Single-phase Switching Research Articles

MAIN ASPECTS OF IMPLEMENTATION OF CHARGING STATIONS FOR ELECTRIC TRANSPORTS IN LOGISTICS

The paper analyzes and compares charging stations for small electric vehicles, including fast and slow boats, electric cars and their components. The analysis of charging modes of electric vehicles showed that four internationally standardized modes are used, three of which use alternating current with single-phase and three-phase switching and only one – direct current. When charging on direct current, the fastest charging is provided. There are three main options for connecting the electric vehicles to the charging station: by means of a special power cable; by means of a pantograph from bottom to top and from top to bottom; wirelesses connection. There are four standardized cases of connecting charging stations to electric vehicles. Three cases of cable connection can be used on alternating current, only the third case – on direct current, and the fourth case – when wirelessly charging an electric vehicle. A comparison of existing types of connectors for charging electric vehicles has shown that the standardized interface between the charging station and the electric vehicle remains one of the most acute problems.

Single phase second order sliding mode controller for complex interconnected systems with extended disturbances and unknown time-varying delays

<p>Novel results on complex interconnected time-delay systems with single phase second order sliding mode control is investigated. First, a reaching phase in traditional sliding mode control (TSMC) is removed by using a novel single phase switching manifold function. Next, a novel reduced order sliding mode observer (ROSMO) with lower dimension is suggested to estimate the unmeasurable variables of the plant. Then, a new single phase second order sliding mode controller (SPSOSMC) is established based on ROSMO tool to drive the state variables into the specified switching manifold from beginning of the motion and reduce the chattering in control input. Then, a stability condition is suggested based on the well-known linear matrix inequality (LMI) method to ensure the asymptotical stability of the whole plant. Finally, an illustrated example is simulated to validate the feasible application of the suggested technique.</p>

Single Phase Second Order Sliding Mode Controller for Mismatched Uncertain Systems with Extended Disturbances and Unknown Time-Varying Delays

In this paper, a novel single phase second order sliding mode controller (SPSOSMC) is proposed for the mismatched uncertain systems with extended disturbances and unknown time-varying delays. The main achievements of this study consist of three tasks: 1) a reaching phase in conventional sliding mode control (CSMC) technique is removed to ensure the global stability of the system; 2) an influence of the undesired high-frequency oscillation phenomenon in control input is vanished; 3) an exogenous perturbation is generally extended to the k-order disturbance of state variable. Firstly, a single phase switching manifold function is defined to eliminate the reaching phase in CSMC. Secondly, an unmeasurable state variable is estimated by using the proposed reduced-order sliding mode observer (ROSMO) tool. Next, a SPSOSMC is built based on the help of ROSMO tool and output information only. Then, a sufficient condition is established by employing the linear matrix inequality (LMI) technique and Lyapunov function theory such that the resulting sliding mode dynamics is asymptotically stable. Finally, a numerical example is simulated via the well-known MATLAB software to validate the effectiveness of the proposed technique.This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium provided the original work is properly cited.

COMPARATIVE ANALYSIS OF TECHNICAL CHARACTERISTICS OF CHARGING STATIONS OF ELECTRIC VEHICLES

The article analyzes and compares charging stations for electric vehicles and their components. The analysis of charging modes of electric vehicles showed that four internationally standardized modes are used, three of which use alternating current with single-phase and three-phase switching and only one – direct current. When charging on direct current, the fastest charging is provided. There are four standardized cases of connecting charging stations to electric vehicles. Three cases of cable connection can be used on alternating current, only the third case – on direct current, and the fourth case – when wirelessly charging an electric car. Analysis of the principles of use of charging stations showed that they classify portable, wall, and stationary stations. National standards introduce road signs for electric vehicles, and a European standard establishes harmonized identifiers for the power supply of electric vehicles. There are some standardized protocols for the interaction of the charging station and the control server, which are designed to optimize energy resources and energy production systems. A comparison of existing types of connectors for charging electric vehicles has shown that the standardized interface between the charging station and the electric vehicle remains one of the most acute problems. Recommendations on approaches to metrological support of charging stations are formulated. The issue of international and regional standardization of electricity meters of direct current for use in charging stations remains relevant. International standards are transformed into relevant European standards without changes. However, in some cases, it is necessary to develop a special European standard, in particular for meters of active electrical energy of the direct current.

