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    <title>Transport Research International Documentation (TRID)</title>
    <link>https://trid.trb.org/</link>
    <atom:link href="https://trid.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
    <description></description>
    <language>en-us</language>
    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
    <image>
      <title>Transport Research International Documentation (TRID)</title>
      <url>https://trid.trb.org/Images/PageHeader-wTitle.jpg</url>
      <link>https://trid.trb.org/</link>
    </image>
    <item>
      <title>A Novel Power Electronic Autotransformer-Based Bipolar MVDC Electrified Railway System</title>
      <link>https://trid.trb.org/View/2512060</link>
      <description><![CDATA[Benefiting from the superior power supply capability, medium-voltage direct current (MVDC) electrified railway is promising for application to long-distance power supply demand high-speed railways, such as cross-strait railways and mountain railways with a high proportion of bridges and tunnels. However, in the conventional MVDC electrified railway under direct power supply mode, abnormal increases in rail potential and stray current cause return current safety issues. To address these issues, this article proposes a novel power electronic autotransformer (PEAT)-based bipolar MVDC electrified railway system. In this system, PEATs are deployed to build a bivoltage power supply circuit and transfer traction return current from rails to negative feeder, which implements the autotransformer (AT) power supply mode. The infrastructure configuration, operation characteristics, and control scheme of the proposed system are introduced in detail. Then, a comprehensive real-time simulation test is implemented to verify the operating principles and performance of the proposed bipolar MVDC electrified railway system. Furthermore, the power supply distances under different voltage levels are calculated, and power supply characteristic comparisons between the direct and AT power supply modes are conducted.]]></description>
      <pubDate>Wed, 28 May 2025 12:01:52 GMT</pubDate>
      <guid>https://trid.trb.org/View/2512060</guid>
    </item>
    <item>
      <title>Defect Diagnosis for Autotransformer Winding in High-Speed Railway Based on Transfer Function Pole Distribution</title>
      <link>https://trid.trb.org/View/2511893</link>
      <description><![CDATA[Winding defect in autotransformer (AT) significantly affects the safety of traction power supply system. Frequency response analysis (FRA) is a widely used method to diagnose the winding status. Since the special structure of AT, it is challenging to detect specific faulty windings accurately. This article presents a defect diagnosis method for AT based on the transfer function pole distribution. First, a test platform for AT is established to obtain the FRA data on axial displacements (ADs), series capacitance variations (SCVs), and an interdisk short circuit (SC), as well as mixed defects. Next, the pole distribution diagram is expressed in the form of polar coordinates, considering the amplitude–frequency and phase–frequency curves and incorporating the fast relaxed vector fitting method. Then, the feature parameter combination for analyzing defect windings and defect types is defined using the gray correlation analysis results in conjunction with the Tamura textural features and gray-gradient co-occurrence matrix (GGCM). Finally, the feature parameters are used as input data to the cuckoo search-support vector machine (CS-SVM) for the classification of faulty windings and defect types. The results show that the proposed method can accurately identify the windings and types of both single and mixed defects.]]></description>
      <pubDate>Fri, 23 May 2025 15:34:44 GMT</pubDate>
      <guid>https://trid.trb.org/View/2511893</guid>
    </item>
    <item>
      <title>Power Quality Improvement Using Hexagon-Connected Autotransformer-Based 24-Pulse AC–DC Converter</title>
      <link>https://trid.trb.org/View/2511409</link>
      <description><![CDATA[In this article, a technique for enhancing the performance of a 24-pulse ac-dc converter through the innovative utilization of a hexagon-connected autotransformer (HCA) is presented. By configuring the autotransformer in this unique geometry, it effectively mitigates the adverse impact on power quality and reduces the equivalent power capacity required for the system. This, in turn, leads to substantial cost savings and a remarkable reduction in overall system volume and weight. The proposed HCA-based 24-pulse ac-dc converter offers a promising solution for industries and applications where high power quality, efficiency, and compactness are paramount considerations due to the low kVA rating of the autotransformer. The designed converter is modeled and simulated in MATLAB/SIMULINK environment. Further, experimental results and analysis confirm the feasibility and advantages of this approach, making it a compelling option for modern power conversion systems. Furthermore, the power quality indices that are calculated under varying load conditions meet the power quality criteria specified by IEEE-519 and IEC 61000-3-2 standards.]]></description>
