• Journal of Electrical Engineering and Technology
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• v.13 no.3
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• pp.1079-1088
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• 2018

A line overload emergency control strategy based on the source-load synergy coefficient is proposed in this paper. First, the definition of the source-load synergy coefficient is introduced. When line overload is detected, the source-load branch synergy coefficient and source-load distribution synergy coefficient are calculated according to the real-time operation mode of the system. Second, the generator tripping and load shedding control node set is determined according to the source-load branch synergy coefficient. And then, according to the line overload condition, the control quantity of each control node is determined using the Double Fitness Particle Swarm Optimization (DFPSO), with minimum system economic loss as the objective function. Thus load shedding for the overloaded line could be realized. On this basis, in order to guarantee continuous and reliable power supply, on the condition that no new line overload is caused, some of the untripped generators are selected according to the source-load distribution synergy coefficient to increase power output. Thus power supply could be restored to some of the shedded loads, and the economic loss caused by emergency control could be minimized. Simulation tests on the IEEE 10-machine 39-bus system verify the effectiveness and feasibility of the proposed strategy.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.6 no.4
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• pp.344-353
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• 1994

This study numerically analyzed the dynamic characteristics of the frequency response on the pneumatic transmission line with load impedances. The pressure transfer function is represented by the distributed parameter line model. To validate the mathematical approximations of Bessel function ratios, the results of frequency response in a blocked line were compared with those obtained by the Infinite-product, Brown's and Square-root approximations. Special emphasis was given to the frequency response characteristics on the pneumatic transmission line with load impedances. Computations were carried out for the wide range of parameters in terms of load capacitance ratio and load resistance ratio. The present results indicated that the theoretical model is capable of accurately predicting the frequency response characteristics for any configuration of a fluid transmission line.

• Proceedings of the KIEE Conference
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• 2006.11a
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• pp.282-284
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• 2006

In this paper, Static load models are developed using measurement based approach which is fundamental for on-line load modeling. The measurement data can be acquired from PMU(phasor measurement units). On the assumption that we have on-line measurement data, a scheme which is for Static load model capable to apply SCADA/EMS is developed. The Least Squares criterion is used for minimizing between measured and simulated data. In this manner, On-line Static load modeling algorithm can be developed. In this paper, a scheme that simple Static load model is applied for On-line load modeling is studied.

• Wind and Structures
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• v.31 no.6
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• pp.509-522
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• 2020

Wind load is the principal cause for a large number of the collapse of transmission lines around the world. The transmission line is traditionally designed for wind load according to a linear equivalent method, in which dynamic effects of wind are not appropriately included. Therefore, in the present study, incremental dynamic analysis is utilized to investigate the stability behavior of a 400 kV transmission line under wind load. In that case, the effects of vibration of cables and aerodynamic damping of cables were considered on the stability behavior of the transmission line. Superposition of the harmonic waves method was used to calculate the wind load. The corresponding wind speed to the beginning of the transmission line collapse was determined by incremental dynamic analysis. Also, the effect of the yawed wind was studied to determine the critical attack angle by the incremental dynamic method. The results show the collapse mechanisms of the transmission line and the maximum supportable wind speed, which is predicted 6m/s less than the design wind speed of the studied transmission line. Based on the numerical modeling results, a retrofitting method has been proposed to prevent failure of the tower members under design wind speed.

• Tribology and Lubricants
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• v.15 no.1
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• pp.24-28
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• 1999

This paper describes a new pivoting technique to improve bearing performance in pivoted pad thrust bearings. This new technique adjusts the pivot line in a line pivoted pad thrust bearing to be parallel to the trailing edge of a sector shaped pad. Bearing performance factors such as load carrying capacity, frictional torque and flow rate are numerically investigated for conventional point-pivoted and line-pivoted pads and for the new parallel-line pivoting technique. It is shown that the load carving capacity can be maximized with the new technique.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.5
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• pp.94-103
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• 1997

It is necesary that analog buffer circuit should drive an external load in the VLSI design such as switched capacitor efilter (SCF), D/A converter, A/d converter, telecommunicatin circuit, etc. The conventional CMOS buffer circuit have many probvlems according as CMOS technique. Firstly, Capacity of large load ar enot able to opeate well. The problem can be solve to use class AB stages. But large load are operated a difficult, because an element of existing CMOS has a quadratic functional relation with inptu and outut voltage versus output current. Secondly, whole circuit of dynamic rang edecrease, because a range of inpt and output voltages go down according as increasing of intergration rate drop supply voltage. In this paper suggests that new differential CMOS line driver make out of operating an external of large load. In telecommunication's chip case transmission line could be a load. It is necessary that a load operate line driver. The proposal circuit is planned to hav ea high generation power rnage of voltage with preservin linearity. And circuit of capability is inspected through simulation program (HSPICE).

• Korean Journal of Computational Design and Engineering
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• v.5 no.2
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• pp.155-167
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• 2000

To be presented is two-dimensional chip-load analysis for cutting-load smoothing which is needed in unmanned machining and high speed machining of sculptured surfaces. Cutter-engagement angle and effective cutting depth are defined as chip-loads which are the geometrical measures corresponding to cutting-load while machining. The extreme values of chip-loads are geometrically derived in the line-line and line-arc-line blocks of the two-dimensional NC-codes. AFA(automatic feedrate adjustment) strategy for cutting-load smoothing is presented based on the chip-load trajectories.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.6
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• pp.699-703
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• 1999

It is known that the LDC(Line-Drop Compensator) becomes to lose the function of proper voltage regulation for its load currents due to the real and reactive power generated by DGS(Dispersed Generation System), when DGS is introduced into the power distribution system of which the voltage is controlled by LDC. Therefore, in that case, it is very difficult to regulate the distribution line voltage properly by using LDC. One possible solution for this problem is the real-time voltage regulation method which is to optimally regulate the sending-end voltage in real-time by collecting the real-time load data of each load data of each load section between measuring points and by calculating the optimal seding-end voltage value from them. For this, we must know the real-time load data of each load section. In this paper, a modeling method of representing a load section on high voltage line with DGSs as an equivalent lumped load is proposed for gaining the real-time load data. In addition a method of locating the measuring points is proposed. Then, these proposed methods are evaluated through computer simulations.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.359-361
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• 2005

This paper presents the method of countermeasures before voltage collapse by load encroachment(impedance of load ability on R-X locus decrease toward zero point) and describes a study of impedance relay(zone-3) operation and voltage instability caused by over load of neighborhood line at contingency of heavy load line.

• Magazine of the Korea Concrete Institute
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• v.9 no.1
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• pp.183-194
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• 1997

Traditional displacmir~nt measurement included an extrancous and cvrntlc. portmn due to test setup and support crushing. The magnitudc of this erroneous deformation was found to be of the same order as the actual displacement, leading to inaccurate determinations of fracture parameters. To overcome this problem, the load-CMOD relationship is a more reliable parameter for determining the fracture characteristics because it is unaffected by the specimen setup and any support crushing. An important step towards the use of load-(:MOD concept as a key fracture parameter depends on relating the CMODto the traditional load-line deflection. This investigation found that there was an unique linear relationship between the CMOD and the load-line deflection. The exact numeric value of relationship between the CMOD and the deflection. that is, the slope ofthe line, is discovered to be a material property. The relationship finds a problem with the existing IZIL,EM recommendations for. measuring the fracture energy of concrete. A proposal to correct the problem is made.