Some decentralized optimization and control algorithms for the control of wind farms

Cheng, Albert Z.

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https://hdl.handle.net/2142/24125 Copy

Description

Title

Some decentralized optimization and control algorithms for the control of wind farms

Author(s)

Cheng, Albert Z.

Issue Date

2011-05-25T15:06:09Z

Director of Research (if dissertation) or Advisor (if thesis)

Langbort, Cedric

Department of Study

Mechanical Sci & Engineering

Discipline

Mechanical Engineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Decentralized control
• Network control
• Wind farm control

Abstract

This is a preliminary study of decentralized algorithms that can be applied to wind farm controls. Traditionally, wind farm control is comprised of the wind farm level control and the wind turbine level control. The wind farm level control is a centralized controller that takes the demands from the grid and generates operating points for each wind turbine within the wind farm. The wind turbine level control then generates the optimal control for each turbine to match the operating point. Unfortunately, this traditional control scheme does not constitute the optimal operation of a wind farm due to it’s disregard at either level of control for the interactions between wind turbines in the wind farm . Consequently, a different two level control scheme is proposed in this thesis. This control scheme is shown to be a decentralized controller in that each wind turbine has the ability to both generate its own operating point and calculate its own optimal control. Through the communication of the wind turbines with each other, the interactions between the wind turbines are incorporated into both levels of control. The generation of the operating point is posed as a stochastic resource allocation problem that takes into account the stochastic wind and other wind farm characteristics. We develop a stochastic algorithm based on network dynamic system theory to solve the resource allocation problem. We show that the algorithm converges to the solution of the resource allocation problem almost surely. The calculation of each wind turbine’s optimal control is formulated as an Linear Quadratic Regulator (LQR) optimization problem with a equality constraint. We develop an algorithm that is based on the Tatonnement process in Economics to solve the LQR problem. We first consider the performance of the algorithm in a dynamically decoupled system and show that the algorithm solves the LQR problem. We then consider the performance of the algorithm in a dynamically coupled system and discuss the difference between the two cases.

Graduation Semester

2011-05

Permalink

http://hdl.handle.net/2142/24125

Copyright and License Information

Copyright 2011 Albert Z Cheng

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