Load following operation

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Load-following operation means that a power plant adapts its electricity generation to the requirements of the transmission system operator . The term “ load following capability ” states the percentage by which the output of a power plant can be increased or reduced in a period of time.

General

The following terms are essential in connection with the ability of a power plant to operate according to load:

Minimum power

The minimum output or the minimum operating output states the percentage of the nominal output to which the power plant can be shut down in normal operation. The minimum output therefore represents the lowest limit in normal operation of the power plant. d. Usually given as a percentage of the power plant's nominal output. 45% minimum power mean z. For example, for a power plant with a nominal output of 1,000  MW , the output can be reduced to 450 MW in normal operation.

Alternatively, the term power stroke is used, i.e. i.e. the difference between the minimum and nominal output of the power plant. For a power plant with a nominal output of 1,000 MW, 45% output lift means that the output can be reduced to 550 MW in normal operation.

Power gradient

The power gradient or the speed of power change indicates how quickly the power plant can increase or decrease its output. The power gradient is i. d. Usually given as a percentage of the nominal output per minute. 10% rate of change in output (correct: 10% / min) means in a power plant with a nominal output of 1,000 MW that the output can be increased or decreased by up to 100 MW per minute in normal operation.

Power plant type

Not every type of power plant is suitable for load-following operation. The following table gives an overview of the power plant types that are suitable for load following operation:

Power plant type Minimum power (%) Power gradient (% / min) Power gradient (MW / min) Duration
Gas power plant 20th 20 to 20
Combined cycle power plant 33 6th
Nuclear power plant 20, 30, 45, 50 2, to 5, (3.8 to 5.2), (5 to 10), 10 up to 65, up to 100 1 hour
  Pressurized water reactor 20, 45 or 50 (3.8 to 5.2), 10 15 minutes, (10 to 40 min.), 60 min., (3 to 4 hours)
  Boiling water reactor 20, 35 or 60 (1.1 to 4.6), 10 (10 to 35 minutes), (1.8 hours)
coal-fired power station 3 to 4
  Lignite power plant 40 3
  Hard coal power plant 38 4th
Run-of-river power plant almost 0
pumped storage power plant 0 up to 200
Wind turbine 0
Photovoltaic system 0
  1. ↑ Boiling water reactor in the range between 60 and 100% of the nominal output
  2. ↑ The system is kept for personal use
  3. ↑ Pre-convoy and convoy systems
  4. ↑ Above 80% of the nominal power
  5. ↑ Power reduction
  6. ↑ From 50% to 90% of full load and another 10 hours to 100% of full load
  7. ↑ Load-following operation is technically possible with run-of-river power plants, but is not carried out because, due to other aspects such as maintaining the level of rivers, uniform operation is preferred.
  8. ↑ a b In Germany, due to the priority regulation of renewable energies in the Renewable Energy Sources Act (EEG), load-following operation is practically irrelevant and is not carried out.

Gas power plant

For a gas-fired power plant , the minimum output is 20% of the nominal output, for a combined cycle power plant, 33%. At minimum power, however, both types of power plants have a z. T. considerable reduction in efficiency. The power gradients given for a gas power plant are 20% of the nominal output per minute, and 6% for a combined cycle power plant.

Nuclear power plant

For most German nuclear power plants (KKW), the ability to operate in a load sequence was a design criterion that determined the concept. For this reason, the core monitoring and the reactor control have already been designed when the reactors are designed so that no subsequent upgrading of the systems for load-following operation is necessary.

The Bavarian state government replied to the request that all Bavarian NPPs are designed for load-following operation. German NPPs that have been or are being operated in load-following mode are e.g. B. Emsland , Grafenrheinfeld , Gundremmingen Block B and C , Isar 2 , Neckarwestheim 1 , Philippsburg 1 . In France, around 40 NPPs are operated in load-following mode.

