WorldWideScience

Sample records for autotransformers

  1. 18-Pulse Converter Using 3/9 Auto-Transformer

    Directory of Open Access Journals (Sweden)

    Ahmad Hoteit

    2012-09-01

    Full Text Available This paper focuses to 3/9 phase auto-transformer with multiple windings per phase is powered a 9-phase AC to DC converter this type of transformer has 40o phase shift between the output voltages, it is supplied from a three phase AC source with star or delta connection, to use this type of transformer in aerospace the operation frequency should be at 400Hz in addition to reduce the current harmonic distortion through a three phase line reactor are connected after three phase AC source in this case the current harmonic distortion decreases to value less than 5% and it can be less than 3% level by using an additional suppression devices (Chokes at the output of the converter, this autotransformer includes three sections each spaced 120o electrically apart. Each section comprises a main winding and a pair of phase shift windings, it is a main element in 18 pulse converters, the multiphase rectification can be analyzed by using orcad simulation software, and shown the comparisons between the odd phases so that the 9 phases has a lower value of the ripple factor which is 0.763 %.

  2. High-Freqeuncy Analysis of Three-Winding Autotransformers 400/121/34 kV

    Directory of Open Access Journals (Sweden)

    Miroslav Gutten

    2008-01-01

    Full Text Available This article deals with a description of methods of an experimental analysis concerning the actual condition of windings and magnetic circuit of the autotransformer, which is required in power transmission companies all over the world.

  3. Testing The Performance Of A Single-Phase Autotransformer On MATLAB/Simulink

    Science.gov (United States)

    Panu, Mihai Gheorghe; Viorel, Alina Cristina

    2015-07-01

    This paper presents a virtual laboratory for testing a single-phase autotransformer using MATLAB Simulink environment. The model is implemented according to a practical laboratory used at electric machines' discipline for the undergraduate level in electrical engineering. The model presented herein is a copy of a practical experiment for an autotransformer made in the test laboratory. The rating of the autotransformer is taken to be 2 kVA, 230/0÷230 V, and it was set at a transformer ratio of 1.5. The used model is a linear one and run for a pure resistive load test. In the same time, it was aimed the simulation accuracy as it was used a linear model, neglecting the magnetic saturation effect.

  4. Zigzag Connected Autotransformer-Based 24-pulse AC-DC Converter

    Science.gov (United States)

    Xiao-qiang, Chen; Hao, Qiu

    2015-02-01

    In this paper, a zigzag connected autotransformer-based 24-pulse AC-DC converter is designed, modeled and simulated to feed direct torque controlled induction motor drives. Winding arrangements and parameters of the autotransformer and interphase reactor are given. Moreover, the design procedure of the autotransformer is modified to make it suitable for retrofit applications. Simulation results indicate that the system is capable of eliminating up to 21st harmonics in the ac mains current. The effect of load variation and load character is also studied to demonstrate the performance and effectiveness of the proposed 24-pulse converters. A set of power quality indices at ac mains and dc side are presented to compare the performance of 6-, 12- and 24-pulse converters.

  5. Measurements at autotransformer system Prenzlau-Stralsund; Messungen am Mehrspannungssystem Prenzlau-Stralsund

    Energy Technology Data Exchange (ETDEWEB)

    Levermann-Vollmer, D. [DB Energie GmbH, Frankfurt a.M. (Germany); Thiede, J. [Balfour Beatty Rail GmbH, Power Systems, Offenbach am Main (Germany)

    2002-10-01

    After conversion of Prenzlau-Stralsund line in 2002 to autotransformer supply measurements have shown advantages of this system by lower impedances and interference voltages compared to the conventional system and delivered decision criterias for future projects. (orig.) [German] Die Strecke Prenzlau-Stralsund wurde im Jahr 2002 auf Speisung mit Autotransformern umgestellt. Messungen haben die Vorteile dieses Systems in Form niedrigerer Impedanzen und Beeinflussungsspannungen gegenueber der herkoemmlichen Speisung bestaetigt und Entscheidungshilfen fuer kuenftige Projekte geliefert. (orig.)

  6. Ultra-Step-Up DC-DC Converter with Integrated Autotransformer and Coupled Inductor

    DEFF Research Database (Denmark)

    Siwakoti, Yam Prasad; Blaabjerg, Frede; Loh, Poh Chiang

    2016-01-01

    This paper introduces a new single-switch nonisolated dc-dc converter with very high voltage transfer ratio and reduced semiconductor voltage stress. The converter utilizes an integrated autotransformer and a coupled inductor on the same core to achieve a high step-up voltage gain without extreme...... to use a low voltage and low RDS-on MOSFET, which reduces the cost, and also the conduction and turn on losses of the switch. The principle of operation and theoretical analysis supported by key simulation and experimental waveforms are presented in details....

