table of contents -...
TRANSCRIPT
viii
TABLE OF CONTENTS
CHAPTER NO. TITLE PAGE NO.
ABSTRACT iii
LIST OF TABLES xvi
LIST OF FIGURES xvi
LIST OF ABBREVIATIONS xxvi
1 INTRODUCTION 1
1.1 MODERN POWER SYSTEM REQUIREMENTS 1
1.2 POWER FLOW CONTROL
IN TRANSMISSION LINES 4
1.3 NEED FOR REACTIVE POWER
COMPENSATION 7
1.4 LITERATURE SURVEY 9
1.5 POWER FLOW CONTROL THROUGH
SHUNT REACTIVE POWER
COMPENSATOR - STATCOM 14
1.6 STRUCTURE OF THE THESIS 18
1.7 CONCLUSION 19
2 CONVENTIONAL STATCOM 20
2.1 COMPENSATION PRINCIPLE OF STATCOM 20
2.1.2 Power Exchange in STATCOM
Application 23
2.2 STATCOM CONTROL STRATEGY 27
2.2.1 Conventional PWM Control Technique 29
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CHAPTER NO. TITLE PAGE NO.
2.3 INTERPOLATION FIRING
CONTROL SCHEME 31
2.3.1 Generation of Interpolation Firing Pulses 31
2.4 STATCOM MODELING 33
2.4.1 STATCOM Transient Stability Model 36
2.4.2 STATCOM Steady State Model 38
2.4.3 Dynamic d-q Modeling of STATCOM 40
2.5 MITIGATION TECHNIQUE REALIZATION
IN PSCAD/ EMTDC 44
2.5.1 STATCOM Control in Simulation Program 45
2.5.2 Interpolation Firing Circuit 48
2.6 IMPLEMENTATION OF VSC
BASED STATCOM IN PSCAD 50
2.7 DISCUSSION ON RESULTS 53
2.8 CONCLUSION 55
3 CASCADED MULTILEVEL INVERTERS 56
3.1 INTRODUCTION 56
3.2 TOPOLOGIES OF MULTILEVEL INVERTERS 59
3.2.1 Diode-Clamped Multilevel Converter 59
3.2.2 Flying-Capacitor Multilevel Converter 61
3.2.3 Cascaded-Multilevel Converters
with Separated DC Sources 63
3.2.4 Comparison of Power Component
Requirements among Multilevel Converters 66
3.2.5 Proposed Asymmetric Cascaded
Multilevel Converter 69
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CHAPTER NO. TITLE PAGE NO.
3.3 MODULATION STRATEGIES 70
3.3.1 Carrier based PWM 73
3.4 POWER FLOW SOLUTIONS 79
3.4.1 Switching Angle Calculation
using Newton-Raphson Method 80
3.5 PROPOSED MODULATION STRATEGY 84
3.5.1 Inverted Sine Carrier PWM Strategy 84
3.5.2 Proposed Variable Frequency
ISPWM Technique 86
3.6 IMPLEMENTATION OF ASYMMETRIC
MULTILEVEL INVERTER 87
3.6.1 Performance Evaluation of CMC
Employing Conventional PWM 90
3.6.2 Performance Evaluation of CMC
Employing Unipolar ISCPWM 92
3.6.3 Performance Evaluation of CMC
Employing VFISCPWM 98
3.7 NEURAL NETWORK CONTROL
OF ACMC 104
3.8 FPGA BASED HARDWARE
IMPLEMENTATION 108
3.8.1 Generation of Gating Pulses for
the Proposed PWM 111
3.9 CONCLUSION 114
xi
CHAPTER NO. TITLE PAGE NO.