      <pubDate>Tue, 22 Apr 2025 15:51:23 GMT</pubDate>
      <guid>https://trid.trb.org/View/2511409</guid>
    </item>
    <item>
      <title>Fault Location of AT Traction Network Adopting Bilateral Power Supply Mode Based on Generalized Symmetrical Components Method</title>
      <link>https://trid.trb.org/View/2511744</link>
      <description><![CDATA[Autotransformer (AT) traction network with bilateral power supply mode (PSM) is an effective and economical electrified railway feeding scheme. However, due to the nonlinear relationship between measured reactance and distance, as well as the complex power flow distribution, the accuracy of fault location is facing severe challenges. This article proposes a precise fault location method applicable to various fault scenarios in the AT traction network. Using a generalized symmetrical components’ method, a composite sequence network (CSN) model including four-sequence components is developed, and the boundary conditions are derived to describe the characteristics of various fault types. Furthermore, a fault location algorithm is developed to determine the fault positions based on the busbar voltages and the feeder currents at trackside traction substations (TSs). The impact factors, such as the rail impedance and the parameter differences between contact wires and feeder wires, are investigated, and then a reasonable correction method is applied to improve the fault location accuracy. Finally, simulations, experimental setups, and field tests show that the proposed method can obtain accurate fault location results, with an improvement of at least 29%. Certainly, this work has significant application prospects in fault analysis and location for electrified railways.]]></description>
      <pubDate>Wed, 16 Apr 2025 11:24:49 GMT</pubDate>
      <guid>https://trid.trb.org/View/2511744</guid>
    </item>
    <item>
      <title>Power Electronic Autotransformer-Based 3 × 25 kV Network for Power Quality Enhancement in Railway Supply Systems</title>
      <link>https://trid.trb.org/View/2511711</link>
      <description><![CDATA[State-of-the-art single-phase ac traction systems are based on a split-phase 2 × 25 kV supply network with multiple regularly spaced autotransformers. The main drawbacks of this arrangement are the unbalanced currents in the three-phase (3- ϕ) grid and reactive power flow due to transformers and autotransformers. This article proposes to solve these issues with a completely new 3 × 25 kV railway power supply supported by a power electronic autotransformer (PEAT). The PEAT circuit comprises single-phase back-to-back voltage source converters (VSCs), connected across different phase pairs of the 3- ϕ network. These voltage-source converters balance the 3- ϕ grid current for all traction load conditions, ensuring grid-compliant power quality performance. Over and above that, the PEAT system enables reactive power control and ensures a unity power factor at the point of connection. Besides detailing the control algorithm for the PEAT system, this article also discusses various design aspects and optimal positioning of the PEAT unit along the railway line. The efficacy of the PEAT topology is illustrated through extensive simulations carried out in MATLAB/Simulink environment. These are further validated via real-time hardware-in-the-loop (HIL) results obtained from a Typhoon HIL 404 device together with a C2000 microcontroller-based interface card.]]></description>
      <pubDate>Mon, 14 Apr 2025 09:35:23 GMT</pubDate>
      <guid>https://trid.trb.org/View/2511711</guid>
    </item>
    <item>
      <title>Correction Scheme and Error Analysis of Compound Fault Location in Direct Power Supply Mode of High-Speed Railway Traction Network</title>
      <link>https://trid.trb.org/View/1975907</link>
      <description><![CDATA[Autotransformer (AT) all-paralleling feeding systems have been widely used in high-speed railways in China. At present, short circuit faults in traction networks are mainly divided into three types, such as T-R, F-R and T-F. When permanent faults occur on traction power supply network, all parallel AT feeding systems are changed into direct power supply mode. If the fault is a compound fault, i.e., T-R-F fault, the traditional fault location based on reactance-distance method will have a large error. Formula of measuring reactance in a compound fault was deduced and fault location errors of a compound fault in direct power supply mode were analyzed in this paper. And then, a new correction scheme was proposed under the existing conditions. MATLAB/Simulink simulation results show that there is almost no error in the correction results under different transition resistance and fault distance.]]></description>
