Modelling and Simulation of Wind Power Plants

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International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976

6545(Print), ISSN 0976 6553(Online) Volume 3, Issue 2, July- September (2012), IAEME

MODELLING AND SIMULATION OF WIND POWER PLANTS

FRAMED WITH SELF-EXCITED INDUCTION GENERATOR AS

WELL AS D.F.I.G. AND A COMPARATIVE PERFORMANCE STUDY

THEREOF IN PSCAD/EMTDC ENVIRONMENT

Sujit Datta, Tanushree Deb Champa Nandi A.K. ChakrabortyM.Tech 4thSemester Student Assistant Professor Associate ProfessorDepartment of EE Department of EE Department of EETripura University Tripura University NIT, Agartala

Email: datta_sujit2003@ Email: champanandi@ Email:Yahoo.com Yahoo.com Yahoo.co.inMobile: 09402155240 Mobile: 09436502334

ABSTRACTThis thesis investigates on the modelling and simulation of wind power plants in agrid connected system. A wind power plant which is comprised of five wind

turbines are connected with self-excited as well as doubly fed induction generatorseparately and total system is framed with Multimass Torsional Shaft Interface. Inboth cases, 50% of system power are connected via through AC/DC/AC powerconverter to utility grid bus and rest of the power are connected directly to the grid.The device 6-pulse bridge converter performs as a rectifier which is connected to aHVDC link and a 6-bridge inverter is connected to another side of the HVDC link.This multi level inverter convert DC power into ac power at desired output andfrequency irrespective of load demands with maintaining suitable voltage stabilitythrough an inverting transformer. The rectifier and L-limiting reactor are utilized tomaintain constant DC link current. The average power is converted partially by theinverter which working as CSI mode, supply currents into the utility grid by

regulating the DC link voltage. With only power converters composed of thyristorsbridge in power conversion, the system can be scaled up to a very high voltage andhigh power applications. The total system voltage is maintained in excitation ofgenerators with series-parallel capacitor banks separately. In both cases, theperformance improvement of the system by the experiment choosing a 12 MVA,4-poles,3-phase,50 hz induction generator. The overall control system is implementedchoosing parameters in varied capacity like variable as well as pitch controllingthrough control of firing angle of power converter and inverter to track the optimum

INTERNATIONAL JOURNAL OF ELECTRICAL ENGINEERING &

TECHNOLOGY (IJEET)

ISSN 0976 6545(Print)

ISSN 0976 6553(Online)

Volume 3, Issue 2, July September (2012), pp. 123-139

IAEME: www.iaeme.com/ijeet.html

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power curve of the wind turbine. Finally, a comparative study is made based onexperimental result in order to validate performance of the proposed systems. Thisproject is modelled and simulated with the help of PSCAD/EMTDC software.

KEYWORDSWind power plant, 6-Pulse converter/inverter, Self-excited I.G., D.F.I.G., Firingangle, PSCAD/EMTDC

1. INTRODUCTIONModern wind turbine generator utilizes power electronics devices and drives for realand reactive power controls in wind power plants to have much better steady stateand dynamic performance compared to wind power plants of the past. For reliabilityand cost effective reasons, it is very important to proper represent steady state anddynamic characteristics in large scale response of positive sequence simulations. Inthis research, the two basic WTG(wind turbine generator) configurations that are

investigated currently in use :(1)Self-excited induction generator,(2)Doubly fedasynchronous generator, also known as Doubly fed induction generator. Windenergy is very promising and effective energy for present and future situations. Oneof the most significant problems to take up the arrangement for installation of windturbines in modern wind power plants. It is well known that the power delivered bywind turbines directly coupled to grid is not constant as a result of wind variability.In absence of storage systems, a fluctuating power supply produced can lead tovoltage variations in the grid and resulting of frequency flickering. Anotherdisturbance of most induction machines utilized in the wind turbines is that therequired reactive power varies with wind speed and time. These problems can makethe use of double fed induction generators attractive for wind turbine applications.