4 STABILITY ANALYSIS OF INDUCTION
GENERATORS USING STATCOM 116
4.1 RENEWABLE WIND POWER SUPPORT
IN THE POWER SYSTEM 116
4.2 WIND POWER INTEGRATION CHALLENGES 118
4.2.1 Low Voltage Ride Through
(LVRT) Capability 120
4.3 STABILITY ANALYSIS OF INDUCTION
GENERATOR BASED WIND TURBINES 121
4.3.1 Voltage Stabilization and Fluctuation
Mitigation 124
4.3.2 Electrical Modeling Issues and
Requirements of Fixed Speed
Induction Generators 127
4.4 WIND TURBINE MODEL 130
4.4.1 Mechanical Model 130
4.4.2 Dynamic dq Model 132
4.5 FACTS BASED SOLUTIONS 136
4.5.1 Proposed CMC based STATCOM 137
4.6 STEADY STATE VOLTAGE CONTROL
WITH STATCOM 139
4.7 PERFORMANCE EVALUATION OF VSC
BASED STATCOM 144
4.8 TEST SYSTEM WITH CMC
BASED STATCOM 147
4.8.1 Reactive Power Compensation using
5-level CMC based STATCOM 152
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CHAPTER NO. TITLE PAGE NO.
4.9 COMPARISON OF RESULTS 153
4.10 PERFORMANCE EVALUATION
OF ACMC STATCOM 156
4.11 HARDWARE IMPLEMENTATION 163
4.12 CONCLUSION 165
5 ACTIVE POWER COMPENSATION
OF STATCOM WITH ENERGY
STORAGE SYSTEMS 167
5.1 INTRODUCTION 167
5.2 ENERGY STORAGE SYSTEM 168
5.2.1 Energy Storage using Capacitors 169
5.2.2 Energy Storage using Batteries 170
5.2.3 Energy Storage using SMES 171
5.2.4 Comparison between SMES and
other Energy Storage Devices 173
5.3 THE SMES SYSTEM AND ITS ROLE
IN POWER SYSTEMS 174
5.4 INTEGRATION OF SMES WITH A STATCOM 176
5.4.1 Active and Reactive Power Control 177
5.4.2 Control Scheme of STATCOM / SMES 179
5.4.3 ESS-Chopper Topology 182
5.4.4 Interface between ESS and the DC Link
of the VSC 188
5.5 CONVERTER CONTROL FOR ACTIVE
POWER EXCHANGE 191
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CHAPTER NO. TITLE PAGE NO.
5.6 SIMULATION OF POWER SYSTEM
RESPONSE TO ACTIVE POWER
COMPENSATION 197
5.6.1 Integration of ESS with STATCOM 200
5.6.2 Simulation Results 201
5.7 LOCATION OF STATCOM 203
5.8 CONCLUSION 206
6 CONCLUSION AND FUTURE WORK 207
6.1 CONCLUSION 207
6.2 SCOPE FOR FUTURE RESEARCH 210
REFERENCES 211
LIST OF PUBLICATIONS 227
VITAE 229
xiv
LIST OF TABLES
TABLE
NO.TITLE
PAGE
NO.
3.1 Diode-clamped 5-level converter voltage levels
and their switch states 61
3.2 Flying capacitor 5-level voltage levels and
their corresponding switch states 63
3.3 CMC 5-level voltage levels and their corresponding
switch states 66
3.4 Comparison among multilevel converters based on
power component requirements for phase leg 67
3.5 Comparison of number of devices required per
phase 68
3.6 Switching angles for various modulation indexes 83
3.7 Switching sequence for 7-level ACMC 89
3.8 Comparison of unipolar ISCPWM with
conventional PWM 96
3.9 Comparison of THD values - VFISPWM
with unipolar ISPWM technique 103
3.10 Switching sequence 107
3.11 Comparison of HEM with conventional SPWM 108
4.1 Comparison of simulation results 151
xv
TABLE
NO.TITLE
PAGE
NO.
4.2 Comparison of results with 3-level and 5-level
STATCOM 156
5.1 Chopper switching signals sequence during
charging mode 186
5.2 Chopper switching signals sequence during
discharging mode 186
xvi
LIST OF FIGURES
FIGURE
NO.TITLE
PAGE
NO.
1.1 Operational limits of the system for voltage
collapse 2
1.2 Equivalent circuit model 5
1.3 Power angle curve 5
1.4 Equivalent circuit of an AC power system with
compensator 7
1.5 Phasor diagram (uncompensated) 8
1.6 Phasor diagram (compensated for constant
voltage) 9
1.7 Power transmission characteristic with dynamic
shunt compensation 15
1.8 Mid-point compensation by STATCOM 16
1.9 P- characteristics with and without STATCOM 17
2.1 Functional model of a STATCOM 20
2.2 Single line diagram 21
2.3 Operating modes of STATCOM 24
2.4 STATCOM phasor diagrams 26
2.5 STATCOM phasor diagrams 27
xvii
FIGURE
NO.TITLE
PAGE
NO.