      <pubDate>Fri, 23 Aug 2024 16:53:42 GMT</pubDate>
      <guid>https://trid.trb.org/View/1975907</guid>
    </item>
    <item>
      <title>Performance Evaluations of DCAT Position for the Floating DCAT System in DC Railways</title>
      <link>https://trid.trb.org/View/1975770</link>
      <description><![CDATA[DC auto-transformer (DCAT) traction power supply system has been studied for the stray current and rail potential issues in DC railways, and the solidly grounded DCAT system of equal sections has been analyzed in detail. However, in practice, the floating scheme more tends to be adopted in DC railways, and the sections of DCAT system is hard to achieve complete equality. Therefore, the performance evaluations of DCAT position for the floating DCAT system were proposed in this paper. The performances of floating DCAT system with equal sections were analyzed comparing with the existing system. Then the theoretical analysis and the relationships between DCAT position, rail potential, and stray current were discussed in detail. Finally, the correctness of the proposed analysis was verified by the simulation results.]]></description>
      <pubDate>Fri, 23 Aug 2024 15:26:24 GMT</pubDate>
      <guid>https://trid.trb.org/View/1975770</guid>
    </item>
    <item>
      <title>An Adaptive Reclosing Scheme for All-Parallel Autotransformer Traction Network of High-Speed Railway Based on Multisource Information</title>
      <link>https://trid.trb.org/View/2364787</link>
      <description><![CDATA[In high-speed railway (HSR), directly reclosing a circuit breaker after a fault trip can result in a large second overcurrent, causing insulation degradation, equipment damage, and even system instability. Meanwhile, existing direct reclosing schemes fail to simultaneously identify the faulty line, fault property, and fault type, especially for all-parallel autotransformer traction networks (AATNs). Therefore, an adaptive reclosing scheme for AATNs based on multisource information is proposed in this article, including two critical methods of faulty line identification, and fault property and type identification. Specifically, a multisource fault impedance angle integrated faulty line identification method is proposed to effectively distinguish the faulty line and the healthy line. Moreover, a novel approach is developed to incorporate multisource line-to-line-induced voltages obtained by reclosing the healthy line, which facilitates the fault property and the type identification. The effectiveness and superiority of the proposed reclosing scheme are demonstrated using field tests and simulation experiments. In addition, the proposed scheme not only shortens the power outage time of the healthy line, but also completely avoids second damages to equipment, and prevents power outages when the feeder is permanently faulted to the ground, presenting its remarkable robustness benefiting from multisource information.]]></description>
      <pubDate>Thu, 16 May 2024 16:34:30 GMT</pubDate>
      <guid>https://trid.trb.org/View/2364787</guid>
    </item>
    <item>
      <title>A low-rating 40-pulse AC–DC rectifier based on a new passive harmonic mitigation circuit</title>
      <link>https://trid.trb.org/View/2085709</link>
      <description><![CDATA[A novel 40-pulse autotransformer rectifier is proposed to reduce total harmonic distortion (THD) of the input current in aircraft electrical power systems. The 40-pulse rectifier (40PR) includes a passive harmonic reduction circuit (PHMC) with a low kVA rating (about 0.95% of the load power) to enhance the performance of the conventional 40PR. This PHMC is based on 2 harmonic suppression circuits and contains four tapped reactor and 4 auxiliary diodes. 50 Hz simulations of the improved 40PR indicate that THD of the input current and voltage is less than 2%, which meets the IEEE-519 standard. In addition, without using any input and output filters, input current harmonic components at 400–800 Hz are less than the requirements mentioned in the DO-160G and MIL-STD-704F standards. The suggested PHMC can easily be implemented. A prototype is developed to verify the proposed design. A good agreement can be seen in simulation and experimental results.]]></description>
      <pubDate>Tue, 24 Jan 2023 09:30:19 GMT</pubDate>
      <guid>https://trid.trb.org/View/2085709</guid>
    </item>
    <item>
