System and method for stabilizing sub-synchronous interaction of a wind turbine generator

Patent metadata

Field	Value
Publication number	US-9941828-B2
Application number	US-201514633452-A
Country	US
Kind code	B2
Filing date	Feb 27, 2015
Priority date	Feb 27, 2015
Publication date	Apr 10, 2018
Grant date	Apr 10, 2018

Abstract

The present disclosure is directed to a system and method for stabilizing sub-synchronous interaction (SSI) of a wind turbine generator connected to a power grid. More specifically, the method includes measuring an alternating-current (a-c) quantity of the power grid. Another step includes converting the a-c quantity to a d-q quantity and providing the d-q quantity to a d-q control loop within the controller. Another step includes altering, with a symmetric control component, a transfer function of the d-q control loop. The method also includes generating at least one d-q reference signal for the wind turbine generator based on the altered transfer function so as to achieve symmetric control of the generator. A further step includes generating a control signal for the generator based, at least in part, on the at least one d-q reference signal. The method also includes operating the generator based on the control signal.

First claim

What is claimed is:

1. A method for operating a wind turbine generator connected to a power grid using direct-quadrature (d-q) control technology, the wind turbine generator having a stator and a rotor, the rotor being coupled to the power grid via a power conversion assembly, the power conversion assembly having a rotor-side power converter and a grid-side power converter, the method comprising:
measuring an alternating-current (a-c) quantity of the power grid; converting the a-c quantity to a d-q quantity in a controller of the wind turbine generator;
providing the d-q quantity to a d-q control loop within the controller;
calculating, via the d-q control loop, a q-axis current reference via a voltage input path by determining an error signal using a terminal voltage of the wind turbine generator and filtering the error signal using a first symmetric control filter using a blocking frequency or a blocking frequency range, the q-axis current reference regulating voltage of the wind turbine generator;
calculating, via the d-q control loop, a d-axis current reference via a torque input path as a function of a torque reference and a magnetic flux, the d-axis current reference regulating torque of the wind turbine generator;
determining the magnetic flux by filtering the terminal voltage of the wind turbine generator using a second symmetric control filter using the blocking frequency or the blocking frequency range, the second symmetric control filter being outside of the torque input path;
determining a control signal for the wind turbine generator as a function of the d-axis current reference and the q-axis current reference via the rotor-side converter;
and, operating the wind turbine generator based on the control signal so as to stabilize sub-synchronous interaction of the wind turbine generator.

2. The method of claim 1 , wherein the first and second filters each comprise at least one of a notch filter, a low-pass filter, a high-pass filter, or combinations thereof.

3. The method of claim 1 , wherein the wind turbine generator comprises a doubly-fed generator, wherein the control loop is configured to control a voltage of the rotor via the rotor-side power converter.

4. The method of claim 1 , wherein the control signal comprises at least one of a current signal or a voltage signal.

5. The method of claim 1 , wherein determining the magnetic flux further comprises multiplying the filtered terminal voltage by a multiplier.

6. A method for improving sub-synchronous interaction (SSI) damping of a doubly-fed generator of a wind turbine connected to a power grid, the generator having a stator and a rotor, the rotor being coupled to the power grid via a power conversion assembly, the power conversion assembly having a rotor-side power converter and a grid-side power converter, the method comprising:
calculating, via the d-q control loop, a q-axis current reference via a voltage input path by determining an error signal using a terminal voltage of the wind turbine generator and filtering the error signal using a first symmetric control filter using a blocking frequency or a blocking frequency range, the q-axis current reference regulating voltage of the wind turbine generator;
calculating, via the d-q control loop, a d-axis current reference via a torque input path as a function of a torque reference and a magnetic flux, the d-axis current reference regulating torque of the wind turbine generator;
determining the magnetic flux by filtering the terminal voltage of the wind turbine generator using a second symmetric control filter using the blocking frequency or the blocking frequency range, the second symmetric control filter being outside of the torque input path;
determining a control signal for the wind turbine generator as a function of the d-axis current reference and the q-axis current reference via the rotor-side converter;
and, operating the wind turbine generator based on the control signal.

7. A system for operating a doubly-fed generator connected to a power grid using direct-quadrature (d-q) control technology, the generator having a stator and a rotor, the rotor being coupled to the power grid via a power conversion assembly, the power conversion assembly having a rotor-side power converter and a grid-side power converter, the system comprising:
one or more sensors configured to measure an alternating-current (a-c) quantity of the power grid;
a controller communicatively coupled to a processor, the processor comprising a d-q control loop having at least one symmetric control component, the d-q control loop being configured to perform one or more operations, the one or more operations comprising:
converting the a-c quantity to a d-q quantity:
providing the d-q quantity to a d-q control loop within the controller;
calculating, via the d-q control loop, a q-axis current reference via a voltage input path by determining an error signal using a terminal voltage of the wind turbine generator and filtering the error signal using a first symmetric control filter using a blocking frequency or a blocking frequency range, the q-axis current reference regulating voltage of the wind turbine generator;
calculating, via the d-q control loop, a d-axis current reference via a torque input path as a function of a torque reference and a magnetic flux, the d-axis current reference regulating torque of the wind turbine generator;
determining the magnetic flux by filtering the terminal voltage of the wind turbine generator using a second symmetric control filter using the blocking frequency or the blocking frequency range, the second symmetric control filter being outside of the torque input path;
determining a voltage-current signal for the wind turbine generator as a function of the d-axis current reference and the q-axis current reference via the rotor-side converter;
and, operating the wind turbine generator based on the voltage-current signal so as to stabilize sub-synchronous interaction of the wind turbine generator.

8. The system of claim 7 , wherein the first and second symmetric control filters comprise at least one of a notch filter, a low-pass filter, a high-pass filter, or combinations thereof.

9. The system of claim 7 , wherein determining the magnetic flux further comprises multiplying the filtered terminal voltage by a multiplier.

Assignees

• Gen Electric

Inventors

• Ren Wei
• Larsen Einar Vaughn

Classifications

• H02P9/007

  Control circuits for doubly fed generators · CPC title

• H02P9/105 Primary

  for increasing the stability · CPC title

• F03D9/255

  connected to electrical distribution networks; Arrangements therefor · CPC title

• H02J3/002

  Flicker reduction, e.g. compensation of flicker introduced by non-linear load · CPC title

• F03D7/00 Primary

  Controlling wind motors  (supplying or distributing electrical power H02J, e.g. arrangements for adjusting, eliminating or compensating reactive power in networks H02J3/18; controlling electric generators H02P, e.g. arrangements for controlling electric generators for the purpose of obtaining a desired output H02P9/00) · CPC title