Stabilize AC grids in milliseconds and get the most out of existing infrastructure


Increasingly decentralized energy systems and the associated uncontrolled power flows pose new challenges for the existing, mature grid infrastructure. Thermal overloads in the lines and a growing number of cases in which frequency and voltage come critically close to acceptable range limits, or even exceed them, threaten grid stability and the transmission infrastructure, and often require costly redispatch intervention to deal with current and voltage factors. Compared to traditional power flow controllers, UPFC PLUS® controls power flow in just milliseconds. The Unified Power Flow Controller UPFC PLUS® thus stabilizes the AC grid even when critical situations develop suddenly (Grid Code N-1). That means UPFC PLUS® lets you get the most from your existing grid capacity while maintaining maximum protection, reducing the risk of power failures, and minimizing redispatch costs.      

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Overview of technical benefits

Dynamics ms

With a response time of just milliseconds, UPFC PLUS® is significantly faster than a phase shifter so you can intervene much faster in critical situations.

Functionality +2

Unlike a phase shifter, UPFC PLUS® is not only able to control power flow but also enables dynamic reactive power compensation and voltage control and it can also compensate for disruptive factors like vibration.

Flexibility kV

System voltages of 220, 400, and 500 kV can be accommodated, and for the 110 kV voltage level, a comparable solution can be implemented with MVDC PLUS®. Semiconductor technology makes UPFC PLUS® freely programmable, so it’s easy to adapt to local requirements and circumstances.

Performance %

UPFC can control power distribution over a wide range, depending on the installed capacity and the nature of the transmission cable.

Efficiency €

Compared to other solutions, this system comes with low investment costs and space requirements.

Protection when line outages occur (N-1)

Even when sudden faults occur, UPFC PLUS® stabilizes the AC grid, offering highly efficient support for Grid Code N-1 situations affecting the existing grid infrastructure. Its Modular Multilevel Converter (MMC) technology enables a sufficiently rapid response time of just a few milliseconds in order to prevent power failures.


Affordable investment costs

Make better use of existing infrastructure

Alternative to expanding infrastructure

Future-proof (Master-Control, AI)

Fewer redispatches

Economic benefit

Scope of application of UPFC PLUS®

The UPFC PLUS® solution is based on the Modular Multilevel Converter (MMC) architecture from voltage source converters (VSC) in semiconductor technology, as developed by Siemens Energy and already proven in SVC PLUS® and HVDC PLUS®.

A Unified Power Flow Controller (UPFC) is used to control and influence the electrical energy transmitted through individual lines in intermeshed, supra-regional power networks. UPFC can therefore be used to meet specific, contractually agreed power throughputs in intermeshed grids.

The scope of application is aimed at high-voltage electricity transmission networks using three-phase AC at voltage ranges of 220 kV to 500kV, and its control functions make use of power electronics similar to the systems used in HVDC transmission. Unlike HVDC, the power electronics are not used directly for power transmission but to influence and modulate the AC current being transmitted. In power electronics, UPFC is an example of a flexible AC transmission system (FACTS).

The level site building contributes to environmental protection and ease of maintenance.

Like a traffic guidance system

Like smart traffic guidance systems, UPFC PLUS® controls the power flow via available line capacity in the AC grid.

Reducing throughput costs

Short-term, high-volume infeed of renewables often leads to costs for energy throughput via third-party grids. UPFC PLUS® directs the electricity through your own high-voltage grid.

Avoiding line overload

Unexpectedly high infeed levels from PV systems and wind turbines can cause overloads on individual lines. UPFC PLUS® directs the electricity effectively using available line capacity.

Additional information

Brochure UPFC PLUS®
PDF (782 KB)

Stay up to date with the latest news

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