The Experts below are selected from a list of 3408 Experts worldwide ranked by ideXlab platform

Yong Li - One of the best experts on this subject based on the ideXlab platform.

  • Vibration modal analysis and calculation of a new HVDC Converter Transformer with inductive filtering method
    2015 5th International Conference on Electric Utility Deregulation and Restructuring and Power Technologies (DRPT), 2015
    Co-Authors: Yuehui Chen, Yong Li, Yanjian Peng
    Abstract:

    In this paper, the vibration modal characteristics are investigated for a new high-voltage direct current (HVDC) Converter Transformer with inductive filtering method. A 3-D finite element model of the Transformer is established by means of ANSYS and used to extract natural frequencies and vibration modes of the windings and cores of the Converter Transformer. First, a new Converter Transformer based on the inductive filtering is proposed, and its physical structures are described in brief. Then, 3-D model of windings of the new Converter Transformer is established to calculate the vibration mode. Then, the vibration mode of iron core is investigated, and an effective method of installing pre-tighten clamping is proposed to reduce the vibration of iron core. Finally, the vibration mode of whole Transformer is investigated and the results show that proposed Transformer has a good performance in vibration. Besides, the proposed vibration modal analysis is useful for the design of the new HVDC Converter Transformer. Based on the vibration analysis results, we can take the corresponding method to reduce the possibility of resonance caused by harmonic currents.

  • A new method highly integrated with Converter Transformer for harmonic suppression and reactive power compensation
    2014 International Conference on Power System Technology, 2014
    Co-Authors: Chonggan Liang, Yong Li, Wendi Liao, Qi Qi
    Abstract:

    A new method for harmonic suppression and reactive power compensation which is integrated with Converter Transformer is proposed to deal with the oversize problems of Transformer and harmonic filter system in the cases where physical space is of limit Based on the presented non-orthogonal decoupling mechanism, the integrated filter is designed and constructed. In this paper studies are performed on the decoupling effect, the inductor winding linearity and inductance computation, and the harmonic reduction and reactive power compensation performance of the described integrated filter. Simulation and experimental verifications of an integration Converter Transformer prototype are provided.

  • Electromagnetic vibration analysis of the winding of a new HVDC Converter Transformer
    IEEE Transactions on Power Delivery, 2012
    Co-Authors: Pengfei Shao, Longfu Luo, Yong Li, Christian Rehtanz
    Abstract:

    HVDC Converter Transformers suffer from serious noise pollution caused by the electromagnetic vibration of their windings and cores, since the nonlinear behavior of Converters produces a large number of harmonic currents. This paper presents an electromagnetic vibration analysis of a new autoinductive harmonic suppression (AIHS) Converter Transformer's windings, taking harmonic currents into consideration. The currents of the windings are computed by using the multiwinding Transformer theory. Then, the electromagnetic forces in the radial and axial direction of three windings are calculated by using Lagrange's theorem. Three windings and the corresponding core of the AIHS Converter Transformer are constructed and simulated by a 3-D finite-element method model. The transient dynamic (time-domain) simulation results reveal that the AIHS Converter Transformer and its corresponding inductive filters can suppress the electromagnetic vibration of windings.

  • Simulation model's design of a new Converter Transformer based on multi-coil coupling
    Transactions of China Electrotechnical Society, 2010
    Co-Authors: Jie Zhang, Raj Aggarwal, Yong Li
    Abstract:

    In order to study the electromagnetic transient course and electric parameter's variation rules when the new Converter Transformer operates under normal or all kinds of external and internal faulty and saturated core conditions, develop suitable protection schemes for the new Converter Transformer, it is essential to design simulation models to research accordingly. Based on the coupling concept, according to the special winding wiring mode of the new Converter Transformer, with a finite element simulation software, multi-coil coupling module of Matlab is used to design the normal and internal faulty simulation model of the new Converter Transformer separately, and a nonlinear inductance branch is designed to simulate the characteristic of saturated core of the new Converter Transformer. The correctness of the simulation models designed by this paper are verified by simulation results. The physical concept of the simulation models designed by this paper is very clear and the designing course is simple. The calculation precision is comparative high, and the methods which designing the simulation model of the new Converter Transformer can be used to design and analyze normal, external and internal faulty and inrush current simulation models of arbitrary complex multi-winding Transformers in actual projects.

