Power conversion device simulating a synchronous generator

Patent metadata

Field	Value
Publication number	US-12549110-B2
Application number	US-202118567806-A
Country	US
Kind code	B2
Filing date	Jun 24, 2021
Priority date	Jun 24, 2021
Publication date	Feb 10, 2026
Grant date	Feb 10, 2026

Abstract

A power conversion device includes a power converter and a control device. The power converter converts a DC power output from a power storage element into an AC power. The control device includes a phase synchronizing unit to estimate a reference phase of an output voltage of the power converter synchronized with a phase of an AC voltage at an interconnection point, a characteristics simulating unit to generate an active power command value based on a phase difference between a reference phase and the phase of the AC voltage at the interconnection point, a DC voltage command generating unit to generate a DC voltage command value, a voltage command generating unit to generate an AC voltage command value so that an output current of the power converter becomes less than a threshold, and a signal generating unit to generate a control signal based on the AC voltage command value.

First claim

The invention claimed is:

1 . A power conversion device comprising:
a power converter to perform power conversion between a power storage element and a power grid; and a control device to control the power converter, wherein the power converter converts a DC power output from the power storage element into an AC power and outputs the AC power to the power grid, the control device includes
a phase synchronizing unit to estimate a reference phase of an output voltage of the power converter synchronized with a phase of an AC voltage at an interconnection point between the power grid and the power converter, based on the AC voltage at the interconnection point,
a characteristics simulating unit to generate an active power command value for the power converter by simulating characteristics of a synchronous generator based on a phase difference between the reference phase estimated by the phase synchronizing unit and the phase of the AC voltage at the interconnection point,
a DC voltage command generating unit to generate a DC voltage command value for the power converter, based on the active power command value and a DC voltage of the power storage element,
a voltage command generating unit to generate an AC voltage command value for the power converter so that an output current of the power converter becomes less than a threshold, based on the DC voltage command value, a grid voltage command value indicating a target value of the AC voltage at the interconnection point, and the reference phase, and
a signal generating unit to generate a control signal for the power converter, based on the AC voltage command value.

2 . The power conversion device according to claim 1 , wherein
the voltage command generating unit includes
a DC voltage control unit to generate an active current command value for allowing the DC voltage to follow the DC voltage command value,
a grid voltage control unit to generate a reactive current command value for allowing the AC voltage at the interconnection point to follow the grid voltage command value, and
an AC current control unit to calculate an active component and a reactive component of an AC current flowing between the interconnection point and the power converter, based on the reference phase and the AC current, and generate an active voltage command value for allowing the active component to follow the active current command value and a reactive voltage command value for allowing the reactive component to follow the reactive current command value, and
the AC voltage command value includes the active voltage command value and the reactive voltage command value.

3 . The power conversion device according to claim 2 , wherein the active current command value is limited to within a range in accordance with an active current limit value, and the reactive current command value is limited to within a range in accordance with a reactive current limit value.

4 . The power conversion device according to claim 3 , wherein the phase synchronizing unit outputs the reference phase to the voltage command generating unit and outputs the phase difference to the characteristics simulating unit.

5 . The power conversion device according to claim 3 , wherein
the phase synchronizing unit includes
a first phase output unit to output the phase difference to the characteristics simulating unit, and
a second phase output unit to output the reference phase to the voltage command generating unit, and
a response of the first phase output unit is set to be slower than a response of the second phase output unit.

6 . The power conversion device according to claim 2 , wherein the phase synchronizing unit outputs the reference phase to the voltage command generating unit and outputs the phase difference to the characteristics simulating unit.

7 . The power conversion device according to claim 2 , wherein
the phase synchronizing unit includes
a first phase output unit to output the phase difference to the characteristics simulating unit, and
a second phase output unit to output the reference phase to the voltage command generating unit, and
a response of the first phase output unit is set to be slower than a response of the second phase output unit.

8 . The power conversion device according to claim 1 , wherein
the voltage command generating unit includes
a DC voltage control unit to generate a first active current command value for allowing the DC voltage to follow the DC voltage command value,
a grid voltage control unit to generate a reactive current command value for allowing the AC voltage at the interconnection point to follow the grid voltage command value, and
a computing element to calculate a second active current command value by dividing the active power command value by the AC voltage at the interconnection point, and calculate a third active current command value by adding the first active current command value and the second active current command value, and
an AC current control unit to calculate an active component and a reactive component of an AC current flowing between the interconnection point and the power converter, based on the reference phase and the AC current, and generate an active voltage command value for allowing the active component to follow the third active current command value and a reactive voltage command value for allowing the reactive component to follow the reactive current command value, and
the AC voltage command value includes the active voltage command value and the reactive voltage command value.

9 . The power conversion device according to claim 8 , wherein the third active current command value is limited to within a range in accordance with an active current limit value, and the reactive current command value is limited to within a range in accordance with a reactive current limit value.

10 . The power conversion device according to claim 9 , wherein the phase synchronizing unit outputs the reference phase to the voltage command generating unit and outputs the phase difference to the characteristics simulating unit.

11 . The power conversion device according to claim 9 , wherein
the phase synchronizing unit includes
a first phase output unit to output the phase difference to the characteristics simulating unit, and
a second phase output unit to output the reference phase to the voltage command generating unit, and
a response of the first phase output unit is set to be slower than a response of the second phase output unit.

12 . The power conversion device according to claim 8 , wherein the phase synchronizing unit outputs the reference phase to the voltage command generating unit and outputs the phase difference to the characteristics simulating unit.

13 . The power conversion device according to claim 8 , wherein
the phase synchronizing unit includes
a first phase output unit to output the phase difference to the characteristics simulating unit, and
a second phase output unit to output the reference phase to the voltage command generating unit, and
a response of the first phase output unit is set to be slower than a response of the second phase output unit.

14 . The power conversion device according to claim 1 , wherein the phase synchronizing unit outputs the reference phase to the voltage command generating unit and outputs the phase difference to the characteristics simulating unit.

15 . The power conversion device according to claim 1 , wherein
the phase synchronizing unit includes
a first phase output unit to output the phase difference to the characteristics simulating unit, and
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Assignees

• Mitsubishi Electric Corp

Inventors

• Fujii Toshiyuki
• MUKUNOKI Kaho
• Ishihara Hiroki
• Uda Ryosuke
• Hamanaka Kota

Classifications

• H02J3/381

  Dispersed generators · CPC title

• H02M1/0003

  Details of control, feedback or regulation circuits · CPC title

• H02M7/79

  using devices of a triode or transistor type requiring continuous application of a control signal · CPC title

• Y02E10/56

  Power conversion systems, e.g. maximum power point trackers · CPC title

• H02J3/32

  using batteries or super capacitors with converting means · CPC title