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Designs of 10 MW Air-core and Iron-core HTS Wind Power Generators

  • Sung, Hae-Jin;Park, Minwon;Yu, In-Keun
    • Journal of Electrical Engineering and Technology
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    • v.10 no.2
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    • pp.545-550
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    • 2015
  • High Temperature Superconducting (HTS) synchronous generators can be designed with either an air-core type or iron-core type. The air-core type has higher efficiency under rated rotating speed and load than the iron-core type because of the iron losses which may produce much heat. However, the total length of HTS wire in the air-core type is longer than the iron-core type because the generated magnetic flux density of the air-core type is low. This paper deals with designs of 10 MW air-core and iron-core HTS wind power generators for wind turbines. Fully air-core, partially iron-core, and fully iron-core HTS generators are designed, and various stator winding methods in the three HTS generators are also considered, such as short-pitch concentrated winding, full-pitch concentrated winding, short-pitch distributed winding, and full-pitch distributed winding. These HTS generators are analyzed using a 3D finite elements method program. The analysis results of the HTS generators are discussed in detail, and the results will be effectively utilized for large-scale wind power generation systems.

Cell Balancing Method in Flyback Converter without Cell Selection Switch of Multi-Winding Transformer

  • Kim, Jin-Woong;Ha, Jung-Ik
    • Journal of Electrical Engineering and Technology
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    • v.11 no.2
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    • pp.367-376
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    • 2016
  • This paper presents a cell balancing method for a single switch flyback converter with a multi-winding transformer. The conventional method using a flyback converter with a multi-winding transformer is simple and easy to control, but the voltage of each secondary winding coil might be non-uniform because of the unequal effective turn-ratio. In particular, it is difficult to control the non-uniform effect using turn-ratios because secondary coil has a limited number of turns. The non-uniform secondary voltages disturb the cell balancing procedure and induce an unbalance in cell voltages. Individual cell control by adding a switch for each cell can reduce the undesirable effect. However, the circuit becomes bulky, resulting in additional loss. The proposed method here uses the conventional flyback converter with an adjustment made to the output filters of the cells, instead of the additional switch. The magnitude of voltage applied to a particular cell can be reduced or increased according to the adjusted filter and the selected switching frequency. An analysis of the conventional converter configuration and the filter design method reveals the possibility of adequate cell balancing control without any additional switch on the secondary side.

Comparison of High Frequency Detailed Generator Models for Partial Discharge Localization

  • Hassan Hosseini, S.M.;Hosseini Bafghi, S.M.
    • Journal of Electrical Engineering and Technology
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    • v.10 no.4
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    • pp.1752-1758
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    • 2015
  • This paper presents partial discharge localization in stator winding of generators using multi-conductor transmission line (MTL) and RLC ladder network models. The high-voltage (HV) winding of a 6kV/250kW generator has been modeled by MATLAB software. The simulation results of the MTL and the RLC ladder network models have been evaluated with the measurements results in the frequency domain by applying of the Pearson’s correlation coefficients. Two PD generated calibrator signals in kHz and MHz frequency range were injected into different points of generator winding and the signals simulated/measured at the both ends of the winding. For partial discharge localization in stator winding of generators is necessary to calculate the frequency spectrum of the PD current signals and then estimate the poles of the system from the calculated frequency spectrum. Finally, the location of PD can be estimated. This theory applied for the above generator and the simulation/measured results show the good correlation for PD Location for RLC ladder network and MTL models in the frequency range of kHz (10kHz<f<1MHz) and MHz (1MHz<f<5MHz) respectively.

