Germany faces struggle to balance electricity system as loop flows curbed
A lack of grid investments has pushed Germany to use neighbouring grids for balancing, the German Energy Agency has warned. So-called phase shifters targeting loop flows on the Polish border could make the German grid more unstable and make new investments urgent, according to the agency.
"When excess wind and solar power cannot be discharged abroad, then the German power grid will become unstable," Stephan Kohler, head of the German Energy Agency, said in German daily der Spiegel last week.
Poland has two power lines to Germany, allowing 1.1GW of exports and 2.0GW of imports. In the past, there have been problems with loop flows on the interconnectors which cause congestion on the border points and are difficult to manage.
This creates a situation where wind power from Germany is routed through Poland and the Czech Republic, which in essence means that Germany is using its neighbours to balance its power system.
Sources say this could cause instability in the Polish and Czech grids. Polish transmission system operator (TSO) PSE-Operator said it plans to install phase shifters across the Polish-German border to reduce loop flows and potentially increase Polish import capacity (see EDEM 9 March 2009).
Kohler told ICIS Heren that installing phase shifters on the Polish interconnector would make the German grid more unstable because it would limit the possibility of using neighbouring grids for balancing. This means internal German investments are key. "Germany should expand its own grid and not rely on neighbouring countries to do its balancing," Kohler said in a statement.
The Polish TSO said installing phase shifters on the German-Polish border was not meant to curb the development of renewable generation in Germany.
The new phase shifters would limit the risk of cascading outages which could otherwise endanger the operational security in both Poland and Germany, the TSO added in a statement on its website.
A representative for PSE Operator said that problems associated with loop flows on Polish and German systems had increased both in number and scale.
"The loop flows that go from Germany through Poland to the Czech Republic and Slovakia are the result of the existing configuration of generation sources and insufficient expansion of the inner German system," the TSO said in a written statement. "For this reason, the safety of the system is deteriorating in spite of investments in the Polish system.
"Because of the loop flows, the Polish ability to provide import capacity to the market participants is very limited," it added.
Polish market participants previously have complained about cross-border capacity cuts because of loop flows.
German energy regulator BNetzA told ICIS Heren that grid upgrades were underway to ease the tress placed on neighbouring winds by loop flows.
One line under construction would transport energy from northeastern Germany to load centres in the west of the country, while permit procedures for three more lines have started. One of these is expected to be commissioned in 2013, the regulator said.
BNetzA also called for shared funding to deal with the loop flow issue. One way would be to use the inter-TSO compensation, part of the EU's laws on how to pay for transit of electricity over borders, the regulator said. SR
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