  • Study on the effects of the dc bias on the harmonic characteristics of the new Converter Transformer
    Asia-Pacific Power and Energy Engineering Conference, APPEEC, 2010
    Co-Authors: Yong Li, Longfu Luo, Dajiang He, Dechang Yang, Christian Rehtanz, Sven Rüberg
    Abstract:

    DC bias is the problem that must be faced in the course of the design of the Converter Transformer for the high-voltage direct current (HVDC) transmission system, especially the new Converter Transformer that has the unique wiring scheme. This paper will theoretically analyze the basic cause of the dc bias of the new Converter, and then according to the real no-load characteristic of the new Converter Transformer, its simulation model, which considers the hysteresis loss of the core of the new Converter Transformer, will be established by the means of data fitting. Based on the established simulation model, the harmonic characteristic of the new Converter Transformer caused by the dc bias will be simulated and analyzed in detail. Furthermore, this paper will propose a new inductive filtering technology to suppress the harmonic caused by the dc bias. Finally, compared with the traditional Converter Transformer, the superiority that the new suppression scheme has will be revealed. ?2010 IEEE.

Lin Wang - One of the best experts on this subject based on the ideXlab platform.

  • Numerical calculation of the lightning transient voltage distribution on Converter Transformer winding based a dual winding model
    The Journal of Engineering, 2019
    Co-Authors: Shijin Tian, Lin Wang
    Abstract:

    The insulation co-ordination of Converter Transformer winding has a great influence on power system security. An equivalent circuit of a 500 kV Converter Transformer winding structure, including a LC equivalent network circuit and an ideal Transformer in parallel, was firstly established. A combined 12-pulse rectifier equivalent circuit model, mainly consisting of six single-phase Converter Transformer and 12 Converter valves, was built in Power Systems Computer Aided Design (PSCAD) software. In certain operating states of the Converter value, the transient voltage distribution was analysed when lightning strokes the DC bus of a typical Converter station. The results show that the dual winding model can present the transient voltage characteristics of the Converter Transformer. The maximum lightning transient voltage is located at the end of the star-connected winding near the neutral point and reaches 1270 kV, and also the maximum gradient voltage occurs at the winding near the terminal point. In different operating states for the Converter valve, the transient voltages of a three-phase winding behave as per the similar distributing rules. For the star-connected phase winding, the lightning transient voltage of the winding disc reaches the maximum magnitude when lightning strike occurs at the peak of the phase voltage on the valve side.

  • Numerical analysis of lightning transient voltage distributions in HV Converter Transformer winding
    2016 International Conference on Condition Monitoring and Diagnosis (CMD), 2016
    Co-Authors: Shijin Tian, Lin Wang
    Abstract:

    High voltage (HV) Converter Transformer is one of the most important power equipment in DC transmission system. The determination of transient voltage distribution along the winding plays an important role in the insulation design of Converter Transformer. In this paper an equivalent circuit model for the single-phase Converter Transformer with the double wound windings has been established, which is mainly composed of longitudinal capacitance, longitudinal inductance and radial capacitance. Both finite element and analytical methods were applied in the calculation of winding capacitance parameters. A combined twelve-pulse rectifier equivalent circuit model, consisted of six single-phase Converter Transformer and twelve Converter valves, was established by means of the PSCAD/EMTDC software. The maximum transient voltage on the terminals of six Converter Transformers caused by a lightening stroke to the DC transmission line was analyzed. And therefore, the transient voltage characteristics along six Converter Transformer windings, such as maximum potential distribution and the gradient voltage of each winding disk, were obtained, respectively. The calculated results show that voltage and gradient voltage corresponding to the conducting phase and the non-conducting phase Transformers have the same variation trend. The maximum voltage occurs at the end of the winding next to the neutral point of the Transformer, while the maximum gradient voltage locates at the head of the winding.

Jiazhu Xu - One of the best experts on this subject based on the ideXlab platform.

  • Study on harmonic losses of Inductive Filtering Converter Transformer (IFCT) in HVDC system
    Asia-Pacific Power and Energy Engineering Conference, APPEEC, 2010
    Co-Authors: Dechang Yang, Longfu Luo, Yong Li, Christian Rehtanz, Jiazhu Xu
    Abstract:

    Based on the wiring scheme and the operating principle of the inductive filtering Converter Transformer (IFCT), this paper analyzes the effect of harmonic on the Converter Transformer, and establishes the harmonic losses model for the traditional Converter Transformer (TCT) and the IFCT, respectively. Furthermore, according to the IEC61378-2 standard and the superposition principle, the harmonics losses are calculated in detail. The simulation results verify the correctness of the theoretical analysis, and show that the harmonic losses of the IFCT are lower than that of the TCT, and the implement of the inductive filtering method can reduce the losses of Converter station greatly. ?2010 IEEE.