2.6 Block diagram of a STATCOM with PWM
voltage control 30
2.7 Firing angle measurement with and
without interpolation 31
2.8 Equivalent circuit of STATCOM 34
2.9 Transient stability model of a STATCOM 37
2.10 Phasor diagram of a PWM converter 39
2.11 Three phase to two phase transformation 41
2.12 to d-q transformation 42
2.13 Functional model of the proposed system 44
2.14 Control scheme implemented in PSCAD /
EMTDC 45
2.15(a) Generation of triangular pulses 46
2.15(b) Generation of sine wave pulses 46
2.16 Logic and control blocks in interpolation 48
2.17 Interpolation firing component 49
2.18 Load voltage wave form without STATCOM 51
2.19 Load voltage wave form with STATCOM 51
2.20 Real power consumption without STATCOM 51
2.21 Real power consumption with STATCOM 52
2.22 Reactive power consumption with STATCOM 53
xviii
FIGURE
NO.TITLE
PAGE
NO.
2.23 Reactive power consumption without STATCOM 52
2.24 Capacitor voltage wave form 53
2.25 Reactive power injected by STATCOM 53
3.1 One phase leg of an inverter 56
3.2 Power circuit of one phase leg of a 5-level
DCMLI 60
3.3 Power circuit of one phase leg of a 5-level FCMC 62
3.4(a) Single phase leg structure of a CMC with SDCS 64
3.4(b) Individual H-Bridge cell of a CMC 64
3.5 Switching modes of 5-level CMC 65
3.6 Asymmetric cascaded-multilevel converter 70
3.7 SPWM modulation 75
3.8 Multilevel SPWM with PS method in a 7-level
inverter 76
3.9 Generation of pulses using ISPWM 85
3.10 Asymmetric cascaded 7-level inverter 88
3.11 Simulation circuit for the generation of triangular
wave 90
3.12 Simulation circuit of conventional cascaded MLI 91
3.13 Triangular carrier waves 91
3.14 Triangular carrier and reference sine waveforms
for conventional PWM 91
3.15 Output voltage of CMC (Conventional PWM) 92
xix
FIGURE
NO.TITLE
PAGE
NO.
3.16 FFT Window for output voltage (Conventional
PWM) 92
3.17 Simulation circuit for the generation of unipolar
inverted sine carrier waves 93
3.18 Waves employed for generating inverted sine
waves 93
3.19 Unipolar inverted sine carrier waves 94
3.20 Inverted sine carrier waves (7-level) 94
3.21 Reference and inverted sine waveforms
for unipolar ISPWM 95
3.22 Output voltage of conventional 7-level CMC
employing Unipolar ISCPWM 95
3.23 FT window for output voltage (Unipolar ISPWM) 96
3.24 Output voltage waveform of single phase 7-level
ACMC 97
3.25 Output voltage waveform of three phase 7-level
ACMC (Unipolar ISCPWM) 97
3.26 Simulation circuit for the generation of variable
frequency inverted sine carrier waves 98
3.27 Carrier and inverted sine waveforms
for VFISCPWM technique 99
3.28 Variable frequency inverted sine carrier waves 99
3.29 Output voltage waveform of single phase 7-level
ACMC employing VFISCPWM 100
xx
FIGURE
NO.TITLE
PAGE
NO.
3.30 Output voltage waveform of three phase 7-level
ACMC 100
3.31 Output voltages waveform of three phase 7-level
ACMC 101
3.32 FFT window for output voltage (Unipolar
ISPWM) 101
3.33 FFT window for output voltage (VFISPWM) 102
3.34 Multiport system 105
3.35 ACMC Simulation circuit using ANN controller 105
3.36 ACMC simulation circuit using conventional
SPWM controller 106
3.37 Output voltage of the 7-level ACMC using ANN
controller 106
3.38 Block diagram of Spartan 3E-Xilinx (Xc3s500-
Fg320) 108
3.39 FPGA kit programmed with Xilinx ISE tool 109
3.40 FPGA kit (Spartan 3E-[Xc3s500-Fg320])
and two stage cascaded inverter 109
3.41 Generation of PWM pulses from FPGA 111
3.42 VLSI simulation : model SIM PWM Pulses 112
3.43 5-level output voltage waveform for ISCPWM
inverter 112
3.44 Generated pulses using ISPWM technique in
CRO 113
xxi
FIGURE
NO.TITLE
PAGE
NO.