General

For the German NPP, the minimum output is 20, 30, 45 or 50% of the nominal output. The power gradients are 2, up to 5, (3.8 to 5.2), (5 to 10) or 10% of the nominal output per minute or 65 or up to 100 MW per minute.

Pressurized water reactor

For German pressurized water reactors (PWR) the minimum output is 20, 45 (or 50)% of the nominal output. The power gradients indicated are 3.8 to 5.2 or 10% of the nominal power per minute.

With PWR, load changes of 50% of the nominal output are possible in a time of a maximum of a quarter of an hour, both when increasing and reducing the output. An even higher load following capability is possible in the range above 80% of the nominal power with maximum power gradients of up to 10% of the nominal power per minute.

For the Isar 2 nuclear power plant , the following performance gradients were specified in the operating manual: 2% per minute for changes in output in the range from 20 to 100% of the nominal output, 5% per minute in the range from 50 to 100% of the nominal output and 10% per minute in the range of 80 to 100% of the nominal power.

Boiling water reactor

For German boiling water reactors (BWR), the minimum output is 20, 35 and 60% of the nominal output. The power gradients specified are 1.1 to 4.6 or 10% of the nominal power per minute.

The output control of the BWR is done either by varying the coolant throughput (circulation control range) or by extending or retracting control rods. Beyond the circulation control range, changes in output are implemented by moving control elements, so that output increases between approx. 20 and 100% are possible.

coal-fired power station

Lignite power plant

For a lignite power plant, 40% of the nominal output is specified as the minimum output. At minimum power there is a reduction in efficiency. The power gradient is given as 3% of the nominal power per minute.

Hard coal power plant

For a hard coal-fired power plant, the minimum output stated is 38 (or 40%)% of the nominal output. At minimum power there is a reduction in efficiency. The power gradients given are 4 (or 3 to 6%) of the nominal power per minute.

