Student : TRUONG XUAN LOC (MA02B206) Professor : CHI-JO-WANG

MODELING AND SIMULATION OF WIND TURBINE –DOUBLY FED INDUCTION GENERATOR (WT-DFIG) IN WIND FARM USE MATLAB/SIMPOWERSYSTEM

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1. INTRODUCTION

2. WIND TURNINE MODEL

3. DFIG MODEL

4. WIND FARM USING DFIG

CONTENTS OF TOPICCONTENTS OF TOPIC

6. CONCLUSION

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5. SIMULATION RESULT

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•Now day, wind energy has become a viable solution for energy production, in addition to other renewable energy sources. One way of generating electricity from renewable sources is to use wind turbines that convert the energy contained in flowing air into electricity.

•With increased penetration of wind power into electrical grids, DFIG wind turbines are largely deployed due to their variable speed feature and hence influencing system dynamics. This has created an interest in developing suitable models for DFIG to be integrated into power system studies.

1. INTRODUCTION

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• Up to this moment, the amount of wind power integrated into large‐scale electric power systems only covers a small part of the total power system load. The rest of the power system load is for the largest part covered by conventional thermal, nuclear, and hydropower plants.

• This paper presents the modeling and simulation of a wind turbine doubly-fed induction generator in wind farm. The Matlab/Simulink/SimPowerSystems software is used to develop the model for simulation of wind power systems

1. INTRODUCTION

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• The model is based on the steady-state power characteristics of the turbine. The output power of the turbine is given by the following equation.

where • Pm: Mechanical output power of the turbine (W)• Cp: Performance coefficient of the turbine• Ρ: Air density (kg/m3)• A: Turbine swept area (m2)• Vwind: Wind speed (m/s)• λ:Tip speed ratio of the rotor blade tip speed to wind

speed• Β:Blade pitch angle (deg)

2. WIND TURBINE MODEL

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2. WIND TURBINE MODEL• Can be normalized. In the per unit (pu) system we have:

• Performance or power coefficient Cp depends on wind speed, the speed of the turbine and the pitch of the blades. The power coefficient of the turbine is given by :

With

• Fixing the ratio λ and the pitch blades β to their optimum values, the wind system will provide optimum electrical power.

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2. WIND TURBINE MODEL• This ratio λ, called also the tip speed ratio :

Where: Ω is the speed of turbine, R the blade radius and v the wind velocity.

• The coefficients c1 to c6 are: c1 = 0.5176, c2 = 116, c3 = 0.4, c4 = 5, c5 = 21 and c6 = 0.0068. The cp-λ characteristics, for different values of the pitch angle β, are illustrated below. The maximum value of cp (cpmax = 0.48) is achieved for β = 0 degree and for λ = 8.1. This particular value of λ is defined as the nominal value (λ_nom

Figure -1- Power coefficient versus λ and β

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3. DFIG MODEL

Fig. 2. The wind turbine and the doubly-fed induction generator system

A. Operating Principle of the Wind Turbine Doubly-Fed Induction Generator

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P m: Mechanical power captured by the wind turbine and transmitted to the rotorPs: Stator electrical power outputPr: Rotor electrical power outputPgc: Cgrid electrical power outputQs: Stator reactive power outputQr: Rotor reactive power outputQgc: Cgrid reactive power outputTm: Mechanical torque applied to rotorTem: Electromagnetic torque applied to the rotor by the generatorωr: Rotational speed of rotorωs: Rotational speed of the magnetic flux in the air-gap of the generator, this speed is named synchronous speed. J: Combined rotor and wind turbine inertia coefficient

Fig. 3. Active and reactive power flows

3. DFIG MODEL

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The Power Flow

- The mechanical power and the stator electric power output are computed as follows:

P m = Tm ωr

Ps = Tem ωs

- For a lossless generator the mechanical equation is:J.d ωr/dt = Tm – Tem

- In steady-state at fixed speed for a lossless generator:Tm = Tem

P m = P s + P r- It follows that:P r = P m - P s = Tm ωr - Tem ωs = - Tm (ωs – ωr). ωs/ ωs = = -s Tm ωs = -s Ps

- where s is defined as the slip of the generator:S = (ωs – ωr)/ ωs

3. DFIG MODEL

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Fig. 5. Rotor-side and grid-side converters and control systems

3. DFIG MODEL

B. Control systems

Fig. 4. Turbine characteritics and tracking characteristic

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3. DFIG MODEL

Rotor side converter (Crotor)

Fig .6. rotor-side controller.

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3. DFIG MODEL

Grid side converter

Fig. 7.Grid-side controller

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3. DFIG MODEL

Pitch angle control system

The pitch angle is kept constant at zero degree until the speed reaches point D speed of the tracking characteristic. Beyondpoint D the pitch angle is proportional to the speed deviationfrom point D speed.

Fig. 8. Pitch angle control

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4. Wind Farm Using DFIG

Description of the Wind Farm

In this section illustrates application of SimPower Systems software to study the steady-state and dynamic performance of a 9 MW wind farm connected to a distribution system.

Fig. 9. Single-Line Diagram of the Wind Farm Connected to a Distribution System

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4. Wind Farm Using DFIG

SimPower Systems Diagram of the Wind Farm Connected to the Distribution System

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Generator Data4. Wind Farm Using DFIG

Control Parameters

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5. SIMULATION RESULT

Turbine response to a change in wind speedwind speed is set at 8 m/s, then at t = 5s, wind speed increases suddenly at 14 m/s

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Simulation of grid parameters when the mode of operation is set to Control Parameters

5. SIMULATION RESULT

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6. CONCLUSIONS

• The model is a discrete-time version of the Wind Turbine Doubly-Fed Induction Generator (Phasor Type) of Matlab/SimPowerSystems.

• Operation of DFIG and it’s controls using AC/DC/AC converter. DFIG wind generator and investigate the effects of wind speed and pitch angle on voltage, real power and reactive power of a DFIG wind generator .

• The DFIG is able to provide a considerable contribution to grid voltage support during short circuit periods. Considering the results it can be said that DFIG proved to be more reliable and stable system when connected to grid side with the proper converter control systems

• The rotor side converter (RSC) usually provides active and reactive power control of the machine while the grid-side converter (GSC) keeps the voltage of the DC-link constant.

• we simulated grid side and wind turbine side parameters and the corresponding results have been displayed.

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1. Richard Gagnon, Gilbert Sybille, Serge Bernard, Daniel Paré, Silvano Casoria, Christian Larose. “Modeling and Real-Time Simulation of a Doubly-Fed Induction Generator Driven by a Wind Turbine”

2. Karim Belmokhtar, Mamadou Lamine Doumbia and Kodjo Agbossou “ Modelling and Power Control of Wind Turbine Driving DFIG connected to the Utility Grid”

3. Ashish Kumar Agrawal. Bahskar Munshi. Srikant Kayal. Under the guidance of Prof. K. B. Mohanty. Department of Electrical Engineering, National Institute of Technology, Rourkela ‘STUDY OF WIND TURBINE DRIVEN DFIG USING AC/DC/AC CONVERTER’

4. Dr M S R Murty ‘Wind Turbine Generator Model’.5. MATLAB SimPowerSystems User's Guide, Version 5.5 (R2011b),

http://www.mathworks.com/access/helpdesk/help/toolbox/physmod/powersys/

6. Matlab Simulink toolbox of the \SimPowerSystems\Distributed Resources Library\Wind Generation\, the Help file of the model of DFIG (phasor type).

REFERENCES

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THANKS FOR YOUR ATTENTION!

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