• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1452-1454
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• 2002

Large turbine generator(rated 22kV) has failed in the stator winding area during normal operation. The capacitance and tan${\delta}$ were measured by Schering bridge in the zone 1, 2 and zone 3-6 stator windings. The capacitance and tan${\delta}$ in the zone 1, 2 of stator winding were higher than those of zone 3-6 in the stator winding. Experiments on microstructure property were conducted in the zone 1, 2 and zone 3-6 insulations, which were drawn out from stator windings of the large turbine generator. Microstructure analysis was characterized using scanning electron microscope(SEM). SEM results indicated that several isolated delaminations occurred at the interface of mica/epoxy insulations. Both thermal and mechanical aging cause the delamination.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.04a
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• pp.116-120
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• 1997

The modal testing results of a generator stator frame for a 500MW fossil power plant are presented, which will be used to tune and to validate the finite element model of the stator frame.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2212-2214
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• 1999

In this paper, a novel Generator On-line Diagnosis System (GODS) is proposed. This system monitors the insulation condition of the stator winding by on-line measurements of partial discharge (PD). Sensor, such as SSC (Stator Slot Coupler) and RFCT (Radio Frequency Current Transformer) are used for PD measurement. PD signals are continuously measured and digitized with a high speed A/D converter to build the database of the generator's insulation condition. Also this system can communicate with the central monitoring system via RS-485. This helps more efficient operation and maintenance of the generator.

• Journal of Power Electronics
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• v.13 no.5
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• pp.798-805
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• 2013

This paper presents the control and implementation of the dual-stator-winding induction generator for variable frequency AC (VFAC) generating system. This generator has two sets of stator windings embedded into the stator slots. The power winding produces the VFAC power to feed the loads, and the control winding is connected to the static excitation controller to control the generator for output voltage regulation with speed and load variations. On the basis of the idea of power balance, an instantaneous slip frequency control (ISFC) strategy using the information of both the output voltage and the output power is used in this system. A series of experiments is carried out on a 15 kW prototype for verification. Results show that the system has good static and dynamic performance in a wide speed range, which demonstrates that the ISFC strategy is suitable for this system.

• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.1
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• pp.61-66
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• 2014

The evaporative cooling technology used in Wind generator stator has unique advantages. Combined with the structure of motor stator and operating conditions, this report based on the research project for the evaporative cooling sleeve of the 3.6MW wind generator, introduces the material requirements and structural characteristics of the sleeve, simulates on the stress, displacement and stability by finite analysis method, and tests the products experimentally. The research results show that the epoxy resin-glass materials have a higher strength and better insulation properties, but the evaporative cooling of the wind generator stator sleeve, because of its thin-walled, and the external pressure, so it's the less rigid. Should make full use of the motor stator core structure, increase its stiffness and improve the stability of the epoxy resin-glass sleeve, which for thin-walled the epoxy resinglass sleeve on the successful application of wind turbines has played an important role.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.11
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• pp.735-741
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• 1999

The monitoring and assessment on the insulation condition of generator stator windings have been an important task of utility companies. The interest for the assessment of insulation condition has been increasing due to the need to keep old generating equipment reliable in order to extend the equipment life and to increase the generating capacity. Even though many developments and research activities for the condition assessment of generator insulation have been performed for decades, the assessment criterion in order to consistently predict the actual insulation condition is still in question. In this paper, the correlation between the parameters and the insulation condition is analyzed through the various non-destructive diagnostic tests in order to establish the assessment criterion on insulation deterioration of generator stator windings. By analyzing the correlation, PDI(Partial Discharge Index) as a novel parameter for the assessment criterion on insulation diagnosis of stator winding is proposed and verified.

• Journal of KSNVE
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• v.9 no.4
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• pp.747-753
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• 1999

This paper presents results of vibration analysis of a generator-stator core for 500 MW fossil power plant. A finite element analysis using a commercial S/W is performed to estimate alternating electromagnetic forces, mainly of 120 Hz in 60 Hz machines, acting on the core, and then to calculate forced response of the core. Results are compared with design requirements.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.11
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• pp.73-82
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• 2011

The solid insulation system of stator windings in high voltage rotational machines is usually aging in accordance with long time operation. The partial discharge test have been known to check whether insulation deterioration exist or not, and the PD test can effectively diagnose a solid insulation condition regardless of during operation(on-line) or not(off-line). The on-line PD measurement have proven to be a successful technique in monitoring stator insulation condition nowadays. This paper describes the characteristics of comparing the on-line PD measurement data using PDMS-HG(Partial Discharge Monitoring System for Hydro-electric Generator) installed in field with the off-line diagnosis measurement data(insulation resistance, winding resistance, PI, ${\Delta}tan{\delta}$ and PD) on hydro generator(13[kV]) stator windings. These results make good use of managing rotational machines through evaluating the solid insulation condition of stator windings.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.11 s.188
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• pp.50-57
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• 2006

The water leak in water-cooled generator stator windings can generate the serious accidents such as insulation breakdown and it brings a generator to the unexpected sudden outage. Accordingly, it is important to diagnose the water absorption of them for the effective operation of power plant. Especially, the capacitance value which is measured for diagnosis is very small so the special diagnosis methods like stochastic theory are needed. KEPRI developed the water absorption test equipment and diagnosis technology for them. The developed diagnosis technology is applied to the real system and the results of water absorption test for stator windings are agreed to them of water leak test.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.10
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• pp.528-534
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• 2003

A grid connection algorithm is proposed for the doubly-fed induction generator (DFIG) which is widely adopted in high power variable speed wind turbine. Before the stator of DFIG is connected to grid, rotor-side converter is used to control the induced stator voltage. As a result, the stator transient current is limited below the rate value during the connection by the proposed synchronization of the stator voltage to the grid voltage. A wind power generation simulator using DC motor and wound-rotor induction generator is built and the dynamic characteristics of proposed algorithm is verified experimentally.