Voltage transient management for Alternating Current trains with vacuum circuit breakers

Alternating current power supplies and rolling stock with 25 kV (50 or 60 Hz) and 15 kV (16.7 Hz) traction systems do not have the characteristics and behaviour of a typical three-phase medium-voltage distribution system. Switching inductive loads with a vacuum circuit breaker (VCB) in MV traction systems poses familiar challenges as well as some unique challenges, such as the crossing of phase change neutral sections. Transformers represent highly inductive loads due to their iron core and, thus, the consequences of energizing and disconnecting a transformer and dealing with the energy stored in its inductance must be considered within a system context. The authors of this study consider two transient phenomena associated with switching single-phase, medium voltage, AC traction transformer loads using a VCB on railway rolling stock: (i) switching transients that occur when disconnecting a transformer, particularly if lightly loaded and (ii) pre-ignition and current inrush that occurs when energizing a transformer. Both phenomena can cause reliability problems, requiring increased system maintenance or resulting in premature failures of system components. The authors review the use of controlled switching and other state-of-the-art methods to prevent or limit voltage transients when switching a transformer load by means of a VCB. The effective application of such techniques has been demonstrated in previous research or established in practical applications by manufacturers and electrical distribution network companies.

Magnetic property modulation in sputter-grown BaTiO3–Y3Fe5O12 composite films

Herein, we present the structural and magnetic properties of composite thin films consisting of garnet-structured Y3Fe5O12 and perovskite-structured BaTiO3 on SrTiO3 (001) substrates, obtained by sputtering and sequential heat treatment. The BaTiO3–Y3Fe5O12 thin films deposited at room temperature exhibited an amorphous phase with negligible magnetization, whereas the post-annealed films showed a self-assembled composite structure in which BaTiO3 grew with the same crystallographic orientation within the Y3Fe5O12 matrix. The magnetic hysteresis loops of the annealed thin films revealed two distinct slopes at room temperature. The steeper slope near the zero field originated from the soft magnetic Y3Fe5O12, whereas the smaller slope originated from the secondary phase of the hard magnetic BaFe12O19. The formation of the secondary phases, YFeO3 and BaFe12O19, was clearly confirmed by high-resolution transmission electron microscopy and elemental mapping. However, the composite thin films grown at 650 °C displayed a different surface morphology and single-phase switching in the magnetic hysteresis loops after annealing. This new report on single- or multi-switching in perovskite-garnet composite thin films is a promising development in the design of multi-bit memory devices.

Investigation of Resonance and Ferroresonance Overvoltages due to Cable-Transformer Interactions

In this paper, the resonance and ferroresonance phenomena are deeply investigated considering two different cable-transformer power systems. The internal transformer resonance overvoltage case is initiated due to a single-phase earth fault, while the studied ferroresonance case is due to a single-phase switching in the source feeding an unloaded transformer via a power cable. The resulted secondary overvoltage and the core flux signatures are used as a classifier, where the transient features are extracted using three algorithms. Although the voltage frequency spectrum and phase-plane diagrams have been previously utilized for the ferroresonance mode evaluation, they are exploited in this paper for the comparison study and accordingly for the detection of resonance and ferroresonance phenomena. Salient features found in the transients extracted using the well-known DWT are used as inputs of the third algorithm. A new detection approach is attained based on the DWT-based transient feature extraction of resonance and ferroresonance overvoltages.

HARMONIC ANALYSIS OF THE COMBINED CIRCUIT OF SINGLE-PHASE SWITCHING OF INDUCTION ELECTRIC DRIVE WITH THYRISTOR CONTROL

Purpose. The purpose of this article is to provide a comparative analysis of influence of the phase controlled single-phase induction electric drive coordinates harmonic components on the operational characteristics of the electric drive under different variants of the power part. Methodology. A mathematical model of the combined circuit of a single-phase induction motor with a variable structure of the power part and a constant capacitance of the phase-shifting capacitor is generalized for various variants of connection of the power part of the electric drive with thyristor control. The comparative harmonic analysis of currents and torques of the motor is carried out and the factors influencing the energy efficiency of the electric drive at different circuit of connection of the power part are determined. Results. The analysis of the obtained data shows that the series-parallel circuit has the best harmonic composition of the consumed current in practically the whole range of changes of load torque and speed. The main effect on the loss increase is due to the asymmetry of the currents in the series-parallel circuit and the higher harmonics in the Steinmetz circuit. Originality. For the analysis of the processes in these circuits, a generalized thyristor control single-phase electric drive mathematical model, in which the structure of differential equations remains unchanged regardless of the circuit of connections of the power part, is developed. Practical value. Using of the combined circuit of single-phase switching on of a three-phase induction motor allows to use a constant capacity in the range of slips from nominal to critical without exceeding the nominal losses.