In this research works, a self-excited induction generator and a doubly fed inductiongenerator are excited and simulated with same set of series-parallel capacitancebanks and choosing other related parameters and finally a comparative performancestudy is made based on simulated experimental results in PSCAD/EMTDCsoftware.[ 1,2,8,10]

2. SELF-EXCITED INDUCTION GENERATORAn induction motor works as a generator when sufficient amount of capacitance isconnected across the machine terminals to sustain the excitation requirement whilethe rotor speed is maintained by some mechanical means. Self-excited induction

generators are good member for generating wind electric power especially in remoteareas as they do not need external power supply to produce the magnetic field.Permanent magnet generators may also be used for wind energy applications butthey suffer from uncontrollable magnetic field, which decays over a period due toweakening of the magnets, and the generated voltage tends to fall steeply with load.The SEIG has a self-protection mechanism because the voltage collapses whenthere is a short circuit at its terminals. Further, the SEIGs have more advantagessuch as cost, reduced maintenance, rugged and simple construction, brush-less rotor


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mechanical power, typically 25-30 %, is fed to the grid through the converter, therest being fed to grid directly from the stator. The efficiency of the DFIG is verygood for the same reason.[6,14]

4. SIX PULSE BRIDGE CONVERTER/INVERTERhe output of the rotor power is feed to the grid through back to six pulse convertersvia common DC link. Machine side converter act as a six pulse rectifier and gridside converter acts as six pulse inverter during the machine working in supersynchronous mode. Six pulse converter works in rectifying mode is used to convertthe variable magnitude, variable frequency voltage at the induction generator rotorterminals to DC voltage. For smooth output DC voltage, limiting reactor isconnected in the DC link. DC link reactor acts as stiff voltage/current source and itprovides dc isolation between the two converters.[7,11]

5. SIMULATION AND DESCRIPTION

This thesis deals with performance of the Self-excited as well as Doubly FedInduction Generator type variable speed WT to fabricate the wind power plants. Aspecific configuration of this plant consist of 5(five) wind turbines is examined,corresponding to each WT of 2.40 MW. This paper is organized of three projectmodels and simulation results for same set of operating parameters are finallyprovided and analyzed using the PSCAD/EMTDC code.

A) Simulation Diagram of project Model -1:When 50% of generated power is connected via through AC/DC/AC to grid and restof power is connected directly to the grid is shown in Fig. 3. at 10 pitch angle andat variable speed of wind 13-20 mtr/second , the system behaviour are analyzed in

result section.B) Simulation Diagram of project Model -2When whole generated power is connected via through AC/DC/AC to utility griddirectly is shown in Fig. 4 at 10 pitch angle and at variable speed of wind 13-20mtr/second , the system behaviour are analyzed in result section.C) Simulation Diagram of project Model -3When 50% of generated power of doubly fed induction generator is regulated byconnecting via through AC/DC/AC to utility grid and rest of power is connected toutility grid directly as shown in Fig 5 at 10 pitch angle and at variable speed ofwind 13-20 m/sec , the system behaviour are analyzed in result section.


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International Journal of

6545(Print), ISSN 0976 65

Fig.3. Wind power plantgenerated power via throthe power is connected d

Fig.4.Wind power planwhole generated poAC/DC/AC power c

lectrical Engineering and Technology (IJEE

53(Online) Volume 3, Issue 2, July- September (

PROJECT MODEL-1

connected with self-excited induction geneugh AC/DC/AC power converter to utilityirectly to grid.

PROJECT MODEL- 2

connected with self-excited inductioner is transmitted to utility grid via regnverter.

), ISSN 0976

012), IAEME

ator when 50%grid and rest of

enerator whenlating through


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International Journal of

6545(Print), ISSN 0976 65

Fig.5. Wind power plantgenerated power is reguconnected to the grid or l

6. RESULTS AND DThe simulation results a20 m/s. The change dpower tracking operatidamping and absence of

is also maintained at itsvariations are shown varspeed time series, whichthe WT. The smoothingcompared to the input mreactive power balancsuccessfully.

lectrical Engineering and Technology (IJEE

53(Online) Volume 3, Issue 2, July- September (

PROJECT MODEL-3

connected with doubly fed induction generated by AC/DC/AC power converter andoad circuit directly.

SCUSSIONe presented for an indicative fast wind spemonstrates the action of the speed contron). The good response characteristics,any over speed or overpower is apparent.

rated value. The response in case of stochaious figures and concerned data tables usinincludes intervals below and above the rateachieved in the electromagnetic torque anechanical power of the turbine, is evident.

during the whole operation interval

), ISSN 0976

012), IAEME

ator when 50%est of power is

d for 13 m/s toller (maximumwith adequatehe DC voltage

stic wind speeda1 to 2s windwind speed ofoutput power,

The active andis maintained


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(A)Project model-1Result analysis of wind power plants with self-excited induction generator: when50% of Generated power of self-excited induction generator is connected viathrough AC/DC/AC power converter and rest of the power directly connected togrid at wind speed, m/s, torque of wind turbine, Tm=2.39KN-m, series-parallel compensation bank, C2=150, C1=40:Table-I.A. results with firing angle 0for

converter & 90 for inverter

Fig.6.various characteristics ofwind power plant for firingangle is 0 for converter and90 for inverter when 50% ofgenerated power is regulated

via through AC/DC/AC powerconverter and rest of power isconnected directly to grid.

