A NON-LINEAR CONTROL ALGORITHM FOR IMPROVING PERFORMANCE OF WIND GENERATOR USING DOUBLY-FED INDUCTION GENERATOR

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A NON-LINEAR CONTROL ALGORITHM FOR IMPROVING
PERFORMANCE OF WIND GENERATOR USING DOUBLY-FED
INDUCTION GENERATOR
INSTITUTE OF ELECTRICAL POWER ENGINEERING
Chair Electric Drives and Basics of Electrical
Power Engineering

• M.Sc. Phung, Ngoc Lan
• Athens, Feb/Mar.2006

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Introduction

• Conventional control of doubly fed induction
  machine (DFIM) in wind generator
• Based on the continuous or discreet model of DFIM
• Decoupling in active- and reactive power (PQ)
  control
• A voltage dip what happened ?
• A new control scheme !
• Decoupling of PQ is guaranted
• Better performance in dynamical operation mode
• Non-linear control of DFIM with
  Exact-Linearization
• Current model of DFIM is able to be exactly
  linearized !
• A new current controller is with only P-Type
  controllers
• The complete control structure is simple.
• Decoupling is guaranteed - Direct-Decoupling

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Contents

1. DFIM Model and its characters.
2. Conventional control of DFIM in wind generator
3. Exact-Linearization Concept and
   implementation with DFIM
4. Control structure with Direct-Decoupling
5. Conclusion and prospects

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Contents

1. DFIM Model and its characters.
2. Conventional control of DFIM in wind generator
3. Exact-Linearization Concept and
   implementation with DFIM
4. Control structure with Direct-Decoupling
5. Conclusion and prospects

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Control system of DFIM in wind generator
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Demonstration of voltage-, flux- and current
vector in d-q coordinator
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Electrical model of DFIM in d-q coordinator
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Electrical model of DFIM in state-space

• Rotor angular speed Input variable of
  the model
• Model of DFIM in state-space shows a
  bilinear system

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Contents

1. DFIM Model and its characters.
2. Conventional control of DFIM in wind generator
3. Exact-Linearization Concept and implemetation
   with DFIM
4. Control structure with Direct-Decoupling
5. Conclusion and prospects

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Control variables of the active- and reactive
power
The active power P and reactive power Q will be
separately controlled through ird and irq
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A control structure of DFIM in wind generator
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Contents

1. DFIM Model and its characters.
2. Conventional control of DFIM in wind generator
3. Exact-Linearization Concept and
   implementation with DFIM
4. Control structure with Direct-Decoupling
5. Conclusion and prospects

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Why do we apply Exact-Linearization ?

• The nonlinear characters of DFIM

• Performance of system in dynamical operation mode
  should be improved

• Exact linearization guarantees not only the
  linearity between inputs and outputs but also the
  decoupling between each pair of input and output
  variable in the new model ---gt noninteracting

• With the success of exact-linearization,
  different methods to design controllers for the
  new linear model could be applied.

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Exact-Linearization the concept (1)

• Given a nonlinear MIMO-System with m inputs and m
  outputs

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Exact-Linearization the concept (2)

• With a coordinator transformation

• And with a state feedback controller

• The new linear system will be

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Exact-Linearization Implementation with DFIM
Considering three equations of DFIM
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Exact-Linearization Implementation with DFIM
(1)
The model in state-space will be in form of
with
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Exact-Linearization Implementation with DFIM
(2)
In the new state-space, system will be
In detail
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Contents

1. DFIM Model and its characters.
2. Conventional control of DFIM in wind generator
3. Exact-Linearization Concept and
   implementation with DFIM
4. Control structure with Direct-Decoupling
5. Conclusion and prospects

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Structure of the new linear model
v
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Control system of DFIM in wind generator with
direct-decoupling
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Circuit diagram with Plecs
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Performance of linearized model and current
controller
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Simulation Grid voltage and electrical torque
Grid voltage
100
75
50
Torque Linear Control
Torque Nonlinear Control
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Simulation Active and reactive power
P Linear Control
P Nonlinear Control
Q Linear Control
Q Nonlinear Control
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Simulation Rotor current
ird Linear Control
ird Nonlinear Control
irq Linear Control
irq Nonlinear Control
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Conclusion and perspectives

• Control system of DFIM with exact-linearization
  practical and easy to implement.

• Performance of system is improved with the static
  direct-decoupling current controller

• The simulation with Matlab/Simulink/Plesc shows
  good results, the complete control system is
  being verified on experiment rig

• Advanced methods can be used in design process of
  controllers

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Thank you for your attention !