Simulation of Single Phase Switching Capacitor 49 Level Inverter with Reduced THD

The study of single phase Switched Capacitors Multi Level Inverter (MLI) is used with Switched Capacitor Converter (SCC) units. The SCC is used to increase the input DC voltage by connecting capacitor in string and shunt. This increassed DC link voltage is converted in to multilevel i.e. 49 level AC output. This SCMLI topology is used to reduce the number of switches, diodes, isolated dc power supply and Total Harmonic Distortion (THD). The SCMLI provides 49 level output voltage using 14 power switches and 3 isolated power supply. The performance of the SCMLI topology is confirmed by using MATLAB simulation result.

Analysis of DC Link Energy Storage for Single-Phase Grid-Connected PV Inverters

Single-phase grid-connected photovoltaic (PV) inverters (GCI) are commonly used to feed power back to the utility. However, the inverter output power fluctuates at 100 Hz, which can be seen by the PV panel, and this reduces the PV output power. It is important to determine and analyze the correlation between the array voltage and current ripple and the average output power reduction of PV array. Therefore, this paper investigates the relationships between the oscillations due to single-phase switching and the DC link energy storage for PV GCIs. The balanced ripple definition is introduced and compared with the more common centered ripple definition. Some examples are provided that demonstrate the importance of these results, in the inverter design industry. The analysis presented here incorporates inductor trade-offs, which are verified with experimental results.

A novel methodology for the management of distribution network based on neutral losses allocation factors

A multi-phase losses allocation method is proposed to provide explicit information about losses allocated to the neutral conductor. This information from the proposed methodology can be utilized by distribution system operators in the identification of highly unbalanced nodes in a network and consequently, allows them to implement suitable unbalance compensation schemes at these nodes in order to improve network balancing. The newly developed approach, based upon neutral losses allocation factors, reduces the unbalance in a network by switching single-phase loads across phases of highly unbalanced nodes. Two-phase switching algorithms, based upon individual and combined load commutation, are proposed to achieve this objective. The developed technique is implemented on a real LV Italian distribution network by adopting real customer’s power profiles. Results indicate a significant improvement in network balancing and losses reduction, which clearly represent the positive active role that neutral losses allocation factors can play in the assessment and management of distribution networks.

Analysis of Ferroresonance Phenomenon in 22 kV Distribution System with a Photovoltaic Source by PSCAD/EMTDC

Overvoltage and overcurrent in the middle voltage (MV) 22 kV and low voltage (LV) 0.4 kV distribution network with photovoltaic (PV) rooftop system of the Provincial Electricity Authority of Thailand (PEA) have been investigated in order to show that these unwanted situations are caused by the ferroresonance phenomenon. This information would be useful to improve a better solution for the system protection when PV rooftops are integrated into the PEA distribution system. The software tool, PSCAD/EMTDC is used to study the overvoltage at the high side of open-delta and open-wye distribution transformer- and overcurrent at the low side of distribution transformer linked to the grid system via three single-phase fuse cutouts. The ferroresonance phenomenon can be observed when the PV rooftop system is linked to the low voltage side of the distribution transformer via three single-phase fuse cutouts. The results show a good similarity with the results from the simulation of the MV side and LV side of distribution transformers. Finally, the physical phenomena described to the overvoltage, overcurrent, and the destruction of the distribution transformer and other apparatus in load customers will occur when the system consists of the PV rooftop source, capacitance in long transmission line, nonlinear distribution transformer with saturation characteristic and the usage of single-phase switching cutouts in the system.

Design of a High Starting Torque Single-Phase DC-Excited Flux Switching Machine

Because single-phase dc-excited flux switching machines (DCFSMs) consist of only copper windings and iron cores, they have great potential in low-cost and high-speed applications, such as home appliances. However, similar to other types of single-phase ac machines, single-phase DCFSMs have insufficient initial torque at some rotor positions. A novel single-phase, eight-slot, four-pole DCFSM design is presented in this paper. The key feature of this design is the enhancement of reluctance torque at positions where the machine cannot deliver sufficient initial torque output. This is accomplished by modifying the outline of a section of the rotor. Consequently, the machine has a two-layer rotor structure along the axial direction. The proposed design is validated experimentally using a prototype. The results show that the machine can start from any rotor positions with initial torque higher than 50% of the rated output torque.

Topological analysis of unbalanced distribution networks with single‐phase switching equipment and temporary elements

Summary A need to minimize the duration of outages in weakly meshed distribution networks leads to the intensive application of single-phase switching equipment and temporary elements. The result creates a wide range of allowed, but not typical, network topologies such as cross-phase jumpers, meshed islands, pseudo loops, and bidirectional branches, which cannot be processed in a simple/efficient way with existing algorithms for topological analyses. This paper proposes improvement of the traditional practice in distribution network modeling and topological analysis by using the phase granular adjacent matrix model with static and dynamic data, which provides a simple and efficient update of the mathematical model after switching and temporary element application. Additionally, the proposed algorithm provides a wide range of topological information such as network-layered structure, tracing, islands, energization, and active network phases. The results of the proposed algorithm are shown in an 84-bus test and 502,113-bus real-world schemes of unbalanced distribution networks.

