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Equivalent wind farm for increasing optimization speed of wind farm's mechanical fatigue minimization

IP.com Disclosure Number: IPCOM000249875D
Publication Date: 2017-Apr-21
Document File: 6 page(s) / 494K

Publishing Venue

The IP.com Prior Art Database

Related People

DaWei Yao: AUTHOR [+4]

Abstract

With the fast development of wind power and massive installation of wind farms, the owners are expecting higher profit and longer service life with following grid operator's power generation command. This results in various research on wind farm control. This area can chiefly be divided into two main categories. The first one is the quality control of the generated electrical power. The second one is the coordinated control of power generated by individual turbine such that the aerodynamic interactions between turbines are minimized. One particular motivation is maximization of active power. While most presently implemented control systems in the field individually maximize the active power extracted at each WT based on the limitations of the physical system, such as voltage, voltage stability, generator power, etc. Studies show that this is not optimal because of the wake. Instead, WTs which are located upwind of other WTs should damp their power extraction in order to maximize the total harvested power in the wind farm (WF). Considering grid issues (such as reliability or constrains), the power generation command is not always the same as wind farm's max output. Instead in many cases, the wind farm has to be working at curtailment mode with lower power generation than capability. For example in China, curtailment mode is very commonly seen. This leaves the opportunity to properly dispatch the power of each wind turbine. Reference [1] shows a method to realize the combined optimization of power and fatigue load. This is a controller that distributes power references among wind turbines while it also reduces their structural loads. Equation based optimization discussed in the literature papers is to reduce the structural load. However, only thrust force applied on the tower is modeled and treated. That method might be too simple for practical application, if more stress loads are considered. Also how to apply this method into large scale wind farm is not mentioned.

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Disclosure Title: Equivalent wind farm for increasing optimization speed of wind farm’s mechanical fatigue minimization

This disclosure can be applied in the area of optimization on the fatigue damage of mechanical

components for prolonging wind farm’s service life. With the proposed method, the optimization speed

used in the controller can be increased significantly.

Abstract of the Disclosure

Background

With the fast development of wind power and massive installation of wind farms, the owners are

expecting higher profit and longer service life with following grid operator’s power generation command.

This results in various research on wind farm control. This area can chiefly be divided into two main

categories. The first one is the quality control of the generated electrical power. The second one is the

coordinated control of power generated by individual turbine such that the aerodynamic interactions

between turbines are minimized.

One particular motivation is maximization of active power. While most presently implemented control

systems in the field individually maximize the active power extracted at each WT based on the

limitations of the physical system, such as voltage, voltage stability, generator power, etc. Studies show

that this is not optimal because of the wake. Instead, WTs which are located upwind of other WTs

should damp their power extraction in order to maximize the total harvested power in the wind farm

(WF).

Considering grid issues (such as reliability or constrains), the power generation command is not always

the same as wind farm’s max output. Instead in many cases, the wind farm has to be working at

curtailment mode with lower power generation than capability. For example in China, curtailment mode

is very commonly seen. This leaves the opportunity to properly dispatch the power of each wind turbine.

Reference [1] shows a method to realize the combined optimization of power and fatigue load. This is

a controller that distributes power references among wind turbines while it also reduces their structural

loads.

State of problem

Equation based optimization discussed in the literature papers is to reduce the structural load. However,

only thrust force applied on the tower is modeled and treated. That method might be too simple for

practical application, if more stress loads are considered.

Also how to apply this method into large scale wind farm is not mentioned.

The objective function of this optimization can be expressed as:

: max ( , − ,

, + ,

− , ,

+ , − ,

, )

⇒ (3 − ∑ ,

,

∑ , ,

− ∑ ,

,

∑ , ,

− ∑ ,

,

∑ , ,

)

This is a highly non-linear transcendental equation because of:

• Four kinds of stresses are regulated by controlling the TSR and/or beta by four transcendental

equations

• The cycle amount n is obtained by rainflow counting algorithm with an input of time-serial

stresses. It is very hard to summarize a simplified equation for this process.

• The cycle-to-failure N is a transcendental equation because the...