  • Study on characteristic parameters of a new Converter Transformer for HVDC systems
    IEEE Transactions on Power Delivery, 2009
    Co-Authors: Yong Li, Longfu Luo, Jiazhu Xu, Kazuo Nakamura, Christian Rehtanz, Fusheng Liu
    Abstract:

    Different from the traditional Converter Transformer and ac passive filtering method, this paper presents a new Converter Transformer and a corresponding inductive filtering method for HVDC systems. Based on this, characteristic parameters of the new Converter Transformer are studied in detail by theoretical analysis, simulation, calculation, and experimental verification. By deducing voltage relation, the constraint condition of the turn ratio is obtained, which can satisfy the demand of a 12-pulse Converter in HVDC systems. By deducing current relations, the characteristics of the fundamental and the harmonic currents in the winding are obtained. According to the established operation equations, the simple but practical calculation methods for the short-circuit impedance and the rated capacity are proposed. Then, the change characteristic of the short-circuit impedance is analyzed and calculated. The detailed simulation and test results verified the correctness of the aforementioned theoretical analysis and calculation. ? 2009 IEEE.

  • Harmonic characteristics of new HVDC transmission system based on new Converter Transformer
    2008 Third International Conference on Electric Utility Deregulation and Restructuring and Power Technologies, 2008
    Co-Authors: Yong Li, Kazuo Nakamura, Ji Li, Gerhard Krost, Jiazhu Xu
    Abstract:

    The study on the harmonic characteristics of HVDC transmission system is important for analyzing the effect of harmonics on the operation of the electrical installation and the system. The new HVDC transmission system adopts the new Converter Transformer and the corresponding inductive filtering method, and it is a new electrical topological structure. As for a new system, the harmonic characteristics of the new HVDC transmission system are completely different from that of the traditional one. This paper introduces the main circuit topology of the new HVDC transmission system, and then analyzes the connection of the new Converter Transformer and the filtering mechanism of the inductive filtering method. Based on these, the mathematic model has been established to calculate the harmonic characteristics of the new HVDC transmission system. Furthermore, the amplitude and phase angle of the main characteristic harmonics of the new HVDC transmission system have been calculated by the established mathematic model and then simulated by MATLAB/SIMULINK. Tested results have verified the correctness of above analysis and calculated results. The research findings are useful for the design of the characteristic parameters of the new HVDC transmission system, the selection of the wire cross-section of the new Converter Transformer, and the design of the inductive filtering installations.

  • Transient response characteristics of new HVDC transmission system based on new Converter Transformer
    2008 Third International Conference on Electric Utility Deregulation and Restructuring and Power Technologies, 2008
    Co-Authors: Yong Li, Jie Zhang, Kazuo Nakamura, C. Rehtanz, Jiazhu Xu
    Abstract:

    The new HVDC transmission system adopts the new Converter Transformer and the corresponding inductive filtering method, and its electrical topology structure is completely different from that of the existential HVDC transmission system. For the change of the controlled system, the transient response characteristics of the new HVDC transmission system will be accordingly changed when it adopts the standard control model that the traditional HVDC transmission system adopts. Referring to the parameters of the main circuit of the OGRE HVDC first benchmark model, this paper designs a similar benchmark model of the new HVDC transmission system based on the technical characteristics of the new Converter Transformer and the corresponding inductive filtering method, which mainly contains the rated parameters of the new Converter Transformer and the inductive filtering device. Then, the typical transient response characteristics of the new HVDC transmission system have been analyzed and simulated by PSCAD/EMTDC. The results express that the new HVDC transmission system, which adopts the standard control model that the HVDC transmission engineering adopts, has a good transient response characteristic, and can operate stably when subjecting to various typical disturbance.

