Wind_Energy_Essentials_Lecture 4

Wind_Energy_Essentials_Lecture 4 - Electric Power Basics...

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Unformatted text preview: Electric Power Basics – Harnessing of Wind Energy Wi Ned Mohan Department of Electrical Engineering University of Minnesota Minneapolis, MN 55455 USA EE 5940 Wind Energy Essentials Fall 2010 © Copyright N. Mohan 2010 1 ‘We Need Energy Miracles’ (Bill Gates: TED Speech 2010) Source: www.huffingtonpost.com © Copyright N. Mohan 2010 2 Financial Cost Production and Consumption 700 B$/yr © Copyright N. Mohan 2010 3 Electric Power Source: DOE © Copyright N. Mohan 2010 4 Electric Power Generation by Fuel Type: Type: Source: DOE © Copyright N. Mohan 2010 5 Wind On-land Offshore Electricity from Renewables Solar Concentrated Solar Power (CSP) Photovoltaic (PV) Wave Geothermal © Copyright N. Mohan 2010 6 Source: DOE © Copyright N. Mohan 2010 7 Wind Turbines 161 kV V 0 Time Low-Voltage Ride-Through 0 690V 10 60 Hz Generator 690V 34.5 kV 60 Hz 8 Power Electronics Electronics Converters © Copyright N. Mohan 2010 GE 1.5 MW Turbine m/s 1 m / s 2.25 miles / hr © Copyright Source: N. Mohan 2010 9 Power from the Wind © Copyright N. Mohan 2010 Source: 10 Electrical System Model: Source: © Copyright N. Mohan 2010 11 El Electric Power Basics Basics Power Systems Electric Generators Generators Power Electronics Research (2 slides) (2 slides) Curricular Reform (2 slides) © Copyright N. Mohan 2010 12 Power System Basics Power System Basics 161 kV V 0 Time Low-Voltage Ride-Through 0 690V 10 60 Hz Generator 690V 34.5 kV 60 Hz 13 Power Electronics Electronics Converters © Copyright N. Mohan 2010 Reason for using AC: Ability to Transformer Voltage Levels © Copyright N. Mohan 2010 14 Phase Relationship between Voltage and Current: p (t ) 2V 2I average power / v(t ) p (t ) average power 0 v(t ) t 0 t (a ) Average P V I i (t ) ( b) Average P V I cos cos i (t ) © Copyright N. Mohan 2010 15 Phasors Imaginary v (t ) 2 V cos t positive angles i (t ) 2 I cos(t ) V V 0 Real i( t ) I I I j L j X L v( t ) 2V cos( t ) L V V 0 Z R jX L jX c R 1 j j XC C (b) R C (a ) V V I Z Z Ri (t ) L di (t ) 1 i (t ) • dt 2 V cos(t ) dt C © Copyright N. Mohan 2010 16 P and Q I Subcircuit 1 V Subcircuit 2 S P jQ Im (a) IP V V v Im S QQ j IQ Re P (c) Re I I i (b) P V I cos IP S VI P Q 2 2 Q V I sin IQ © Copyright N. Mohan 2010 P P Power Factor= cos S VI 17 Three-phase Circuits: Ia V an V cn n V bn V ph Vcn Vca a Vb Vab 30 o ZL N c VLine-Line 3 V ph Van Ic Ib b Vbn Vbc P3 phase VLine Line 3 VI cos 3 I cos 3VLine Line I cos 3 © Copyright N. Mohan 2010 18 Clicker Question In a wind turbine, the generator is rated at 690 V and 2.3 MW. It operates at a power factor of 0.85 (lagging) at its rated conditions. Calculate the phase current. A. ~2264A B. ~3922A C. ~1307A © Copyright N. Mohan 2010 19 Per Unit: actual value value Per-Unit Value = base value base value © Copyright N. Mohan 2010 20 Effect of Real and Reactive Power VWF WF I jX L I VGrid VWF jX L VWF VGrid jX L I WF VWF I jX L I VWF VGrid VGrid VGrid VWF jX L I © Copyright N. Mohan 2010 VWF VGrid 21 I Power Transformers © Copyright N. Mohan 2010 22 Transformer Basics I1 