Single‐phase auto‐reclosing mitigation procedure for half‐wavelength transmission line

In this study, the main results of a new mitigation method to single-phase auto-reclosing switching in half-wavelength transmission lines are presented. Initially, the behaviour of single-phase reclosing on conventional lines was evaluated, then, the results obtained for half-wavelength lines are presented. Finally, the proposed solution for the manoeuvre to be successfully executed is described. The study proposes a very advantageous solution for the application of the single-phase switching in half-wavelength lines.

Structural analysis for dynamic model of time‐varying switch in bond graph – a case study of single phase switch converters

This study proposes a new dynamic model of a time-varying switch bond graph for further improvement of the bond graph modelling method. The previous reference to the time-varying switch only discussed the on and off modes, but the dynamic model of a time-varying switch was not presented. This study proposes a bond graph modelling method of a time-varying switch which is mainly used for obtaining insights into the important dominant behaviour of the switch converter, such as the converter modelling, design of the controller, stability analysis and simulation of the converter; this is the reason why this study does not consider the multi-frequency modelling or generalised state-space averaging as the switch converter of a high-frequency switch behaviour.

Impacts of Water-Tree Fault on Ferroresonance in Underground Cables

Nowadays, more and more electrical power is being distributed to customers by underground cables rather than overhead transmission lines due to their advantage of providing better protection in inclement weather. They also have significantly reduced electromagnetic field emission because of their copper shielding. But underground cables have larger capacitance than transmission lines per unit. Thus, ferroresonance is more likely to occur in distribution systems using underground cables. Moreover, soil humidity at a depth of one meter remains 100 percent for most of the year, a factor that risks the occurrence of water tree (WT) in cables. Consequently, both ferroresonance and WT are prone to occur in underground cable systems. The objective of this paper is to determine the relationship between ferroresonance and water tree. A test system was designed to simulate and analyze ferroresonance in a cable system caused by single-phase switch and water tree. Eight scenarios of water tree were compared in the simulation. There sponses of ferroresonance are presented in this paper and two common patterns are observed from the simulation results.

Modeling of Six Switch Single Phase to Three Phase Matrix Converters

The Matrix Converter (MC) chosen in this work is capable of providing a variable three phase output voltage from a fixed single phase input using single stage phase conversion principle. This MC effectively provides three phase power to three phase variable speed drives. The implementation of MC requires solid state bidirectional switches. A new pulse generation scheme is developed to produce three phase voltage at the output. The performance of the Matrix Converter is evaluated using MATLAB/SIMULINK for different frequencies. Simulation results for three phase resistive and inductive loads are presented. The simulation results validate the developed conversion strategy.

Characteristic Investigation and Control of a Modular Multilevel Converter-Based HVDC System Under Single-Line-to-Ground Fault Conditions

This paper presents the analysis and control of a multilevel modular converter (MMC)-based HVDC transmission system under three possible single-line-to-ground fault conditions, with special focus on the investigation of their different fault characteristics. Considering positive-, negative-, and zero-sequence components in both arm voltages and currents, the generalized instantaneous power of a phase unit is derived theoretically according to the equivalent circuit model of the MMC under unbalanced conditions. Based on this model, a novel double-line frequency dc-voltage ripple suppression control is proposed. This controller, together with the negative- and zero-sequence current control, could enhance the overall fault-tolerant capability of the HVDC system without additional cost. To further improve the fault-tolerant capability, the operation performance of the HVDC system with and without single-phase switching is discussed and compared in detail. Simulation results from a three-phase MMC-HVDC system generated with MATLAB/Simulink are provided to support the theoretical analysis and proposed control schemes.

Cogging Torque Optimization of Flux-Switching Transverse Flux Permanent Magnet Machine

In this paper, cogging torque characteristics in both single-phase and three-phase flux switching transverse flux permanent magnet machines (FS-TFPMM) are analyzed by 3-D finite element method (FEM). It is found that the cogging torque of the FS-TFPMM is significantly influenced by the ratios of stator and rotor core circumferential widths to pole pitch, $k_{s}$ and $k_{r}$ . When $k_{r}>1-k_{s}$ , the cogging torque waveform has additional two zero-crossing points, whilst its amplitude is significantly reduced. The optimal ratios of $k_{s}$ and $k_{r}$ are selected to reduce the cogging torque and to maximize the permanent magnet flux linkage. A 380 W three-phase prototype is designed, manufactured, and tested to verify the optimization.