| Abstract |
The static system tie frequency converter E5 at Nuernberg/Germany with GTOs at the three-phase as well as the railway supply side feeds directly into the overhead traction line at an output voltage of 16.5 kV nominal and at the frequency of about 16.7 Hz. For signalling purposes (free track signal 100 Hz) the current component of 100 Hz (the 6th harmonic) produced by the system tie converter has to be extremely low. However, also from the line or load, 100 Hz current components are generated which the converter is not responsible for. The special design and measurement circuitry enables distinguishing between critical internal and given external 100 Hz current sources. At the single phase output, the current at the transformer as well as the line output current is measured. In between the current measurement spots there is a filter unit. Taking the 6th harmonic in amplitude and phase of the 2 measured currents into a computation the internally and the externally originating harmonic currents can be separated. Thus the converter control can minimise the internal 100 Hz component while not being influenced by the external harmonic current. |
