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A Novel Electric Traction Power Supply System

using Hybrid Parallel Power Quality Compensator

by

Keng Weng Lao

Master of Science in Electrical and Electronics Engineering

2011

Faculty of Science and Technology

University of Macau

A Novel Electric Traction Power Supply System with Hybrid Parallel Power Quality Compensator

by

Keng Weng Lao

A thesis submitted in partial fulfillment of the

requirements for the degree of

Master of Science in Electrical and Electronics Engineering

Faculty of Science and Technology University of Macau

2011

Approved by __________________________________________________

Supervisor

__________________________________________________

__________________________________________________

__________________________________________________

Date __________________________________________________________

In presenting this thesis in partial fulfillment of the requirements for a Master's degree at the University of Macau, I agree that the Library and the Faculty of Science and Technology shall make its copies freely available for inspection. However, reproduction of this thesis for any purposes or by any means shall not be allowed without my written permission. Authorization is sought by contacting the author at

Address: Rua de Bras da Rosa, Pou Seng Kok, no.29, 10/S Telephone: +853 6663 9741 Fax: N/A E-mail: [email protected]

Signature Date

University of Macau

Abstract

A NOVEL ELECTRIC TRACTION POWER SUPPLY SYSTEM USING HYBRID POWER QUALITY

COMPENSATOR

by Keng Weng Lao

Thesis Supervisor: Prof. Man-Chung Wong Thesis Co-Supervisors: Dr. NingYi Dai; Dr. Chi-Kong Wong

Electrical and Electronics Engineering

Massive transportation system is especially essential for city development nowadays.

In contrast to traditional diesel railway, electrified railway is considered to be safer,

cleaner and more efficient. The policies in “Revising the Long and Mid-Term Plan of

the China’s Railway” and the construction plan of Macau light rail transit both signify

the importance of electrified traction. The recently proposed co-phase traction power

supply possesses numerous advantages such as higher transformer utilization and

elimination of neutral sections compared to conventional one. In this thesis, a

co-phase traction power supply with proposed hybrid power quality compensator

(HPQC) compensation is being studied and investigated.

Although co-phase traction power supply is more advantageous, its development is

somehow limited by the high operation voltage and initial cost of the compensator.

The proposed HPQC is composed of one back-to-back converter with a common DC

link. Since locomotive loadings are mostly inductive, a capacitive coupled impedance

design is adopted in proposed HPQC to reduce the compensator operation voltage

when comparing with conventional railway power quality compensator (RPC).

Reduction in operation voltage can effectively reduce the device ratings and the initial

cost of the compensator.

The operation voltage of proposed HQPC can be minimized when the parameters are

properly designed. The design procedures of HPQC parameters are explored using

vector diagrams and mathematical derivations. PSCAD simulation verifications are

also provided based on real settings and parameters in real applications.

The parameter design for minimum HPQC operation voltage is derived based on

constant rated load power factor and capacity. However, locomotive loadings are

rarely constant and are unpredictably changing dynamically. Full compensation for

system power quality may be accomplished under such conditions by raising the

HPQC operation voltage. The mathematical relationship between HPQC operation

voltage and loading condition is being investigated. Moreover, the range of load

conditions that full compensation can be provided under a specific HPQC operation

voltage is also concerned. Given a specified HPQC operation voltage, the load

condition limit which full compensation can be provided is studied. All theoretical

studies concerned are supported by PSCAD simulations under realistic parameters

and settings.

Finally, the system performances of co-phase traction power supply system with

proposed HPQC are verified experimentally. A scaled-down laboratory scale

hardware prototype is designed and constructed. It is verified through experimental

results that the operation voltage of proposed HPQC can be lower than that of

conventional RPC while providing the same compensation current. The system

performances of co-phase traction power supply system used proposed HPQC and

conventional RPC are also similar. Reduction on operation voltage can effectively

reduce the device ratings and thus the initial installation cost of the traction power

supply system.

