• Journal of Electrical Engineering and Technology
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• 제7권3호
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• pp.297-303
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• 2012

This paper presents the simulation results for the analysis of a lightning surge, switching transients and very fast transients within a thermal plant. The modeling of gas insulated substations (GIS) makes use of electrical equivalent circuits that are composed of lumped elements and distributed parameter lines. The system model also includes some generators, transformers, and low voltage circuits such as 24V DC rectifiers and control circuits. This paper shows the simulation results, via EMTP (Electro-Magnetic Transients Program), for three overvoltage types, such as transient overvoltages, switching transients, very fast transients and a lightning surge.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.241-243
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• 2003

By development of power electronics technology, the increasing of inverter's switching frequency lead to the development of speed control technology of induction motor. But the surge voltage including harmonic component in output waveform can cause the motor to generate power losses, torque ripple, acoustic noise and oscillation. This paper is analyzed the characteristics for switching surge of adjustable speed drive and is presented the problem by inverter.

• KIEE International Transactions on Power Engineering
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• 제5A권1호
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• pp.22-30
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• 2005

The PWM inverter drive may cause an over voltage at the motor terminal, which imposes severe electric stresses on the inter-turn insulation of motor windings. Unlike low-voltage induction motors, high-voltage induction motors have a stator type of form-wound coil for insulation and are insulated to the slot and the coil. So, this paper presents a PWM 3-level inverter, H-Bridge cascaded 7-level inverter and High-voltage induction motor model. It then analyzes the voltage that generates at the input terminal of the high-voltage induction motor fed by each inverter. Also, in order to examine a factor that influences the switching surge voltage, this paper proposes the system equivalent model and performs the case studies using EMTP.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.1151-1153
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• 2003

In this paper, switching surge voltage distribution in stator windings of induction motor driven by IGBT PWM inverter is studied. To analyze the irregular voltage of stator winding, equivalent circuit model of inverter-cable-motor was proposed and high frequency parameter is computed by using finite element method (FEM). Electromagnetic transient program (EMTP) analysis of the whole system for induction motor and PWM inverter is proposed. In order to experiment, an induction motor, 380 [V], 50 [HP], with taps from one phase and a switching surge generator was built to consider the voltage distribution.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 추계학술대회 논문집 학회본부
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• pp.276-278
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• 1996

The breakdown Process in large gaps is greatly influenced by the gap geometry. Therefor full scale test are essential for the economical and reliable air insulation design. For switching surge design of 765 kV double circuit transmission line KEPRI is carrying the verifying tests using impulse voltage generator at Gochang test site. In this paper, the intermediate results of verifying tests are presented and the switching surge design criteria of 765 kV transmission tower flashover paths are discussed.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제2B권3호
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• pp.115-124
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• 2002

This paper presents an active auxiliary edge-resonant DC link snubber with a ringing surge damper and a three-phase voltage source type zero voltage soft-switching inverter with the resonat snubber treated here for the AC servo motor driver applications. The operation of the active auxiliary edge-resonant DC link snubber circuit with PWM voltage is described, together with the practical design method to select its circuit parameters. The three-phase voltage source type soft-switching inverter with a single edge-resonant DC link snubber treated here is evaluated and discussed for the small-scale permanent magnet (PM) type-AC servo motor driver from an experimental point of view. In addition to these, the AC motor stator current and its motor speed response for the proposed three-phase soft-switching inverter employing Intelligent Power Module(IPM) based on IGBTS are compared with those of the conventional three-phase hard-switching inverter using IPM. The practical effectiveness of the three-phase soft-switching inverter-fed permanent magnet type AC motor speed tracking servo driver is proven on the basis of the common mode current in a novel type three-phase soft-switching inverter-fed AC motor side and the conductive noise on the mains terminal interface voltage as compared with those of the conventional three-phase hard-switching inverter-fed permanent magnet type AC servo motor driver for the speed tracking applications.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 E
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• pp.1712-1714
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• 1997

This paper deals with the surge counter drived by lightning and switching currents. In order to install the effective surge protective devices, it is important to find the parameters of incident surges. In this paper, for the purpose of protecting the electronic circuits and counting the occuring frequency, the current driving type surge counter is designed and fabricated. The surge counter consists of surge protective divices, current detector, metal oxide varistor(MOV), rectifier, capacitor, and electromagnetic counter. This surge counter is able to count the occuring frequency of surges and to clamp lightning surge current. To evaluate the performance of the surge counter, impulse voltage and current were applied at the surge counter by the surge generator. As a result, applied surges were exactly counted and clamped.

• 조명전기설비학회논문지
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• 제23권9호
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• pp.98-107
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• 2009

기존의 하드 스위칭 고주파 PWM DC-DC 컨버터는 펄스 변조 캐리어 주파수의 고주파화를 수반하고, 전력용 반도체 스위칭 소자의 스위칭 손실의 증대나 스위칭 과도현상이 수반된 전압 서지나 전류 서지에 의한 EMI 등의 문제점들이 있다. 이러한 문제를 효과적으로 해결하기 위해 본 논문에서는 새로운 소용량 승압형 PWM 쵸퍼 회로의 동작원리를 서술하고, 시뮬레이션과 실험을 통하여 특성을 도출하였다.

• 전기학회논문지P
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• 제53권1호
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• pp.14-21
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• 2004

Most adjustable-speed drives (ASDs) designed to operate low voltage induction motors incorporate voltage-source inverters (VSIs), which create motor voltages at high switching frequencies. The motor leads used to connect an ASD to a motor can behave like transmission lines for voltage pulses, which can be reflected at the motor terminals. The resulting oscillatory transient, known as the long-lead effect, can stress and consequently degrade the stator insulation system of a motor. This paper describes the results of tests to 1) determine the correlation between peak motor voltage and the length of motor leads and 2) determine the correlation between peak motor voltage and the switching frequency of the ASD Insulation failures like this usually are caused by voltage surges. Voltage surges are often the result of switching power circuits, lightning strikes, capacitor discharges and solid-state power devices.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.558-560
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• 2004

Studies on the controlled switching method have been done to prevent the power system surges which cause the insulation deterioration and electro magnetic compatibility (EMC) problems during closing and opening of a circuit breaker. The controlled switching method controls the closing and tripping time in coincidence with the voltage or current to suppress switching surge. It is used to switch condenser bank, no load transformer, and shunt reactor. In this study, basic concept of the controlled switching is introduced, and also the test is performed to find parameters of the controlled switching in a 24kV vacuum circuit. And then, the control device hardware using TMS320C31 DSP has been designed and manufactured. It has been found that the application of IT technology to a circuit breaker is very effective to depress the switching surge.