3.45 Cascaded 7-level inverter output waveform in
CRO 114
4.1 Voltage dip profile 117
4.2 Fixed-speed system with stall or active-stall
control 118
4.3 LVRT requirement for wind generation facilities 120
4.4 Fixed speed wind energy conversion system 122
4.5 CP - curves for different pitch angles 123
4.6 Single line diagram of a WECS 127
4.7 Equivalent circuit of an induction generator 128
4.8 Mechanical model for the wind turbine 130
4.9 dq model of wind turbine 132
4.10 CMC based topology 138
4.11 Block diagram for voltage control using
STATCOM 139
4.12 STATCOM control scheme 140
4.13 Simplified model of the CMC based STATCOM
in both abc and dqo coordinates 142
4.14 Reactive power absorbed by the induction
generator 145
4.15 Active power 146
4.16 Power factor 146
xxii
FIGURE
NO.TITLE
PAGE
NO.
4.17 THD measurement 147
4.18 Single line diagram of the test system 148
4.19 Active power without STATCOM 148
4.20 Reactive power without STATCOM 149
4.21 Grid voltage without STATCOM 149
4.22 Load voltage without STATCOM 149
4.23 Active power with 3-level inverter STATCOM 150
4.24 Reactive power with 3-level inverter STATCOM 150
4.25 Grid voltage with 3-level inverter STATCOM 150
4.26 Load voltage with 3-level inverter STATCOM 151
4.27 Active power with cascaded 5-level inverter
STATCOM 152
4.28 Reactive power with cascaded 5-level inverter
STATCOM 152
4.29 Load voltage with cascaded 5-level inverter
STATCOM 153
4.30 Grid voltage with cascaded 5-level inverter
STATCOM 153
4.31 Comparison of grid active power 154
4.32 Comparison of grid reactive power 154
4.33 Comparison of load active power 154
4.34 Comparison of load reactive power 155
4.35 Comparison of wind farm active power 155
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FIGURE
NO.TITLE
PAGE
NO.
4.36 Comparison of wind farm reactive power 155
4.37 Generation of carrier signals 157
4.38 Switching signals using multicarrier based
SPWM 158
4.39 Load voltage profile 158
4.40 Load current waveforms 159
4.41 Real Power waveforms 160
4.42 Reactive power waveforms 160
4.43 Per phase voltage output of CMC 161
4.44 7-level voltage output of CMC 161
4.45 THD for 7-level CMC based STATCOM 162
4.46 THD for 9-level CMC based STATCOM 162
4.47 THD for 9-level ACMC based STATCOM 162
4.48 Hardware circuit implementation 163
4.49 Single H1 bridge output waveform in CRO 164
4.50 Single H2 bridge output waveform in CRO 164
4.51 Cascaded 5-level inverter output waveform in
CRO 165
5.1 Basic components of a SMES system 175
5.2 PCS for SMES-based FACTS devices 175
5.3 Integration of SMES with a STATCOM 176
5.4 STATCOM/SMES configuration 178
xxiv
FIGURE
NO.TITLE
PAGE
NO.
5.5 STATCOM/ESS output characteristics 179
5.6 Internal control block of the VSI and DC-DC
chopper 180
5.7 External control block of the STATCOM/SMES
system 181
5.8 DC-DC chopper topology 183
5.9 2-level two-quadrant DC-DC chopper 184
5.10 Sub topologies for the chopper 185
5.11 Chopper equivalent circuit 187
5.12 DC link regulator 189
5.13 24-pulse VSI 191
5.14(a) Single-phase equivalent circuit of a
STATCOM/ESS and utility System 192
5.14(b) Phasor diagram 192
5.15 V-I characteristics in different reference
co-ordinates 194
5.16 Cyclic load model 198
5.17 48-pulse voltage source inverter 199
5.18 STATCOM integration with SMES 200
5.19 Active power at sending end with and without
compensation 201
5.20 Reactive power at sending end with and without
compensation 201
xxv
FIGURE
NO.TITLE
PAGE
NO.
