• Title, Summary, Keyword: harmonic loading

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The Evaluation of Medium Voltage Motor's Current and Voltage Harmonics during Loading

  • Alboyaci, Bora;Yorukeren, Nuran
    • Journal of Electrical Engineering and Technology
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    • v.2 no.1
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    • pp.35-41
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    • 2007
  • This paper presents the results of investigating harmonic levels on medium voltage motors at loading conditions in air separation plant. The essential results of the measurements of the medium voltage motor harmonics are summarized in the values for the total harmonic distortion (THD). Motors loading case is used to assess the current and voltage harmonic distortions. Proper system analysis is important when adding a new motor starting and controlling the equipment. With the result of the paper it is possible to suggest the most appropriate starting and control method. Two medium voltage motors of air separation unit measurement results and simulations are summarized. Both current and voltage harmonic distortions are fitted by using a linear and exponential regression model. The prediction of THD values can be used for this kind of process for future planning by utilities.

Static and Dynamic Instability Characteristics of Thin Plate like Beam with Internal Flaw Subjected to In-plane Harmonic Load

  • R, Rahul.;Datta, P.K.
    • International Journal of Aeronautical and Space Sciences
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    • v.14 no.1
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    • pp.19-29
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    • 2013
  • This paper deals with the study of buckling, vibration, and parametric instability characteristics in a damaged cross-ply and angle-ply laminated plate like beam under in-plane harmonic loading, using the finite element approach. Damage is modelled using an anisotropic damage formulation, based on the concept of reduction in stiffness. The effect of damage on free vibration and buckling characteristics of a thin plate like beam has been studied. It has been observed that damage shows a strong orthogonality and in general deteriorates the static and dynamic characteristics. For the harmonic type of loading, analysis was carried out on a thin plate like beam by solving the governing differential equation which is of Mathieu-Hill type, using the method of multiple scales (MMS). The effects of damage and its location on dynamic stability characteristics have been presented. The results indicate that, compared to the undamaged plate like beam, heavily damaged beams show steeper deviations in simple and combination resonance characteristics.

Performance Improvement of an Active Neutral Harmonic Suppressor System Under Unbalanced Load Conditions

  • Choi, Se-Wan;Jang, Min-Soo
    • Journal of Power Electronics
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    • v.3 no.3
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    • pp.151-158
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    • 2003
  • Three-phase four-wire electrical distribution systems are widely employed in manufacturing plants, commercial and residential buildings Due to the nonlinear loads connected to the distribution system, the neutral conductor carries excessive harmonic currents even under balanced loading since the triplen harmonics in phase currents do not cancel each other This may result in wiring failure of the neutral conductor and overloading of the distribution transformer In response to these concerns, a cost-effective neutral current harmonic suppressor system has been proposed. This paper proposes an improved control method for the harmonic suppressor system under unbalanced load conditions The proposed control method compensates for only the harmonic components in the neutral conductor, and the zero-sequence fundamental component due to unbalanced loading is prevented from flowing through the harmonic suppressor system This remedies overloading and power loss of the system The experimental results on a prototype validate the proposed control approach.

Performance Improvement of an Active Neutral Harmonic Suppressor System Under Unbalanced Load Conditions

  • Choi, Se-Wan;Jang, Min-Soo
    • Proceedings of the KIPE Conference
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    • pp.822-828
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    • 2001
  • Three-phase four-wire electrical distribution systems are widely employed in manufacturing plants, commercial and residential buildings. Due to the nonlinear loads connected to the distribution system, the neutral conductor carries excessive harmonic currents even under balanced loading since the triplen harmonics in phase currents do not cancel each other. This may result in wiring failure of the neutral conductor and overloading of the distribution transformer. In response to these concerns, a cost-effective neutral current harmonic suppressor system has been proposed [6]. This paper proposes an improved control method for the harmonic suppressor system under unbalanced load conditions. The proposed control method compensates for only the harmonic components in the neutral conductor, and the zero-sequence fundamental component due to unbalanced loading is prevented from flowing through the harmonic suppressor system. This remedies overloading and power loss of the system. The experimental results on a prototype validate the proposed control approach.

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Optimum Air-Gap Flux Distribution with Third Harmonic Rotor Flux Orientation Adjustment for Five-Phase Induction Motor

  • Kang, Min;Yu, Wenjuan;Wang, Zhengyu;Kong, Wubin;Xiao, Ye
    • Journal of Electrical Engineering and Technology
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    • v.13 no.1
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    • pp.315-325
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    • 2018
  • This paper investigates optimum air-gap flux distribution with third harmonic rotor flux orientation adjustment for five-phase induction motor. The technique of objective is to generate a nearly rectangular air-gap flux, and it improves iron utilization under variation loading conditions. The proportional relations between third harmonic and fundamental plane currents is usually adopted in the conventional method. However, misalignment between fundamental and third harmonic component occurs with variation loading. The iron of stator teeth is saturated due to this misalignment. This problem is solved by third harmonic rotor flux orientation adjustment simultaneously, and direction and amplitude are changed with mechanical load variation. The proposed method ensures that the air-gap flux density is near rectangular for a maximum value from no load to rated load. It is confirmed that the proposed method guarantees complete both planes decoupling with third harmonic flux orientation adjustment. The effectiveness of the proposed technique is validated experimentally.

