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Article
Publication date: 13 May 2022

Marcel Ciesielski and Pawel Zygmunt Witczak

The aim of this paper is to find a fast-acting numerical model of the phase shifter.

Abstract

Purpose

The aim of this paper is to find a fast-acting numerical model of the phase shifter.

Design/methodology/approach

The 3D FE model of the investigated unit is presented and compared with the results of the measurements. Due to its size, it is not suitable for transient analyses. The simplified 2D finite elements approach is discussed afterwards, with the identity of the magnetic energy stored in both models as the criterion of similarity between 2D and 3D models.

Findings

The introduction of scaling factors for the magnetic permeability values in particular volumes of the two-transformer set of the phase shifter enabled acceptable accuracy in calculations of the basic exploitation parameters of the phase shifter.

Research limitations/implications

The developed methodology allows the analysis of the exploitation conditions of two separated transformers connected in a power grid inside the single finite elements model.

Originality/value

Although the numerical models of power transformers are extensively discussed in the literature, the usage of the equivalent fast 2D model for the representation of two cooperating transformers at load conditions was not published yet.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering , vol. 41 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 5 July 2013

Björn Riemer, Enno Lange and Kay Hameyer

Depending on the load the flux‐density distribution inside power transformers core shows significant local variations due to stray fluxes which enter the transformer core. As…

Abstract

Purpose

Depending on the load the flux‐density distribution inside power transformers core shows significant local variations due to stray fluxes which enter the transformer core. As saturation of the core has to be avoided the flux‐density distribution has to be determined early in the design stage of the transformer. This paper seeks to address these issues.

Design/methodology/approach

To determine the load dependent flux‐density distribution the operating point of the transformer is calculated considering linear and non‐linear material properties. The operating point is determined using a linearised lumped parameter model of the transformer under various load conditions. Considering non‐linear material properties the inductance matrix depends on the operating point and will be extracted by means of the FEM whenever the magnetic energy within the transformer changes notably.

Findings

This paper presents a numerical stable approach to calculate the operating point of a transformer by using the magnetic flux linkage as state variable for the coupled field problem.

Research limitations/implications

The proposed approach uses a fixed time‐step to update the lumped parameters by means of the FEM. This results in long simulation times. In further research it is planned to implement an adaptive time‐step method based on the change of the magnetic energy.

Originality/value

A numerical stable approach to calculate the operating point of a transformer by using the magnetic flux linkage as state variable for the coupled field problem is proposed. The methodology is applied to a 2D model of a three‐phase transformer. However, it also can be applied to 3D FE models. Based on the calculated operating point, the flux‐density distribution can be determined and several post‐processing methods can be executed (e.g. determination of core losses, …).

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 32 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 16 September 2021

JiaRong Wang, Bo He and XiaoQiang Chen

This paper aims to obtain a symmetrical step-down topology with lower equivalent capacity and wider step-down range under the condition of the same output. Two new symmetrical…

38

Abstract

Purpose

This paper aims to obtain a symmetrical step-down topology with lower equivalent capacity and wider step-down range under the condition of the same output. Two new symmetrical step-down topologies of star-connected autotransformers are proposed in this paper. Taking the equivalent capacity as the main parameter, the obtained topologies are modeled and analyzed in detail.

Design/methodology/approach

This paper adopts the research methods of design, modeling, analysis and simulation verification. First, the star-connected autotransformer is redesigned according to the design objective of symmetrical step-down topology. In addition, the mathematical model of two topologies is established and a detailed theoretical analysis is carried out. Finally, the theoretical results are verified by simulation.

Findings

Two symmetrical star-connected autotransformer step-down topologies are designed, the winding configurations of the corresponding topology are presented, the step-down ranges of these three topologies are calculated and the influence of step-down ratio on the equivalent capacity of autotransformer are analyzed. Through analysis, the target step-down topologies are obtained when the step-down ratio is [1.1, 5.4] and [1.1, 1.9] respectively.

