共查询到20条相似文献,搜索用时 15 毫秒
1.
Kerkman R.J. Leggate D. Skibinski G.L. 《Industry Applications, IEEE Transactions on》1997,33(3):722-731
This paper investigates overvoltage transients on AC induction motors when connected through a cable of arbitrary length to a variable frequency drive (VFD) consisting of a pulsewidth modulation (PWM) inverter with insulated gate bipolar transistor (IGBT) power devices. Factors contributing to a motor overvoltage transient equal to a theoretical twice DC bus voltage are first described using existing transmission line analysis. A critical cable distance Ic is defined where this 2-pu overvoltage occurs. However, literature is lacking on flow motor voltage transients >2-pu bus voltage and up to 3-4 pu are generated. This phenomenon is observed on all PWM inverters with output cable lengths greater than lc distance. Contributing factors to the >2-pu overvoltage phenomenon are investigated by exploring the complex interaction between drive modulation techniques, carrier frequency selected, cable natural frequency of oscillation, cable high-frequency damping losses, and, to a lesser extent, inverter output rise time. Theoretical calculations of cable frequency and damping are correlated with simulation and experimental results. Novel modifications to the PWM modulator, as well as external hardware apparatus, are proposed solutions to the >2-pu overvoltage problem; both are simulated and experimentally confirmed 相似文献
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von Jouanne A. Rendusara D.A. Enjeti P.N. Gray J.W. 《Industry Applications, IEEE Transactions on》1996,32(4):919-926
In this paper, filtering techniques are investigated to reduce the motor terminal overvoltage, ringing, and dv/dt in inverter-fed AC motor drive systems where long leads are required. Analysis is presented to show that the distributed LC of a cable and the pulse-width modulated (PWM) inverter switching action lead to motor terminal voltage reflections and ringing that stress the turn insulation and contribute to bearing currents. First- and second-order shunt filter designs are analyzed and compared. Detailed design equations to match the filter impedance to the cable surge impedance and to determine the filter component values are presented. It is demonstrated that a first-order shunt filter connected at the motor terminals significantly reduces the overvoltage stress and ringing, and also lowers the dv/dt of the PWM switching pulse. Simulation and experimental results are presented to verify the proposed filter designs for 50-ft and 100-ft cable lengths for 460-V PWM insulated gate bipolar transistor (IGBT) AC motor drive systems 相似文献
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Leggate D. Pankau J. Schlegel D.W. Kerkman R.J. Skibinski G.L. 《Industry Applications, IEEE Transactions on》1999,35(6):1383-1392
Reflected-wave transient voltages that result from fast insulated gate bipolar transistor (IGBT) voltage-source inverters have received considerable investigation. The modeling and simulation of these transients require sophisticated motor and cable models. Most voltage-source pulsewidth modulated (PWM) adjustable-speed drive suppliers now provide combinations of passive and active control techniques to mitigate the adverse effects of overvoltage stress, however, the costs of the passive fixes often exceed the cost of the drive. Another aspect of low-rise-time devices, heretofore not examined to the extent of the overvoltage problem, is the resulting current from traveling waves. In this paper, a historical perspective of the overvoltage problem is presented. Models of system components are reviewed, and simulation results are compared with experimental results. These models are then employed to predict the peak currents from voltage-source inverters as the cable, load, and IGBT rise time are altered. The paper will then examine the consequences of reflected wave currents on current sensing, drive control and device performance. From these results, a minimum rise time is established 相似文献
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为进一步抑制永磁风电机组变流器PWM高频脉冲波经长电缆传输反射造成机侧过电压,并降低电机轴承电流,基于共模电流衰减法,提出一种新型RLC-plus-C无源滤波器及其设计方法。首先建立长电缆传输等效电路模型,分析过电压产生机理,引入传递函数,优化滤波器参数。其次对新型滤波器的参数Rf、Cc和Cf进行设计,在此基础上,针对电感Lf的值在Matlab中设计一套完整的计算方法。最后通过Matlab/simulink软件搭建含PWM变流器-长电缆-发电机的仿真模型,引入新型滤波器,分析其过电压抑制效果,轴承电流衰减量以及功率损耗,与RLC和RL-C滤波器比较。结果表明:RLC-plus-C滤波器进一步抑制了机端过电压,同时显著的降低了轴承电流。 相似文献
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对发生自激时变频装置的滤波器和异步电机的单相等值电路进行分析,推导出自激时LC滤波电容与异步电机频率及电机参数的关系。建立变频装置驱动空载异步电动机JSQ 157-8的仿真系统,通过对封锁脉冲后自激现象的观察,分析了自激幅度与电机参数、滤波电容以及直流电容电压等的关系。仿真结果与正在研制的变频装置脉冲封锁后发生自激的实验结果吻合,表明理论分析与仿真计算正确。最后提出了LC滤波器参数选择及其避免自激的措施。 相似文献
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Hanigovszki N. Poulsen J. Blaabjerg F. 《Industry Applications, IEEE Transactions on》2004,40(3):845-852