  7. INVESTIGATION OF SPECIAL ASYMMETRICAL MODES OF THREE-PHASE THREE-LEG AUTOTRANSFORMERS

    Directory of Open Access Journals (Sweden)

    Bosneaga V.A

    2014-04-01

    Full Text Available the base of earlier proposed model calculations were made and were investigated peculiarities of special asymmetric modes of three-phase three legs autotransformer (AT with tertiary winding, connected in triangle. Calculations were carried out taking into account the electromagnetic coupling of coils, located on different legs. Modules and angles of currents and voltages vectors in autotransformer windings were calculated at breakage of one of the phases of the supply voltage and its simultaneous fault to ground at the side of AT. Based on these data vector diagrams were constructed, which give a visual representation of specific features of such regimes. Considered mode at grounded neutral is characterized by the occurrence of significant currents of the same value in all windings, app. equal to nominal current. Voltage of the windings varies slightly from the nominal values, except for the short-circuited phase. Furthermore, there is a considerable flow of the zero sequence flux, which may lead to additional heating of AT. At ungrounded neutral in this particular mode and absence of load on the secondary AT side, only a small magnetizing currents flows and neutral is significantly displaced. If the load is present, despite of the absence of the current in the neutral, currents in the windings, comparable with the nominal one appeared, also zero sequence flux appeared. In the general case, the currents of this failure (as in the previous case are much smaller, than the usual short-circuit currents, so are insufficient to trigger the relay protection, this may require additional measures to protect AT against such damage.

  8. Pulse doubling in zigzag-connected autotransformer-based 12-pulse ac-dc converter for power quality improvement

    Science.gov (United States)

    Abdollahi, Rohollah

    2012-12-01

    This paper presents a pulse doubling technique in a 12-pulse ac-dc converter which supplies direct torque controlled motor drives (DTCIMDs) in order to have better power quality conditions at the point of common coupling. The proposed technique increases the number of rectification pulses without significant changes in the installations and yields in harmonic reduction in both ac and dc sides. The 12-pulse rectified output voltage is accomplished via two paralleled six-pulse acdc converters each of them consisting of three-phase diode bridge rectifiers. An autotransformer is designed to supply the rectifiers. The design procedure of magnetics is in a way such that makes it suitable for retrofit applications where a six-pulse diode bridge rectifier is being utilized. Independent operation of paralleled diode-bridge rectifiers, i.e. dc-ripple re-injection methodology, requires a Zero Sequence Blocking Transformer (ZSBT). Finally, a tapped interphase reactor is connected at the output of ZSBT to double the pulse numbers of output voltage up to 24 pulses. The aforementioned structure improves power quality criteria at ac mains and makes them consistent with the IEEE-519 standard requirements for varying loads. Furthermore, near unity power factor is obtained for a wide range of DTCIMD operation. A comparison is made between 6-pulse, 12-pulse, and proposed converters from view point of power quality indices. Results show that input current total harmonic distortion (THD) is less than 5% for the proposed topology at various loads.

  9. 12脉冲自耦变压整流器的优化与滤波电感的设计%Optimization of 12-pulse autotransformer rectifier units and design of filter inductor

    Institute of Scientific and Technical Information of China (English)

    蒋磊磊; 陈乾宏; 毛浪

    2012-01-01

    多脉冲整流器作为一种无源整流装置,具有系统可靠性高,结构简单,效率高,过载能力强等特点,广泛应用于航空领域.相关航空标准规定交流用电设备输入电流THD<10%,而12脉冲整流器输入电流THD的理论值为15.2%,不能满足要求.为满足谐波标准,通常在交流侧和直流侧串入电感来降低输入电流的THD,针对P型12脉冲自耦变压整流器,从理论上推导输入电流谐波表达式,为交直流侧电感设计提供依据,同时采用高饱和磁通密度的铁钴钒材料设计磁性元件,减小了系统体积和重量,完成了一台4kW 12脉冲自耦变压器的设计,输入电流THD满足航空标准.%Because of its simple structure, high reliability and strong overload capacity, multi-pulse rectifier is widely used for the electronic facilities applied in the aircraft. Related aviation standards require that the THD of input current of AC electrical equipments must be less than 10% . However, theoretical value of 12-pulse ATRU input current THD is 15. 2% , and it doesn't meet the related aviation standards. To satisfy the standards, AC and DC inductor are added to reduce input current THD so that the original method can meet engineering requirements. In this paper the expression of input current harmonic which provides a theoretical basis for AC and DC inductor is derived. This paper also uses Fe-Co-V alloy which has high saturation flux density to reduce system' s volume and weight. At last, this paper designed a 4kW P-type 12-pulse auto-transformer rectifier whose input current THD satisfies the aviation standards.

  10. Voltage Sag Mitigation Using Pulse Width Modulation Switched Autotransformer through Matlab Simulation

    Directory of Open Access Journals (Sweden)

    P. Shyam Kiran

    2014-04-01

    Full Text Available In this paper, a new voltage sag compensator for critical loads in electrical distribution system discussed. The proposed scheme employs a Pulse width modulation ac-ac converter along with a auto transformer. During a disturbance such as voltage sag, the proposed scheme supplies the missing voltage and helps in maintaining the rated voltage at the terminals of the critical load. Under normal condition the approach work in bypass mode and delivering utility power directly to load. The proposed system has less number of switching devices and has good compensating capability in comparison to commonly used compensators. Simulation analysis of three-phase compensator is performed in MATLAB/SIMULINK and performance analysis of the system is presented for various levels of sag and swell.