TABLE OF CONTENTS

LIST OF FIGURES .......................................................................................................v

LIST OF TABLES .......................................................................................................xv

LIST of Abbreviations ............................................................................................... xix

Chapter 1: Introduction ............................................................................................1

1.1 Project study background .................................................................................. 1

1.2 Development of Electrified Railway Traction Power ....................................... 2

1.2.1 Alternating Current (AC) Traction Power ...................................... 3

1.2.2 Direct Current (DC) Traction Power .............................................. 3

1.3 Introduction to Traction Power Supplies .......................................................... 3

1.3.1 Various Traction Power Supplies ................................................... 4

1.3.2 Power Quality of Traction Power Supplies .................................... 6

1.3.3 Existing Solutions of Traction Power Quality Problems .............. 11

1.4 Various Power Quality Compensators ............................................................ 14

1.4.1 Fixed Shunt Capacitor Bank ......................................................... 14

1.4.2 Passive Filter ................................................................................. 14

1.4.3 Static Var Compensator (SVC) ..................................................... 15

1.4.4 Static Synchronous Compensator (STATCOM) .......................... 16

1.4.5 Dynamic Voltage Restorer (DVR) ................................................ 17

1.4.6 Unified Power Quality Compensator (UPQC) ............................. 18

1.4.7 Hybrid Active Power Filter (HAPF) ............................................. 19

1.4.8 Comparisons among Various Compensators ................................ 19

1.5 Recent Developments on Traction Power FACTS Compensation Devices ... 21

1.6 Research Goals and Challenges ...................................................................... 23

1.7 Thesis Organization ........................................................................................ 24

Chapter 2: System Configurations and Control Algorithm of Co-phase

Traction Power .......................................................................................................26

2.1 Proposed Circuit Configurations and Definitions ........................................... 26

2.2 System Modeling ............................................................................................ 30

ii

2.2.1 System Unbalance ......................................................................... 30

2.2.2 System Source Reactive Power .................................................... 38

2.2.3 System Harmonics ........................................................................ 39

2.3 Compensation Principles ................................................................................ 42

2.3.1 System Unbalance and Reactive Power Compensation................ 43

2.3.2 Harmonic Compensation .............................................................. 54

2.4 Control Algorithm for Comprehensive Compensation ................................... 58

2.4.1 Theoretical Studies........................................................................ 58

2.4.2 Simulation Verifications ............................................................... 61

2.5 Chapter Summary ........................................................................................... 65

Chapter 3: System Analysis and Compensator design based on minimum

DC link voltage Ratings .........................................................................................67

3.1 Operation Voltage Rating Analysis based on System Unbalance and

Reactive Power Compensation ....................................................................... 67

3.1.1 Conventional Inductive Coupled RPC .......................................... 67

3.1.2 Proposed Capacitive Coupled HPQC ........................................... 74

3.1.3 Comparisons between conventional RPC and proposed HPQC ... 80

3.2 HPQC Parameter Design for Minimum DC Link Voltage Rating ................. 84

3.2.1 Vac Phase Converter Coupled Inductance and Capacitance ........ 85

3.2.2 Vbc Phase Converter Coupled Inductance ................................... 90

3.2.3 Minimum HPQC Operation Voltage Achievable ......................... 93

3.2.4 Simulation Verification ................................................................. 95

3.3 Comprehensive Compensation with Harmonic Consideration ....................... 95

3.3.1 Parameter Design with Harmonic Consideration ......................... 96

3.3.2 Minimum HPQC DC Link Voltage Rating ................................ 101

3.3.3 Simulated System Performance .................................................. 106

3.4 Chapter Summary ......................................................................................... 117

Chapter 4: Enhanaced HPQC Operation Voltage and Compensation Range ......120

4.1 Required HPQC Operation Voltage according to Load Conditions ............. 120

4.1.1 Theoretical Studies...................................................................... 120

4.1.2 Simulation Verifications ............................................................. 125

iii

4.2 HPQC Operation Voltage and Compensation Range ................................... 130



4.3 HPQC Operation Voltage and Load Limitations .......................................... 137



4.4 Chapter Summary ......................................................................................... 145

Chapter 5: Hardware Implementation and Experimental Results .......................147