Stator Winding Fault Diagnosis in Small Three-Phase Induction Motors by Park's Vector Approach (Park's Vector 기법을 이용한 소형 3상 유도 전동기의 권선 고장 진단)

  • 박규남;한민관;우혁재;송명현
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.7 no.6
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    • pp.1291-1296
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    • 2003
  • This paper deals with efficient diagnostic for stator winding fault of 3-phase induction motor using a current Park's vector approach. This method firstly transforms 3-phase stator current to vertical axis current and horizontal axis current of Park's Vector, and then obtains the each Park's Vector Pattern and detects stator winding fault by comparing to Park's Vector Pattern of healthy and fault. Experimental results, obtained by using induction motor having inter-turn fault of 2, 10, 20 turn, demonstrate the effectiveness of the proposed technique, for detecting the presence of stator winding fault under 25%, 50%, and 100% of full load condition.

Thermal Conductivity and Dielectric Strength Measurement of the Impregnating Materials for the Next Generation Winding Type Superconducting Fault Current Limiter (차세대권선형한류기를 위한 함침용 재료의 열전도도 및 절연 내력 측정)

  • Yang Seong Eun;Bae Duck Kweon;Ahn Min Cheol;Kang Hyoung Ku;Seok Bok Yeol;Chang Ho Myung;Kim Sang Hyun;Ko Tae Kuk
    • Progress in Superconductivity and Cryogenics
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    • v.7 no.1
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    • pp.42-46
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    • 2005
  • The resistive type high temperature superconducting fault current limiter (HTSFCL) limits the fault current using the resistance generated by fault current. The generated resistance by fault current makes large pulse power which makes the operation of HTSFCL unstable. So, the cryogenic cooling system of the resistive type HTSFCL must diffuse and eliminate the pulse energy very quickly. Although the best way is to make wide direct contact area between HTS winding and coolant as much as possible, HTS winding also needs the impregnation layer which fixes and protects it from electromagnetic force. This paper deals with the thermal conductivity and dielectric strength of some epoxy compounds for the impregnation of high temperature superconducting (HTS) winding in liquid nitrogen. The measured data can be used in the optimal design of impregnation for HTS winding. Aluminar filling increased the thermal conductivity of epoxy compounds. Hardener also affected the thermal and electric characteristic of epoxy compounds.

Operating Characteristics of Hybrid Type Superconducting Fault Current Limiter (하이브리드형 초전도 한류기의 동작 특성)

  • Cho, Yong-Sun;Nam, Gueng-Hyun;Lim, Sung-Hun;Choi, Hyo-Sang
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.55 no.6
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    • pp.255-258
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    • 2006
  • We investigated the operating characteristics of the hybrid-type superconducting fault current limiter (SFCL) according to the inductance of secondary windings. The hybrid type SFCL consists of a transformer that has a primary winding and a secondary winding with serially connected $YBa_2Cu_3O_7$ (YBCO) films. The resistive-type SFCL has difficulty when it comes to raising the capacity of the SFCL due to slight differences of critical current densities between units and structure of the SFCL. The hybrid-type SFCL with closed-loop is able to achieve capacity increase through the electrical isolation and reduction of the inductance of the secondary winding with a superconducting element of the same critical current. On the other hand, the current limiting characteristics were nearly identical in the hybrid-type SFCL with open-loop compared to closed-loop, but quench time was longer than the hybrid-type SFCL with closed-loop. We confirmed that the capacity of the SFCL was increased effectively by the reduced inductance of the secondary winding. In addition, the power burden of the system also could be lowered by reducing the inductance of secondary winding.

A Low Cogging Force Permanent Magnet Linear Motor Having 3 Phase 9 Pole 10 Slot Structure (코깅력이 저감된 3상 9극 10슬롯 구조의 영구자석 선형 전동기)

