• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.476-478
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• 2005

This paper describes a method for the detection of shorted-turn in the cylindrical synchronous generator rotor windings based on the discrete wavelet transform. Multi-resolution analysis(MRA) based on discrete wavelet transform provides a set of decomposed signals in independent frequency bands. In the proposed method, shorted-turn detection in rotor windings is based on the decomposition of the rotor currents, where wavelet coefficients of these signals have been extracted. Comparing these extracted coefficients is used for diagnosing the healthy machine from faulty machine. Experimental results show the effectiveness of the proposed method for shorted-turn detection in the cylindrical synchronous generator rotor windings.

• KEPCO Journal on Electric Power and Energy
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• 제6권4호
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• pp.467-472
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• 2020

The superconducting synchronous generator is one of the breakthrough elements for direct-drive wind turbines because it is light and small. Normally the superconducting one has copper armature windings in the stator and superconducting field windings on the rotor. The high resistance of the armature can make large copper losses, comparing with the conventional generators with a gear box. One of the solutions for the large copper losses could be a fully superconducting generator. But the high magnetic fields from the superconducting field windings on the rotor also make high perpendicular magnetic fields on the superconducting tapes in the armature windings. We have proposed a fully superconducting synchronous generator with dual field windings. It could immensely decrease the circumferential component of the magnetic field from the field windings at the armature windings. In this paper, we conceptually designed 3 types of superconducting synchronous generators. The first one is the fully superconducting one with conventional structure, which has superconducting armature windings in the stator and superconducting field windings on the rotor. The second one is the one with dual superconducting field windings and superconducting armature windings between them. The last one is the same as the third one except the structure of the armature. If the concentrated armature windings are superconducting ones with cryostats, then they cannot be installed within the span of 2 poles. So, we adopted 3 phases windings within 4 poles system. It makes more AC losses but can be manufactured really.

• 전기학회논문지
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• 제60권8호
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• pp.1555-1559
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• 2011

Turbine generator(13.8 kV, 137.5 MW) has high bearing vibration at rotation speed. Shorted turns in generator rotor windings have strong correlation with increased field current which is thus related to increase in bearing vibration. The recurrent surge oscillograph (RSO) test is performed on the rotor winding in turbine generator to detect shorted turns. The result of the RSO test indicates that shorted turns of rotor winding are generated in two locations. The RSO test was capable of identifying the presence, number, and location of shorted turns in generator rotor windings.

• 전력전자학회논문지
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• 제11권6호
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• pp.570-576
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• 2006

본 논문에서는 이산 웨이브렛 변환을 이용하여 원통형 동기발전기 회전자 권선의 층간단락을 진단하는 방법에 대해 기술하였다. 제안하는 방법에서는 회전자 권선의 층간단락 진단을 위해 다중해상도 분석을 이용하여 회전자 전류를 여러 스케일 영역으로 분할한 후, 각 영역에서의 신호의 에너지 값을 비교하였다. 실험적인 결과는 특정 회전자 슬롯 내에 25%, 42%, 67%, 83%, 99%단락이 발생한 경우와 정상적인 경우를 비교한 것으로, 그 편차는 층간단락 비율에 반비례하여 나타났다. 이러한 실험적인 결과는 제안한 이산 웨이브렛 변환을 이용한 방법이 원통형 동기발전기 회전자 권선의 충간단락 진단에 적절함을 보여준다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제55권11호
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• pp.572-576
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• 2006

As the increasing of capacity and technology of power facilities, rotating machines such as turbine generators and water turbines are getting higher at capacity but smaller in size. Thus the monitoring and diagnosis of generators for fault detection and protection has attracted intensive interest. Most of electrical faults of rotating machines appear in their windings. In case of an after-fault in high capacity rotating machines, the recovering cost is usually very expensive and additional time is necessary for returning in a normal situation. In this paper, the magnetic flux patterns in air-gap of a generator under various fault states as well as a normal state are simulated by a conventional FEM tool. These results are successfully applied to detection and diagnosis of the short-circuit condition in rotor windings of a high capacity generator.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.493-497
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• 1998

In this paper, a three phase voltage source inverter synchronous motor drive is introduced which is capable of producing an approximate to sine-wave currents in the stator windings. Compare to a conventional current forced synchronous machine drive, for the same machine loss, a gain in out put per unit overall volume of 125% at a 50Hz supply frequency has been achieved. In addition, the torque pulsation has been drastically reduced. These improvements are achieved by introducing new rotor windings which are capable of controlling the stator current waveforms an approximate to sine-wave. A computer program has been developed which can be used to predict the dynamic performance of this drive/system. The paper describes the design of rotor windings for cylindrical rotor motor but the theory is equally applicable to salient-pole designs.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제53권6호
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• pp.324-329
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• 2004

Six stator slot couplers(SSC) and a flux probe sensor installed on the stator winding slots of large turbine generator. Assessment of insulation condition has been based upon the measurements of partial discharge(PD) of stator windings and shorted-turn of rotor windings in operating large turbine generator. The maximum PD magnitude(Qm), normalized quantify number(NQN), PD pattern and shorted-turn were measured using on-line insulation condition monitoring system. The NQN and Qm of slot PD side in the phase A are indicated the highest value in six SSC sensors. Monitoring system results showed that discharge at conductor surface and internal discharge were detected at the surface of stator winding and in voids of the groundwall insulation. Insulation of stator and rotor windings in large turbine generator was judged to be in good condition.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.2019_2020
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• 2009

A recurrent surge oscillograph(RSO) test was performed at the Taean thermal power plant on #5 turbine generator. The test was conducted using a rotor reflectometer and digital oscilloscope. A DC voltage step is applied to each end of the rotor winding in turn. Each reflected wave, at the input end of the winding, is monitored and the two waveforms are superimposed automatically and monitored on a single channel oscilloscope. As the half windings in a rotor are identical, the two waveforms monitored at each end of the rotor will also be identical for a healthy winding. A winding with a fault will cause different voltages to be monitored at the two ends.

• 대한전기학회논문지
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• 제37권7호
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• pp.434-441
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• 1988

This paper proposes a new invention of the integrated generator converter system for the HVDC transmission. And it analyses the general formula for eddy currents in the rotor iron using the double Fourier series in order to trace the smallest eddy current losses of the system which connects a new designed synchronous generator windings or conventional synchronous generator windings with the v Graetz bridges.

• 전기학회논문지
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• 제64권1호
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• pp.72-77
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• 2015

When connecting 6 lead wires from stator windings to the terminals of 3 phase induction motors for Y or ${\triangle}$ connection, it is feared that the polarities of windings could be reversed each other if the wire tags are lost or erased, resulting in inadmissibly high current to motors in case of starting. To protect motors against such situations, some test procedures are necessary during wire connection which need to be easy ways to electricians without particular tools except a general multi-tester and with less time-consuming in the field. This study focuses on a test measure to satisfy these requirements which is able to provide them a convenient procedure for winding polarity discrimination considering the field condition. Here, the proposed measure utilizes the residual magnetism of the rotor and checks the indication of voltage or current at windings which are induced by the residual flux of rotor when rotating it by hands with 3 stator windings connected in the form of I connection. Principle characteristics and experiment results for this method are analyzed in the view of the effectiveness and applicability for the winding polarity discrimination.