• Title/Summary/Keyword: load-transfer method

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An Expert System for Optimal Load Transfer in Distribution Systems (배전계통에서의 최적 부하절체를 위한 전문가 시스템)

  • 문영현;최병윤;김세호
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.39 no.9
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    • pp.903-911
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    • 1990
  • When load areas on a feeder are deenergized due to faults and scheduled outage, operators need to identify neighboring feeders, try to restore customers and minimize out-of-service areas. These cases include knowledge of system states and various constraints such as voltage drop. This paper concerns the load transfer in fault restoration and scheduled outage. Also, the operating constraints such as line current capacity, relay trip current, transformer capacity, voltage drop and line loss are considered. This expert system can propose the optimal load transfer method by analyzing the system state and considering the constraints.

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A Study on the Impact Load Quantification of the Jaw Crusher (쇄석기의 충격하중 정량화에 대한 연구)

  • Hong, Sung Ju;Yang, Hae Jeong
    • Journal of Drive and Control
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    • v.16 no.2
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    • pp.1-7
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    • 2019
  • Jaw crusher is a device that breaks rock collected from mines or quarries to produce aggregates of the size desired by user. A representative method for measuring load is to measure them by attaching force sensors directly to the part where the load is generated. However, the direct method has many limitations such as high-impact loads generation in equipment or space constraints, sensor capacities and costs. Therefore, Transfer Path Analysis (TPA) was used to indirectly measure impact loads by attaching acceleration sensors. In this study, both direct and TPA methods were used to measure the impact load of Jaw crusher. This study finally quantifies the impact of the load generated by the Jaw crusher using direct method and TPA method, and comparing the impact load measured calculated the derive the error rate.

A Numerical Analysis of Load Transfer Behavior of Axially Loaded Piles (축하중 재하말뚝의 하중전이 거동에 대한 수치해석)

  • 오세붕;최용규
    • Geotechnical Engineering
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    • v.14 no.2
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    • pp.93-106
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    • 1998
  • The behavior of axially loaded pile was analyzed by two methodologies: one is the finite difference method using load transfer curves recommended by API(1993) , and the other is the numerical analysis using the FLAC program. From both analyses, load-displacement curves and load distributions along the depth were evaluated appropriately for the measured. The analysis using the FLAC could capture the nonlinearity of load-displacement curve even for unloading and reloading cases, since the unloaded stress paths of fill layer elements occurred on the failure envelop. Futhermore, the measured load transfer curves were compared with the API recommendations and with the calculations obtained front the results of the FLAC analysis for the interpretation of the transfer behavior between the soil and the pile under axial loadings. It was concluded that the atrial behavior of open ended piles at Pusan could be evaluated by both the finite difference analysis using API load transfer curves and the numerical analysis using FLAC.

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Vibration Analysis of the Helical Gear System by Spectral Transfer Matrix (스펙트럴 전달행렬에 의한 헬리컬 기어계의 진동해석)

  • Park, Chan-Il
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.05a
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    • pp.774-781
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    • 2006
  • This paper presents a study on the analytical prediction of vibration transmission from helical gears to the bearing. The proposed method is based on the application of the three dimensional helical gear behaviors and complete description of shaft by the spectral method. Helical gear system used in this paper consists of the driving element, helical gears, shafts, bearings, couplings and load element. In order to describe all translation and rotation motion of helical gears twelve degree of freedom equations of motion by the transmission error excitation are derived. Using these equations, transfer matrix for the helical gear is derived. For the detail behavior of shaft motion, the $12{\times}12$ transfer matrix for the shaft is derived. Transfer matrix for the bearing, coupling, driving element, and load is also derived. Application of the boundary conditions in the assembled transfer matrix produces the forces and displacements in each element of the helical gear system. The effect of the proposed method is shown by numerical example.

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Prediction of load transfer depth for cost-effective design of ground anchors using FBG sensors embedded tendon and numerical analysis

  • Do, Tan Manh;Kim, Young-Sang
    • Geomechanics and Engineering
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    • v.10 no.6
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    • pp.737-755
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    • 2016
  • The load transfer depth of a ground anchor is the minimum length required to transfer the initial prestressing to the grout column through the bonded part. A thorough understanding of the mechanism of load transfer as well as accurate prediction of the load transfer depth are essential for designing an anchorage that has an adequate factor of safety and satisfies implicit economic criteria. In the current research, experimental and numerical studies were conducted to investigate the load transfer mechanism of ground anchors based on a series of laboratory and field load tests. Optical FBG sensors embedded in the central king cable of a seven-wire strand were successfully employed to monitor the changes in tensile force and its distribution along the tendons. Moreover, results from laboratory and in-situ pullout tests were compared with those from equivalent case studies simulated using the finite difference method in the FLAC 3D program. All the results obtained from the two proposed methods were remarkably consistent with respect to the load increments. They were similar not only in trend but also in magnitude and showed more consistency at higher pullout loading stages, especially the final loading stage. Furthermore, the estimated load transfer depth demonstrated a pronounced dependency on the surrounding ground condition, being shorter in hard ground conditions and longer in weaker ones. Finally, considering the safety factor and cost-effective design, the required bonded length of a ground anchor was formulated in terms of the load transfer depth.