V1 I2 V2 N1 turns of wire N2 turns of wire V2 N 2 a V1 N1 I 2 N1 1 I1 N 2 a V2 aV1 I2 I1 a © Copyright N. Mohan 2010 23 Generator Basics: 161 kV V 0 Time Low-Voltage Ride-Through 0 690V 10 60 Hz Generator 690V 34.5 kV 60 Hz 24 Power Electronics Electronics Converters © Copyright N. Mohan 2010 Electro-Mechanical Energy Conversion: Electrical System Electrical Mechanical System Machine Motoring mode Pelec Pmech Pelec Generating mode Pmech © Copyright N. Mohan 2010 25 Types of Generators Permanent-Magnets AC (PMAC) Generators Induction (Asynchronous) Generators Squirrel-Cage Wound-rotor (doubly-fed) © Copyright N. Mohan 2010 26 Basic Principles Electromagnetic Force: external B field f em f em subtract add resultant f em i B [ Nm ] © Copyright N. Mohan 2010 [T ] [ A] [ m ] 27 Induced Voltage: B (into paper) fq u fq e l B [V ] u [T ] [ m ][ m / s ] © Copyright N. Mohan 2010 28 Basic Basic Structure: Stator Air gap Rotor © Copyright N. Mohan 2010 29 Three-Phase Stator Windings: Windings: © Copyright N. Mohan 2010 30 PMAC Generator: http://www.ece.umn.edu/users/riaz/animations/alternator.html © Copyright N. Mohan 2010 31 Induction Machines with a Squirrel-Cage Rotor: Squirrel b axis ib 2 / 3 2 / 3 2 / 3 a axis ia ic c axis © Copyright N. Mohan 2010 32 Production of Magnetic Field a ima b imb c imc a 0 o 60 o 120 o 180 o 240 o 300 o 360 o t http://www.ece.umn.edu/users/riaz/animations/spacevectors.html © Copyright N. Mohan 2010 33 Induced Voltages in the Rotor Rotor Bars at t 0 m syn vs a axis syn Bms © Copyright N. Mohan 2010 34 Induced Voltages and currents in the rotor Bars m,ir ' m,ir at t 0 ebar m net flux = 0 vs a axis Rbar ima ira ' ibar ( ) syn Bms front end-ring back end-ring © Copyright N. Mohan 2010 35 Slip frequency (fslip) in the rotor circuit slip syn - m f slip f slip syn © Copyright N. Mohan 2010 36 Torque – Speed Characteristics Tem,rated 0 m,rated slip,rated syn,ratedm http://www.ece.umn.edu/users/riaz/animations/sqmoviemotgen.html © Copyright N. Mohan 2010 37 Doubly-Fed Induction Generator: Source: © Copyright N. Mohan 2010 38 Power Electronics Basics 161 kV V 0 Time Low-Voltage Ride-Through 0 690V 10 60 Hz Generator 690V 34.5 kV 60 Hz 39 Power Electronics Electronics Converters © Copyright N. Mohan 2010 Power Electronics as an Interface: Power Electronics Interface Converter Source Controller Load © Copyright N. Mohan 2010 40 Voltage-Link System conv1 utility conv2 Load controller © Copyright N. Mohan 2010 41 Power and Reactive Power Control conv1 utility conv2 Load controller I Vconv jX Vconv Vs I ( b) Vs jXI Re (a ) © Copyright N. Mohan 2010 42 Step-Down (Buck) Converter Filter Vin A vA Vo d Tup Ts vA vA V A Vo V A Vo dVin © Copyright N. Mohan 2010 43 Realizing a Bi-Positional Switch in Step Co A Step-Down Converter q 1 iL iL Vo (a) Vin q iL Vin qA 1 Vo iL Vo (c) Vin (b) qA 0 © Copyright N. Mohan 2010 44 Step-Up (Boost) Converter iL Vo C vL Vin q p © Copyright N. Mohan 2010 45 Bi-Directional Power Flow iL V1 A vA V2 q q (1 q ) © Copyright N. Mohan 2010 46 Synthesizing Sinusoidal AC: q 1 iL q vaN Vd vaN vaN 0 vaN 0 0 Ts t © Copyright N. Mohan 2010 47 Interface for Wind Generator va (t ) ia (t ) A i A (t ) e A (t ) B Vd