doubly-fed induction conversion using matrix …this paper presents functional structure of a wind...

DOUBLY-FED INDUCTIONGENERATOR WIND ENERGYCONVERSION USING MATRIX

CONVERTER

Saravanan K1, Maharajan D2,Pradeep A3, Vigneshwaran N4

1,2Asst Prof3,4M.Tech , student

Department of Electrical andElectronics Engineering,

SRM Institute of Science and Technology,Chennai -603203, India.

[email protected],[email protected],

[email protected],[email protected]

July 3, 2018

Abstract

This paper presents functional structure of a windenergy conversion system with Doubly Fed Inductiongenerator. The most commonly used generators in windenergy are Doubly Fed Induction Generator andPermanent Magnet Synchronous Generator. A gridconnected wind power generation scheme using doubly fedinduction generator is studied. The aim is modelling andsimulation of DFIG operating in two quadrants(torque-speed) by a suitable control technique to control

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International Journal of Pure and Applied MathematicsVolume 120 No. 6 2018, 10693-10703ISSN: 1314-3395 (on-line version)url: http://www.acadpubl.eu/hub/Special Issue http://www.acadpubl.eu/hub/

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the rotor current. This method will also replace theconventional converter by Indirect Matrix Converter. Themain objective is modeling and simulation of DFIG withsuitable control technique using indirect matrix converterto reduce the switching losses and harmonics. This willincrease the efficiency of power conversion which will beanalytically verified. The DC-link voltage cannot beboosted as that of back to back converter. Withoutentering the over modulation range the maximum outputvoltage of the matrix converter is 0.866 times the inputvoltage. So we overcome this problem in this paper.

Proposed control of an Indirect Matrix Converter(IMC) is combined with predictive rotor current control ofa DFIG to achieve a very good dynamic response as therotor currents smoothly, which consists of an input sidematrix converter and an output side voltage sourceconverter. The proposed method leads to a reduction inthe commutation losses in the output converter andreduced common mode voltage. Because, it can utilize thevector control and realize torque control. For the inputconverter, soft switching commutation is obtained bysynchronizing the input and output converter pulsewidth-modulation patterns. Taking a comparison study ofall PWM techniques we choose the space vector pulsewidth modulation as the best one because of its lowswitching losses and high harmonic density, power factor &switching frequency. The output voltage, output currentwaveforms, voltage transfer ratio and THD spectrum ofswitching waveforms connected to load are to be analysedby using MATLAB/ SIMULINK software.

1 Introduction

India now ranks 4th in the world after Germany, USA and Spainwith a wind power installed capacity of 4434 MW. The 10th Planaim at 1500 MW grid-interactive wind power has been exceededas capacity deployed up to 31.12.2005 exceeded 2800 MW takingthe cumulative deployment to over 4500 MW. Indias wind powerpotential has been assessed at around 45,000 MW assuming 3percent land availability for wind farms requiring at 12

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hector/MW in sites having wind power density in excess of250W/sq. meter with 50 meters hub-height.

Power quality relates to factors which describe the variabilityof the voltage level, as well as the distortion of voltage and currentwaveforms. When it comes to the power quality of wind turbinegenerators only some specific power quality problems are relevant.Many people have been investigating those problems with worksconcerning the power quality improvement of wind farm and powerquality and grid connection of wind.

The first part will introduce an indirect matrix converter tocontrol which is a direct AC to AC converter. Second part of thethesis will contain an introduction into wind energy conversionsystem with Doubly Fed Induction and the advantages of DFIGrather to other generating systems and the overall efficiency willbe simulated through MATLAB/ SIMULINK.

2 Objective

The main objective is modelling and simulation of DFIG withsuitable control technique using indirect matrix converter toreduce the switching losses and harmonics. This will increase theefficiency of power conversion which will be analytically verified.The DC-link voltage cannot be boosted as that of back to backconverter. Without entering the over modulation range themaximum output voltage of the matrix converter is 0.866 timesthe input voltage.

3 Scope of work

The present work describes the wind energy conversion systemwith considering the doubly fed induction generator (DFIG) asbecause of its various advantages and producing energy effectively.Further to control the rotor we introduce a matrix converterinstead of conventional back to back converters. The switchingphenomenon of matrix converter is obtained with space vectormodulation technique. The application of MATLAB andimplementation of system in MATLAB/ SIMULINK are to be

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studied and performance results are to be justified fromsimulation result.

4 Motivation

Matrix converters are devices which could be used for real worldup to 100kw in controlling DFIG to enhance the efficiency ofWind energy conversion system in terms of output voltage,current, switching frequency, harmonic distortion, power factor,active reactive power and device technology will increasemagnetism for research.