  • A New Converter Transformer and a Corresponding Inductive Filtering Method for HVDC Transmission System
    IEEE Transactions on Power Delivery, 2008
    Co-Authors: Yong Li, Jiazhu Xu, Ji Li, Bo Hu
    Abstract:

    A new Converter Transformer and an inductive filtering method are presented to solve the existing problems of the traditional Converter Transformer and the passive filtering method of the high-voltage direct current (HVDC) system. It adopts the ampere-turn balance of the Transformer as the filtering mechanism. A tap at the linking point of the prolonged winding and the common winding of the secondary windings is connected with the LC resonance circuit. It can realize the goal that once theharmonic current flowsinto the prolonged winding, the common winding will induct the opposite harmonic current to balance it by the zero impedance design of the common winding and the proper configuration of LC parameters, so there will be no inductive harmonic current in the primary winding. Moreover, the reactive power that the Converter needs can be partly compensated in the secondary winding. Simulation results have verified the correctness of the theoretical analysis. The new Converter Transformer can greatly reduce the harmonic content in the primary winding, loss, and noise generated by harmonics in the Transformer, and the difficulty of the Transformer's insulation design.

Fred Wang - One of the best experts on this subject based on the ideXlab platform.

  • HVDC Converter Transformer saturation in hybrid AC/DC system caused by coupled transmission lines
    2017 IEEE Applied Power Electronics Conference and Exposition (APEC), 2017
    Co-Authors: Shuoting Zhang, Yalong Li, Leon M. Tolbert, Fred Wang
    Abstract:

    Hybrid ac/dc transmission can increase the power transfer capability of long ac transmission lines. High voltage dc (HVDC) Converters are needed, and the line-commutated Converter (LCC) is used considering the dc fault current controllability. However, zero-sequence current can be generated due to the coupled transmission lines, and it will flow into the HVDC Converters as a fundamental frequency current component on dc side (i60). The LCC will convert i60 to dc current components on the ac side, which may cause potential Converter Transformer saturation. This paper analyzes the influence of coupled transmission lines on i60 and the Converter Transformer saturation and proposes two possible solutions to avoid Converter Transformer saturation. The simulation results verify the effectiveness of the proposed methods.

Kaijian Ou - One of the best experts on this subject based on the ideXlab platform.

  • rtds real time digital simulator real time digital closed loop Converter Transformer protection test system
    2011
    Co-Authors: Kaijian Ou
    Abstract:

    The utility model relates to a RTDS real-time digital closed-loop Converter Transformer protection test system. The test system comprises a real-time digital simulator (RTDS) and a Converter Transformer protection, the real-time digital simulator outputs the voltage and the current analog signals and the tap position digital signal in a Converter Transformer simulation model to the Converter Transformer protection, the Converter Transformer protection inputs a protective tripping digital signal into the real-time digital simulator, a direct-current power transmission system simulation model of a Converter Transformer, which is built in the real-time digital simulator, is a single-phase model, and moreover, additional inductors Xp are connected between the Converter Transformer and a Converter valve. The test system can provide the three-phase current outputs of the head ends of the primary side and the secondary side of the Converter Transformer, which are needed by a real-time Converter Transformer protection simulation test, and also can provide the three-phase current outputs of the tail ends of the primary side and the secondary side of the Converter Transformer in order to meet the requirements of the RTDS Converter Transformer protection test.

  • Converter Transformer protection rtds real time digital closed loop test system for and method thereof
    2011
    Co-Authors: Kaijian Ou
    Abstract:

    The invention discloses a Converter Transformer protection real-time digital system (RTDS) real-time digital closed loop test system and a method thereof. The test system comprises an RTDS real-time digital simulator and a Converter Transformer protection device, wherein the RTDS real-time digital simulator outputs a voltage analog signal, a current analog signal and a tap joint gear digital signal in a Converter Transformer simulation model to the Converter Transformer protection device; the Converter Transformer protection device inputs a protection trip digital signal to the RTDS real-time digital simulator; a direct-current power transmission system simulation model, established in the RTDS real-time digital simulator, of the Converter Transformer is a single-phase model; and an additional inductor Xp is connected between a Converter Transformer and a Converter valve. The test system can provide the primary side head-end three-phase current output and the secondary side head-end three-phase current output, required for a Converter Transformer protection real-time simulation test, of the Converter Transformer, and also can provide the primary side tail-end three-phase current output and the secondary side tail-end three-phase current output of the Converter Transformer, thereby meeting the requirements on a Converter Transformer protection RTDS test.