Pout = real power generation; Qout = reactive power generationEdc = HVDC Link voltage; Idc= HVDC Link currentVg = Grid voltage or Load voltage

SlNo

VariableName

Generation inMaximum

1 Pout 7663.51KW

2 Qout 5079.05KVAR3 Edc 93.50 KV4 Idc 3.04 KA

5 Vg 10.99 KV


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Table-II.A: results with firing angle15for converter & 90 for inverter Table-III.A: results with firing angle30for converter & 90 for inverter

Table-IV.A: results with firing angle45for converter & 90 for inverter

Table-V.A: results with firing angle60for converter & 90 for inverter

Fig.7.various characteristics ofwind power plants firing angle60 for converter and 90 for

inverter when 50% generatedpower is regulated throughAC/DC/AC power converterand rest of the power is directlyconnected to grid in case self-excited induction generator.

Sl.No

VariableName


1 Pout 7660.17 KW2 Qout 5077.33 KVAR3 Edc 93.50 KV4 Idc 3.04 KA5 V 10.99 KV

SlNo

VariableName



Sl.No

VariableName


1 Pout 7657.77 KW

2 Qout 5026.41 KVAR3 Edc 93.50 KV4 Idc 3.04 KA5 Vg 10.99 KV

SlNo

VariableName


1 Pout 7658.77 KW

2 Qout 5076.41 KVAR3 Edc 93.50 KV4 Idc 3.04 KA5 V 10.99 KV


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Table-VI.A: results with firing angle90for converter & 90 for inverter

Table-VII.A: results with firing angle0for converter & 105 for inverter

Table-VIII..A: results with firingangle 60for converter & 165 forinverter

Table-IX..A: results with firing angle90for converter & 180 for inverter

It is observed from the above results that the direct connection of 50% of generatedpower by self-excited induction generator to grid bus or load circuit and rest of thepower is regulated by power converter, no controlling over the power generation bythe AC/DC/AC power converter. There is negligible changes of power dispatch ingrid on varying the firing angle delay of power converter and inverter. Moreover,

large amount of DC-link voltage and current is to handle for power regulation,power dispatch etc and this model may not be appropriated for real purposes. Thevoltage regulation is also not to be affective due to the same reasons.

(B) Project model-2

Result analysis of wind power plant with self-excited induction generator: whenwhole generated power is connected via through AC/DC/AC power converter toutility grid at wind speed, m/s, torque of wind turbine,Tm=2.39 KN-m., series-parallel capacitance bank, C2=150 , C1=40 :

Table-I.B. results with firing angle 0for

converter & 90 for inverter

SlNo

VariableName


1 Pout 7658.77 KW2 Qout 5075.41KVAR

3 Edc 93.50 KV4 Idc 3.04 KA5 Vg 10.99 KV

SlNo

VariableName


1 Pout 7663.51 KW2 Qout 5079.06 KVAR3 Edc 93.50 KV4 Idc 3.02 KA5 Vg 10.99 KV

SlNo

VariableName


1 Pout 7665.77 KW2 Qout 5076.41 KVAR3 Edc 93.50 KV4 Idc 3.02 KA

5 V 10.99 KV

SlNo

VariableName


1 Pout 7658.77 KW2 Qout 5076.41KVAR3 Edc 93.50 KV4 Idc 3.04 KA

5 Vg 10.99 KV

Sl No Variable Name Generation in Maximum

1 Pout 10005.52 KW2 Qout 6105.76 KVAR

3 Edc 31.51 KV4 Idc 0.31 KA5 Vg 10.93 KV


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Fig.8 various characteristics for firing angle is 0 for converter and 90 for inverterwhen whole generated power is regulated via through AC/DC/AC power converterinterfaced with directly to the utility grid in case self-excited induction generator

Table-II.B. results with firing angle15for converter & 90 for inverter

Table-III.B. results with firing angle30for converter & 90 for inverter

SlNo

VariableName


1 Pout 11960.66 KW2 Qout 5486.32 KVAR3 Edc 29.97 KV

4 Idc 0.32 KA5 V 10.87 KV

SlNo

VariableName


1 Pout 9885.46 KW2 Qout 6378.00KVAR3 Edc 11.37 KV

4 Idc 0.27 KA5 V 10.87 KV


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Table-IV.B. results with firing angle45for converter & 90 for inverter