  11. Auto-Transformation from IDEF0 to CPN%IDEF0与CPN的自动转换方法研究

    Institute of Scientific and Technical Information of China (English)

    周小舟

    2012-01-01

    在大型工程系统的建模与分析中,将系统的静态IDEF0模型转换为动态CPN模型的方法得到大量的应用,但是人工转换既繁琐也容易出错.该文在IDEF0和CPN模型的形式化表示分析的基础上,提出两种模型自动转换的一般步骤和方法.%In the practice of the modeling and analysis of the large-scale engineering system, transformation from the IDEFO models, applied for the static descriptions of the systems, to the CPN models which describe the dynamic attributes of the systems have been widely applied. Usually the manual transformations are trivial and prone to making mistakes. Based on the formal analysis and representation of the IDEFO and CPN models, a method is proposed to automate this process.

  12. 新型12脉冲自耦变压整流器的研究%Research on a new Type 12-Pulse Autotransformer Rectifier Units

    Institute of Scientific and Technical Information of China (English)

    马义林; 陈宇; 任志新; 张方华

    2008-01-01

    对一种新型12脉冲自耦变压整流器的工作原理、输入电流特性、输出电压特性和移相变压器的等效容量进行了详细的理论分析.与传统的12脉冲变压整流器相比,新型12脉冲自耦变压整流器不仅保证了良好的输入、输出性能,而且大大减轻了整流器的重量,减小了体积与成本.通过一台9kW原理样机验证了理论分析的正确性.

  13. Reducing the Risk of Damage to Power Transformers of 110 kV and Above Accompanying Internal Short Circuits

    Energy Technology Data Exchange (ETDEWEB)

    L’vova, M. M. [JSC “R& D Center at Federal Grid Company of the Unified Power System” (Russian Federation); L’vov, S. Yu. [Presselektro LLC (Russian Federation); Komarov, V. B. [IPCE RAS (Russian Federation); Lyut’ko, E. O. [JSC “R& D Center at Federal Grid Company of the Unified Power System” (Russian Federation); Vdoviko, V. P. [EMA Ltd. (Russian Federation); Demchenko, V. V. [JSC “Boguchanskaya HPP” (Russian Federation); Belyaev, S. G. [PKF Konif Ltd. (Russian Federation); Savel’ev, V. A. [Ivanovo State Power University (Russian Federation); L’vov, M. Yu., E-mail: timashova@nte-power.ru; L’vov, Yu. N. [JSC “R& D Center at Federal Grid Company of the Unified Power System” (Russian Federation)

    2015-03-15

    Methods of increasing the operating reliability of power transformers, autotransformers and shunting reactors in order to reduce the risk of damage, which accompany internal short circuits and equipment fires and explosions, are considered.

  14. 10 CFR 431.192 - Definitions.

    Science.gov (United States)

    2010-01-01

    ... Distribution Transformers § 431.192 Definitions. The following definitions apply for purposes of this subpart: Autotransformer means a transformer that: (1) Has one physical winding that consists of a series winding part and...) During step-down operation, has a primary voltage that is equal to the total of the series and...

  15. 30 CFR 35.20 - Autogenous-ignition temperature test.

    Science.gov (United States)

    2010-07-01

    ...-constantan or chromelalumel—and a potentiometer shall be used for all temperature measurements. (3) Syringe...) Temperature control. Each autotransformer shall be so adjusted that the temperature at the neck, mid-section... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Autogenous-ignition temperature test....

  16. Power transformers - Part 1: General

    CERN Document Server

    International Electrotechnical Commission. Geneva

    2000-01-01

    Applies to three-phase and single-phase transformers including autotransformers. Defines the rating and connection symbols. Gives certain specifications for transformers having a tapped winding. Defines information which shall be marked on the rating plate and the tests to be conducted. Supersedes IEC 60076-1(1976) and IEC 60076-4 (1976).

  17. 30 CFR 75.901 - Protection of low- and medium-voltage three-phase circuits used underground.

    Science.gov (United States)

    2010-07-01

    ... auto-transformer is used. (see Figure III in Appendix A to subpart J of this part) (3) Each three-phase...-fault current transformers. (5) Each three-phase circuit interrupting device must be provided with a...-voltage three-phase circuits used underground. (a) Low- and medium-voltage three-phase...

  18. Zero sequence blocking transformers for multi-pulse rectifier in aerospace applications

    DEFF Research Database (Denmark)

    Yao, Wenli; Blaabjerg, Frede; Zhang, Xiaobin

    2014-01-01

    The power electronics technology plays an even more important role in the aerospace applications of More Electric Aircrafts (MEA). AutoTransformer Rectifier Units (ATRU) have been widely adopted in aircrafts due to its simplicity and reliability. In this paper, Zero Sequence Blocking Transformers...

  19. A-Source Impedance Network

    DEFF Research Database (Denmark)

    Siwakoti, Yam Prasad; Blaabjerg, Frede; Galigekere, Veda Prakash;

    2016-01-01

    A novel A-source impedance network is proposed in this letter. The A-source impedance network uses an autotransformer for realizing converters for any application that demand a very high dc voltage gain. The network utilizes a minimal turns ratio compared to other Magnetically Coupled Impedance S...... with an example single-switch 400 W dc-dc converter. For the closed-loop control design and stability assessment, a small signal model and its analysis of the proposed network are also presented in brief.......A novel A-source impedance network is proposed in this letter. The A-source impedance network uses an autotransformer for realizing converters for any application that demand a very high dc voltage gain. The network utilizes a minimal turns ratio compared to other Magnetically Coupled Impedance...

