Reactive power compensation device

Patent metadata

Field	Value
Publication number	US-12355245-B2
Application number	US-202018031010-A
Country	US
Kind code	B2
Filing date	Oct 21, 2020
Priority date	Oct 21, 2020
Publication date	Jul 8, 2025
Grant date	Jul 8, 2025

Abstract

A reactive power compensation device includes a power converter and a converter control unit, and compensates reactive power of an AC power grid by output reactive power of the power converter. The converter control unit includes an AC voltage detection unit and an output limit unit. The AC voltage detection unit detects voltage information of the AC power grid to which the power converter is connected. The output limit unit determines whether or not the output reactive power of the power converter needs to be limited, on the basis of the voltage information detected by the AC voltage detection unit, and in a case where the output reactive power needs to be limited, limits the output reactive power of the power converter.

First claim

The invention claimed is:

1. A reactive power compensation device comprising:
a power converter connected to an AC power grid with a plurality of phases, and having a self-turn-off switching element; and
a converter control circuitry which controls the switching element of the power converter, wherein
reactive power of the AC power grid is compensated by output reactive power of the power converter,
the converter control circuitry includes an AC voltage detection circuitry and an output limit circuitry,
the AC voltage detection circuitry detects voltage information of the AC power grid to which the power converter is connected,
the AC voltage detection circuitry includes a positive-phase-sequence voltage detection circuitry for detecting positive-phase-sequence voltage of grid voltage of the AC power grid, and
the output limit circuitry determines whether or not the output reactive power of the power converter needs to be limited, on the basis of the voltage information detected by the AC voltage detection circuitry including the positive-phase-sequence voltage detected by the positive-phase-sequence voltage detection circuitry, and in a case where the output reactive power needs to be limited, limits the output reactive power of the power converter.

2. The reactive power compensation device according to claim 1 , wherein
in the case where the output reactive power needs to be limited, the output limit circuitry limits the output reactive power of the power converter so that output voltage of the power converter is kept within an output possible range of the power converter.

3. The reactive power compensation device according to claim 2 , wherein
in the case where the output reactive power of the power converter needs to be limited, the output limit circuitry limits output reactive current of the power converter.

4. The reactive power compensation device according to claim 3 , wherein
the AC voltage detection circuitry calculates a reactive current reference value on the basis of the positive-phase-sequence voltage detected by the positive-phase-sequence voltage detection circuitry and a voltage command value for the power converter, and
the output limit circuitry subtracts a reactive current subtraction amount from the reactive current reference value, to calculate a reactive current command value, thus limiting the output reactive current of the power converter.

5. The reactive power compensation device according to claim 4 , wherein
the output limit circuitry subtracts the reactive current subtraction amount set in advance on the basis of an impedance of the AC power grid, from the reactive current reference value, to calculate the reactive current command value, thus limiting the output reactive current of the power converter.

6. The reactive power compensation device according to claim 2 , wherein
the AC voltage detection circuitry detects magnitudes of voltages for the respective phases of grid voltage of the AC power grid, and
the output limit circuitry calculates a maximum value among the magnitudes of the voltages for the respective phases detected by the AC voltage detection circuitry, and determines whether or not the output reactive power of the power converter needs to be limited, on the basis of the maximum value among the magnitudes of the voltages for the respective phases.

7. The reactive power compensation device according to claim 1 , wherein
in the case where the output reactive power of the power converter needs to be limited, the output limit circuitry limits output reactive current of the power converter.

8. The reactive power compensation device according to claim 7 , wherein
the AC voltage detection circuitry calculates a reactive current reference value on the basis of the positive-phase-sequence voltage detected by the positive-phase-sequence voltage detection circuitry and a voltage command value for the power converter, and
the output limit circuitry subtracts a reactive current subtraction amount from the reactive current reference value, to calculate a reactive current command value, thus limiting the output reactive current of the power converter.

9. The reactive power compensation device according to claim 8 , wherein
the output limit circuitry subtracts the reactive current subtraction amount set in advance on the basis of an impedance of the AC power grid, from the reactive current reference value, to calculate the reactive current command value, thus limiting the output reactive current of the power converter.

10. The reactive power compensation device according to claim 9 , wherein
the AC voltage detection circuitry detects magnitudes of voltages for the respective phases of grid voltage of the AC power grid, and
the output limit circuitry calculates a maximum value among the magnitudes of the voltages for the respective phases detected by the AC voltage detection circuitry, and determines whether or not the output reactive power of the power converter needs to be limited, on the basis of the maximum value among the magnitudes of the voltages for the respective phases.

11. The reactive power compensation device according to claim 8 , wherein
the AC voltage detection circuitry detects magnitudes of voltages for the respective phases of grid voltage of the AC power grid, and
the output limit circuitry calculates a maximum value among the magnitudes of the voltages for the respective phases detected by the AC voltage detection circuitry, and determines whether or not the output reactive power of the power converter needs to be limited, on the basis of the maximum value among the magnitudes of the voltages for the respective phases.

12. The reactive power compensation device according to claim 7 , wherein
the AC voltage detection circuitry detects magnitudes of voltages for the respective phases of grid voltage of the AC power grid, and
the output limit circuitry calculates a maximum value among the magnitudes of the voltages for the respective phases detected by the AC voltage detection circuitry, and determines whether or not the output reactive power of the power converter needs to be limited, on the basis of the maximum value among the magnitudes of the voltages for the respective phases.

13. The reactive power compensation device according to claim 1 , wherein
the power converter includes three arms connected to the AC power grid,
each of the arms is formed such that one unit cell or a plurality of unit cells connected in cascade, and a reactor, are connected in series, and
the unit cell includes a series unit composed of a plurality of the switching elements connected in series to each other, and a DC capacitor connected in parallel to the series unit.

14. The reactive power compensation device according to claim 13 , wherein
the three arms are delta-connected.

15. The reactive power compensation device according to claim 13 , wherein
the unit cell has a full-bridge configuration in which a plurality of the series units each composed of the switching elements are connected in parallel.

16. A reactive power compensation device comprising:
a power converter connected to an AC power grid with a plurality of phases, and having a self-turn-off switching element; and
a converter control circuitry which controls the switching element of the power converter, wherein
reactive power of the AC power grid is compensated by output reactive power of the power converter,
the converter control circuitry includes an AC voltage detection circuitry and an output limit circuitry,
the AC voltage detection circuitry detects magni

Assignees

• Mitsubishi Electric Corp
• Toshiba Mitsubishi Electric Industrial Systems Corp
• Tmeic Corp

Inventors

• MUKUNOKI Kaho
• Fujii Toshiyuki
• Matsuda Akihiro
• Okuyama Ryota

Classifications

• Y02E40/30

  Reactive power compensation · CPC title

• H02J3/16

  by adjustment of reactive power · CPC title

• G05F1/70 Primary

  Regulating power factor; Regulating reactive current or power · CPC title

• H02J3/1864

  using reactive elements connected in series with semiconductor switches, e.g. static VAR compensators [SVC], thyristor-controlled reactors [TCR] or thyristor-switched capacitors [TSC] · CPC title

• H02J3/1857 Primary

  the bridge converters being multilevel bridge converters or modular multilevel converters · CPC title