Flexible frequency ties with the national grid are a suitable method of ensuring a reliable supply of 16.7 Hz resp. 25 Hz single phase current for railway networks.
Static frequency converters are today the equipment of choice for the links that exchange energy between railway power supplies and national electricity grids. Further development of the semiconductor elements, which are connected in series, plus a new type of Gate Unit, made the high rating and the good economy of the link possible.
So far several standard static converters rated 15 MW / 19 MVA for the energy exchange between the 50 Hz three phase grid (3 AC) and the 16.7 Hz (1AC) traction power network have been sold. Other installations between 8 and 100 MW per converter have also been delivered. The advantages of the new installations over rotating conversion include high availability and a considerably better efficiency over the full power range. Special features are compact modular design and short installation time, which enables a large variety of applications.
The main components of such an installation (e.g. for 50 Hz Grid / 16.7 Hz railway Grid) are:
- Input transformer 3 AC 50 Hz
- Output summation transformer 1 AC 16.7 Hz
- Container including converter and control unit
- Cooling unit
- 33 Hz DC link Filter
- 16.7 Hz Filter