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EP-3602722-B1 - METHOD FOR STARTING AN ENERGY GENERATION NETWORK

EP3602722B1EP 3602722 B1EP3602722 B1EP 3602722B1EP-3602722-B1

Inventors

  • BROMBACH, Johannes
  • Mackensen, Ingo
  • BUSKER, Kai

Dates

Publication Date
20260506
Application Date
20180322

Claims (20)

  1. A method for starting an energy generation grid, in particular a farm grid (114, 730) of a wind farm (112), wherein the energy generation grid has at least one grid connection point connected to an electrical supply grid (120, 724, 806), and wherein the energy generation grid, in a normal operating mode, exchanges electrical power with the electrical supply grid (120, 724, 806) via the grid connection point, comprising the steps of: - selecting an establishment mode, which is different than the normal operating mode, if the electrical supply grid (120, 724, 806) has a voltage drop, and/or the energy generation grid is isolated from the electrical supply grid (120, 724, 806), and - operating the energy generation grid in the establishment mode, wherein in the establishment mode - at least one voltage influencing means (808), in particular a voltage influencing wind power installation (100, 704), an energy generation grid voltage, in particular a wind farm grid voltage, is provided, wherein the at least one voltage influencing means (808) operates in a voltage influencing manner to provide the energy generation grid voltage and - at least one initial supply means (810), namely a current influencing wind power installation (100, 704), synchronizes to the energy generation grid voltage provided via the voltage influencing means, wherein the at least one initial supply means (808) operates in a current influencing manner to provide an electrical power in the energy generation grid and - the voltage influencing means (808) and the initial supply means (810) in total provide an electrical power in the energy generation grid at the level of an inherent need of the energy generation grid, wherein - the at least one voltage influencing means (808) provides the energy generation grid voltage substantially without power, or supplies a power having a distinctly lower absolute value than the at least one initial supply means (810), preferably provides no more than 20%, in particular no more than 10%, of the power of the at least one initial supply means (810). - the at least one voltage influencing means (808) is based on at least one first droop and the at least one initial supply means (810) is based on at least one second droop, wherein each droop describes a respective relationship, particularly a linear relationship, between a voltage (u(t)) of the energy generation grid and a reactive power (Q) that is to be supplied or that has been supplied or between a frequency (f) of the energy generation grid and a real power that is to be supplied or has been supplied, and charactertized in that, that the first droop has a smaller gradient than the second droop.
  2. The method as claimed in one of the preceding claims, characterized in that - the at least one voltage influencing means (808) is based on a first reactive power droop describing a relationship between a voltage to be provided by the voltage influencing means in the energy generation grid and a reactive power (Q) supplied by the voltage influencing means (808), and - the at least one initial supply means (810) is based on a second reactive power droop describing a relationship between a voltage (u(t)) recorded in the energy generation grid and a reactive power (Q) to be supplied by the initial supply means (10), and - the first reactive power droop has a smaller gradient than the second reactive power droop, and/or in that - the at least one voltage influencing means (808) is based on a first real power droop describing a relationship between a frequency (f) to be provided in the energy generation grid by the voltage influencing means (808) and a real power supplied by the voltage influencing means (808), and - the at least one initial supply means (808) is based on a second real power droop describing a relationship between a frequency (f) recorded in the energy generation grid and a real power to be supplied by the initial supply means (810), and - the first real power droop has a smaller gradient than the second real power droop.
  3. The method as claimed in claim 2, characterized in that - the at least one voltage influencing means (808) provides the voltage (u(t)) that is to be provided on the basis of the supplied reactive power (Q) in each case according to the first reactive power droop, and - the at least one initial supply means supplies (810) the reactive power (Q) that is to be supplied on the basis of the recorded voltage (u(t)) in each case according to the second reactive power droop and/or - the at least one voltage influencing means (808) provides the frequency (f) that is to be provided on the basis of the supplied real power in each case according to the first real power droop, and - the at least one initial supply means (810) supplies the real power that is to be supplied on the basis of the recorded frequency (f) in each case according to the second real power droop.
  4. The method as claimed in one of preceding claims 1 to 3, characterized in that the gradient or gain of the second droop, second reactive power droop and/or second real power droop is at least twice as great, in particular at least three times as great, as the gradient or gain of the corresponding first droop, reactive power droop and real power droop respectively.
  5. The method as claimed in one of the preceding claims, characterized in that - the selecting of the establishment mode, in particular changing from the normal operating mode to the establishment mode, is effected if alternatively or additionally the energy generation grid has a voltage drop.
  6. The method as claimed in one of the preceding claims, characterized in that - the operating of the energy generation grid in the establishment mode is effected only when the energy generation grid is de-energized.
