Power factor correction device and method for operating a power factor correction device

1. A power factor correction device for an AC grid system, comprising:

a high-leakage-reactance transformer having a secondary side connected up in a star point circuit with a star point, said high-leakage-reactance transformer being configured to have a short-circuit voltage relative to a rated voltage that is at least 20% when a secondary winding is shorted;

said transformer having one secondary-side connection per phase;

a respective module series circuit connected between each of said secondary-side connections of said transformer and said star point of said star circuit, said module series circuit including at least two series-connected switching modules each having at least four switches and a capacitor.

2. The power factor correction device according to claim 1 , wherein each said module series circuit is inductor-free.

3. The power factor correction device according to claim 1 , wherein each said module series circuit is air-cored-inductor-free.

4. The power factor correction device according to claim 1 , wherein said high-leakage-reactance transformer has a secondary side with a star winding forming said star point and a primary side with a delta winding forming primary-side transformer connections of said high-leakage-reactance transformer.

5. The power factor correction device according to claim 4 , further comprising a switching device connected between each outer system connection of the power factor correction device and said primary-side transformer connections of said high-leakage-reactance transformer or between each of said secondary-side transformer connections and an associated said module series circuit, wherein said switching device has a series circuit with a first switch and a parallel circuit with a nonreactive resistor and a second switch connected in parallel therewith.

6. The power factor correction device according to claim 5 , further comprising a control device configured:

to leave said first and second switches in an open switch position when the power factor correction device is switched off;

to first close said first switch and leave said second switch open in a first sequence step when the power factor correction device is started up, and then to close said second switch in a subsequent second sequence step when the power factor correction device is started up.

7. The power factor correction device according to claim 1 , wherein each said module series circuit has, in addition to said switching modules, an impedance connected in series with said switching modules and/or a capacitor.

8. The power factor correction device according to claim 1 , wherein said high-leakage-reactance transformer and said module series circuits are physically accommodated in a room sealed from an exterior.

9. The power factor correction device according to claim 8 , wherein all electrical components of the power factor correction device are physically accommodated in a single building or a single enclosure that is sealed towards the exterior.

10. The power factor correction device according to claim 1 , wherein each said module series circuits includes a series resonant circuit connected in series with said switching modules, said series resonant circuit having a resonant frequency three times a system frequency or an integer multiple of three times the system frequency.

11. The power factor correction device according to claim 10 , wherein at least one of said series resonant circuits comprises an inductance and a capacitor connected in series therewith or said at least one series circuit consists of said inductance and said capacitor.

12. The power factor correction device according to claim 11 , wherein said inductance is an inductance having an iron core.

13. The power factor correction device according to claim 1 , wherein said switching modules are H-bridge modules each with four semiconductor switching elements having a respective diode connected in parallel therewith, and a capacitor.

14. The power factor correction device according to claim 1 , which comprises an impedance and/or a capacitor connected between said secondary-side star point of said high-leakage-reactance transformer and an electrical connecting point for said module series circuits.

15. The power factor correction device according to claim 14 , wherein said impedance is an inductance having an iron core.

16. A power factor correction device for an AC grid system, comprising:

a high-leakage-reactance transformer having a secondary side connected up in a star point circuit with a star point;

said transformer having one secondary-side connection per phase;

a respective module series circuit connected between each of said secondary-side connections of said transformer and said star point of said star circuit, said module series circuit including at least two series-connected switching modules each having at least four switches and a capacitor; and

secondary-side leakage inductances acting on said secondary-side connections and being influenced by leakage fields of said high-leakage-reactance transformer, and wherein each of said secondary-side leakage inductances is in series with said module series circuit connected to the respective said secondary-side connection of said transformer.

17. A power factor correction device for an AC grid system, comprising:

a high-leakage-reactance transformer having a secondary side connected up in a star point circuit with a star point;

said transformer having one secondary-side connection per phase;

a respective module series circuit connected between each of said secondary-side connections of said transformer and said star point of said star circuit, said module series circuit including at least two series-connected switching modules each having at least four switches and a capacitor; and

each said module series circuit having, in addition to said switching modules, an impedance being an inductance having an iron core connected in series with said switching modules and/or a capacitor.