When an induction machine is supplied with a voltage-source pulsewidth-modulation (PWM) inverter, a ringing voltage overshoot appears at motor terminals due to steep PWM voltage pulse propagation along the motor cable. It has been reported that in particular situations, when very long motor cables are used and retrofit installations, the overvoltage could stress motors with poor insulation. This paper presents a novel inverter output filter topology consisting of an LC filter which has the star point of the common-mode capacitors clamped to the + and - dc-link rails by the means of two diodes. The proposed filter drastically reduces the voltage overshoot at the motor terminals, thus reducing motor insulation stress. This is a cheap alternative to more known industrial solutions. 相似文献
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Output filters for PWM drives with induction motors 总被引:1,自引:0,他引:1
When an induction motor is energized from a pulse width modulated (PWM) inverter, through long connecting cables, its insulation system can be severely stressed. The high dv/dt voltage pulses at the output of the inverter cause traveling waves in the connecting cable between the inverter and the motor. When the traveling wave reaches the motor, a large impedance mismatch is present which leads to a reflected voltage wave that, when added to the incoming incident wave, can reach two times the inverter output voltage. The resulting overvoltage at the motor terminals stresses the insulation system and can lead to reduced motor life. Various output filter arrangements can be used to condition the inverter output voltage before it is applied to the cable. The advantage of adding output filtering is that the dielectric stress on the motor insulation and the inverter cable charging current can both be reduced. The major disadvantages of adding filtering is that they represent extra cost, they require extra mounting space, and they introduce extra losses in the system. The most commonly used types of inverter output filters are: simple output line inductors; output limit filter; sine wave output filter; and motor termination filter. These filters are discussed 相似文献
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Due to the widespread use of electronic power converters, low-voltage high-frequency cable models are being increasingly applied in industry, automobile or aeronautics applications among others. It is known that depending on switching frequency, cable configuration and length, transient overvoltage effects comprising a wide frequency range from dc up to several tens of MHz can appear. However, to accurately reproduce the wide-band frequency response, such models often require the use of ladder networks, thus being necessary to adjust the values of a relatively large number of R, L and C components, which is a complex task. This paper is focused to solve this problem, which is done by applying an iterative genetic algorithm (IGA) optimization approach. From a set of experimental short circuit and open circuit tests the high-frequency cable model of a given cable configuration is obtained, whose parameters are fitted by means of the proposed IGA-based method. Finally, the accuracy of the model obtained is validated experimentally by comparing the frequency-domain and time-domain responses through overvoltage predictions of different samples of the analyzed cable. 相似文献
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讨论了脉冲波在电缆中的传播过程以及电缆长度对线圈端的过电压和脉冲上升时间的影响.由于线圈电压的升高和电压分布极不均匀,在线圈中产生了局部放电,导致绝缘老化严重时会使绝缘击穿.为了有效提取局部放电信号,设计了一个高频脉冲电流传感器,构建了一套类似于电桥的专门用于SPWM变频电动机线圈局部放电测试电路,测试结果表明该局部放电测试系统可以在强干扰下(SPWM)检出局部放电信号. 相似文献
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This paper presents a new approach to thermal field sensitivities and ampacity computations of underground power cables using a proposed algorithm of perturbed finite-element analysis. The new approach involves the use of derived sensitivity coefficients associated with various cable parameters of interest, and use these coefficients to achieve optimal cable performance. The proposed model provides a quick methodology, based on the finite-element model, to assess the cable thermal performance subject to variations in the cable thermal circuit parameters. The developed algorithm was applied to various practical cable systems. The effect of multilayered thermal conductivities and boundary parameters variations on the actual cable system ampacity was investigated using the proposed methodology. A comparison was made of the obtained results with the conventional finite-element approach in order to show the applicability and usefulness of the developed methodology. Our objective was to assess the effects of operating parameter variations in a straightforward manner, without repeating the thermal field analysis for each parameter change. The thermal field of an underground power cable sample directly buried in the soil was measured in the laboratory using a developed full-size experimental setup. The investigations involve all parts of the thermal circuit parameters representing cable composition, surrounding soil and boundary phenomena. The experimental setup was used to validate the simulation model by comparing the simulation results with the real laboratory measurements. Such experimental verification confirmed the accuracy of the new introduced finite-element sensitivity methodology. 相似文献
