• Journal of Korean Society of Water and Wastewater
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• v.31 no.1
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• pp.1-6
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• 2017

Surge pressure is created by rapid change of flow rate due to operation of hydraulic component or accident of pipeline. Proper control of surge pressure in distribution system is important because it can damage pipeline and may have the potential to degrade water quality by pipe leakage due to surge pressure. Surge relief valve(SRV) is one of the most widely used devices and it is important to determine proper parameters for SRV's installation and operation. In this research, determining optimum parameters affecting performance of the SRV were investigated. We proposed the methodology for finding combination of parameters for best performance of the SRV. Therefore, the objective function for evaluate fitness of candidate parameters and surge pressure simulation software was developed to validate proposed parameters for SRV. The developed software was integrated into genetic algorithm(GA) to find best combination of parameters.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.578-579
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• 2011

This paper describes the analysis of induced lightning surge phenomena at underground power cables under construction when the lightning surge strikes at phase conductor of grounding wire of overhead line in service. Therefore, This paper proposes the optimal protection methods establishment against lightning surge induced from operating transmission.

• 전기의세계
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• v.20 no.6
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• pp.7-18
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• 1971

Secondary-side transfer phenomena of primary-side surge voltage in concentric-cylindrical transformers of a high turn-ratio still present a problem in transformer insulation design even in the case of a neutral solid-grounding type. The conventional methods of analyzing them so far are much complicated for practical applications. Therefore, this paper describes a new approach to the analysis of secondary-side transfer phenomena of surge in concentric-cylindrical transformers of high turn-ratio and solid-grounding type. This generalized approach is thought to be more simple with the use of minor network concepts than the conventional one by major network only. The result shows that the secondary-side transfer phenomena of surge voltage could not be neglected even in concentric-cylindrical transformer of high turn-ratio and solid-grounding type, and will be satisfactorily applicable to the design of neutral-solid-grounding type transformers.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.2
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• pp.47-53
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• 2015

The study concerning about the grid connection of the large-capacity energy storage system(ESS) is increasing. However, the transient study such as lightning or switching surge necessarily occurred at power system with ESS has been hardly performed. Therefore, this paper performs the analysis of lightning surge in distribution system with ESS using electromagnetic transient program(EMTP). The battery model in Matlab/Simulink is modeled by EMTP, which is the specialized software for power system transient study. Also, the bi-directional power electronics for interconnection of the battery and distribution system are modeled by EMTP. When the lightning is occurred at interconnection point of ESS, this paper simulates the existence of ESS and operation conditions of ESS and analyzes the surge in distribution system and ESS according to the various conditions.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.5
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• pp.670-678
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• 1997

A method to mitigate the thermal stratification phenomenon of pressurizer surge line is proposed by heating bottom outside of horizontal pipe. Unsteady two dimensional model has been used to numerically investigate an effect of heating the bottom of pipe. The dimensionless governing equations are solved by using the control volume formulation and SIMPLE algorithm. Temperature and streamline profiles of fluids and pipe walls with time are compared with the previous study result. The numerical result of this study shows that the outside heating can relaxate the thermal stratification flow of the pressurizer surge line. Maximum dimensionless temperature difference between hot and cold sections of the pipe inner wall which causes thermal stratification was reduced from 0.514 to 0.424 at dimensionless time 1, 632 and 1, 500 respectively.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.441-444
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• 2007

Surge tank generally are used near the downstream end of tunnels of penstocks to reduce change in pressure caused by waterhammer resulting from load changes on the turbines. In this paper, the surge tank with chamber is selected to analyze water surface oscillation. the governing equation are derived using the law of conservation of mass and momentum. the water surface oscillation in the surge tank are computed using governing equation. In the case of upsurging, water surface oscillation is damped gradually and in the case of downsurging, it is damped rapidly.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.204-205
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• 2006

This paper describes the protective ability of lightning arrestor in combined distribution system with power cable. To evaluate the protective ability, change of arrestor and grounding location are considered. On the other hand, arrestor developed by Cooper Power Systems for underground power cable system, is considered to evaluate surge protective ability as in underground system, when arrestor occurs failure has overhead line. The result shows that lightning arrestor in combined distribution system with power cable protect effectively when failure at arrestor in overhead line. On the other hand, arrestor developed by Cooper Power Systems for underground power cable system, is considered to evaluate surge protective ability in underground distribution system, when arrestor of overhead line has failure. The result shows that lightning arrestor installed in underground cable can effectively protected cables from surge when arrestor of overhead line has failure. And also even though grounding locations are decreased, it is revealed that protective ability is nearly similar.

• 한국정보통신설비학회:학술대회논문집
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• 2009.08a
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• pp.15-18
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• 2009

In recent years electric devices and telecommunication facilities were often damaged by surge generated lightning discharge. When the service was interrupted by failure of electrical devices due to surge the social loss is very enormous. Therefore in order to protect electrical systems against lightning, SPDs(Surge protective device) have been used But damaged SPDs often make some troubles like fire and interrupt of service. In this work, 3rd harmonic leakage current defection method was applied as the diagnosis of SPD degradation and the effectiveness of this method was verified by field survey.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.05a
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• pp.58-62
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• 2004

The PWM inverter drive my cause motor terminals voltage surge and oscillation(ringing), which impose severe electric stresses on inter-turn insulation of motor windings. This paper describes the technique used to simulate the problems associated with the use of PWM ASD's(Adjustable Speed Drive) to drive induction motor. The characteristic of switching surge was analyzed by EMTP(Electromagnetic transient program) model. The effects of switching surge by surge impedance, rise-time and cable lengths are also discussed.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.5
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• pp.761-769
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• 1994

VCB (Vacuum Circuit Breaker), with the strong arc extinction capability in switching the source of an induction motor, occurs the severe switching surge voltage which can cause the breakdown or the deterioration of motor insulation. Therefore, a method which reduces surge voltage across motor windings is necessary. So, it is analyzed that fast-rise-time surges resulting from VCB switching operations give rise to severe voltage stress on turn insulation. Additionally, the switching surge simulation algorithms using EMTP are developed, and C, R values of surge suppressor minimizing the steep-fronted stress in winding insulation surges are calculated.