5.1 Hardware Design and Implementation ......................................................... 147

5.1.1 Hardware Schematics.................................................................. 147

5.1.2 Microcontroller ........................................................................... 150

5.1.3 Signal Conditioning Circuits....................................................... 153

5.1.4 IGBT Drivers .............................................................................. 155

5.1.5 Hardware Appearances ............................................................... 158

5.2 Control Algorithm ......................................................................................... 164

5.3 Experimental Results .................................................................................... 167

5.3.1 System Performance without Compensation .............................. 167

5.3.2 System Performance with Conventional RPC (VDC=76V) ......... 169

5.3.3 System Performance with Proposed HPQC (VDC=52V) ............ 172

5.3.4 System Performance with Conventional RPC (VDC=52V) ......... 175

5.4 Chapter Summary ......................................................................................... 178

Chapter 6: Thesis Conclusion ..............................................................................179

bibliography ...............................................................................................................183

APPENDIX A: List of Publications ..........................................................................188

APPENDIX B: Hardware Prototype Appeareances and Detailed Function

Design Diagram ...................................................................................................189

APPENDIX C: Source Code of DSP2812 .................................................................192

v

LIST OF FIGURES

Number Page

Fig. 1.1: Circuit diagram of conventional traction power supply (BT) ....................... 4

Fig. 1.2: Circuit diagram of conventional traction power supply (AT) ....................... 4

Fig. 1.3: Circuit diagram of co-phase traction power supply (BT). ............................. 5

Fig. 1.4: Circuit diagram of co-phase traction power supply (AT). ............................ 5

Fig. 1.5: Well known power triangle showing composition of active and reactive

components in apparent power ..................................................................... 8

Fig. 1.6: Quotation of harmonic standard in National Standard GB/T 14549-93. ..... 11

Fig. 1.7: Typical circuit schematics of Static Var Compensator (SVC) .................... 16

Fig. 1.8: Typical circuit schematic of Static Synchronous Compensator

(STATCOM) or Active Power Filter (APF) ............................................... 16

Fig. 1.9: Typical circuit schematic of Dynamic Voltage Restorer (DVR) ................ 17

Fig. 1.10: Typical circuit schematic of Unified Power Quality Controller (UPQC)

..................................................................................................................... 18

Fig. 1.11: Typical structures of Hybrid Active Power Filter (Hybrid APF) .............. 19

Fig. 1.12: Application of TSR SVC for voltage regulation of traction power ........... 22

Fig. 1.13: Application of hybrid active power filter in traction power supply .......... 22

Fig. 1.14 –Application of two-phase STATCOM in traction power is known as

RPC in Japan ............................................................................................... 22

Fig. 1.15: Three-phase STATCOM proposed for traction compensation ................. 22

Fig. 1.16 –Application of multilevel STATCOM in traction power compensation ..... 22

Fig. 1.17: Proposed individual DC-link cascaded multilevel structure

STATCOM ................................................................................................. 22

Fig. 2.1: Proposed circuit structure of co-phase traction power supply with

HPQC .......................................................................................................... 27

Fig. 2.2: Simplified model of proposed co-phase traction power supply with

HPQC .......................................................................................................... 28

vi

Fig. 2.3: Vector diagram showing the definition of phase angle in the co-phase

traction power. .......................................................................................... 28

Fig. 2.4: Decomposition of traction power system into fundamental and

harmonic models. ...................................................................................... 31

Fig. 2.5: Circuit schematics of traction power system used for verification of

system unbalance modeling ...................................................................... 34

Fig. 2.6: Vector diagram showing three phase source voltage and Vac vectors ..... 35

Fig. 2.7: Vector diagram showing the primary source current vectors IA, IB and

IC ............................................................................................................... 36

Fig. 2.8: Vector diagram showing the system positive and negative sequence

vectors ....................................................................................................... 37

Fig. 2.9: Decomposition of harmonic system model into a combination of nth

harmonic models ....................................................................................... 40

Fig. 2.10: Circuit schematics of traction power system used for verification of

harmonic modeling ................................................................................... 41

Fig. 2.11: Simplified control block diagram of the control algorithm for

compensation in co-phase traction power supply system ......................... 42

Fig. 2.12: Decomposition of traction power supply system (with compensation)

into fundamental and harmonic models. ................................................... 43

Fig. 2.13: Vector diagram showing performance of co-phase traction power

without compensation. .............................................................................. 48

Fig. 2.14: Vector diagram showing performance of co-phase traction power with

compensation. ........................................................................................... 49