n C N Vd v AN v An 1 Vd 2 © Copyright N. Mohan 2010 0 t 48 a b ia ib c v vc b Basic Voltage Vectors v a Vd ic a vs (t ) Vd ( qa e j 0 qbe j 2 / 3 qc e j 4 / 3 ) N qa qb qc Figure 7-1 Switch-mode inverter. v2 (010) sector 2 v3 (011) sector 3 vs sector 1 v6 (110) v1 (001) a -axis sector 4 sector 5 sector 6 a vs (000) v0 0 a vs (001) v1 Vd e j 0 a vs (010) v2 Vd e j 2 / 3 a vs (011) v3 Vd e j / 3 a vs (100) v4 Vd e j 4 / 3 a vs (101) v5 Vd e j 5 / 3 a vs (110) v6 Vd e j a vs (111) v7 0 v4 (100) © Copyright N. Mohan 2010 v5 (101) 49 Present Wind Turbines 20 1800 Stray Currents due to Converter Switchings cause Damage to Bearings Heavy Cables 80-100 m Power Electronics Converter with Large Storage Capacitors Converter 161 kV 690 V, 60-Hz 34.5 kV, 60-Hz Underground Heavy Transformer 60 Hz © Copyright N. Mohan 2010 50 Proposed Generation System: Improving Reliability and Reducing the Nacelle Weight by 20% and Reducing the Nacelle Weight by 20% Open-end Open-end winding ac winding ac machine machine MC MC System System Utility Utility 20 20 1800 1800 High frequency transformer High frequency transformer converter system converter system High-Frequency High-Frequency Transformer and Transformer and Transformer and Transformer and Converter Converter Light Cable att 34..5 kV Light Cable at 34 5kV Cable a 34 kV Cable at 34 kV 34.5 kV, 60-Hz Underground 34.5 kV, 60-Hz Underground 690V 690V © Copyright N. Mohan 2010 690V 690V 51 Curriculum Developed Power Electronics Electric Drives Teaching Machines as a subcomponent of Drive Systems Electric Drive fixed form Power Systems Bus-1 Bus-3 Pm1 Pe1 Bus-2 Pe 2 Features: Switching Power-Pole as the Building-Block Includes dc-dc Converters and dc-ac Inverters Feedback control of Converters Textbook Power Processing Unit (PPU) adjustable form Mot or speed / position Load Pm 2 Electric Source (utility) Sensors Controller measured speed/ position Power Signal Includes Topics such as - Applications: - Harnessing of Wind Energy Wi - Electric and Hybrid-Electric Vehicles input command (speed / position) - Renewables/Storage HVDC, FACTS Voltage Stability Slides Solutions manual Textbook Textbook - Hardware Lab Lab - Slides Solutions manual Slides Solutions manual Software-based Lab: - MATLAB/Simulink, PowerWorld, EMTDC - Complete Lab on CD - 18 Short Video Clips Short Video Clips DSP-Controlled Lab - Course Learning Objectives Online Homework Problems - Course Learning Objectives Online Homework Problems - Course Learning Objectives Online Homework Problems Vendor: HiRel Systems Duluth, Minnesota Phone: 218-727-3115 Lab Manuals can be downloaded from: www.ece.umn.edu/groups/power © Copyright N. Mohan 2010 52 DOE Funded: “A Nationwide Consortium of Universities to Revitalize Electric Power Engineering” •82 Universities “These 82 schools represented about 25% of all the graduates in electrical engineering in 2008 electrical engineering in 2008.” © Copyright N. Mohan 2010 53 ...
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This note was uploaded on 02/26/2011 for the course EE 523 taught by Professor Dr.hopkins during the Spring '11 term at SUNY Buffalo.

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