  20. Control scheme for power modulation of a free piston Stirling engine

    Science.gov (United States)

    Dhar, Manmohan

    1989-01-01

    The present invention relates to a control scheme for power modulation of a free-piston Stirling engine-linear alternator power generator system. The present invention includes connecting an autotransformer in series with a tuning capacitance between a linear alternator and a utility grid to maintain a constant displacement to piston stroke ratio and their relative phase angle over a wide range of operating conditions.

  1. Power electronics improving 3-Wire DC railways electrification

    OpenAIRE

    Rull Duran, Joan; Bergas Jané, Joan Gabriel; Galceran Arellano, Samuel; Sumper, Andreas; Coves Moreno, Jordi

    2009-01-01

    Urban DC railway substations are growing in size due increasing capacity demand. Several challenges associated with the increase of power demand can be met using power electronics. The proposed system is based on DC-autotransformers and active rectifiers working similarly to those in 3-wire AC railway electrification system. Conventional simulation software (Idom-REPS-DC) has been adapted to the system. A real subway line and the same line with the proposed 3-Wire DC working in the same condi...

  2. AC system stabilization via phase shift transformer with thyristor commutation

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Jose Carlos de; Guimaraes, Geraldo Caixeta; Moraes, Adelio Jose [Uberlandia Univ., MG (Brazil); Abreu, Jose Policarpo G. de [Escola Federal de Engenharia de Itajuba, MG (Brazil); Oliveira, Edimar Jose de [Juiz de Fora Univ., MG (Brazil)

    1994-12-31

    This article aims to present initially the constructive and operative forms of a phase-shift autotransformer which provides both magnitude and phase angle change through thyristor commutation, including a technic to reduce the number of thyristors. Following, it is proposed a control system to make such equipment an efficient AC system stabilizing tool. It is presented some simulation results to show the operation of this transformer in an electrical system. (author) 3 refs., 11 figs., 3 tabs.

  3. Traction electrification system planning for California high-speed train project

    Energy Technology Data Exchange (ETDEWEB)

    Schmedes, Richard [Parsons Brinckerhoff, Inc., San Francisco, CA (United States). Transit and Railway Div.

    2011-04-15

    The California High-Speed Train Project will be a $ 43 Billion dedicated 1 300 km (800 miles) system and will connect California's major metropolitan centers with completely new dedicated tracks and infrastructure which will support train operations at up to 400 km/h (250 mph). It will be electrified with a 2 AC 25 kV autotransformer configuration with 50 km (30 miles) spacing between utility connections. The planning of 115 kV and 230 kV connections involves coordination with four utility companies and completion of five-year permitting and planning processes by 2016. (orig.)

  4. Functional modelling of symmetrical multi-pulse auto- transformer rectifier units for aerospace applications

    OpenAIRE

    YANG Tao; BOZHKO, Serhiy; Asher, Greg

    2015-01-01

    This paper aims to develop a functional model of symmetrical multi-pulse Auto-Transformer Rectifier Units (ATRUs) for More-Electric Aircraft (MEA) applications. The ATRU is seen as the most reliable way readily to be applied in the MEA. Interestingly, there is no model of ATRUs suitable for unbalanced or faulty conditions at the moment. This paper is aimed to fill this gap and develop functional models suitable for both balanced and unbalanced conditions. Using the fact that the DC voltage an...

  5. A New Method of Ground Fault Location in 2 × 25 kV Railway Power Supply Systems

    Directory of Open Access Journals (Sweden)

    Jesús Serrano

    2017-03-01

    Full Text Available Owing to the installation of autotransformers at regular intervals along the line, distance protection relays cannot be used with the aim of locating ground faults in 2 × 25 kV railway power supply systems. The reason is that the ratio between impedance and distance to the fault point is not linear in these electrification systems, unlike in 1 × 25 kV power systems. Therefore, the location of ground faults represents a complicated task in 2 × 25 kV railway power supply systems. Various methods have been used to localize the ground fault position in 2 × 25 kV systems. The method described here allows the location of a ground fault to be economically found in an accurate way in real time, using the modules of the circulating currents in different autotransformers when the ground fault occurs. This method first needs to know the subsection and the conductor (catenary or feeder with the defect, then localizes the ground fault’s position.

  6. Interfacing transformer for a pulsed load current exceeding 1 MA

    CERN Document Server

    Cliffe, R J; Brown, J

    2003-01-01

    In much pulsed power experimentation a capacitor bank is discharged into an inductive load, but although sufficient energy may be available in the capacitors their voltage rating may considerably exceed that necessary for the load and the current delivered during the experiment may accordingly be too low. This paper describes a novel design of air-cored transformer that has been used as an interfacing or matching device in such a situation, where peak load currents between 1 and 2 MA were required. Design considerations led to the use of an air-cored autotransformer connection wound with copper sheet conductors. Although thick wide conductors and clamping are needed to prevent deformation due to high magnetic pressure, the transformer is nevertheless relatively simple, easy to make, lightweight and inexpensive. This paper describes the design and the winding arrangement of the transformer that was constructed, and presents typical experimental results.

