Apparatus for the voltage maintenance of an electrical AC voltage supply network and method for operating such an apparatus

• US 7,105,948 B2
• Filed: 09/10/2002
• Issued: 09/12/2006
• Est. Priority Date: 09/10/2002
• Status: Active Grant

• Current Assignee: ABB Schweiz AG (ABB Limited)
• Original Assignee: ABB Schweiz AG (ABB Limited)
• Inventors: Steimer, Peter
• Primary Examiner(s): Sircus, Brian
• Assistant Examiner(s): DESCHERE, ANDREW M
• Application Number:
  US10/237,874
• Publication Number:
  US 20040046460A1
• Time in Patent Office: 1,463 Days
• Field of Search: 307/66, 307/46, 307/80, 307/82, 307/103, 363/73, 363/37, 363/132
• US Class Current: 307/46
• CPC Class Codes: H02J 3/1814 wherein al least one reactive element is actively controlled by a bridge converter, e.g. unified power flow controllers [UPFC]
• CPC Class Codes: H02J 9/061 for DC powered loads
• CPC Class Codes: Y02E 40/10 Flexible AC transmission systems [FACTS]

Abstract

A method and apparatus for the voltage maintenance of an electrical AC voltage supply network comprising a partial converter system, which has a first branch pair and a second branch pair connected in parallel therewith and an electrical energy store connected in parallel with the branch pairs. Each branch pair is formed from two series-connected driveable power semiconductor switches, each with a diode reverse-connected in parallel, and the junction point of the power semiconductor switches of the first branch pair forming a first terminal and the junction point of the power semiconductor switches of the second branch pair forming a second terminal. The partial converter system has a third branch pair connected in parallel with the first and second branch pairs. The junction point of the power semiconductor switches of the third branch pair forms a third terminal.

Claims

1. An apparatus for the voltage maintenance of an electrical AC voltage supply network with a partial converter system, comprising:

a first branch pair and a second branch pair connected in parallel therewith and an electrical energy store connected in parallel with the branch pairs, each branch pair being formed from two series-connected driveable power semiconductor switches with in each case a diode is reverse-connected in parallel with each power semiconductor switch, and the junction point of the power semiconductor switches of the first branch pair is connected to a first terminal of the partial converter system and the junction point of the power semiconductor switches of the second branch pair is connected to a second terminal of the partial converter system, wherein the partial converter system has a third branch pair formed from two series-connected driveable power semiconductor switches with in each case a diode is reverse-connected in parallel with each power semiconductor switch, the third branch pair being connected in parallel with the first and second branch pairs, and

wherein the junction point of the power semiconductor switches of the third branch pair is connected to a third terminal of the partial converter system,

wherein a driveable isolating switch is connected between the first terminal and the second terminal.

2. The apparatus as claimed in claim 1, wherein a first inductance is connected between the junction point of the power semiconductor switches of the third branch pair and the second terminal.

3. The apparatus as claimed in claim 2, wherein a first filter formed by a first filter capacitance and a first filter resistance connected in series therewith is connected in between the third terminal and the second terminal.

4. The apparatus as claimed in claim 1, wherein a second inductance is connected between the junction point of the power semiconductor switches of the first branch pair and the first terminal.

5. Apparatus as claimed in claim 4, wherein a second filter formed by a second filter capacitance and a second filter resistance connected in series therewith is connected in between the third terminal and the first terminal.

6. The apparatus as claimed in claim 1, wherein a third inductance is connected between the junction point of the power semiconductor switches of the third branch pair and the third terminal.

7. The apparatus as claimed in claim 6, wherein a third filter formed by a third filter capacitance and a third filter resistance connected in series therewith is connected between the third terminal and the third inductance.

8. The apparatus as claimed in claim 2, wherein, for a polyphase electrical AC voltage supply network, a partial converter system is provided for each phase and wherein the third terminals are connected to one another.

9. The apparatus as claimed in claim 2, wherein, for a polyphase electrical AC voltage supply network, a partial converter system is provided for each phase, and wherein each third terminal of an associated partial converter system of one phase is connected to a second terminal of a partial converter system of another phase.

10. The apparatus claimed in claim 2, wherein, for a polyphase electrical AC voltage supply network, a partial converter system is provided for each phase,

wherein a first filter formed by a first filter capacitance and a first filter resistance connected in series therewith is connected to the second terminal, and wherein the first filters are connected to one another.