5.21 Active power at receiving end with and without
compensation 202
5.22 Reactive power at receiving end with and without
compensation 202
5.23 Active power at mid point with and without
compensation 202
5.24 Reactive power at mid point with and without
compensation 203
5.25 Optimal location of STATCOM for active
power compensation 204
5.26 Optimal location of STATCOM for reactive
power compensation 205
xxvi
LIST OF ABBREVIATIONS
ACF - AC Filter
ASD - Adjustable Speed Drive
ASVC - Advanced Static Var Compensator
AC - Alternating Current
APOD - Alternative Phase Opposition Disposition
AEP - American Electric Power
ACMC - Asymmetric Cascaded Multilevel Converter
APFR - Automatic Power Factor Regulator
CCMC - Capacitor Clamped Multilevel Converter
CCMLI - Capacitor Clamped Multi Level Inverter
CMC - Cascaded Multilevel Converter
CMI - Cascaded Multilevel Inverter
CSC - Current Source Converter
DAE - Differential Algebraic Equations
DSP - Digital Signal Processor
DCMC - Diode Clamped Multilevel Converter
DCMLI - Diode Clamped Multi Level Inverter
DC - Direct Current
DVR - Dynamic Voltage Restorer
ESR - Effective Series Resistance
EPRI - Electric Power Research Institute
EMTDC - Electro Magnetic Transient DC
ESS - Energy Storage System
FERC - Federal Energy Regulatory Commission
FPGA - Field Programmable Gate Array
xxvii
FC TCR - Fixed Capacitor Thyristor Controlled Reactor
FSIG - Fixed Speed Induction Generator
FSWT - Fixed Speed Wind Turbine
FSWECS - Fixes Speed Wind Energy Conversion System
FACTS - Flexible AC Transmission Systems
FCMC - Flying Capacitor Multilevel Converter
FCMLI - Flying Capacitor Multi Level Inverter
FBC - Full Bridge Converter
FBI - Full Bridge Inverter
FFS - Fundamental Frequency Switching
GTO - Gate Turn Off
HSF - High Switching Frequency
HBBB - Hybrid Bridge Building Block
IPFC - Interline Power Flow Controller
ISPWM - Inverted Sine Pulse Width Modulation
LVRT - Low Voltage Ride Through
MCPWM - Multi Carrier Pulse Width Modulation
MLI - Multi Level Inverter
NPC - Neutral Point Clamped
NPCMC - Neutral Point Clamped Multilevel Converter
NR - Newton Raphson
OLTC - On Load Tap Changing
PD - Phase Disposition
PLL - Phase Locked Loop
PLO - Phase Locked Oscillator
POD - Phase Opposition Disposition
PS - Phase Shifted
PST - Phase Shifting Transformer
PCC - Point of Common Coupling
xxviii
PCS - Power Conditioning System
PSCAD - Power System Computer Aided Design
PI - Proportional Integral
PDM - Pulse Duration Modulation
PWM - Pulse Width Modulation
RMS - Root Mean Square
SHE - Selective Harmonic Elimination
SDCS - Seperated DC Sources
SPWM - Sinusoidal Pulse Width Modulation
SVM - Space Vector Modulation
SVPWM - Space Vector Pulse Width Modulation
SCIG - Squirrel Cage Induction Generator
STATCON - STATic CONdenser
STATCOM - STATic synchronous COMpensator
SSSC - Static Synchronous Series Compensator
SVC - Static Var Compensator
SVG Static Var Generator
SMES - Super Conducting Magnetic Energy Storage
SCADA - Supervisory Control and Data Acquisition
SCMLI - Symmetrical Cascaded Multi Level Inverter
SLBCS - Synchronous Link Based Control Scheme
TVA - Tennessee Valley Authority
TCPAR - Thyristor Controlled Phase Angle Regulator
TCPST - Thyristor Controlled Phase Shifting Transformer
TCR - Thyristor Controlled Reactor
TCSC - Thyristor Controlled Switched Capacitor
TSC - Thyristor Switched Capacitor
THD - Total Harmonic Distortion
TSO - Transmission System Operation