Table-V.B. results with firing angle60for converter & 90 for inverter

Fig.9.various characteristics forfiring angle is 60 for converter

and 90 for inverter whenwhole generated power isregulated via throughAC/DC/AC power converterinterfaced with directly in caseself-excited induction generator

Table-VI.B. results with firing angle90for converter & 90 for inverter

Table-VII.B. results with firing angle0for converter & 105 for inverter

SlNo

VariableName


1 Pout 11488.95 KW2 Qout 8219.59KVAR3 Edc 12.05 KV4 Idc 0.31KA5 V 10.87 KV

SlNo

VariableName


1 Pout 11,990.63 KW2 Qout 7151.36 VAR3 Edc 23.60 KV4 Idc 0.31 KA5 V 11.99 KV

SlNo

VariableName


1 Pout 11,970.82KW2 Qout 7704.34 KVAR3 Edc 24.61KV4 Idc 0.32 KA5 V 10.87 KV

SlNo

VariableName




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Table-VIII.B. results with firing angle60for converter & 165 for inverter

Table-IX.B. results with firing angle90for converter & 180 for inverter

When whole of generated power is regulated through via AC/DC/AC powerconverter, there is an effective variation of power generation occurs on varying offiring angle of power converter and inverter. This project model may be utilized forregulation and controlling of power in modern power circuits.. The smooth powergeneration, operation and control may be adopted in power generation circuits, but

in some cases the load or grid voltage become higher than predefined values whichmay be happened due to Ferranti, harmonics or other charging effects which offersvoltage instability.

(C).Project model-3

Result analysis for wind power plants with doubly fed induction generator: when50% of generated power of doubly fed induction generator is regulated via throughAC/DC/AC power converter to utility grid and whole of the power is connected tothe grid directly at wind speed, m/s, generated torque ofwind turbine, Tm=3.20775 KN-m., series-parallel capacitor bank, C2=150 ,C1=40:

Table-I.C. results with firing angle 0for converter & 90 for inverter

SlNo

VariableName



SlNo

VariableName



Sl NoVariable Name


1 Pout 11553.22 KW2 Qout 9498.21KVAR3 Edc 32.99 KV4 Idc 0.37 KA

5 V 10.94 KV


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Fig.10. various reading for firing angle 0 for converter and 90 for inverter when

whole 50% generated power is regulated via through AC/DC/AC power converterinterfaced with the utility grid and whole of power is directly connected to the gridin case D.F.I.G.

Table-II.C. results with firing angle15for converter & 90 for inverter

Table-III.C. results with firing angle30for converter & 90 for inverter

SlNo

VariableName



4 Idc 0.37 KA5 Vg 10.95 KV

SlNo

VariableName


1 Pout 9123.36KW2 Qout 9402.84 KVAR3 Edc 32.94 KV

4 Idc 0.37 KA5 Vg 10.91 KV


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Table-IV.C. results with firing angle45for converter & 90 for inverter

Table-V.C. results with firing angle60for converter & 90 for inverter

Fig.11.various characteristics for firing angle is 60 for converter and 90 forinverter when whole 50% generated power is regulated via through AC/DC/AC

power converter interfaced with the utility grid and whole of the power is directlyconnected to the grid in case of D.F.I.G.

SlNo

VariableName



4 Idc 0.36 KA5 Vg 10.96 KV

SlNo

VariableName


1 Pout 11958.57 KW2 Qout 9074.85KVAR3 Edc 32.94 KV4 Idc 0.37 KA5 V 10.99 KV


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3. Higher values of capacitor banks is required for production of reactive power.4. The overall system performance is comparatively good.

Project Model-31. Comparatively production of large amount of electrical power with sameoperating set.2. Less sizes of capacitance bank is required as 50% of generated power is fed backto the rotor circuit for excitation of D.F.I.G.3. Moderate sizes of power electronic devices are required to handle comparativelylower voltage and current.4. Maintaining good voltage stability with fixed frequency grid voltages.5. Overall system performance is better than other project models.

