January 8, 2021
4 min read

Phase-shifting transformers will prepare the German power grid for the energy transition

TenneT TSO GmbH relies on phase-shifting transformers from Siemens Energy, for a stable and reliable power supply for all.

Phase-shifting transformers for fluctuating load flows

The energy transition in Germany is picking up speed. The demand on building up sources of renewable energy and the expansion of electro mobility with the necessary charging stations is increasing constantly. Worldwide power grids are facing fluctuating energy supply and load profiles, today and even more in the future. Transmission system operators (TSO) like TenneT TSO GmbH (hereafter referred to as TenneT) want to be well prepared for the requirements and increasing challenges of our power grids.

In total 36 orders of phase-shifting transformers are expected to be awarded by the four German TSOs, in the following years.

In line with the German NOVA-principal, grid optimization before expansion and reinforcement, TenneT invests a lot into possibilities to increase the transport capacity of the existing grid. Therefore, we are looking into innovative system operation methodologies as well as equipment which can help us to reduce congestions. Siemens Energy’s phase-shifting transformers comply to the ambitious requirements of our high-voltage grid to secure the power of supply in accordance with the reliability and resilience of out grid.

Dr. Florian Martin

Head of Asset Technology, TenneT TSO GmbH

Efficient power flow control – with highest performance and lowest losses

TenneT could be convinced by the efficiency of Siemens Energy‘s phase-shifting transformers and is going to install the first 4 units in the southern substation of Wuergau and 4 more in Krempermarsch, in the northern part of Germany. For the stability of two 4000 A lines, customized phase-shifting transformers suitable for rail transportation, have been ordered. They have a compact design for the high performance level of 1420 MVA each, at a rated voltage of 410 kV and a highest possible phase angle of ±24°. Furthermore, phase-shifting transformers from Siemens Energy are very quiet and have low losses, at the lowest possible impedance. The combination of high rating, high phase angle and low impedance with limited product size was the biggest technical challenge for the Siemens Energy engineers.

Additionally, Siemens Energy was awarded a framework contract for the delivery of further phase-shifting transformers. Design, assembly, transportation, installation, and commissioning of the 8 phase-shifting transformers already ordered will be executed by the two factories in Weiz, Austria and Nuremberg, Germany. Both factories are well connected to the German railway network. Furthermore, the parallel production, by the two factories, will ensure the tight delivery schedule can be met. 

TenneT is the German leader when it comes to grid access of wind and solar parks. That makes it even more important to have a strong and reliable partner like Siemens Energy. We are committed to support TenneT with resilient, efficient, and environmentally friendly transmission products.

Eduardo Terzi

Head of the Business Unit Non-Switching Products and Systems of Siemens Energy Transmission, emphasizing the good choice of the customer

Economically best solution for a reliable energy supply

Phase-shifting transformers provide active power flow control to pave the way for the energy transition. With phase shifting transformers it is possible to balance the fluctuating power supply of volatile energy sources, like wind and solar. By changing the effective phase displacement between the input voltage and the output voltage of a transmission line as needed, phase-shifting transformers enforce, block and even revert power flow as well as reduce or eliminate loop flows.

Another increasing stress factor for transmission grids is the growing amount of exchanging power between single European countries. This can be controlled with phase-shifting transformers, by reducing or increasing transferred power between transmission lines.

Intelligent power flow management with phase-shifting transformers does not only increase power reliability but can also reduce dispatching costs of utilities – an economical solution for the benefit of utilities and society.

Siemens Energy delivers phase-shifting transformers of highest quality. All customers can rely on an overall concept: An established factory network with great logistical access, engineering products with highest performance levels, lowest noise emission, and highest possible phase shifting. Furthermore, our phase-shifting transformers can be applied with the very environmentally friendly insulation medium Ester.

All requirements of our customer TenneT will be fulfilled and partly exceeded. The first phase-shifting transformer for the substation in Wuergau has already been successfully tested in Weiz and will be delivered soon.

Eduardo Terzi

Head of the Business Unit Non-Switching Products and Systems of Siemens Energy Transmission

Siemens Energy Transmission

Transmission products play a vital role in the energy value chain. Siemens Energy Transmission offers all key elements including power transformers, gas-insulated and / or air-insulated switchgear and components, individually or bundled, with related engineering and service. Our global factory network and innovations help provide the highest level of quality and reliability to support our customers’ operational and environmental objectives.