Research limitations/implications

Because the selected research object is only a star-connected autotransformer, the research results may lack generality. Therefore, researchers are encouraged to further study the topologies of other autotransformers.

Practical implications

This paper includes the implications of the step-down ratio on the equivalent capacity of autotransformers and the configuration of transformer windings.

Originality/value

The topologies designed in this paper enable star-connected autotransformer in the 12-pulse rectifier to be applied in step-down circumstances rather than situations of harmonic reduction only. At the same time, this paper provides a way that can be used to redesign the autotransformer in other multi-pulse rectifier systems, so that those transformers can be used in voltage regulation.

Article
Publication date: 2 September 2019

JiaRong Wang and XiaoQiang Chen

This paper aims to obtain a symmetrical step-down topology with lower equivalent capacity and wider step-down range under the condition of the same output. Three new symmetrical…

Abstract

Purpose

This paper aims to obtain a symmetrical step-down topology with lower equivalent capacity and wider step-down range under the condition of the same output. Three new symmetrical step-down topologies of zigzag autotransformer are proposed in this paper. Taking the equivalent capacity as the main parameter, the obtained topologies are modeled and analyzed in detail.

Design/methodology/approach

This paper adopts the research methods of design, modeling, analysis and simulation verification. First, the zigzag autotransformer is redesigned according to the design objective of symmetrical step-down topology. Second, the mathematical model of the designed topology is established, and the detailed theoretical analysis is carried out. Finally, the theoretical results are verified by simulation.

Findings

Three symmetrical zigzag autotransformer step-down topologies are designed, the winding configurations of the corresponding topology are presented, the step-down ranges of these three topologies are calculated and the influence of step-down ratio on equivalent capacity of autotransformer is analyzed. Through analysis, the target step-down topologies are obtained when the step-down ratio is [0.969, 1.414] and [1.414, 8].

Research limitations/implications

Because the selected research object is only zigzag autotransformer, the research results may lack generality. Therefore, researchers are encouraged to further study topologies of other autotransformers.

Practical implications

This paper includes the implications of step-down ratio on the equivalent capacity of autotransformer and the configuration of transformer windings.

Originality/value

The topologies designed in this paper enable zigzag autotransformer to be applied in step-down circumstances.

Article
Publication date: 8 March 2021

Rohollah Abdollahi

The purpose of this paper is to provide a T autotransformer based 12-pulse rectifier with passive harmonic reduction in more electric aircraft applications. The T autotransformer…

Abstract

Purpose

The purpose of this paper is to provide a T autotransformer based 12-pulse rectifier with passive harmonic reduction in more electric aircraft applications. The T autotransformer uses only two main windings which result in volume, space, size, weight and cost savings. Also, the proposed unconventional inter-phase transformer (UIPT) with a lower kVA rating (about 2.6% of the load power) compared to the conventional inter-phase transformer results in a more harmonic reduction.

Design/methodology/approach

To increase rating and reduce the cost and complexity of a multi-pulse rectifier, it is well known that the pulse number must be increased. In some practical cases, a 12-pulse rectifier (12PR) is suggested as a good solution considering its simple structure and low weight. But the 12PR cannot technically meet the standards of harmonic distortion requirements for some industrial applications, and therefore, they must be used with output filters. In this paper, a 12PR is suggested, which consists of a T autotransformer 12PR and a passive harmonic reduction (PHR) based on the UIPT at direct current (DC) link.

Findings

To show the advantage of this new combination over other solutions, simulation results are used, and then, a prototype is implemented to evaluate and verify the simulation results. The simulation and experimental test results show that the input current total harmonic distortion (THD) of the suggested 12PR with a PHR based on UIPT is less than 5%, which meets the IEEE 519 requirements. Also, it is shown that in comparison with other solutions, it is cost effective, and at the same time, its power factor is near unity, and its rating is 29.92% of the load rating. Therefore, it is obvious that the proposed rectifier is a practical solution for more electric aircrafts.