5 General introduction of matrix

converter

The matrix converter is a unique topology of AC to AC powerconverter that eliminates the need for an intermediate DCconversion and the passive reactive filter components associatedwith this DC-link. It is a direct or single stage AC to ACconverter topology. The converter consists of an array ofbidirectional switches positioned at the intersection points of theinput and output phases. The output is synthesized by selectiveclosings and openings of the switches. A filter on the input sideaids commutation and prevents switching generated harmonicsfrom propagating to the power input. Matrix converters offer thepotential for significant size and weight reductions in powerconverter applications due to the absence of any large energystorage elements, such as DC-link capacitors. Compared to aconventional back to back converter the MC is of much smallersize. Due to these special features Matrix converters has attractedgreat attention in the last few years. A high power Matrixconverters was patented in 1999. In 2005, a 150 kVA MC has beenfabricated and tested for electric vehicle applications. The Matrixconverters topology was implemented commercially in 2008.Recently MC has attracted interest for wind power applications.

A matrix converter based wind power generation system isdepicted. The output voltage and input current waveforms are

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close to sine wave, as illustrated and respectively. Therefore, theTHD coefficient of Matrix converters is much better than those ofthe back to back and diode rectifier based converters. Thefrequency spectrum of output voltage is depicted. Severalliteratures have introduced the application of matrix converter invariable speed wind turbine generator systems. In 2009, anMatrix converters was implemented for induction generator basedwind turbine generator system. In the same year, for performanceenhancement and efficiency optimization a modified MC wasproposed for SCIG based wind turbine generator systems and asimulation work was reported. Due to its advantages comparedwith back to back converter the MC is currently replacing theback to back converter from DFIG based wind turbine generatorsystems. The layout of an MC converter with DFIG based windturbine generator system is illustrated. An MC was fabricatedand tested with DFIG based wind turbine generator system inwhere space vector modulation (SVM) scheme was used to controlthe MC, regulating the rotor torque and magnetizing currents.

In this matrix converter in wind turbine, we are overcoming inthis process The DC-link voltage cannot be boosted as that of backto back converter. Without entering the over modulation range,the maximum output voltage of the matrix converter is 0.866 timesthe input voltage.

The protection of the matrix converter in a fault situation is notas good as that of back to back converter.

In this matrix converter, the matrix converter includes sixadditional power switches compared to the back to backconverter, the absence of the DC-link capacitor may increase theefficiency and lifetime for the converter.

The back to back converter is a bidirectional power converter,in matrix converter realization of the bi-directional switches, theswitching losses of the matrix inverter may be less than that ofthe back to back converter, because half of the switching becomesnatural commutations.

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Figure 1: Block diagram of DFIG with matrix converter

Figure 2: Full block diagram of DFIG

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6 Simulation results

Figure 3: Active reactive power stator

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Figure 4: output current of the converter

Figure 5: (a) stator voltage (b)Rotor torque characteristics ofmachine

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Figure 6: Three phase rotor voltage

7 Conclusion

In this paper DFIG based wind turbine system using matrixconverter. We explained full details about the matrix converter.Matrix converter is one of the converter. They are back to back ,Zsource converter and etc ., we come to matrix converter thepotential for the size and weight reductions in power converterapplications due to the absence of large energy storage elements,such as DC-link capacitors .so this is the many advantages ofmatrix converter and we simulated in MATLAB /SIMULATION .It observed that the indirect matrix converter are providingsinusoidal input and output current without the DC linkcapacitor.

References

[1] Ruben Pena, Roberto Cardenas, Eduardo Reyes, Jon Clareand Patrick Wheeler, “Control of a Doubly Fed InductionGenerator via an Indirect Matrix Converter With ChangingDC Voltage”, IEEE Transactions On Industrial Electronics,Vol. 58, No. 10, October 2011.

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[2] “Study of doubly fed induction generator for wind powerapplication”, IEEE paper 29 August 2013

[3] Vlastimil Santin, “Model of wind power plant withasynchronous generator in simulink platform”, Intensiveprogramme on “Renewable Energy Sources”, May 2011,University of West Bohemia.

[4] Xinyan Zhang, Weiqing Wang, Dagui Liu, Haiyun Wang, XuanCao, Shan He, “Matrix Converter Control Study of Doubly-fed Induction Wind Turbine Generator System”, IEEE PEDS2015, Sydney, Australia.

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doubly-fed induction conversion using matrix …this paper presents functional structure of a wind...

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