  7. Supplying a Common Distribution Load through Two Different Sources

    Directory of Open Access Journals (Sweden)

    M. H. Naeem

    2005-01-01

    Full Text Available Phase angle difference between any two Busbar voltages of a big power system varies with the loading and operating condition of the power system. Supplying a common distributed load from these two phase shifted sources needs the application of a controlled phase shifter. Three-phase tapped autotransformer connected in delta with properly controlled variation of input and output tap settings may perform the function of this type of phase shifter. Both on-load and off-load tap changing may be used to control the phase angle for scheduled sharing of a common distribution load between these two phase shifted sources. Independent control of voltage magnitude is also possible through the same phase shifter.

  8. Harmonic Domain Modelling of Transformer Core Nonlinearities Using the DIgSILENT PowerFactory Software

    DEFF Research Database (Denmark)

    Bak, Claus Leth; Bak-Jensen, Birgitte; Wiechowski, Wojciech

    2008-01-01

    This paper demonstrates the results of implementation and verification of an already existing algorithm that allows for calculating saturation characteristics of singlephase power transformers. The algorithm was described for the first time in 1993. Now this algorithm has been implemented using t...... in single and three-phase transformers is also presented. This analysis leads to the conclusion that the method can be applied for modelling nonlinearities of three-phase autotransformers.......This paper demonstrates the results of implementation and verification of an already existing algorithm that allows for calculating saturation characteristics of singlephase power transformers. The algorithm was described for the first time in 1993. Now this algorithm has been implemented using...... the DIgSILENT Programming Language (DPL) as an external script in the harmonic domain calculations of a power system analysis tool PowerFactory [10]. The algorithm is verified by harmonic measurements on a single-phase power transformer. A theoretical analysis of the core nonlinearities phenomena...

  9. Motor Starting Control Circuit Fault Diagnosis and Elimination Methods%电动机启动控制线路的故障诊断与排除方法

    Institute of Scientific and Technical Information of China (English)

    胡永春

    2015-01-01

    电动机直接启动控制线路的常见故障有:按启动按钮后电动机不能启动;接通电源无须启动按钮控制,电动机自行运转;电动机启动运转后,手离开按钮电动机便停转;按下停机按钮,电动机不能停转,等等。本文阐述了Y-△降压启动控制线路的故障诊断与排除,自耦变压器降压启动线路的故障排除等问题。%the direct motor starting control circuit common fault are the main press the start button motor can not be started;the power supply is switched on without the start button control, motor bike;electric motor starts to work, the motor stops rotating hands off button; press the stop button, the motor can not stop etc.. This paper mainly introduces Y- reduced voltage starting control circuit fault diagnosis and elimination, autotransformer fault step-down start line to eliminate the problem.

  10. Nuclear power demonstrating

    Energy Technology Data Exchange (ETDEWEB)

    Basmajian, V. V.; Haldeman, C. W.

    1980-08-12

    Apparatus for demonstrating the operation of a closed loop nuclear steam electric generating plant includes a transparent boiler assembly having immersion heating elements, which may be quartz lamps or stainless steel encased resistive immersion heating units with a quartz iodide lamp providing a source of visible radiation when using the encased immersion heating units. A variable voltage autotransformer is geared to a support rod for simulated reactor control rods for controlling the energy delivered to the heating elements and arranged so that when the voltage is high, the rods are withdrawn from the boiler to produce increased heating and illumination proportional to rod position, thereby simulating nuclear reaction. A relief valve, steam outlet pipe and water inlet pipe are connected to the boiler with a small stainless steel resistive heating element in the steam outlet pipe providing superheat. This heater is connected in series with a rheostat mounted on the front panel to provide superheat adjustments and an interlock switch that prevents the superheater from being energized when the steam valve is off with with no flow through the superheater. A heavy blue plastic radiation shield surrounds the boiler inside a bell jar.

  11. Analysis of the monitoring data of geomagnetic storm interference in the electrification system of a high-speed railway

    Science.gov (United States)

    Liu, Lianguang; Ge, Xiaoning; Zong, Wei; Zhou, You; Liu, Mingguang

    2016-10-01

    To study the impact of geomagnetic storm on the equipment of traction electrification system in the high-speed railway, geomagnetically induced current (GIC) monitoring devices were installed in the Hebi East traction power supply substation of the Beijing-Hong Kong Dedicated Passenger Line in January 2015, and GICs were captured during the two geomagnetic storms on 17 March and 23 June 2015. In order to investigate the GIC flow path, both in the track circuit and in the traction network adopting the autotransformer feeding system, a GIC monitor plan was proposed for the electrical system in the Hebi East traction power supply substation. This paper analyzes the correlation between the GIC captured on 17 March and the geomagnetic data obtained from the Malingshan Geomagnetic Observatory and presents a regression analysis between the measured GIC and the calculated geoelectric fields on 23 June in the high-speed railway. The maximum GICs measured in the track circuit are 1.08 A and 1.74 A during the two geomagnetic storms. We find that it is necessary to pay attention on the throttle transformers and track circuits, as the most sensitive elements responding to the extreme geomagnetic storms in the high-speed railway.