  7. The method as claimed in one of the preceding claims, characterized in that - the at least one initial supply means (810) and the further initial supply means (810) are synchronized in cascaded fashion to provide the electrical power in the energy generation grid.
  8. The method as claimed in one of the preceding claims, characterized in that - the electrical power provided by the at least one initial supply means (810) in the energy generation grid has at least one reactive power component that is sufficiently large to cover the reactive power requirement of the energy generation grid.
  9. The method as claimed in one of the preceding claims, characterized in that - the electrical power provided by the at least one initial supply means (810) in the energy generation grid has at least one reactive power component and one real power component, wherein the reactive power component is greater than the real power component, preferably at least twice as great, particularly preferably at least five times as great.
  10. The method as claimed in one of the preceding claims, characterized in that - the electrical supply grid (120, 724, 806) has a supply voltage and the energy generation grid voltage is ramped up to the supply grid voltage in order to synchronize the energy generation grid to the electrical supply grid (120, 724, 806).
  11. The method as claimed in one of the preceding claims, further comprising the step of: - connecting the energy generation grid to the electrical supply grid (120, 724, 806) via an energy generation grid transformer, in particular a wind farm transformer (722), if the energy generation grid has an energy generation grid voltage synchronized to the electrical supply grid (120, 724, 806) or in order to provide a grid reestablishment voltage at the grid connection point if the electrical supply grid (120, 724, 806) has no voltage (u(t)).
  12. The method as claimed in one of the preceding claims, further comprising the step of: - ramping down the at least one voltage influencing means (808) and the at least one initial supply means (810) such that the energy generation grid is de-energized if the electrical supply grid (120, 724, 806) has a voltage drop.
  13. The method as claimed in one of the preceding claims, characterized in that - the at least one voltage influencing means (808) provides an energy generation grid voltage only when the energy generation grid is de-energized.
  14. The method as claimed in one of the preceding claims, characterized in that - the voltage drop is defined in relation to a rated voltage of the electrical supply grid (120, 724, 806) as: - a voltage (u(t)) less than 90 percent of the rated voltage or - a voltage (u(t)) less than 70 percent of the rated voltage or - a voltage (u(t)) less than 30 percent of the rated voltage or - a voltage (u(t)) less than 10 percent of the rated voltage.
  15. The method as claimed in one of the preceding claims, characterized in that - the at least one voltage influencing means (808) has a DC link circuit fed from a capacitance to provide the energy generation grid voltage (710), wherein the capacitance is configured to supply the DC link circuit (710) with a DC voltage in the event of a voltage drop in the electrical supply grid(120, 724, 806) and/or in the event of a de-energized energy generation grid such that the at least one voltage influencing means (808) can provide a stable energy generation grid voltage.
  16. The method as claimed in one of the preceding claims, further comprising the step of: - recording a voltage drop in the electrical supply grid (120, 724, 806) and/or detecting a loss of voltage in the energy generation grid by means of a voltage recording of the at least one voltage influencing means (808).
  17. The method as claimed in one of the preceding claims, characterized in that - the energy generation grid comprises a power controller by means of which the at least one initial supply means supplies (810) an electrical power to the electrical supply grid (120, 724, 806) on the basis of a power setpoint value (P soll ) wherein preferably a power setpoint value (P soll ) is prescribed by an energy generation grid operator or by a grid operator of the electrical supply grid (120, 724, 806), and/or the electrical power is increased such that in the event of a system deviation it is slowly corrected, in particular by means of an I controller.
  18. The method as claimed in one of the preceding claims, characterized in that - the energy generation grid has a frequency stability - that holds back a portion of the available electrical power of the at least one initial supply means (810) in order to release it, in particular supply it, for the frequency stability of the electrical supply grid (120, 724, 806) when required and/or - that limits a supply of electrical power of the at least one initial supply means (810) if the energy generation grid and/or the electrical supply grid (120, 724, 806) has a grid frequency that is an overfrequency, and/or - that draws electrical power from the electrical supply grid (120, 724, 806) and preferably consumes it by means of a chopper apparatus.
  19. The method as claimed in one of the preceding claims, characterized in that - the energy generation grid is configured to receive a weather forecast and/or to produce a weather forecast, wherein the weather forecast is used to stipulate a time at which operation of the energy generation grid in the establishment mode can be started.
  20. The method as claimed in one of the preceding claims, characterized in that the voltage influencing means (808) and the initial supply means (810) each form a supply unit and operate as voltage influencing means (808) or initial supply means (810) by means of actuation, wherein in particular the voltage influencing means (808) can operate as initial supply means (810) by virtue of an appropriate change of actuation and the initial supply means (810) can operate as voltage influencing means (808) by virtue of a change of actuation.