Fig. 2.15: Simplified control block diagrams for investigation of ideal system

unbalance and reactive power compensation performance ...................... 50

Fig. 2.16: Comparisons of co-phase traction power source current (top) without

compensation; (bottom) with ideal compensation current signal

(fundamental) ............................................................................................ 51

Fig. 2.17: Simulated vector diagrams of system positive and negative sequence ... 52

Fig. 2.18: Simulated vector diagrams of system three phase primary source

voltage and current .................................................................................... 53

vii

Fig. 2.19: Revised simplified model of proposed co-phase traction power system

with HPQC compensation including harmonic contents. ......................... 55


harmonics compensation performance ..................................................... 57



(harmonic) ................................................................................................. 57

Fig. 2.22: Control block diagram showing the computation details of

comprehensive compensation of system unbalance, reactive power and

harmonics .................................................................................................. 58


with comprehensive compensation performance ...................................... 61



(comprehensive consideration) ................................................................. 62

Fig. 2.25: Simulated vector diagrams of system positive and negative sequence ... 63

Fig. 2.26: Simulated vector diagrams of three phase source voltage and current ... 64

Fig. 2.27: The flowchart showing the determination of required Vac and Vbc

phase compensation current from load parameters in co-phase traction

power supply ............................................................................................. 66

Fig. 3.1: Circuit configuration of conventional inductive coupled compensation

device RPC................................................................................................ 68

Fig. 3.2: Vector diagram showing the operation of the Vac phase converter in

conventional RPC. .................................................................................... 69

Fig. 3.3: A 3D plot showing the variation of VinvaL with XLa under different load

power factors in conventional RPC. ......................................................... 70

Fig. 3.4: The graph of Vac phase operation voltage rating against the Vac

coupled impedance in conventional inductive coupled RPC (PF=0.85) .. 71

Fig. 3.5: Vector diagram showing the operation of the Vbc phase converter in

RPC. .......................................................................................................... 72

Fig. 3.6: Circuit configuration of proposed capacitive coupled HPQC. .................. 74

viii

Fig. 3.7: Vector diagram showing operation of the Vac phase converter in

HPQC. ....................................................................................................... 75

Fig. 3.8: A 3D plot showing the variation of VinvaLC with XLCa under different

load power factors in proposed HPQC. .................................................... 76

Fig. 3.9: The graph of Vac phase operation voltage rating against the Vac

coupled impedance in proposed capacitive coupled HPQC (PF=0.85) .... 77

Fig. 3.10: Vector diagram showing the operation of the Vbc phase converter in

proposed HPQC. ....................................................................................... 78

Fig. 3.11: The graph of VVc phase inverter voltage rating against the Vbc

coupled impedance in proposed capacitive coupled HPQC (PF=0.85) .... 79

Fig. 3.12: Simplified model of conventional inductive coupled RPC. .................... 80

Fig. 3.13: Simplified model of proposed capacitive coupled HPQC. ...................... 80

Fig. 3.14: Vector diagram showing the operation of entire conventional RPC. ...... 81

Fig. 3.15: Vector diagram showing the operation of whole proposed HPQC ......... 82

Fig. 3.16: Vector diagram showing the comparisons of operation in conventional

RPC and proposed HPQC. ........................................................................ 83

Fig. 3.17: The figure of conventional RPC and proposed HPQC operation

voltage rating against the Vac coupled impedance. .................................. 84

Fig. 3.18: The graph showing variation of VinvaLC with XLCa in proposed HPQC

to show the parameter setting for minimum HPQC operation voltage

rating. ........................................................................................................ 85

Fig. 3.19: Vector diagram showing the operation of Vac phase converter voltage

with varying coupled impedance XLCa ...................................................... 86

Fig. 3.20: The variation of Vac coupled capacitance Ca and inductance La

designed for Vac phase operation voltage rating (Load capacity: 15

MVA, PF=0.85) ........................................................................................ 88

Fig. 3.21: Investigation of current tracking performance of Vac phase converter

in proposed HPQC: (a) pt.1, Ca=40uF, La=82.54mH; (b) pt.2, Ca=60uF,

La=1.98mH; (c) pt.3, Ca=80uF, La=44.24. ................................................ 89