11. The apparatus as claimed in claim 4, wherein, for a polyphase electrical AC voltage supply network, a partial converter system is provided for each phase,

wherein a first filter formed by a first filter capacitance and a first filter resistance connected in series therewith is connected between the third terminal and the second terminal of each partial converter system.

12. The apparatus as claimed in claim 4, wherein, for a polyphase electrical AC voltage supply network, a partial converter system is provided for each phase,

wherein a second filter formed by a second filter capacitance and a second filter resistance connected in series therewith is connected to the first terminal of each partial converter system, and

wherein the second filters are connected to one another at a junction point.

13. The apparatus as claimed in claim 8, wherein the voltage sources of the partial converter systems are connected to one another and the junction point forms a neutral point terminal, the junction point of the third terminals being connected to the neutral point terminal.

14. The apparatus as claimed in claim 12, wherein the voltage sources of the partial converter systems are connected to one another to form a neutral point terminal, the junction point of the second filters being connected to the neutral point terminal.

15. The apparatus as claimed in claim 1, wherein a capacitor is provided as electrical energy store.

16. The apparatus as claimed in claim 1, wherein the partial converter system has an electrical battery store connected in parallel with the branch pairs.

17. The apparatus as claimed in claim 1, wherein the partial converter system has a fourth branch pair formed from two series connected driveable power semiconductor switches with in each case a diode reverse connected in parallel with each power semiconductor switch, the fourth branch pair being connected in parallel with the other branch pairs, and wherein a battery store is connected to the fourth branch pair.

18. A method for operating an apparatus for the voltage maintenance of an electrical AC voltage supply network, comprising the steps of:

in the event of a fall in voltage of a voltage source of the electrical AC voltage supply network, said voltage source being connected to the partial converter system, driving the partial converter system in such a way that essentially the rated voltage of the voltage source is established at a first terminal of the partial converter system, the partial converter system comprising a first branch pair and a second branch pair connected in parallel therewith and an electrical energy store connected in parallel with the branch pairs, and each branch pair being formed from two series connected driveable power semiconductor switches with in each case a diode is reverse-connected in parallel with each power semiconductor switch, and the junction point of the power semiconductor switches of the first branch pair is connected to a first terminal of the partial converter system and the junction point of the power semiconductor switches of the second branch pair is connected to a second terminal of the partial converter system;

driving the first branch pair and the second branch pair in such a way that essentially the rated voltage of the voltage source is set at the first terminal; and

driving the second branch pair and a third branch pair of the partial converter system, which is formed from two series-connected driveable power semiconductor switches with in each case a diode reverse-connected in parallel with each power semiconductor switch and is connected in parallel with the first and second branch pairs, the junction point of the power semiconductor switches of the third branch pair being connected to a third terminal of the partial converter system, in such a way that the electrical energy store is charged by the voltage source, wherein, when the fall in voltage of the voltage source occurs, opening a driveable isolating switch connected between the first terminal and the second terminal.

19. The method as claimed in claim 18 wherein, upon the opening of the isolating switch, driving the first branch pair and the second branch pair in such a way that a current flowing via the isolating switch is taken essentially to the value 0A within less than or equal to 1 ms.

20. The method as claimed in claim 18, wherein a current flowing via the second terminal is smoothed by means of a first inductance connected in between the junction point of the power semiconductor switches of the second branch pair and the second terminal.

21. The method as claimed in claim 20, wherein at least one harmonic with regard to the voltage of the voltage source is essentially filtered out by means of a first filter, which is connected in between the third terminal and the second terminal and is formed by a first filter capacitance and a first filter resistance connected in series therewith.

22. The method as claimed in claim 18, wherein a current flowing via the first terminal is smoothed by means of a second inductance connected in between the junction point of the power semiconductor switches of the first branch pair and the first terminal.

23. The method as claimed in claim 22, wherein at least one harmonic with regard to the voltage of the voltage source is essentially filtered out by means of a second filter, which is connected in between the third terminal and the first terminal and is formed by a second filter capacitance and a second filter resistance connected in series therewith.

24. The method as claimed in claim 18, wherein a current flowing via the third terminal is smoothed by means of a third inductance connected in between the junction point of the power semiconductor switches of the third branch pair and the third terminal.

25. The method as claimed in claim 24, wherein at least one harmonic with regard to the voltage of the voltage source is essentially filtered out by means of a third filter, which is connected in between the third terminal and the third inductance and is formed by a third filter capacitance and a third filter resistance connected in series therewith.

