Transformers will not shift German power loop flows west – TSO

Author: Laura Raus


Power flow control devices that will soon become operational on Germany’s borders with Poland and the Czech Republic will not shift the problem of loop flows to the country’s western borders, grid operator 50Hertz has told ICIS.

However the phase-shifter transformers will lead to more network stabilisation measures inside Germany, the transmission system operator (TSO) said.

This means the phase-shifters should not reduce commercial power transmission capacity available on Germany’s western borders, and therefore will not have an adverse bearing on flow-based market coupling, which relies on adequate cross-border capacity to allow power prices to equalise where possible.

The model is a key part of the EU’s push for what will eventually be a single electricity market.

Transmission capacity available for market participants on Germany’s western borders is already restricted by loop flows, which have priority grid access, on days of high wind power in Germany, sometimes causing unexpected spot price outturns.

East of Germany, the problem is even more severe and phase-shifting transformers are being installed on its borders with Poland and the Czech Republic to reduce loop flows via these countries.

The loop flows that carry German wind power from the country’s northern areas to the southern part of the German-Austrian price zone threaten to destabilise the Polish and Czech grids and leave less room for commercial cross-border transactions.

The flows occur due to insufficient transmission capacity between German northern coastal areas, which have increasing wind power capacities, and the country’s southern part.

More wind cuts

“The phase-shifting transformers are expected to contain the problem of loop flows at the mentioned borders and not create new loop flows,” a spokeswoman for Germany’s 50Hertz said.

The transformers will increase load in Germany’s grid, she said. Because they reduce the possibility of transporting excess wind power away from the 50Hertz transmission area, the TSO has to take more costly grid stabilisation measures once they have become operational.

These measures will include conventional power generation adjustments called re-dispatch and renewable energy production cuts, which are already occurring and troubling some electricity traders (see EDEM 17 March 2016).

The intent of 50Hertz to compensate for the destabilising effect of the upcoming transformers on the German grid with more such measures would come as some relief to Belgian regulator CREG, which has spoken up about the problems German loop flows cause to its grid (see EDEM 3 February 2016).

Impact unclear

German-Polish phase-shifting transformers would become operational in the first quarter, Poland’s grid operator PSE said in January. On 21 March, 50Herz said that it will soon make a joint announcement with PSE about the commissioning process. It expects the first German-Czech transformer to become operational by the end of the year.

But it is still unclear how big an effect the transformers would have on loop flows. “There are too many parameters for a valid estimation,” the 50Hertz spokeswoman said. The effect will depend on ongoing German and Polish gird expansion, she said.

No real solution

In any case, there seems to be an agreement that the transformers are not a permanent solution to grid stability problems in the region.

Despite the upcoming transformers, Poland and the Czech Republic continue to demand the split of the German-Austrian wholesale electricity price zone as a way to reduce the loop flows.

Belgian regulator CREG, which has called regional TSOs to investigate the possibility of using phase-shifting transformers for reducing loop flows, has said that only “an adequate delineation” of price zones will lead to an efficient solution.

Restricting cross-border flows with the transformers is against the principles of the common European energy market, a spokesman for German municipal utility network Trianel said.

“On the other hand, it is not justified that Poland and the Czech Republic have to solve Germany’s problems; that they have to reinforce their grids to cope with the instability caused by German loop flows,” the spokesman said.

Accordingly, the company understands the need for phase-shifting transformers, even though it does not consider them a long-term solution. To reach a solution “Germany has to do its homework and expand its grid more quickly,” the spokesman said.


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