Method and device for controlling generator-side terminal voltage of converter, and controller of converter

Patent metadata

Field	Value
Publication number	US-11967918-B2
Application number	US-202017782754-A
Country	US
Kind code	B2
Filing date	May 26, 2020
Priority date	Dec 6, 2019
Publication date	Apr 23, 2024
Grant date	Apr 23, 2024

Abstract

The present application provides a method and device for controlling a generator-side terminal voltage of a converter, and a controller of the converter. The method includes: determining an upper limit of the generator-side terminal voltage based on a present voltage value of a direct-current (DC) bus of the converter, where the generator-side terminal voltage is a voltage of an output terminal of a generator, and the output terminal is connected to the converter; determining an optimal value of the generator-side terminal voltage that minimizes a present value of a generator-side current, where the generator-side current is a current of the output terminal of the generator; setting a target value of the generator-side terminal voltage based on the upper limit and the optimal value of the generator-side terminal voltage. The target value includes a control reference value of the generator-side terminal voltage.

First claim

The invention claimed is:

1. A method for controlling a generator-side terminal voltage of a converter, the method comprising:
determining an upper limit of the generator-side terminal voltage based on a present voltage value of a direct-current (DC) bus of the converter, wherein the generator-side terminal voltage is a voltage of an output terminal of a generator, and the output terminal of the generator is connected to the converter;
determining an optimal value of the generator-side terminal voltage from a preset optimal search interval, wherein the optimal value minimizes a present value of a generator-side current when compared with other values in the preset optimal search interval, wherein the generator-side current is a current of the output terminal of the generator; and
setting a target value of the generator-side terminal voltage based on the upper limit of the generator-side terminal voltage and the optimal value of the generator-side terminal voltage, wherein the target value is used to obtain a control reference value of the generator-side terminal voltage,
wherein determining the optimal value of the generator-side terminal voltage comprises:
determining whether a present value of the generator-side terminal voltage falls into the preset optimal search interval; and
responsive to the present value of the generator-side terminal voltage falling into the preset optimal search interval, searching in the preset optimal search interval for the optimal value of the generator-side terminal voltage that minimizes the present value of the generator-side current; and

wherein searching in the preset optimal search interval for the optimal value of the generator-side terminal voltage that minimizes the present value of the generator-side current comprises:
step (a): setting the target value of the generator-side terminal voltage to an initial value, and obtaining a value I0 of the generator-side current and a given torque value T0 of the generator after the generator-side terminal voltage is stable;
step (b): updating the target value of the generator-side terminal voltage as a sum of the initial value and ΔU, and when the generator-side terminal voltage is stable and the given torque value is T0, determining whether a value I1 of the generator-side current is less than I0, wherein when I1 is greater than I0, step (c) is performed, or, when I1 is less than I0, step (e) is performed;
step (c): updating the target value of the generator-side terminal voltage as a difference between the initial value and ΔU, and when the generator-side terminal voltage is stable and the given torque value is T0, determining whether a value I2 of the generator-side current is less than I0, wherein when I2 is greater than I0, the initial value is determined as the optimal value of the generator-side terminal voltage that minimizes the present value of the generator-side current, or, when I2 is less than I0, step (d) is performed;
step (d): reducing the target value of the generator-side terminal voltage by ΔU, and when the generator-side terminal voltage is stable and the given torque value is T0, determining whether the present value of the generator-side current is smaller than a previous value of the generator-side current, wherein when the present value of the generator-side current is not smaller than the previous value of the generator-side current, the target value of the generator-side terminal voltage is determined as the optimal value of the generator-side terminal voltage, or, when the present value of the generator-side current is smaller than the previous value of the generator-side current, step (d) is repeated; and
step (e): increasing the target value of the generator-side terminal voltage by ΔU, and when the generator-side terminal voltage is stable and the given torque value is T0, determining whether the present value of the generator-side current is smaller than the previous value of the generator-side current, wherein when the present value of the generator-side current is not smaller than the previous value of the generator-side current, the target value of the generator-side terminal voltage is determined as the optimal value of the generator-side terminal voltage or, when the present value of the generator-side current is smaller than the previous value of the generator-side current, step (e) is repeated,
wherein ΔU is greater than 0.

2. The method according to claim 1 , wherein setting the target value of the generator-side terminal voltage comprises:
when the optimal value of the generator-side terminal voltage exceeds the upper limit of the generator-side terminal voltage, setting the target value of the generator-side terminal voltage to be equal to the upper limit of the generator-side terminal voltage; or
when the optimal value of the generator-side terminal voltage does not exceed the upper limit of the generator-side terminal voltage, setting the target value of the generator-side terminal voltage to be equal to the optimal value of the generator-side terminal voltage.

3. The method according to claim 1 , wherein determining the upper limit of the generator-side terminal voltage further comprises:
determining the upper limit of the generator-side terminal voltage further based on at least one of a preset maximum availability of a voltage of the DC bus, a voltage loss corresponding to a dead time of an Insulate-Gate Bipolar Transistor (IGBT) module in a generator-side rectifier unit of the converter, or an on-state voltage drop of the IGBT module in the generator-side rectifier unit of the converter.

4. A controller of a converter, comprising:
a processor; and
a memory having computer programs stored thereon, wherein the computer programs, when executed by the processor, implement a method for controlling a generator-side terminal voltage of the converter, the method comprising:
determining an upper limit of the generator-side terminal voltage based on a present voltage value of a direct-current (DC) bus of the converter, wherein the generator-side terminal voltage is a voltage of an output terminal of a generator, and the output terminal of the generator is connected to the converter;
determining an optimal value of the generator-side terminal voltage from a preset optimal search interval, wherein the optimal value minimizes a present value of a generator-side current when compared with other values in the preset optimal search interval, wherein the generator-side current is a current of the output terminal of the generator; and

setting a target value of the generator-side terminal voltage based on the upper limit of the generator-side terminal voltage and the optimal value of the generator-side terminal voltage, wherein the target value is used to obtain a control reference value of the generator-side terminal voltage,
wherein determining the optimal value of the generator-side terminal voltage comprises:
determining whether a present value of the generator-side terminal voltage falls into the preset optimal search interval; and
responsive to the present value of the generator-side terminal voltage falling into the preset optimal search interval, searching in the preset optimal search interval for the optimal value of the generator-side terminal voltage that minimizes the present value of the generator-side current; and

wherein searching in the preset optimal search interval for the optimal value of the generator-side terminal voltage that minimizes the present value of the generator-side current comprises:
step (a): setting the target value of the generator-side terminal voltage to an initial value, and obtaining a value I0 of the generator-side current and a given torque value T0 of the generator after the generator-side terminal voltage is stable;
step (b): updating the target value of the generator

Assignees

• Xinjiang Goldwind Science & Tech Co Ltd
• Goldwind Science & Technology

Inventors

• Wang Jinpeng
• Guo Rui
• Lv Liangnian

Classifications

• H02P9/14 Primary

  by variation of field (H02P9/08, H02P9/10 take precedence) · CPC title

• H02P9/48 Primary

  Arrangements for obtaining a constant output value at varying speed of the generator, e.g. on vehicle (H02P9/04 - H02P9/46 take precedence) · CPC title

• H02P2103/20

  of the synchronous type · CPC title

• H02P2101/15

  for wind-driven turbines · CPC title