26. The method as claimed in claim 18, wherein, for a polyphase electrical AC voltage supply network, a partial converter system and in each case a voltage source connected thereto are provided for each phase and, in the case of each partial converter system, at least one harmonic with regard to the voltage of the associated voltage source is essentially filtered out by means of a first filter, which is connected in between the third terminal and the second terminal and is formed by a first filter capacitance and a first filter resistance connected in series therewith, the third terminals being connected to one another.

27. The method as claimed in claim 18, wherein, for a polyphase electrical AC voltage supply network, a partial converter system and in each case a voltage source connected thereto are provided for each phase and, in the case of each partial converter system, at least one harmonic with regard to the voltage of the associated voltage source is essentially filtered out by means of a first filter, which is connected to the second terminal and is formed by a first filter capacitance and a first filter resistance connected in series therewith, the first filters being connected to one another.

28. The method as claimed in claim 18, wherein, for a polyphase electrical AC voltage supply network, a partial converter system and in each case a voltage source connected thereto are provided for each phase and, in the case of each partial converter system, at least one harmonic with regard to the voltage of the associated voltage source is essentially filtered out by means of a second filter, which is connected to the first terminal and is formed by a second filter capacitance and a second filter resistance connected in series therewith, the second filters being connected to one another.

29. The method as claimed in claim 18, wherein, in the event of no fall in voltage of the associated voltage source, the driveable isolating switch is closed.

30. The method as claimed in claim 29, wherein, in the event of no fall in voltage of the associated voltage source, each second and third branch pair is driven in such a way that an electrical battery store, which is provided for each partial converter system and is connected in parallel with the respective branch pairs, is charged by the associated voltage source.

31. The method as claimed in claim 29, wherein, in the event of no fall in voltage of the associated voltage source, a fourth branch pair of each partial converter system, which is formed from two series-connected driveable power semiconductor switches with in each case a diode reverse-connected in parallel with each power semiconductor switch and is connected in parallel with the respective branch pairs, is driven in such a way that a battery store connected to the fourth branch pair is charged.

32. The method as claimed in claim 29, wherein, in the event of no fall in voltage of the associated voltage source, the first branch pair and the second branch pair of each partial converter system are driven synchronously and the third branch pair of each partial converter system is driven in such a way that at least one harmonic oscillation—

with regard to the voltage of the associated voltage source of the voltage present at the first terminal of each partial converter system is essentially compensated for.

33. The method as claimed in claim 29, wherein, in the event of no fall in voltage of the associated voltage source, the first branch pair and the second branch pair of each partial converter system are driven synchronously and the third branch pair of each partial converter system is driven in such a way that an adjustable value of a reactive power flowing via the first terminal of each partial converter system is essentially compensated for.

34. The method as claimed in claim 29, wherein, in the event of no fall in voltage of the associated voltage source, the first branch pair and the second branch pair of each partial converter system are driven synchronously and the third branch pair of each partial converter system is driven in such a way that a voltage present at the electrical energy store is corrected to a predeterminable desired value.

35. A method for operating an apparatus for the voltage maintenance of an electrical AC voltage supply network, the apparatus having a partial converter system and the partial converter system having a first branch pair and a second branch pair connected in parallel therewith and an electrical energy store connected in parallel with the branch pairs, and each branch pair being formed from two series-connected driveable power semiconductor switches with in each case a diode reverse-connected in parallel with each power semiconductor switch, and the junction point of the power semiconductor switches of the first branch pair is connected to a first terminal of the partial converter system and the junction point of the power semiconductor switches of the second branch pair is connected to a second terminal of the partial converter system, and the partial converter system having a third branch pair formed from two series-connected driveable power semiconductor switches with in each case a diode reverse-connected in parallel with each power semiconductor switch, the third branch pair being connected in parallel with the first and second branch pairs, and the junction point of the power semiconductor switches of the third branch pair is connected to a third terminal of the partial converter system, in which, in the event of a fall in voltage of a voltage source of the electrical AC voltage supply network, which voltage source is connected to the partial converter system, comprising the steps of:

setting essentially the rated voltage of the voltage source at the first terminal by the partial converter system;

wherein, when the fall in voltage of the voltage source occurs, opening a driveable isolating switch connected in between the first terminal and the second terminal;

impressing a compensation voltage between the first terminal and the second terminal for the purpose of setting the rated voltage by means of the first branch pair and the second branch pair;

charging the energy store with electrical energy from the voltage source by means of the second branch pair and the third branch pair.