Unplanned flows drive rise in Czech grid’s transit load – CEPS

A year-on-year surge in physical flows through the Czech electricity grid in 2015 was down to unplanned flows from the German grid, said grid operator CEPS on Friday.

The transit load of the Czech system increased by 40% in 2015 compared to 2014, but exports were significantly lower, falling by almost 4TWh compared to the previous year, to 12.5TWh.

“In the last year, the physical values of flows through our transmission system increased significantly, but not trade export and import. These were unplanned electricity overflows caused by high generation of wind power in northern Germany, directed to southern and eastern Europe,” said Vladimir Tosovsky, board chairman of CEPS.

Changed flow patterns

Lower exports from the Czech Republic to surrounding countries were probably down to problems with domestic production during 2015.

The Czech Republic suffered longer than expected and unplanned nuclear outages throughout the year at Temelin and Dukovany plants, which have a combined capacity of over 4GW.

The problems reached their peak in September. At one point only 1.5GW of capacity out of a possible 4GW was online. During the same month, the Czech Republic went from being a net exporter of electricity to having to cover shortages in the system with imports (see EDEM 21 September 2015).

CEPS said that for a total 96 hours over 18 days between 1 September and 30 November, the Czech Republic became a net importer of electricity, sourcing power mainly from Germany and Austria.

“No dramatic imports took place. There were several reasons: bridging unplanned outages of large sources, and economic reasons, where it pays for merchants to import electricity instead of operating more expensive sources in the Czech Republic,” said Miroslav Vrba, vice-chairman of CEPS.

A lack of exports from the Czech Republic also led to greater German physical flows through the Polish system.

Loop flows

Unplanned electricity flows are relatively commonplace in the Czech Republic. There is insufficient transmission capacity between north Germany, where many wind farms are sited, to consumption centres in the south of the country and Austria.

This means that power sometimes flows to its destination via the Czech Republic in a “loop flow”, as electricity travels down the path of least resistance.

This causes problems for transmission system operators (TSOs), as surges in power on the grid can cause damage to the system. Unplanned flows have to be mitigated with costly and disruptive measures such as re-dispatching, which involves directing quick-response producers (often coal plants) to start or stop generating power.

CEPS said the increased transit load from unplanned flows had led to a year-on-year rise in losses in the transmission system by about 20% to 1,007GWh.

Regional traders told ICIS that loop flows will continue to cause problems for the Czech Republic with increasing frequency until phase shifting transformers are installed.

Phase shifters between CEPS and German grid 50Hertz, due to start operation at the end of 2016, will prevent electricity generated by wind farms in north Germany from flowing into the CEPS controlled area.

“This will be happening more and more until these phase shifters operate,” said one trader. ellie.chambers@icis.com