  12. 变压器整流电压输出受电压不平衡输入影响的分析

    Institute of Scientific and Technical Information of China (English)

    臧桂美; 刘焕秀

    2015-01-01

    在变压器整流电路中,输出电压的不平衡对设备的影响是是相当大的,因此分析输入电压不平衡对输出电压的影响是非常重要的。在本文中将定量的分析隔离式变压器和自耦变压器不对称和输入电压不平衡对整流系统的影响,通过数据分析来详细的分析不同变压器参数与电压不平衡的关系。%In the transformer rectifier circuit, unbalance of the output voltage of the device is quite large, so the analysis input voltage imbalance on the output voltage is very important. This article wil be a quantitative analysis of isolation transformers and autotransformers asymmetries and imbalances affect the input volt-age of the rectifier system, through data analysis to a detailed analysis of the relationship between different parameters of transformer voltage imbalance.

  13. 挖沙船的变频节能改造分析%Analysis of Frequency Conversion for Energy Saving of Dredging Ship

    Institute of Scientific and Technical Information of China (English)

    李占峰; 杜俊明

    2014-01-01

    Before using Variable frequency adjustable speed, dredging ships main motor mostly use the star delta starter or autotransformer starting mode. This startup mode will produce large starting current, as a consequence a large capacity diesel generator must be chosen. The use of Variable frequency adjustable speed can reduce the starting current of the motor,the capacity of diesel generators, and upfront investment, which can bring considerable economic benefits to the enterprise.%挖沙船上主电机在采用变频调速以前,多用星三角起动或自耦减压起动方式。这种启动方式起动电流较大,导致所选用的柴油发电机的容量过大。采用变频调速以后,可以减小电动机的起动电流,降低柴油发电机的容量,减少前期投资,给企业带来可观的经济效益。

  14. Analysis of energy processes in pulse converters of AC electric power

    Directory of Open Access Journals (Sweden)

    Kadatsky A.F.

    2015-02-01

    Full Text Available The article presents the analysis of energy processes in switched-mode AC-AC converters of buck, boost and buck-boost types. The mathematical model of energy processes is obtained. The mathematical model is generalized to DC-DC and AC-AC converters, to three basic types of converters and considers possibility of autotransformer inclusion of an inductor. It is shown that the use of bi-directional switches allows both DC and AC conversion of electrical energy regardless of the load type and also supports recuperation of electrical energy back to the source. It is shown that the maximum value of instant power in a load circuit in AC—AC converters exceeds twice the rated value of load power in comparison with DC—DC converters. It is shown that the energy capacity of an inductor in AC—AC converters exceeds twice the energy capacity of DC—DC converters at the identical rated power of conversion. It is shown that the energy capacity of an inductor in converters of buck and boost types depends on the ratio of input and output voltage. Also, the energy capacity of an inductor in converters of buck-boost type does not depend on the ratio of input and output voltage. It is shown that the energy capacity of an inductor in converters of buck and boost types is lower than the energy capacity of an inductor in the converter of buck-boost type.

  15. High voltage pulse generator. [Patent application

    Science.gov (United States)

    Fasching, G.E.

    1975-06-12

    An improved high-voltage pulse generator is described which is especially useful in ultrasonic testing of rock core samples. An N number of capacitors are charged in parallel to V volts and at the proper instance are coupled in series to produce a high-voltage pulse of N times V volts. Rapid switching of the capacitors from the paralleled charging configuration to the series discharging configuration is accomplished by using silicon-controlled rectifiers which are chain self-triggered following the initial triggering of the first rectifier connected between the first and second capacitors. A timing and triggering circuit is provided to properly synchronize triggering pulses to the first SCR at a time when the charging voltage is not being applied to the parallel-connected charging capacitors. The output voltage can be readily increased by adding additional charging networks. The circuit allows the peak level of the output to be easily varied over a wide range by using a variable autotransformer in the charging circuit.

  16. Chemistry of Stable Carbenes and «Green» Technologies

    Directory of Open Access Journals (Sweden)

    Korotkikh, N.I.

    2015-11-01

    Full Text Available Brief analysis of fundamental research in the chemistry of stable carbenes and applications in the field of «green» chemistry on their basis carried out at the L.M. Litvinenko Institute of Physical Organic & Coal Chemistry of NAS of Ukraine over the last decade is given. Carbene versions of ester Claisen condensation to form zwitterionic compounds, the Leuckart-Wallach reaction with the autoreduction of carbenoid azolium salts, Hofmann cleavage of aminocarbene insertion products, an induced tandem autotransformation of 1,2,4-triazol-5-ylidenes into 5-amidino-1,2,4-triazoles were found. New carbene reactions of ad dition, deesterification, oxidation and complexation were revealed. Effective methods of obtaining stable carbenes and carbenoids were suggested. New types of carbenes, namely benzimidazolylidenes, superstable conjugated biscarbenes and new types of carbenoids were synthesized. The existence of hypernucleophilic carbenes was theoretically predicted and experimentally confirmed. The prospects of the use of carbenes and their derivatives, in particular, carbene complexes of transition metals in catalysis of organic reactions and the search of biologically active compounds were shown.