Originality/value

The contributions of this paper are summarized as follows. The suggested design uses a retrofit T autotransformer, which meets all technical constraints, and in comparison, with other options, has less rating, weight, volume and cost. In the suggested rectifier, a PHR based on UIPT at its dc link of 12PR is used, which has good technical capabilities and lower ratings. In the PHR based on UIPT, an IPT is used, which has an additional secondary winding and four diodes. This solution leads to a reduction in input current THD and conduction losses of diodes. In full load conditions, the input line current THD and power factor are 4% and 0.99, respectively. The THD is less than 5%, which satisfies IEEE-519 and DO-160G requirements.

Article
Publication date: 29 July 2022

Yumei Song, Jianzhang Hao, Changhao Dong, Xizheng Guo and Li Wang

This paper aims to study a multi-level reinjection current source converter (MLR-CSC) that adds attracting properties such as the self-commutation and pulse multiplication to the…

Abstract

Purpose

This paper aims to study a multi-level reinjection current source converter (MLR-CSC) that adds attracting properties such as the self-commutation and pulse multiplication to the thyristor converter, which is of great significance for increasing the device capacity and reducing current harmonics on the grid side. Particularly, designing advantageous driving methods of the reinjection circuit is a critical issue that impacts the harmonic reduction and operation reliability of the MLR-CSC.

Design/methodology/approach

To deal with the mentioned issue, this paper takes the five-level reinjection current source converter (FLR-CSC), which is a type of the MLR-CSC, as the research object. Then, a method that can fully use combinations of five-level reinjection switching functions based on the concept of decomposition and recombination is proposed. It is worthy to mention that the proposed method can be easily extended to other multi-level reinjection circuits. Moreover, the working principle of the three-phase bridge circuit based on semi-controlled thyristors in the FLR-CSC that can achieve the four-quadrant power conversion is analyzed in detail.

Findings

Finally, the simulation and experimental results of FLR-CSC verify the effectiveness of the proposed reinjection circuit driving method and the operating principle of four-quadrant power conversion in this paper.

Originality/value

The outstanding features of the proposed driving method for FLR-CSC in this paper include combinations of reinjection switching functions that are fully exploited through three simple steps and can be conveniently extended to other multi-level reinjection circuits.

Details

Microelectronics International, vol. 40 no. 3
Type: Research Article
ISSN: 1356-5362

Keywords

Article
Publication date: 1 October 2006

M.R. Qader

Unified power flow controller (UPFC) and advanced static VAR compensator (ASVC) devices are now recognized as the most important flexible AC transmission systems (FACTS) devices…

Abstract

Purpose

Unified power flow controller (UPFC) and advanced static VAR compensator (ASVC) devices are now recognized as the most important flexible AC transmission systems (FACTS) devices. This paper aims to focus on this.

Design/methodology/approach

The effects of the location of such installation FACTS devices are examined.

Findings

The UPFC as a voltage regulator and ASVC devices applied to a non‐linear load are modeled and analyzed. It was found that the optimum installation position for a UPFC device is at the sending end bus where wide range of receiver terminal line voltage and active power can be controlled. However, it was also found that the optimum installation position for an ASVC device is at the receiving end bus where a wide range of receiver terminal line voltage and active power can be controlled. In both cases, it was found that a wider range of reactive power could be controlled when the devices are installed closer to the receiving end bus.

Originality/value

Shows that the mid‐point of a transmission line is the optimal location for some FACTS devices or reactive power support. The proof is based on a fixed receiving end voltage magnitude, which is practically not valid.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 25 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 7 February 2019

Niharika Thakur, Y.K. Awasthi, Manisha Hooda and Anwar Shahzad Siddiqui

Power quality issues highly affect the secure and economic operations of the power system. Although numerous methodologies are reported in the literature, flexible alternating…

Abstract

Purpose

Power quality issues highly affect the secure and economic operations of the power system. Although numerous methodologies are reported in the literature, flexible alternating current transmission system (FACTS) devices play a primary role. However, the FACTS devices require optimal location and sizing to perform the power quality enhancement effectively and in a cost efficient manner. This paper aims to attain the maximum power quality improvements in IEEE 30 and IEEE 57 test bus systems.