Description

Die vorliegende Erfindung betrifft ein Verfahren zum Starten eines Energieerzeugungsnetzes, insbesondere eines Windparks. Außerdem betrifft die vorliegende Erfindung eine Windenergieanlage, und sie betrifft einen Windpark mit wenigstens einer ersten und einer zweiten Windenergieanlage. Elektrische Versorgungsnetze sind bekannt, und mit ihnen wird elektrische Energie zwischen Energieeinspeisern und Energieverbrauchern verteilt. Ein solches elektrisches Versorgungsnetz wird heutzutage mit einer Wechselspannung mit einer vorbestimmten Netzfrequenz betrieben, meist 50 Hz oder 60 Hz. Sowohl die Einspeiser als auch die Verbraucher haben sich auf diese Frequenz eingestellt. Besonders ist es so, dass ein Teil, meist ein großer Teil, des elektrischen Versorgungsnetzes immer in Betrieb ist. Wird eine elektrische Erzeugungseinheit zum Einspeisen elektrischer Energie zu diesem elektrischen Versorgungsnetz zugeschaltet, so kann sich diese Erzeugungseinheit ebenfalls an dem elektrischen Versorgungsnetz orientieren. Besonders erhält eine solche elektrische Erzeugungseinheit regelmäßig zunächst Energie aus dem elektrischen Versorgungsnetz, um damit etwaige Startprozesse zu versorgen. Zusätzlich zu der Energiebereitstellung hierfür gibt das elektrische Versorgungsnetz dabei aber auch Orientierung und Führung besonders für die Netzfrequenz und die Höhe der elektrischen Spannung. Einige Erzeugungseinheiten, wie beispielsweise Windparks mit mehreren Windenergieanlagen, verfügen selbst über ein internes elektrisches Netz, das auch als Energieerzeugungsnetz bezeichnet werden kann. Auch ein solches Energieerzeugungsnetz ist üblicherweise in Betrieb und weist die Netzfrequenz des elektrischen Versorgungsnetzes auf, mit der es synchronisiert ist. Außerdem speist das Energieerzeugungsnetz über einen Verknüpfungspunkt, besonders einen Netzanschlusspunkt, in das elektrische Versorgungsnetz ein oder bezieht dort Energie aus dem elektrischen Versorgungsnetz, und ist in seiner eigenen Spannungshöhe an diesem Verknüpfungspunkt an die Spannungshöhe des elektrischen Versorgungsnetzes angepasst. Diese beiden Spannungen sind dort also gleich oder stehen entsprechend einem Übertragungsverhältnis eines Transformators an diesem Verknüpfungspunkt in einem bestimmten Verhältnis zueinander. Wird nun das Energieerzeugungsnetz, also insbesondere das Parknetz, gestartet, also beispielsweise bei der Erstinbetriebnahme oder nach einem Fall, bei dem es heruntergefahren werden musste, so kann das Energieerzeugungsnetz dafür Energie von dem elektrischen Versorgungsnetz erhalten und sich auf die durch das elektrische Versorgungsnetz vorgegebene Netzfrequenz und Netzspannung einstellen und sich daran orientieren. Es wurde nun aber erkannt, dass Energieerzeugungsnetze, besonders Parknetze von Windparks, in elektrischen Versorgungsnetzen eine zunehmende Bedeutung spielen. Es kann somit vorkommen, dass das elektrische Versorgungsnetz einen solchen Startprozess eines Energieerzeugungsnetzes nicht ausreichend führen oder stützen kann. Besonders kann zu erwarten sein, dass das elektrische Versorgungsnetz selbst eine Stützung benötigt. Es wurde auch erkannt, dass ein Energieerzeugungsnetz, besonders ein Parknetz eines Windparks, daher gegebenenfalls auch in der Lage sein sollte, eigenständig zu starten oder sogar eine Stützung für das elektrische Versorgungsnetz zu schaffen, sodass sich das elektrische Versorgungsnetz gegebenenfalls mithilfe des Energieerzeugungsnetzes wieder starten kann oder zumindest aus einer Situation, in der die Netzspannung signifikant eingebrochen ist, wieder erholen kann. Besonders bisher vorgesehene Kraftwerke, die speziell für einen Netzwiederaufbau oder sogar einen Schwarzstart eines elektrischen Versorgungsnetzes bereitgehalten wurden, können nun seltener vorhanden sein oder sollen eingespart werden, sodass ein elektrisches Versorgungsnetz zu seinem Start oder einer Regeneration ohne ein solches Spezialkraftwerk auskommen muss. Das Deutsche Patent- und Markenamt hat in der Prioritätsanmeldung zu vorliegender Anmeldung folgenden Stand der Technik recherchiert: US 2017/0074244 A1, DE 10 2014 214 151 A1, DE 10 2013 102 603 A1, EP 1 665 494 B1 und US 2015/0159627 A1. US 2015/0028593 A1 betrifft ein Verfahren zum Anfahren eines Windparks. US 2015/380942 A1 betrifft ein Verfahren zum Starten eines Parknetzes eines Windparks gemäß dem Oberbegriff des Anspruchs 1. Der vorliegenden Erfindung liegt somit die Aufgabe zugrunde, zumindest eines der oben genannten Probleme zu adressieren. Insbesondere soll eine Lösung geschaffen werden, dass ein Energieerzeugungsnetz, insbesondere ein Parknetz eines Windparks, selbstständig und ohne Hilfe eines elektrischen Versorgungsnetzes starten kann und dann insbesondere sogar das elektrische Versorgungsnetz beim Starten, Wiederaufbauen oder Erholen aus einem Fall eines Spannungseinbruchs stützen oder unterstützen kann. Zumindest soll zu bisher bekannten Verfahren eine alternative Lösung vorgeschlagen werden. E