      <title>Improved fault location method for AT traction power network based on EMU load test</title>
      <link>https://trid.trb.org/View/2055885</link>
      <description><![CDATA[The autotransformer (AT) neutral current ratio method is widely used for fault location in the AT traction power network. With the development of high-speed electrified railways, a large number of data show that the relation between the AT neutral current ratio and the distance from the beginning of the fault AT section to the fault point (Q–L relation) is mostly nonlinear. Therefore, the linear Q–L relation in the traditional fault location method always leads to large errors. To solve this problem, a large number of load-related current data that can be used to describe the Q–L relation are obtained through the load test of the electric multiple unit (EMU). Thus, an improved fault location method based on the back propagation (BP) neural network is proposed in this paper. On this basis, a comparison between the improved method and the traditional method shows that the maximum absolute error and the average absolute error of the improved method are 0.651 km and 0.334 km lower than those of the traditional method, respectively, which demonstrates that the improved method can effectively eliminate the influence of nonlinear factors and greatly improve the accuracy of fault location for the AT traction power network. Finally, combined with a short-circuit test, the accuracy of the improved method is verified.]]></description>
      <pubDate>Mon, 28 Nov 2022 16:54:49 GMT</pubDate>
      <guid>https://trid.trb.org/View/2055885</guid>
    </item>
    <item>
      <title>DC-DC Converter Control Method for High Voltage DC Feeding System to Improve Use of Regenerative Power</title>
      <link>https://trid.trb.org/View/2008853</link>
      <description><![CDATA[A high voltage DC feeding system, which consists of higher-voltage feeders and DC-DC converters in addition to an existing feeding circuit, is assumed to improve the performance of power supply to trains without changing the nominal voltage of contact lines and onboard traction systems. In this system, the method for controlling the converter is an important element which must be taken into consideration to maximize energy savings. In this paper, the authors propose a converter control method to make the voltage ratio constant between the contact line and the higher-voltage feeder. In this paper, the high voltage DC feeding system with this converter control method is called a "DC-AT feeding system." They evaluated the energy savings of this system through simulation, and case studies on a model line confirmed that this system can reduce energy consumption by 4.5% at most, and on average 3.5%, compared to conventional DC feeding systems.]]></description>
      <pubDate>Thu, 27 Oct 2022 13:47:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/2008853</guid>
    </item>
    <item>
      <title>High Voltage DC Auto-Transformer Traction Power Supply for Braking Energy Utilization, Rail Potential, and Stray Current Mitigation</title>
      <link>https://trid.trb.org/View/2003195</link>
      <description><![CDATA[For urban rail transit, high-voltage ac power is generally transmitted from the main substation to the traction substation (TS), which employs isolated diode–rectifiers to feed the dc traction power supply system. The train current feeds back to the negative cubicle of TS through the running rail, which is not totally isolated from the Earth. However, the traditional traction power supply (TTPS) shows limitations on braking energy-wasting, high rail potential, stray current, and so on. Thus, a high-voltage dc autotransformer (DCAT) traction power supply (HDATPS) is proposed in this article. Both configurations and principles of three typical HDATPSs are analyzed, which mainly consists of the dc main substation, the dc TS, and the DCAT substation. Then, through modeling of HDATPS and TTPS, the comparisons on braking energy utilization, rail potential, and stray current mitigation are discussed in detail. Finally, the simulation model and experimental platform of HDATPS are built, respectively, and the theoretical analysis is verified with the simulation and experimental results.]]></description>
      <pubDate>Mon, 26 Sep 2022 09:12:47 GMT</pubDate>
      <guid>https://trid.trb.org/View/2003195</guid>
    </item>
    <item>
      <title>Multi-Level Transient Modeling of the Aeronautic Asymmetric 18-Pulse Phase-Shifting Auto-Transformer Rectifier in Full-Cycle Design</title>
      <link>https://trid.trb.org/View/2003179</link>
