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Coordinated Pitch and Generator Control for Wind Turbine Flexible Power Tracking

IP.com Disclosure Number: IPCOM000239785D
Publication Date: 2014-Dec-02

Publishing Venue

The IP.com Prior Art Database

Related People

Xing Huang: AUTHOR [+2]

Abstract

The invention is composed of method and system for coordinating the pitch and the generator controls of wind turbine to realize flexible power tracking. With the proposed method, the output power of wind turbine can be regulated by pitch control system and/or the generator control system, in order to ensure the steady-state power balance and the dynamic response for power tracking, to limit the mechanical stress so as to extend the life cycle of wind turbine.

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Disclosure Title:

Coordinated WTG pitch and generator control for flexible power tracking

Abstract of Invention:

The invention is composed of method and system for coordinating the pitch and the generator controls of wind turbine to realize flexible power tracking. With the proposed method, the output power of wind turbine can be regulated by pitch control system and/or the generator control system, in order to ensure the steady-state power balance and the dynamic response for power tracking, to limit the mechanical stress so as to extend the life cycle of wind turbine.

Background of the Invention:

Morden wind turbines have pitch and generator control systems to regulate the output power. Normally, the control methods for pitch and generator control systems will be designed to realize Maximum Power Point Tracking (MPPT), i.e. to output the power as much as possible at a given wind speed. More specifically:

When the wind speed is lower than the rated speed, the pitch angle will be controlled to be fully open to take the wind power as much as possible; the speed of the generator will be controlled to follow an optimal Tip Speed Ratio (TSR = wR/v, w and R are the angular frequency and the radius of the rotor-blade system of WTG, v is the wind speed) for MPPT;

When the wind speed is higher than the rated speed, and the generator speed also reaches the rated value, the generator speed will be controlled constantly to avoid over-speed; the pitch angle will be controlled to limit the input wind power to avoid over-current.

However, there are more and more cases that the wind power needs to be regulated in a more flexible way instead of simple MPPT, e.g. the curtailment that happens very frequently in the north of China due to the integration capability of power grid, the Automatic Generation Control (AGC) which might become a tech trend that wind power plants must follow as conventional power plants, the islanding operation of individual or several wind turbines during transmission system failure, etc. All these cases will put critical requirements on the Flexible Power Tracking (FPT) capability and power balance capability of wind turbine, which the existing control methods cannot fulfil.

Statement of the Problem:

This invention aims to solve four problems of coordinating pitch and generator control systems of wind turbine to realize flexible power tracking:

1. How to determine the control reference for the pitch control system for flexible power tracking;

2. How to determine the control reference for the generator control system for flexible power tracking;

3. How to determine the control references for the pitch and generator control systems in a coordinated way considering the capability of pitch and generator control system;

4. How to optimize the control references for the pitch and generator control systems considering the dynamic response and mechanical stress limitation.

Claims of the Invention:


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The concept and t...