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| Titel: |
TORQUES IN TURBINE-GENERATOR-EXCITER SHAFTS DUE TO DC CURRENTS IN ASYNCHRONOUS HVDC LINKS |
| Auteur: |
Hammons, T. J. Kacejko, P. A. Bremner, J. J. |
| Verschenen in: |
Electric power components & systems |
| Paginering: | Jaargang 25 (1997) nr. 1 pagina's 87-105 |
| Jaar: |
1997-01-01 |
| Inhoud: |
This paper makes an indepth analysis of excitation of shaft torsional vibrations in steam turbine-generator-exciter shafts by variable-frequency ripple currents superimposed on DC currents in asynchronous Links. First, frequencies at which sympathetic shaft torsional vibrations would be excited by modulation product harmonics in 50Hz/50Hz asynchronous Links as a function of deviation in system frequency is illustrated. Then steady-state torque excitation due to injected harmonic stator currents due to the DC ripple currents is analysed. Time constants for decay of shaft torsional vibrations based on electrical and steam viscous damping for generators operating at full-load and no-load for reduced shaft models which are used with the torque excitation to give amplitude of modal torque are also evaluated. Amplitude of shaft torque for a given torque excitation using reduced shaft models is illustated. The effect of generator load on shaft torque which results from resonant excitation for reduced shaft models is also illustrated. Typical shaft torques for generators connected close to HVDC Link inverters which results from resonant excitation by non-characteristic currents at full-load and no-load are also illustrated. Shaft torques in multi-machine networks are estimated by proportioning HVDC Link disturbance current to each machine at risk using system network data, generator data, fault analysis data and load flow data, considering the frequency dependence of the system parameters. 660MW andlOOOMWmachines are considered in the analyses that are made. |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
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