February 27, 2025
Challenge
To increase availability and reduce maintenance efforts while maintaining the traction power supply service level at the lowest possible cost, DB wished to replace its existing rotating equipment in Bützow and Schwerin (Germany). For both locations, two static converter stations of 2x15 MW each to feed the 16.7 Hz 15 kV overhead catenaries were contracted as a turn-key project to a consortium with Power Conversion & Storage as the key participant. The systems are currently in commissioning phase.
System overview
Each station consists of two independent blocks operating fully redundantly. They connect to the 110 kV 3-phase grid through an oil-immersed transformer (ONAN cooling system) and feed the 15kV 16.7Hz overhead catenary system directly. For maximum efficiency, each block employs air-core reactors on the 15 kV rail electrification side (transformer-less design). Connection of a 50 Hz filter is not necessary thanks to the innovative converter concept and control algorithm. On the 15 kV rail side, only a small passive filter is required to meet the strict harmonics requirements of DB.
Providing the interface to the distribution grid
Cooling system
Each converter block has its own dedicated closed-loop cooling system with a mix of glycol and water The power electronics is directly cooled with this fluid, to achieve compact design and small space requirements. The heat is then dissipated in a water-air heat exchanger. A high-availability canned motor pump is installed to provide continuous circulation. All systems are monitored automatically. Additional secondary air-cooling is provided for the E-house in each block.
Control system
Internal converter control enables the following operation modes:
- Standard control in all 4 quadrants (according to the P/f, Q/U characteristic)
- Reactive Compensation/ STATCOM (supply of reactive power to the railway grid only)
- Parallel operation with other generation units integrated on the 15kV line
- Isolated mode (creating independent rail grid), with automatic synchronization to three-phase grid before reconnection
- Remote control by sinusoidal reference signal (Pilot Mode) or Autonomous Mode based on asynchronous telemetry reference signal can be provided as well.
- Black Start-Up of rail grid
Remote short circuits are handled reliably by the control algorithms. The control system allows for either local or remote operation via a user-friendly HDM interface and integration to SCADA according to IEC 61850 (IEC60870-105-4 can be provided as well).
Our SFC technology brings multiple advantages to the operator
Static frequency converter for railway application