  17. 带多脉波整流的级联逆变器研究%Research on Cascaded Inverter With Multiple Pulse Waveform Rectifier

    Institute of Scientific and Technical Information of China (English)

    徐海波; 朱忠尼; 陈元娣; 王永攀

    2012-01-01

      This paper presents a combined converter circuit of high power inverter consisted of multiple pulse waveform rectifier with autotransformer and cascaded inverter, by combining the advantages of multiple pulse waveform rectifier and cascaded inverter. In view of the problem that the triggering angle control algorithm of the current cascaded inverter with staircase control can only apply to a constant voltage difference mode and not be on line calculation, this paper proposes an easy algorithm that can be applied to a varying voltage differential mode and the on line calculation of triggering angle implemented. Finally, by the experimental results, the correctness of the theoretical analysis is verified, which shows the proposed combinative converter circuit is of higher utility value for high power inverter.%  将多脉波整流和级联逆变器两者的优点相结合,提出了一种采取带自耦变压器的多脉波整流和级联逆变器构成大功率逆变器的组合式变换电路。针对目前阶梯波控制级联逆变器的触发角控制算法仅适用于等电压差模式且不能在线计算的问题,提出了一种适用于电压级差不等模式且可实现触发角在线计算的简易算法。最后通过实验结果验证了理论分析的正确性。该组合式变换电路在大功率逆变器应用中具有较高的实用价值。

  18. Tissue Microarray Study of Vasculogenic Mimicry in Bi-directional Differentiated Malignant Tumors

    Institute of Scientific and Technical Information of China (English)

    XishanHao; BaocunSun; ShiwuZhang; XiulanZhao

    2004-01-01

    OBJECTIVE To determine if vasculogenic mimicry (VM) exists in bi-directional differentiated malignant tumors. METHODS The blood supply models for bi-directional differentiated tumors were studied with immunohistochemical and PAS double-staining techniques. New sections were made from 158 paraffin-embedded bi-directional malignant-tumor samples, including melanoma (high malignancy n=30, low malignancy n=30); synoviosarcoma(SS) (high malignancy n=26, low malignancy n=13); acinar rhabdomyosarcoma (All) (high malignancy n=16,low malignancy n=13); malignant mesothelioma (MM) (n=26), and epithelioid sarcoma (ES)(n=4). Tissue microarrays were made. The representative points in the paraffin sections were labeled and two tissue microarrays were made, one included 60 cases of melanoma, and the other included the other tumors. Immunohistochemical staining of the platelet-endothelial cell adhesive molecule(CD31 antigen) and periodic acid Schiff(PAS) staining were conducted. The areas were calculated of vessel-like channels consisting of CD31 antigen-positive tumor cells and of PAS positive materials. The VM was studied using the data obtained. RESULTS Some of these bi-directional tumor cells secreted PAS-positive materials and 0D31 positive materials. The walls of the VM consisted of PAS-positive materials lined with CD31 negative tumor cells with red blood cells inside the channel, whereas the walls of the epithelium-dependent vessels were comprised of CD31 positive materials. The positive areas of CD31 were significantly less than that of PAS (P<0.01). The number of cases with VM in highly malignant tumors was greater than that found in the lowly malignant tumors. CONCLUSIONS Bi-directional differentiated malignant tumor cells have the ability to auto-transform and might interact with the extracellular matrix to form a vessel channel system which mimics blood vessels for transporting blood. That process is called VM. Results in this study show that bi

  19. Simulation study of DC bias enduring ability of 500 kV power transformer%500 kV电力变压器直流偏磁耐受性能的仿真研究

    Institute of Scientific and Technical Information of China (English)

    杨晓辉; 王丰华; 段若晨; 郑含博

    2014-01-01

    In order to further study the DC bias enduring ability of 500 kV power transformer, DC bias simulation model of 500 kV auto-transformer is built based on the electric circuit and magnetic circuit combined model according to the J-A hysteresis loop theory. The effects of magnetizing property of silicon steel sheet including coercive force, remanence, hysteresis loss to the enduring ability of 500 kV power transformer are simulated through the variations of key parameters in J-A model. It is seen that the magnetic currents are distorted with the occurrence of even harmonics when the DC component enters into the power transformer. The magnetizing currents are increased with different amplitudes with the increasing of DC component. When the coercive force of hysteresis loop is increased, the variations of magnetic currents and its total harmonics distortion are increased gradually. When remanence and hysteresis loss are increased, the variations of magnetic currents and its total harmonics distortion are increased greatly. The obtained results could provide theoretical references and new thoughts for the improvement of DC bias enduring ability of power transformer and suppression measure of DC bias with certain practical value. This work is supported by National Natural Science Foundation of China (No. 51207090).%为了深入研究500 kV电力变压器的直流偏磁耐受性能,根据J-A磁滞回线理论,基于电路磁路模型建立了500 kV自耦变压器的直流偏磁仿真模型,通过改变J-A模型中的关键参数,仿真研究了矫顽力、剩磁和磁滞损耗等硅钢片磁化特性对500 kV变压器直流偏磁耐受性能的影响。仿真结果表明,变压器直流偏磁时,励磁电流出现畸变,有偶次谐波出现,励磁电流随直流分量的增大呈现不同的增幅。当磁滞回线的矫顽力增大时,励磁电流及其总谐波畸变率随外加直流分量的增幅变小。当剩磁和磁滞损耗增大时,励磁

  20. Analysis and design of modular three-phase power factor correction schemes for utility interface

    Science.gov (United States)