Analysis of Spectral Fatigue Damage of Linear Elastic Systems with Different High Cyclic Loading Cases using Energy Isocline (에너지 등고선을 이용한 고주파 가진 조건들에 따른 선형 시스템의 피로 손상도 분석)

  • Shin, Sung-Young;Kim, Chan-Jung
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.24 no.11
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    • pp.840-845
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    • 2014
  • Vibration profiles consist of two kinds of pattern, random and harmonic, at general engineering problems and the detailed vibration test mode of a target system is decided by the spectral condition that is exposed under operation. In moving mobility, random responses come generally from road source; whereas the harmonic responses are triggered from rotating machinery parts, such as combustion engine or drive shaft. Different spectral input may accumulate different damage in frequency domain since the accumulated fatigue damage dependent on the pattern of input spectrum in high cyclic loading condition. To evaluate the sensitivity of spectral damage according to different loading conditions, a linear elastic system is introduced to conduct a uniaxial vibration testing. Measured data, acceleration and strain, is analyzed using energy isocline function and then, the calculated fatigue damage is compared by different loading cases, random and harmonic.

Nonlinear analysis of stepped beam with immovable ends for free and forced vibration (양단고정된 변단면보의 자유 및 강제진동의 비선형해석)

  • 심재수;함원식
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.12-17
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    • 1990
  • Stepped bean with immovable ends for large amplitude of vibration including effects of longitudinal displacement, shear deformation and rotary inertia is investigated for free and forced vibration using finite element method. Modified harmonic force matrix is introduced for analysis of vibration with finite amplitude of the stepped beam under uniform hamonic loading and beam with nonuniform harmonic loading. Numerical examples of stepped beam with various support conditions are analysed for deflections and natural frequencies. Results show that the proposed method is valid and efficient.

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Nonlinear Analysis of Stepped Beam Immovable Ends for Free and Forced Vibrations (양단지지된 변단면보의 자유 및 강제진동의 비선형해석)

  • 심재수;함원식
    • Computational Structural Engineering
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    • v.3 no.2
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    • pp.67-75
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    • 1990
  • A stepped beam with immovable ends under the free and forced vibrations with large amplitude is investigated by using the finite element method to show the effects of longitudinal displacement, shear deformation and rotary inertia. A modified harmonic force matrix is introduced for analysis of finite amplitude vibration of the stepped beam under uniform harmonic loading and a beam under nonuniform harmonic loading. Numerical examples are analysed for deflections and natural frequencies of stepped beam under various support conditions. Results show that the proposed method is valid and efficient.

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Harmonic Response Estimation Method on the Lévy Plate with Two Opposite Edges Having Free Boundary Conditions (마주보는 양단이 자유 경계조건을 갖는 Lévy 판의 조화 응답 해석)

  • Park, Nam-Gyu;Suh, Jung-Min;Jeon, Kyeong-Lak
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.23 no.11
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    • pp.943-950
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    • 2013
  • This paper discusses a harmonic response estimation method on the L$\acute{e}$vy plate with two opposite edges simply supported and the other two edges having free boundary conditions. Since the equation of motion of the plate is not self-adjoint, the modes are not orthogonal to each other on the domain. Noting that the L$\acute{e}$vy plate can be expressed using one term sinusoidal function that is orthogonal to other sinusoidal functions, this paper suggested the calculation method that is equivalent to finding a least square error minimization solution of the finite number of algebraic equations. Example problems subjected to a distributed area loading and a distributed line loading are defined and their solutions are provided. The solutions are compared to those of the commercial code, ANSYS. According to the verification results, it is expected that the suggested method will be useful to predict the forced response on the L$\acute{e}$vy plate with the distributed area or line loading conditions.

Analysis of Harmonic Currents Propagation on the Self-Excited Induction Generator with Nonlinear Loads

  • Nazir, Refdinal
    • Journal of Electrical Engineering and Technology
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    • v.9 no.6
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    • pp.1935-1943
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    • 2014
  • In recent years, the induction machines are increasingly being used as self-excited induction generators (SEIG). This generator is especially widely employed for small-scale power plants driven by renewable energy sources. The application of power electronic components in the induction generator control (IGC) and the loading of SEIG using nonlinear loads will generate harmonic currents. This paper analyzes the propogation of harmonic currents on the SEIG with nonlinear loads. Transfer function method in the frequency domain is used to calculate the gain and phase angle of each harmonic current component which are generated by a nonlinear loads. Through the superposition approach, this method has also been used to analyze the propagation of harmonic currents from nonlinear load to the stator windings. The simulation for the propagation of harmonic currents for a 4 pole, 1.5 kW, 50Hz, 3.5A, Y-connected, rotor-cage SEIG with energy-saving lamps, have provided results almost the same with the experiment. It can prove that the validity of the proposed models and methods. The study results showed that the propagation of harmonic currents on the stator windings rejects high order harmonics and attenuates low order harmonics, consequently THDI diminish significantly on the stator windings.