Wind turbine transformer control

Patent metadata

Field	Value
Publication number	US-12346140-B2
Application number	US-202017613193-A
Country	US
Kind code	B2
Filing date	May 12, 2020
Priority date	May 24, 2019
Publication date	Jul 1, 2025
Grant date	Jul 1, 2025

Abstract

A method of controlling a wind turbine transformer is provided. The transformer has a primary side with a primary winding coupled to a power grid and a secondary side with a secondary winding coupled to an electrical power generating system of the wind turbine. The wind turbine transformer further includes an electronic on-load tap changer having semiconductor switches that are controllable to change a turns ratio of the primary winding to the secondary winding of the wind turbine transformer. The method includes the step of monitoring a voltage on the primary side of the wind turbine transformer, a voltage on the secondary side of the wind turbine transformer, or both. In response to detecting a change in the monitored voltage, the semiconductor switches of the electronic on-load tap changer are automatically controlled to adjust the turns ratio of the wind turbine transformer to compensate for the change.

First claim

The invention claimed is:

1. A method of controlling a wind turbine transformer, comprising:
providing the wind turbine transformer, the wind turbine transformer having a primary side with a primary winding coupled to a power grid and a secondary side with a secondary winding coupled to an electrical power generating system of the wind turbine, wherein the wind turbine transformer further comprises an electronic on-load tap changer having semiconductor switches that are controllable to change a turns ratio of the primary winding to the secondary winding of the wind turbine transformer, wherein the electronic on-load tap changer includes at least one, or at least two tap changer modules, wherein each tap changer module comprises a first arm connected at one end to a first tap of the respective transformer winding and a second arm connected at one end to a second tap of the respective transformer winding, wherein the other ends of the first and second arms are connected together at a connection point, and wherein the tap changer module further includes a third arm connected at one end to a third tap of the respective transformer winding and at its other end to the connection point, wherein in at least two of the three arms, a changeover impedance is connected in series with the respective semiconductor switch, wherein a control system is coupled to the electronic on-load tap changer to control the turns ratio, wherein the control system comprises a converter controller of a converter of the electrical power generating system, wherein the converter controller controls the electronic on-load tap changer,
monitoring a voltage on the primary side of the wind turbine transformer, a voltage on the secondary side of the wind turbine transformer, or both;
detecting a change in the monitored voltage; and
automatically controlling the semiconductor switches of the electronic on-load tap changer to adjust the turns ratio of the wind turbine transformer to directly compensate for the change in the monitored voltage, wherein directly compensating for the change in the monitored voltage includes adjusting the turns ratio of the transformer so as to keep the voltage on the secondary side of the transformer within a predetermined voltage range, and wherein directly compensating for the change in the monitored voltage is independent of a current reference and/or is independent of current monitoring.

2. The method of claim 1 , wherein at least the voltage on the primary side of the wind turbine transformer is monitored, wherein upon detecting a voltage increase in the monitored voltage, the semiconductor switches of the electronic on-load tap changer are controlled to increase the turns ratio so as to maintain the voltage on the secondary side below a predefined upper voltage limit, and/or wherein upon detecting a voltage drop in the monitored voltage, the semiconductor switches of the electronic on-load tap changer are controlled to decrease the turns ratio so as to maintain the voltage on the secondary side above a predefined lower voltage limit.

3. The method of claim 1 , wherein at least the voltage on the secondary side of the wind turbine transformer is monitored, wherein monitoring the voltage on the secondary side of the wind turbine transformer comprises measuring the voltage on the secondary side of the wind turbine transformer, wherein upon determining a voltage change in the monitored voltage on the secondary side, the semiconductor switches of the electronic on-load tap changer are controlled to adjust the turns ratio so as to compensate the change.

4. The method according to claim 1 , wherein controlling the semiconductor switches of the electronic on-load tap changer to adjust the turns ratio of the wind turbine transformer comprises determining a new tap setting required to obtain the adjusted turns ratio, and switching the semiconductor switches within 500 ms upon detecting the change in the monitored voltage, or within 300 ms, 200 ms or 100 ms upon detecting the change in the monitored voltage, to change the tap of the electronic on-load tap changer to the new tap setting.

5. The method according to claim 1 , wherein adjusting the turns ratio of the wind turbine transformer by controlling the semiconductor switches comprises changing a current path through the primary winding and/or through the secondary winding from the first tap to the second tap, wherein changing the current path comprises closing a second semiconductor switch coupled to the second tap to provide a connection from the first tap to the second tap via the second semiconductor switch and via a changeover impedance.

6. The method according to claim 5 , wherein adjusting the turns ratio further comprises opening a first semiconductor switch coupled to the first tap to interrupt the connection from the first tap to the second tap via the changeover impedance, the second semiconductor switch remaining closed and forming part of the current path.

7. The method according to claim 1 , wherein controlling the semiconductor switches to adjust the turns ratio of the transformer comprises switching the semiconductor switches at a zero-crossing of a current through the respective semiconductor switch that is to be switched.

8. The method according to claim 1 , wherein detecting the change in the monitored voltage and automatically controlling the semiconductor switches of the electronic on-load tap changer to adjust the turns ratio of the wind turbine transformer to compensate for the change comprises:
detecting if the voltage on the secondary side of the transformer reaches or exceeds a predefined upper or lower voltage limit; and
if the predefined upper or lower voltage limit is reached or exceeded, adjusting the turns ratio of the wind turbine transformer so as to keep the voltage on the secondary side of the transformer within a voltage range determined by the upper and lower voltage limits.

9. A wind turbine electrical system comprising:
a transformer comprising a primary side with a primary winding configured to be coupled to a power grid and a secondary side with a secondary winding configured to be coupled to an electrical power generating system of the wind turbine, wherein the wind turbine transformer further comprises an electronic on-load tap changer, wherein the electronic on-load tap changer comprises semiconductor switches that are connected and configured such that by controlling the semiconductor switches, a turns ratio of the primary winding to the secondary winding of the wind turbine transformer is adjustable to compensate for voltage changes on the primary side and/or the secondary side of the wind turbine transformer; and
a control system coupled to the electronic on-load tap changer to control the turns ratio, wherein the control system comprises a converter controller of a converter of the wind turbine electrical system, wherein the converter controller is configured to control the electronic on-load tap changer, wherein the control system is configured to perform:
monitoring a voltage on the primary side of the wind turbine transformer, a voltage on the secondary side of the wind turbine transformer, or both; and
in direct response to a change in the monitored voltage, automatically controlling the semiconductor switches of the electronic on-load tap changer to adjust the turns ratio of the wind turbine transformer to compensate for the change in the monitored voltage, wherein compensating for the change in the monitored voltage includes adjusting the turns ratio of the transformer so as to keep the voltage on the secondary side of the transformer within a predetermined voltage range, wherein compensating for the change in the monitored voltage is independent of a current

Assignees

• Siemens Gamesa Renewable Energy Innovation & Technology SL

Inventors

• Rebollo López Emilio David
• Barrenetxea Iñarra Manex
• Canales Segade Jose María
• Linares Fano Miguel
• Santodomingo Llamas Fernando

Classifications

• H02J2101/28

  Wind energy · CPC title

• H02J3/1878

  using tap changing or phase shifting transformers · CPC title

• Y02E40/30

  Reactive power compensation · CPC title

• Y02E10/76

  Power conversion electric or electronic aspects · CPC title

• H02J3/381

  Dispersed generators · CPC title