Evaluation of Transfer Capability based on Load Supplying Capability Calculation using Nonlinear Primal-Dual Interior Point Method (비선형 주.쌍대내점법을 이용한 부하공급능력의 산정에 기반한 전력수송능력의 평가)

  • Jeong, Min-Hwa;Lee, Byeong-Jun;Song, Gil-Yeong
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.49 no.4
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    • pp.161-167
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    • 2000
  • This paper presents a new methodology that can evaluate transfer capability of composite power systems from the adequacy point of view in power system planning stages. First of all, to evaluate practical load supplying capability, nonlinear optimization problems of maximum load supplying capability(MLSC) and economic load supplying capability(ELSC) are formulated and solved by nonlinear primal-dual interior point method. Here, physical constraints considered in the optimization problems are the limits of bus voltage, line overloading, and real & reactive power generation. Also, an evaluation method of transfer capability is presented based on margins calculated by the MLSC and ELSC. Especially, to evaluate transfer capability flexibly, simple indices such as expected MLSC, transfer capability margin, and power not supplied are respectively proposed by considering (N-1) line outage probability. Numerical results on IEEE RTS 24, IEEE 118, and IEEE 300 bus system show that the proposed algorithm is effective and useful for power system planning stages.

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Simplified Application of Load Transfer Method (하중전이법의 간편 적용)

  • Lee, Seung-Hyun;Lee, Su-Hyung
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.5
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    • pp.2403-2407
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    • 2012
  • Finite number of pile elements are considered in load transfer method. And section force and movement of each pile element are computed by considering compatibilities between pile displacement and the load transfer along a pile and between displacement and resistance at the tip of the pile. For the conventional load transfer method, large amount of computations due to iterations are needed. Formulation of finite difference equation from the differential equation which depicts pile behavior under axial loading was accomplished in order to simplify the computation for obtaining pile section forces and displacements. By comparing the results between the simplified computation method and the reported data, there was no difference between the two results.

FE Analysis of Rock-Socketed Drilled Shafts Using Load Transfer Method (유한요소해석을 통한 암반에 근입된 현장타설말뚝의 하중전이거동 분석)

  • Seol, Hoon-Il;Jeong, Sang-Seom;Kim, Young-Ho
    • Journal of the Korean Geotechnical Society
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    • v.24 no.12
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    • pp.33-40
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    • 2008
  • The load distribution and deformation of rock-socketed drilled shafts subjected to axial loads are evaluated by a load-transfer method. The emphasis is on quantifying the effect of coupled soil resistance in rock-socketed drilled shafts using the 2D elasto-plastic finite element analysis. Slippage and shear load transfer behavior at the pile-soil interface are investigated by using a user-subroutine interface model (FRlC). It is shown that the coupled soil resistance provides the influence of pile toe settlement as the shaft resistance is increased to an ultimate limit state. The results show that the coupling effect is closely related to the value of pile diameter over rock mass modulus (D/$E_{mass}$) and the ratio of total shaft resistance against total applied load ($R_s$/Q). Through comparisons with field case studies, the 2D numerical analysis reseanably presented load transfer of pile and coupling effect due to the transfer of shaft shear loading, and thus represents a significant improvement in the prediction of load deflections of drilled shafts.

A Load Identification Method for ICPT System Utilizing Harmonics

  • Xia, Chen-Yang;Zhu, Wen-Ting;Ma, Nian;Jia, Ren-Hai;Yu, Qiang
    • Journal of Electrical Engineering and Technology
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    • v.13 no.6
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    • pp.2178-2186
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    • 2018
  • Online identification of load parameters is the premise of establishing a stable and highly-efficient ICPT (Inductive Coupled Power Transfer) system. However, compared with pure resistive load, precise identification of composite load, such as resistor-inductance load and resistance-capacitance load, is more difficult. This paper proposes a method for detecting the composite load parameters of ICPT system utilizing harmonics. In this system, the fundamental and harmonic wave channel are connected to the high frequency inverter jointly. The load parameter values can be obtained by setting the load equation based on the induced voltage of secondary-side network, the fundamental wave current, as well as the third harmonic current effective value received by the secondary-side current via Fourier decomposition. This method can achieve precise identification of all kinds of load types without interfering the normal energy transmission and it can not only increase the output power, but also obtain higher efficiency compared with the fundamental wave channel alone. The experimental results with the full-bridge LCCL-S type voltage-fed ICPT system have shown that this method is accurate and reliable.

Estimation of Dynamic Load of the Utility in Building by TPA Method (TPA 기법을 이용한 건물 내 설비 동하중 산정)

  • Jeong, Min-Ki;Lee, Seong-Soo;Kim, Yong-Ku;Ahn, Sang-Kyung;Lee, Sang-Yeop
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.19 no.8
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    • pp.773-780
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    • 2009
  • The facility equipments generate dynamic force on building floor and the force can be measured with force transducer. However, this method depends on the measuring capacity or range of sensor, or mounts installation condition of equipments. Because of this restricting condition on force measuring system, this paper suggests a indirect method, the TPA(transfer path analysis) method, that produces a closely approximate dynamic force of equipments. This method calculates the dynamic force by using transfer response function. Firstly, the calculated dynamic force of impact load and continuous load was respectively compared with the sensor-measured value to examine the accuracy of TPA method. After that, the dynamic force and response induced by large facility equipments - a cooling tower, AHU and a large ventilator - were calculated by TPA method and the validity of these value were examined.