Generator Arc Detection
Publication Date: 2016-Mar-23
The IP.com Prior Art Database
Mathias Schult: AUTHOR [+4]
A method is provided that allows to use the well-known fact that the rotor frequency is linearly coupled to the voltage induced in the stator for permanently excited synchronous machines to realize an arc detection function. This arc detection function could also detect such arcs or short circuits which could not be detected via a current measurement. Advantageous out of the determined relation of generator frequency and voltage the flux linkage could be calculated. Based on the regular calculated flux linkage the aging of the permanent magnets could be determined to initiate preventative maintenance
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The present disclosure describes a new solution of a generator arc detection.
BACKGROUND OF THE DISCLOSURE
Because of the significant landscape consumption for today's state of the art multi-megawatt wind turbines resp. wind parks, there is the trend to erect such wind turbines resp. wind parks offshore. The additional benefit of these offshore locations is much higher wind yield.
All structures erected in an offshore environment are much harder to maintain than those erected onshore. This is caused by the more difficult access itself as well as by the weather dependency of such maintenance activities.
For the reason above as well as the fact that such generators have the highest degree of efficiency, permanently excited synchronous machines in combination with a full power converter are used. For permanently excited synchronous machines it is a well-known fact that the rotor frequency is linearly coupled to the voltage induced in the stator.
The well-known correlation of frequency and voltage of such permanently excited synchronous machines could be used to introduce new protection resp. preventive maintenance functions.
A very important topic for such wind turbines is an effective overall arc protection. If an arc in such permanently excited synchronous machine is not detected reliable and fast enough the turbines gets out of control and could be destroyed completely. Because the wind as source of energy could not turn off, an out of control turbine would not stop rotating. Means that electrical energy is still produced which is feeding the arc. Together with the difficult accessibility in an altitude of more than 100 m and the fire loads such as hydraulic oils and fiberglass, enormous damages has to be expected.
Generator Arc Detection
Authors: M. Schult, Ch. Schlegel, D. Flum, J. Eckerle
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Different methods to detect arc in general are well-known. The most common detection methods are:
• Light based detection
• Pressure detection
• Heat detection
• Sound detection
• Current limitation with fuses
Also several electronic data processing based arc detection methods are introduced during the last years. The most common electronic data processing based arc detections are:
• Impedance analyze
• Frequency response analyze
• Supervisor of harmonic content of measured voltage
• Amplitude independent comparison of measured and stored voltage waveform
The usage of electronic data processing of the measured generator voltage resp. current to detect arc is described in several publications. One idea is to use current and voltage waveform to detect an arc. A further idea is to detect an arc based on the integration of the measured voltage.An additional idea is to detect an arc based comparison of measured voltage with given voltage waveforms.
The disclosure provides a method that allows to use the well-known fact that the rotor freque...