9 May 2012:
Increased pressure on German Grids during the Winter 2011/12
120 pages report from the German Grid Agency

The Federal German Grid Agency has confirmed the assumptions of a strained grid in a 120 pages report on the supply situation for electricity and gas in Germany during the winter season 2011/12.

It is useful for the general understanding of the significance of the infrastructure when an authority evaluates actual system conditions and publishes annual reports for better or for worse. Unfortunately that sort of reports is rare in the electricity business.

This is my attempt to translate the 10 points of the summary:
1. The situation of the power grid was very strained during the winter 2011/12.
2. Besides the scenarios described in the Grid Agency report of 31 August 2011 the shortage of natural gas in February 2012 was followed by an unexpected event which added to the load on the electric grids, respectively required additional measures from the transmissions system operators for maintaining system security.
3. In addition to that also unusual high forecast errors caused an exhaustion of the regulating reserves. Therefore the transmissions system operators had to resort to additional measures. The Grid Agency will create incentives for improvements of the forecasts by adaptation of the price system for balancing power.
4. The synchronous compensator Biblis was commissioned in February 2012 and provided the expected relief of the voltage problems.
5. German and Austrian power plant reserves were used in several cases for the relief of power lines and as a supplement to already exhausted regulating capacity. About the same magnitude of power reserves will be needed next winter.
6. The power plant capacity has developed unfavourably. Planned extensions have been delayed. Further decommissioning of conventional power plants cannot be defended in Germany for the time being. The prevention of decommissioning of power plants for conventional production will require regulating and legal measures. If more power stations nevertheless should be decommissioned in Southern Germany the needed reserve capacity would increase correspondingly. Besides, the need for capacity mechanisms should be intensively investigated in the medium term.
7. The supply of more power from renewable sources than can actually be transferred by the grid would add to overloading of the grid because the price signals would displace conventional power plants in the merit order and the electricity export from Germany in the internal market would increase. It is the understanding of the grid agency that the existing legal framework allows the transmission system operators to use measures which can reduce the supply to a level which can be transferred by the grid. Nevertheless, a normative clarification seems to be expedient.
8. The cooperation between grid operators for electricity and gas must be improved in order to take account of the growing significance of gas power plants and gas supply to the security of supply of the electric grids. Even here changes of the legal framework are recommended.
9. No technical valid measures can replace grid extensions. A consistent use of the established instruments for acceleration of the reinforcement of the grids is required.
10. The reduced supply of gas in February 2012 has revealed the weak points of the gas grids. Action is needed for the gas grids. Fortunately this need is clearly inferior to the need for action in the electricity grids.

The general view seems to be concern for the future capacity of power plants, regulating power and reserves. The rigid point 9 seems surprising, but it may reflect a typical view of a grid agency.

The development from 2011/11 to 2011/12
The increasing trend in the use of §13.1 of the German Energy Industry Act (EnWG) for redispatch and in the use of 11 of the RES Act (EEG) and §13.2 of EnWG for reduction of feed-in of power is quantified in the report. The data is valid for the transmission grid.

Redispatch is used for the relief of highly loaded grid components..
Winter season 2010/11 2011/12
Number of relieved components 5 9
Redispatched energy GWh 120 2.295

For both years most redispatch concerned the line Remptendorf-Redwitz between Germany and Austria.

Feed-in reduction was initiated 197 times during the winter season 2011/12 against 39 times the previous year.
In 184 cases wind power caused high feed-in from distribution grids into the transmission grids.
5 cases were remarkable and affected the entire grid:
Winter season 2011/12 Facility Consequence
3 Dec 2011 Rörsdorf-Hradec > 1000 MW
29 Dec 2011 Remptendorf-Redwitz
>1000 MW
15 Feb 2012 Remptendorf-Redwitz
1200 MW
22-23 Feb 2012 Remptendorf-Redwitz 4000 MW
n-1 problem
28-29 Mar 2012 Remptendorf-Redwitz
4800 MW
n-1 problem

This information confirms that German electricity supply had narrow margins during the wnter 2011/12 without room for additional heroic political decisions. Hopefully the messages of the Grid Agency will be understood, so a better harmony between the transition of the production facilities towards green solutions and the necessary adaptation of the infrastructure.

* Bericht zum Zustand der leitungsgebundenen Energieversorgung im Winter 2011/12 Bundesnetzagentur, 3 May 2012 (in German)
* Frequent German Wind Power Curtailments, Paul-Frederik Bach, 14 April 2012
* Interconnected system operation conditions in Continental Central Europe, ENTSO-E, 13 March 2012

Opdateret d. 21.5.2012