      <description><![CDATA[The higher failure rate of the rectifier unit severely affects the reliability of the more electric aircraft (MEA). In order to provide an insight into the electrical and magneto-thermal behavior in the full-cycle design evaluation, a novel multi-level modeling scheme for the aeronautic asymmetric 18-pulse dynamic phasor (DP)-type phase-shifting auto-transformer (PS-AT) rectifier is proposed in this article. The behavioral level modeling is built up to reveal the electrical characteristics since the ontology parameters are designed for the 18-pulse PS-AT, where the computation non-convergence posed by matrix singularity is alleviated by improving the condition number. Besides, the DP model crossing architecture level and functional level is proposed by transforming the nonlinear electrical variables in the time domain into the frequency domain with time-varying Fourier decomposition and frequency shift. To illustrate the comprehensive electrical and magneto-thermal characteristics of the 18-pulse PS-AT rectifier at the component level, field-circuit coupling, and magneto-thermal coupling with the finite-element method (FEM) are adopted. Furthermore, simulations of the 18-pulse PS-AT rectifier system are also carried out, to validate the simulation accuracy and computation efficiency of the proposed multi-level modeling scheme. An aided design program integrating the multi-level modeling methods is also developed to help designers achieve high-quality products with a short development cycle.]]></description>
      <pubDate>Mon, 26 Sep 2022 09:12:46 GMT</pubDate>
      <guid>https://trid.trb.org/View/2003179</guid>
    </item>
    <item>
      <title>A Novel More Electric Aircraft Power System Rectifier Based on a Low-Rating Autotransformer</title>
      <link>https://trid.trb.org/View/1933661</link>
      <description><![CDATA[From a theoretical and practical point of view, to increase rating and decrease the cost and complexity of a multi-pulse rectifier (MPR), its pulse number has to be increased. In many industrial applications, a 20-pulse rectifier is suggested as the practical solution considering its simple structure and low weight. But the 20-pulse rectifiers, suggested in different studies, must use filters to satisfy the DO-160G requirements for 21st and 39th harmonics for ac–dc more electric aircraft (MEA) power systems. To overcome this problem, this article proposes a novel 20-pulse rectifier for the ac–dc MEA power system based on a low-rating autotransformer (LRA). Also, a passive harmonic reduction circuit (PHRC) is used on the dc side of the 20-pulse rectifier to suppress the harmonics up to the 40th order according to DO-160G without using any filter. In this article, simulations are provided to show the merits of this new rectifier over other proposed solutions. Then, an experimental prototype is implemented for evaluating and verifying the simulation results. By investigating the captured outcomes, this article concludes that the introduced design is practical and can simultaneously consider the trade-off among autotransformer structure, pulse number, complexity, rating, and cost.]]></description>
      <pubDate>Thu, 19 May 2022 10:41:56 GMT</pubDate>
      <guid>https://trid.trb.org/View/1933661</guid>
    </item>
    <item>
      <title>Dynamic Performance Analysis, Optimization, and Verification of DC Auto-Transformer System With Rail Potential and Stray Current Emulator</title>
      <link>https://trid.trb.org/View/1933649</link>
      <description><![CDATA[DC auto-transformer (DCAT) traction power supply system has been studied to suppress the rail potential and stray current for urban rail transit (URT), which generally takes the constant train load to simplify the analysis. However, in practice, the train is a non-linear load with frequent accelerating and braking, which leads to the rail potential and stray current changing with different train operating conditions. Therefore, the dynamic performance analysis and optimization of DCAT system are discussed in this article. The rail potential and stray current dynamic emulator (RSDE) for DCAT system verification is proposed because it is difficult to test the DCAT system directly in the actual URT. Based on the configurations and operation principles of both DCAT system and RSDE, the comparisons between DCAT system and the existing system on the rail potential and stray current are discussed. Meanwhile, considering the train dynamic performance, define the dynamic performance index (DPI) to evaluate the effects of the DCAT system on the rail potential and stray current mitigation and optimize the DCAT system with DPI. Finally, the correctness and effectiveness of DCAT system on the rail potential and stray current mitigation are validated by the simulation results and experimental verification.]]></description>
      <pubDate>Thu, 19 May 2022 10:41:56 GMT</pubDate>
      <guid>https://trid.trb.org/View/1933649</guid>
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