

Analysis of Six-Phase Transmission Lines for Increasing Power

In the India, especially in metropolitan areas, transmission infrastructure is congested due to a combination of increasing load demands, declining investment, and aging facilities. It is anticipated that significant investments will be required for new construction and upgrades in order to serve load demands. This paper explores higher phase order systems, specifically, six-phase, as a means of increasing power transfer capability, and provides a comparison with conventional three-phase double circuit transmission lines. Line parameters calculations performed in this thesis show that line impedances in six-phase lines have a slight difference, compared to three-phase double circuit line. The electric and magnetic fields calculations show that, ground level electric fields of the six-phase lines decline more rapidly as the distance from center of the lines increase. The six-phase lines have a better performance on ground level magnetic field. Based on the electric and magnetic field results, right of way requirements for the six-phase lines and three-phase double circuit line were calculated. The calculation results of right of way show that six-phase lines provide higher power transfer capability with a given right of way.

Design a three-phase step-down power supply based on ANSI/IEEE standard

An alternating current three-phase step-down power supply design is a system development process that creates an existing three-phase system whereby the primary side of the Y relationship and the secondary side of the Y relationship. The problems in the design of three-phase step-down power supply circuit are the existence of harmonics, losses and unbalance voltage. The power supply test is carried out using no-load and linear load resistance with the value of resistances in range of hundreds ohm. The circuit is tested for resistance number one, resistance number two, resistance number three and resistance number four transformers to obtain a power supply design that meet American National Standards Institute or Institute of Electrical and Electronic Engineering standards. The test results of four transformers in the form of three-phase step-down found that resistance number one and resistance number two type transformers have the lowest copper loss percentage, core loss, voltage THD and low unbalance voltage, so that these power supply can be made according to ANSI/IEEE provisions.

Transient Characteristics Analysis of Shunt Capacitor Asynchronous Energizing

The capacitor energizing transient as a kind of typical disturbance is used in the studies of power quality, condition monitoring, and other fields, and all studies heavily rely on transient characteristics. However, most characteristics are established based on the three-phase capacitor synchronous energizing (SE), and the effect of asynchronous energizing (AE) is neglected, which may affect the relevant studies. In this paper, the main characterizations of the capacitor AE transient, such as the oscillation frequency, time constant, and transient magnitude are analyzed considering the operation modes of the system and capacitor neutral points. The effect of the three-phase circuit asymmetry on the characterizations is investigated. The downstream voltage magnification phenomena in not only positive-sequence circuit but also zero-sequence circuit caused by the capacitor AE are also revealed. The theoretical analysis, computer simulation and lab experiment results have verified the effectiveness of the characteristics.