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基于低压电弧故障测试中电缆碳化路径的加速形成机理和制备过程,对制备结果进行分类和分析,提出了一种电缆碳化路径的判别方法。该方法利用幅值检测、滑动平均滤波算法和小波分析方法分别区分电缆碳化路径处于欠碳化、碳化断路、碳化短路和碳化成功的4种制备结果。在Simulink中搭建具有电弧电流高频分量的电路仿真模型对所提方法进行分析和验证,并利用该方法进一步测试通过电弧故障测试系统制备完成的碳化电缆试品。最终,仿真和实验结果验证了所提方法的有效性和可行性,其可以有效提高电缆碳化路径制备结果的识别率和电弧故障测试的效率。 相似文献
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Cable lines impart attenuation and distortion to overvoltages coming from overhead lines. In particular the attenuation is an important factor for the insulation coordination of a cable line and consequently for its reliability. The evaluation of such attenuation needs the utilization of numerical programs and their utilization, although it becomes an obliged step, is not an easy task without a specific skill. In this paper a simplified method is proposed which is based on the results of a specific numerical program, in order to evaluate the overvoltage attenuation introduced from cable lines for both the conductor screen (insulation stress) and screen to ground (jacket stress) modes of propagation. Although such method introduces some approximation, it is a useful tool in order to have both a first and conservative evaluation of the overvoltage stressing the cable line insulation when the impinging overvoltage to the cable line is known. 相似文献
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Ryszard Batura Władysław Opydo 《Electrical Engineering (Archiv fur Elektrotechnik)》2005,87(4):181-189
The paper presents results of the studies on overvoltages generated while switching unloaded medium voltage (MV) power cable lines by a vacuum switch. The studies were carried out while switching real MV cable lines and their physical models. It has been found that overvoltages and overcurrents are generated during switching, and that under certain conditions they may reach significant values. These values depend on the source side circuit parameters, on kinematics vacuum switch parameters as well as on parameters of a switched cable line.Abbreviations AR Arc reignition - Vp Test voltages - tbpn Time without current between subsequent ARs - kszn Coefficient of ground overvoltage in the source side circuit after AR occurrence - kswn Coefficient of ground overvoltage in the source side circuit after switching off n AR - kczn Coefficient of overvoltage in the research circuit after AR occurrence - kcwn Coefficient of overvoltage in the research circuit after switching off current of n AR - kpcn Coefficient of overvoltage in the research circuit as an effect of overloading the capacity of the cable line or its physical model as a result of AR 相似文献
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随着330 kV超高压电缆在西北电网的应用,暴露出电缆过电压特性方面仍存在诸多亟待解决的问题。首先在电磁暂态仿真(EMTP)平台建立典型的超高压电缆过电压仿真模型,对架空线和电缆线路中过电压的幅值变化研究对比,结果表明电缆线路的过电压幅值整体低于架空线路。然后应用模域回路理论对过电压的传播特性与主导频率特性进行分析,结果表明相同条件下,电缆线路操作过电压主导频率相对较低,传播模电压衰减严重,从而影响了过电压的最大值。仿真结果证明超高压电缆在形成操作过电压的同时,会导致下一级出线电缆送电端电压的稳定性受到影响。 相似文献
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The switching of HV motor circuits in the megawatt range can cause large overvoltages on motor terminals. The amplitude of the resulting voltage spikes depends on breaker type and circuit characteristics. If the amplitude of switching overvoltages exceeds the basic insulation level of the motor, overvoltage protection circuitry should be installed to prevent a motor insulation failure. The decision whether overvoltage protection circuitry (surge pack) must be installed requires a prediction of the overvoltage level. This paper deals with switching overvoltages in motor circuits with a unit transformer between switchgear and motor. Overvoltages of motor circuits were simulated using specially developed simulation models. The results of three case studies revealed a large impact of cabling and transformer on motor overvoltages. In most of the cases, a unit transformer connected between switchgear and motor will provide an overvoltage protection to the motor. However, the transformer can also be a main cause of large overvoltages when connected to cables of specific length and capacitance. The paper provides some simple rules to recognize such critical configurations 相似文献
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This paper proposes an equivalent circuit analysis to suppress overvoltage and ringing in pulsewidth modulation inverter-fed ac motor drive systems where long motor leads are required. Conventional analysis of the phenomenon is based on voltage reflection theory for the terminal end of the long cable. The authors implemented another analytical method using equivalent lumped L and C of the cable, and a transfer function for the equivalent circuit with a simple damping circuit, C-R or L-R damping circuit constants are determined from the nonoscillatory condition of the transfer function. Digital simulations and experiments are used to verify that a simple damping circuit can satisfactorily suppress overvoltage and ringing in a drive system with a long cable, such as a 100-m cable 相似文献