Design/methodology/approach

This paper contributes the adaptive whale optimization algorithm (AWOA) algorithm to solve the power quality issues under deregulated sector, which enhances available transfer capability, maintains voltage stability, minimizes loss and mitigates congestions.

Findings

Through the performance analysis, the convergence of the final fitness of AWOA algorithm is 5 per cent better than artificial bee colony (ABC), 3.79 per cent better than genetic algorithm (GA), 2,081 per cent better than particle swarm optimization (PSO) and fire fly (FF) and 2.56 per cent better than whale optimization algorithm (WOA) algorithms at 400 per cent load condition for IEEE 30 test bus system, and the fitness convergence of AWOA algorithm for IEEE 57 test bus system is 4.44, 4.86, 5.49, 7.52 and 9.66 per cent better than FF, ABC, WOA, PSO and GA, respectively.

Originality/value

This paper presents a technique for minimizing the power quality problems using AWOA algorithm. This is the first work to use WOA-based optimization for the power quality improvements.

Details

Journal of Engineering, Design and Technology, vol. 17 no. 3
Type: Research Article
ISSN: 1726-0531

Keywords

Article
Publication date: 1 July 1945

A pump comprising a valve casing provided with inlet and outlet ports arranged at diametrically opposite positions, a valve provided with at least one recess transversely arranged…

Abstract

A pump comprising a valve casing provided with inlet and outlet ports arranged at diametrically opposite positions, a valve provided with at least one recess transversely arranged to the axial movement of said valve reciprocating within said casing, a pump piston contained in each recess in said valve, an eccentric housed within an extension provided in said valve casing, and a connecting rod driven by said eccentric pivotally connected to said valve, said rod provided with an extension beyond the pivot point and engaging with at least one piston.

Details

Aircraft Engineering and Aerospace Technology, vol. 17 no. 7
Type: Research Article
ISSN: 0002-2667

Article
Publication date: 29 September 2022

Kaiyuan Wu, Hao Huang, Ziwei Chen, Min Zeng and Tong Yin

This paper aims to overcome the limitations of low efficiency, low power density and strong electromagnetic interference (EMI) of the existing pulsed melt inert gas (MIG) welding…

Abstract

Purpose

This paper aims to overcome the limitations of low efficiency, low power density and strong electromagnetic interference (EMI) of the existing pulsed melt inert gas (MIG) welding power supply. So a novel and simplified implementation of digital high-power pulsed MIG welding power supply with LLC resonant converter is proposed in this work.

Design/methodology/approach

A simple parallel full-bridge LLC resonant converter structure is used to design the digital power supply with high welding current, low arc voltage, high open-circuit voltage and a wide range of arc loads, by effectively exploiting the variable load and high-power applications of LLC resonant converter.

Findings

The efficiency of each converter can reach up to 92.3%, under the rated operating condition. Notably, with proposed scheme, a short-circuit current mutation of 300 A can stabilize at 60 A within 8 ms. Furthermore, the pulsed MIG welding test shows that a stable welding process with 280 A peak current can be realized and a well-formed weld bead can be obtained, thereby verifying the feasibility of LLC resonant converter for pulsed MIG welding power supply.

Originality/value

The high efficiency, high power density and weak EMI of LLC resonant converter are conducive to the further optimization of pulsed MIG welding power supply. Consequently, a high performance welding power supply is implemented by taking adequate advantages of LLC resonant converter, which can provide equipment support for exploring better pulsed MIG welding processes.

Details

Circuit World, vol. 50 no. 1
Type: Research Article
ISSN: 0305-6120

Keywords

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