    Hahn, Jae-Hong

    The extensive use of non-linear and electronically switched loads in power system has lead to higher incidences of harmonic distortion of the voltage and current waveforms. Harmonic currents degrade power quality and are considered the main source of many system malfunctions. Technical guidelines and standards regarding suppressions of system harmonic contents have been enacted. This dissertation proposes several new three-phase power factor correction (PFC) schemes using single-phase PFC modules. An integrated single-switch approach is first proposed. This is essentially an add-on solution to standard ASD's. This approach is based on circulating third harmonic current between neutral and DC mid-point by utilizing a lossless resistor. Single-phase PFC emulates this resistor to control the amplitude of the current, which is implemented by the dynamic breaking chopper available in standard adjustable speed drives (ASD's). This approach is also capable of reducing harmonic distortion in multiple drives. Analysis, design and simulations are conducted to determine the performance of the proposed scheme with different line impedances and with and without dc-link inductance in the ASD. Experimental results are presented using commercial ASD retrofitted with the proposed approach. Second scheme proposes a three-phase PFC using two standard single-phase PFC modules. In this approach, three-phase input is transformed into two-phase by means of 0.14 pu autotransformer. Two standard single-phase PFC modules are employed to process two-phase power to do output. Split inductors and diodes are employed to limit the interaction between the two phases. A method to eliminate the interaction between phases is also described. Due to cascade operation of two PFC stages, low frequency (120Hz) ripple in dc-link is cancelled. An active interphase transformer (IPT) scheme is proposed to draw sinusoidal input line currents, in the third study. This scheme utilizes a unique combination of a

  1. 交流传动机车与直流传动机车混合运用条件下牵引网电压控制技术%Traction Network Voltage Control Techniques under the Condition of Hybrid Application of AC Drive and DC Drive Locomotives

    Institute of Scientific and Technical Information of China (English)

    李强; 吴命利

    2014-01-01

    在大秦重载铁路上,担当万吨和两万吨重载列车牵引任务的即有 HXD1型、HXD2型交流传动电力机车,也有S S4型直流传动电力机车。由于这两种电力机车具有不同的电气负荷特性,在大秦线的部分区段,保持牵引变电所母线电压处在适当水平成为一个需要解决的技术问题。结合算例,本文给出因S S4型电力机车功率因数低而导致的网压降低和 HXD1型电力机车再生制动引起的网压升高的仿真计算结果,分析电源短路容量、牵引变压器、无功补偿装置以及牵引网阻抗对网压变动的影响。对包括使用有载调压牵引变压器、有载调压自耦变压器、晶闸管控制串联变压器、串联电容器和功率平衡调节器等在内的不同改善网压技术方案进行比较。基于现代电力电子技术的功率平衡调节器不但能有效稳定网压还能综合治理电能质量,有望为该问题提供最佳解决方案。%Both the AC drive locomotives , HXD1 and HXD2 , and the DC drive locomotive , SS4 , are designated for 10 000 t and 20 000 t heavy-duty haul on the Datong-Qinhuangdao Heavy-haul Railway Line . Due to the distinct electric loading characteristics of these two types of locomotives , how to maintain the bus bar voltage in traction substations in some sections of the Line at an appropriate level has become a technical issue to be handled .By a numerical example , the voltage drop caused by the low power factor of Locomotive SS4 and the voltage rise caused by the regenerative braking of Locomotive HXD1 were computed . The influences of the power source capacity , the traction transformer , the reactive power compensator and the impedance of the traction network on the voltage variations were analyzed . Different voltage improving schemes , including those schemes with use of the on-load tap changing traction transformer , the on-load voltage regulating auto-transformer , the thyristor

  2. A Novel Full-Size Power Converter for Wind Energy Conversion System%一种新型的风力发电全功率变流器

    Institute of Scientific and Technical Information of China (English)

    陈杰; 龚春英; 陈家伟; 张方华; 严仰光

    2012-01-01

    Abstract A novel full-size power converter which consists of a machine side auto-transformer rectifier unit (ATRU) and grid side Z-source inverter(ZSI)is proposed in this paper. The power converter owns the merits of simple structure, high reliability, and high efficiency, which could cater for the off shore wind turbines where high reliability is required. The operational principle of the ATRU and ZSI is briefly introduced. Some design rules are concluded based on the feasibility analysis of applying ATRU to variable speed wind turbines. Then, the relationship between input voltage and dc link voltage of ZSI is carefully discussed, which decides the design requirements of PMSG and inverter A control strategy including the functions of maximum power point tracking (MPPT) function and dc link voltage stabilizing is devised for the wind energy conversion system (WECS), based on the proposed full-scale power converter, and the input voltage feed forward control method is adopted for the ZSI. to improve the dynamic performance of do link peak voltage. Finally, a simulation case is implemented, and the simulation results show the correctness and feasibility of the proposed power converter and its control strategy.%提出了一种新型的风力发电全功率变流器,由电机侧自耦调压整流器(ATRU)和网侧z源逆变器(ZSI)组成,具有结构简单、可靠性高、转换效率高等优点,为风力发电系统提供了一种可选的解决方案。文中首先简要地介绍了ATRU和ZSI的基本工作原理,对ATRU在变速风电机组中应用的可行性展开了推导分析,提出了相关设计要求。随后,针对网侧ZSI,详细地分析了其输入电压和直流链电压之间的内在关系,揭示了发电机和逆变器之间的参数匹配要求。设计了一种系统控制策略,实现了机组的最大功率跟踪,并提出了一种基于输入电压前馈的逆变器直流链电压控制方法,保证机组在各