Noise reduction means for a dynamic stabilizer for synchronous machines having torsional oscillations and method
US4454428A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 22, 1981 |
| Grant date | Jun 12, 1984 |
| Priority date | — |
| Expiry date | Jul 22, 2001 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02T10/64
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
Abstract
Signal conditioning apparatus for reducing the noise frequencies of a speed sensing means signal being fed into a compensating means for compensating the output of a synchronous generator for the effect of torsional oscillation between masses in the main AC generator system. The signal conditioning apparatus includes two speed sensing transducers mounted 180.degree. apart on opposite sides of a tooth gear wheel and summing the two FM output signals from the transducers to eliminate odd harmonics of the synchronous frequency in FM noise due to eccentricity. The preferred embodiment of the invention reduces the remaining noise from the sensed speed signal by the use of a three-pole Butterworth low-pass filter in combination with a notch filter tuned to the turbine-generator synchronous frequency to thereby reduce the unwanted noise to a large degree while providing a minimal phase shift to the sensed speed signal. Another embodiment of the invention may be used to determine the machining accuracy of the toothed gear wheel.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.