8. CONCLUSIONIn this thesis , three dynamic models of wind power plants has been presented for a

pitch-controlled and variable speed wind Turbine, equipped with self-excitedInduction generator as well as a wound-rotor doubly fed induction Generator andstatic AC/DC/AC power converters with power transformer cascade. The necessaryseries-parallel capacitor banks have been included in the power circuits formaintaining voltage stability for reactive power balance. Three models have beenframed with self-excited induction generator as well as D.F.I.G. and implementedusing PSCAD/EMTDC software. The simulations performed and analysis ofconcerned results indicates that the system presents various dynamic characteristicsin those three project models, with/without any stability problems.PSCAD/EMTDC proved to be a valuable tool in predicting the behaviour of theWT, in selecting controller parameters and optimizing in general the control and

operation of the machine and a case study has been analyzed and all those modelsanalysis is helpful to select the project model in real situation.

REFERENCES:

1.Final Project Report WECC Wind Generator Development. Appendix V Modelvalidation of Wind Turbine Generator; Prepared for CIEE By: National RenewableEnergy Laboratory, University of California.[19]

2. Shahnia1 Farhad and Sharifian2 Mohammad B.B,PSCAD/EMTDC BASEDSIMULATION OF DOUBLE FED INDUCTION GENERATOR FOR WINDTURBINES--1East Azarbayjan Electric Power Distribution Company, Tabriz, Iran;2Faculty of Electrical and Computer Engineering, University of Tabriz, Tabriz,Tabriz, iran.[20]

3. Mustafa. A. A1-Saffar1, Eui-Cheol Nho2 Thomas A. Lipo3 Controlled ShuntCapacitor Self-Excited Induction Generator-1Dept. of Electrical EngineeringCollege of Technological Studies P.O. BOX 39525 A1-Nuzha, Kuwait 73056,2Dept. of Electrical Engineering College of Engineering Pukyoung NationalUniversity San 100, YongDang-Dong, NamKuj Pusan, 608-739, 3Dept. of


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Electrical Engineering College of Engineering University of Wisconsin Madison1415 Engineering Drive Madison WI 53706-1691[32]4 . Seyoum.D, Grantham.C and Rahman .F, Analysis of an Isolated self-excitedinduction generator driven by a Variable speed prime mover-- School of ElectricalEngineering and Telecommunications, The University of New South Wales [33]

5. Renewable energy- Principles of Doubly Fed Induction Generator(DFIG) Courseware sample by Staff of Lab-Volt Ltd., Canada, May 2011[22]

6. Patnaik. Ishan,Wind as a Renewable Source of Energy-- A project report,Student of NIT, Rourkela, Orissa:[4]

7. Babu . B.Chitti and Mohanty. K.B.,,Doubly Fed Induction Generator forvariable speed wind Energy Conversion System-Modelling & Simulation---International Journal of computer and Electrical Engineering, Vol.2,No.1,February,2010,1793-8163[26]8. Skolthanarat .Siriya, The Modeling and Control of a Wind Farm and GridInterconnection in a Multi-machine System- Dissertation submitted to the facultyof the Virgina Polytechnic institute and State University in partial fulfilment of therequirements for the degree of Ph.D.,August 26th,2009, Blackburg, VA. Hansen .LH, L. Helle, Blaabjerg .F, Ritchie .E, S. Munk-Nielsen .S,Bindner.H, , Srensen .P and Bak-Jensen .B,Conceptual survey of Generators andPower Electronics for Wind Turbines, Ris National Laboratory, Roskilde,Denmark, December 200110. Petru .Tomas,Modeling of Wind Turbines for Power System Studies-Department of Electrical Power engineering, Chalmers university of technology,Goteborg, Sweden 2001.

11. Muljadi .E and Butterfield C.P.1 and Sallan .J and Sanz .M2,.Investigation ofSelf-Excited Induction Generator for Wind Turbine Application - 1NationalRenewable energy Laboratory, Golden, Colorado; 2University of Zaragoza, Spain;Presented at the 1999 IEEE Industry Applications Society, annual Meeting,Phoenix, Arizona, October 3-7, 1999

12. Kulworawanichpong .T and Sangsarawant .P, Power flow Modelling of Self-excited Induction Generator--- proceedings of the World congress on Engineering2007 vol I, WCE 2007, july 2-4,2007, London, U.K.

Gupta JB ,Theory and performance of electrical machinesS.K. Kataria &Sons,4424/6 Guru Nanak Market, Nai Sarak, Delhi 11006

14. Vaidya Jay, Advanced Electric Generator & Control for high SpeedMicro/Mini Turbine based Power Systems-- President Electrodynamics Associates,Inc. 409 East bridge Drive, Oviedo, FL 32765 And Earl Gregory, PowerGeneration, Propulsion Directorate AFRL/PRPG, Wright-Patterson AFB, OH45433

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Modelling and Simulation of Wind Power Plants