See also

Individual evidence

  1. ↑ a b Isar 2 nuclear power plant for the 10th time world class. (No longer available online.) E.ON , May 5, 2014, archived from the original on September 24, 2015 ; accessed on July 27, 2015 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  @1@ 2Template: Webachiv / IABot / www.eon.com
  2. ↑ a b c d nuclear energy. RWE , accessed on May 27, 2015 .
  3. ↑ a b c d e f The energy market in focus - Nuclear energy - Special edition for the 2010 annual edition . In: BWK THE ENERGY TRADE MAGAZINE . No.  5 , 2010, p. 10 ( ruhr-uni-bochum.de [PDF; 2.1 MB ; accessed on May 27, 2015]).
  4. ↑ a b c d e f g h Holger Ludwig, Tatiana Salnikova and Ulrich Waas: Load changing capabilities of German NPPs . In: International magazine for nuclear energy . tape 55 , no. 8/9 , p. 2 ( areva.com [PDF; 2.4 MB ; accessed on October 26, 2014]). Load change capabilities of German NPPs ( memento of the original from July 10, 2015 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice.  @1@ 2Template: Webachiv / IABot / de.areva.com
  5. ↑ a b c d e f g h i j k l m M. Hundt, R. Barth, N. Sun, S. Wissel, A. Voß: Will extending the service life of nuclear power plants slow down the expansion of renewable energies? Ed .: University of Stuttgart - Institute for Energy Economics and Rational Energy Use. February 16, 2010, p. 7 ( bdi.eu [PDF; 1.8 MB ; accessed on July 23, 2015]). Will extending the life of nuclear power plants slow down the expansion of renewable energies? ( Memento of the original from September 23, 2015 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  @1@ 2Template: Webachiv / IABot / www.bdi.eu
  6. ↑ a b c d e f g h i j k l m n o M. Hundt, R. Barth, N. Sun, S. Wissel, A. Voß: Will extending the service life of nuclear power plants slow down the expansion of renewable energies? Ed .: University of Stuttgart - Institute for Energy Economics and Rational Energy Use. February 16, 2010, p. 25–30 ( bdi.eu [PDF; 1.8 MB ; accessed on July 23, 2015]). Will extending the life of nuclear power plants slow down the expansion of renewable energies? ( Memento of the original from September 23, 2015 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  @1@ 2Template: Webachiv / IABot / www.bdi.eu
  7. ↑ a b c d e Status Report 2013 - Fossil-fired large power plants in Germany. (PDF; 15.1 kB, p. 29 (19)) (No longer available online.) VDI , December 2013, archived from the original on July 30, 2014 ; accessed on May 29, 2015 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  @1@ 2Template: Webachiv / IABot / m.vdi.de
  8. ↑ a b c d e f g h i j k l m n o p q Holger Ludwig, Tatiana Salnikova and Ulrich Waas: Load changing capabilities of German NPPs . In: International magazine for nuclear energy . tape 55 , no. 8/9 , p. 3, 5–6 ( areva.com [PDF; 2.4 MB ; accessed on October 26, 2014]). Load change capabilities of German NPPs ( memento of the original from July 10, 2015 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice.  @1@ 2Template: Webachiv / IABot / de.areva.com
  9. ↑ a b c d e Matthias Hundt, Rüdiger Barth, Ninghong Sun, Steffen Wissel, Alfred Voß: Compatibility of renewable energies and nuclear energy in the generation portfolio - technical and economic aspects . Ed .: University of Stuttgart - Institute for Energy Economics and Rational Energy Use. October 2009, p. iii ( uni-stuttgart.de [PDF; 291 kB ; accessed on July 23, 2015]).
  10. ↑ a b c d e f g h i j k Matthias Hundt, Rüdiger Barth, Ninghong Sun, Steffen Wissel, Alfred Voss: Compatibility of renewable energies and nuclear energy in the generation portfolio - technical and economic aspects . Ed .: University of Stuttgart - Institute for Energy Economics and Rational Energy Use. October 2009, p. 6–7 ( uni-stuttgart.de [PDF; 291 kB ; accessed on July 23, 2015]).
  11. ↑ a b c d e f g h i j Bavarian State Parliament, 16th electoral period (ed.): Written request from Member of Parliament Ludwig Wörner SPD from July 16, 2013 - Regulability of Bavarian nuclear power plants . Printed matter 16/18315, September 13, 2013 ( ludwig-woerner.de [PDF; 15 kB ; accessed on May 27, 2015]). Written request from the MP Ludwig Wörner SPD from July 16, 2013 - Regulability of Bavarian nuclear power plants ( Memento of the original from May 24, 2016 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice.  @1@ 2Template: Webachiv / IABot / www.ludwig-woerner.de
  12. ↑ a b Great flexibility makes Emsland nuclear power plant a reliable partner for renewable energies. RWE, August 15, 2014, accessed on May 28, 2015 .
  13. ↑ a b c d RP-Energie-Lexikon, keyword load sequence operation (accessed on December 3, 2017)
  14. ↑ a b M. Steininger: [ https://energie.labs.fhv.at/Masterarbeiten/ETW14/Masterarbeit_Steininger.pdf What opportunities and risks for pumped storage power plants result from the changes in the electricity industry?], P. 27 (accessed on December 4, 2017)
  15. ↑ a b LOAD FOLLOWING OPERATION AND PRIMARY CONTROL - EXPERIENCE WITH THE BEHAVIOR OF THE REACTOR - Isar nuclear power plant. (PDF; 743 kB; p. 1) E.ON, accessed on August 5, 2015 .
  16. ^ Michael Bolz and Andreas Speck, Philippsburg; Fred Böttcher and Steffen Riehm, Neckarwestheim: Influence of load following operation on the chemistry of the primary and secondary circuit of a nuclear power plant with a pressurized water reactor . In: atw . tape 58 , no. 7 , July 2013, p. 440–445 ( kernenergie.de [PDF; 3.2 MB ]).
  17. ^ Operating times of nuclear power plants in Germany. Öko-Institut , accessed on May 28, 2015 .