  • Youn, Sung-Whan;Lee, Jong-Jin;Koh, Chang-Seop
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.55 no.11
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    • pp.547-554
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    • 2006
  • The detent force of a permanent magnet linear motor(PMLM) consists of the end force and cogging force, and should be reduced for high precision purpose applications. The cogging force comes from the electromagnetic interaction between the permanent magnets and interior teeth(or the slots) of the stator, and of which the magnitude depends on the ratio of the numbers of the armature and permanent magnet poles as well as the geometrical shape of the permanent magnet and armature pole. In order to reduce the cogging force of a PMLM, this paper proposes a new configuration which has 9 permanent magnet poles and 10 armature winding slots. By theoretical investigation of the principle of cogging force generation and simulating using finite element method, the proposed PMLM configuration is proven to give much less cogging force than the conventional configuration which has 8 permanent magnet poles and 12 armature winding slots. A proper winding algorithm, modified (A, A, A) winding method, for the proposed configuration is also suggested when the proposed PMLM is operating as a 3 phase synchronous machine. A theoretical and numerical calculation shows that the proposed configuration makes slightly bigger back-emf and thrust force under same exciting current and total number of winding turns condition.

Test Results of a Three Phase 10㎸A HTS Transformer With Double Pan Cake Coils (3상 10kVA 더블 팬케익 코일형 고온초전도 변압기 특성시험 결과)

  • 이승욱;이희준;차귀수;이지광;최경달;류경우;한송엽
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.52 no.3
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    • pp.101-106
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    • 2003
  • The high temperature superconductor transformers gain interests from the industries. This paper described construction and test results of 10㎸A HTS transformer Three phase transformer with double pancake windings were constructed. To reduce the leakage magnetic field, secondary coil were placed between the two primary coils. BSCCO-2223 wire. silicon sheet steel core and FRP cryostats were used to construct the transformer. Three coils were stacked in one cryostat. Two double pancake coils were connected in series for the primary coil and one double pancake coil was used for the secondary coil. Total number of turns of the primary winding and the secondary winding were 112turns and 98urns, respectively, The rated voltages of each winding were 440/220V. The rated currents of each winding were 13.1/26.2A. After the tests of basic properties of the three phase HTS transformer using no-load test, short-circuit test and full-load test, continuous operation of 100 hours with pure resistive load has been carried out. Test results proved over-load capability and reliability of the HTS transformer.

Comparative Study on the Flexural Characteristics of Composite Bridge Deck Fabricated with Filament Winding and Pultrusion (필라멘트 와인딩과 인발성헝 제작 복합소재 교량 바닥판의 휨 특성 비교분석)

  • Lee, Sung-Woo
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.18 no.2
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    • pp.191-200
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    • 2005
  • To develop composite bridge deck, comparative study on the flexural characteristics of deck fabricated with filament winding and pultrusion was performed. In this study, composite deck of triangular shape was fabricated with filament winding process and flexural tests were conducted along with pultruded 'Duraspan' deck. Failure load, maximum deflection and strains were compared with each other. Also finite element analysis for filament winding deck was carried out and the results were compared with those from experiments.

Analysis of Off-Line and On-Line Partial Discharge in High Voltage Motor Stator Windings

  • Kim, Hee-Dong;Kong, Tae-Sik;Lee, Sang-Kil;Kim, Beom-Soo;Kim, Doo-Young
    • Journal of Electrical Engineering and Technology
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    • v.10 no.3
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    • pp.1086-1092
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    • 2015
  • The off-line and on-line partial discharge (PD) in the stator winding of three high-voltage (HV) motors (1,400 HP, 6.6 kV) is measured and analyzed in this paper. The off-line PD is measured at high values between 24,300 ~ 36,100 pC after 18 years of motor operation. Spare replacement motors were not available for testing the degree of deterioration of the stator windings in standstill status. Therefore, on-line periodic analysis was conducted to monitor the trend of PD after installing a ceramic sensor (110 pF, 6.6 kV) in the terminal box for each phase of each motor. In the stator winding of the No.1 and No.2 HV motors, which showed high magnitudes of off-line PD and low magnitudes of on-line PD, defects are expected to appear in the neutral end of the winding. On the contrary, in the stator windings of the No.3 HV motor, which exhibits high off-line and on-line PD magnitude, defects are expected to appear in the terminal end of the winding where a voltage close to the phase voltage is applied.