Fig. 3.22: The selection of Vbc coupled impedance for Vac phase inverter rating

matching. ................................................................................................... 91

ix

Fig. 3.23 (cont): The Vbc phase current tracking performance with different

values of XLCb, (c) Lb=80 mH (point1); (d) Lb=100 mH (outside range) . 93

Fig. 3.24: Variation of minimum HPQC operation voltage rating (k_min) with

load power factor (PL) .............................................................................. 94

Fig. 3.25: The graph of harmonic impedance of Vac coupled LC when designed

at nth harmonic frequency ........................................................................ 97

Fig. 3.26: The current tracking performance of Vac converter for HPQC

parameters designed according to harmonic filter (a) Ca=40uF,

La=10mH; (b) Ca=60uF, La=6.8mH (proposed design); (c) Ca=80uF,

La=1.78mH. ............................................................................................... 99

Fig. 3.27: The current tracking performance of Vac converter for HPQC

parameters designed according to fundamental compensation (a)

Ca=20uF, La=34.6mH; (b) Ca=40uF, La=92mH (c) Ca=60uF,

La=7.6mH (proposed design). ................................................................. 100

Fig. 3.28: The figure of harmonic impedance of Vac converter in conventional

RPC and proposed HPQC ....................................................................... 103

Fig. 3.29: Harmonic spectrum of a typical pulse signal (in percentage) ............... 104

Fig. 3.30: Operation Voltage Rating with Harmonics Consideration in

conventional and proposed HPQC under different load power factor

(Worst Case) ........................................................................................... 105

Fig. 3.31: HPQC Operation Voltage Rating with Harmonics Consideration

under different load power factor (Worst Case) ..................................... 106

Fig. 3.32: Circuit schematics of co-phase traction power supply with

compensation device used in the simulation verifications ...................... 107

Fig. 3.33– System performances of proposed co-phase traction power without

compensation: (a) three phase power source voltage and current

waveforms; (b) Vac and Vbc phase voltage and current waveforms ..... 108

Fig. 3.34: Harmonic spectrum of the Vac phase load current ............................... 109

Fig. 3.35: System performances of co-phase traction power with RPC (Vdc = 41

kV): (a) three phase power source voltage and current waveforms; (b)

Vac and Vbc phase voltage and current waveforms ............................... 110

x

Fig. 3.36 (cont’): System performances of proposed co-phase traction power

supply system with HPQC (Vdc = 27 kV): (a) three phase power source

voltage and current waveforms; (b) Vac and Vbc phase voltage and

current waveforms .................................................................................. 112

Fig. 3.37: Simulated system zero, positive and negative sequence current vectors

(a) without compensation; (b) with proposed HPQC compensation ...... 112

Fig. 3.38: Simulated system three phase source voltage and current vectors (a)

without compensation; (b) with proposed HPQC compensation ............ 113

Fig. 3.39: Simulated system performances of co-phase traction power supply

system with RPC (Vdc = 27 kV): (a) three phase power source voltage

and current waveforms; (b) Vac and Vbc phase voltage and current

waveforms ............................................................................................... 115

Fig. 3.40: Simulated system performances of proposed co-phase traction power

supply system with HPQC (Vdc = 22 kV): (a) three phase power source

voltage and current waveforms; (b) Vac and Vbc phase voltage and

current waveforms .................................................................................. 116

Fig. 3.41: The flowchart showing the process for determining HPQC coupled

impedance parameters (without harmonic compensation consideration)118

Fig. 3.42: The flowchart showing the process for determining HPQC coupled

impedance parameters (with harmonic compensation consideration) .... 119

Fig. 4.1: Operation of Vac phase converter in HPQC under minimum voltage

operation at rated condition. ................................................................... 121

Fig. 4.2: Operation of Vac phase converter in HPQC when load changes. ........... 121

Fig. 4.3: A 3D plot showing the changes of kinv with load capacity and power

factor (rated Load power factor = 0.85) .................................................. 123

Fig. 4.4: A graph showing the relationship between HPQC operation voltage

with load capacity and power factor. ...................................................... 124

Fig. 4.5: Circuit schematic of the system used in simulation verification of

HPQC operation voltage when load changes.......................................... 125

Fig. 4.6: System performances on 12 MVA load capacity and power factor of

0.9: (a) without compensation; (b) with HPQC compensation under

xi

minimum operation voltage of rated load power factor of 0.85 (Vdc =

18.67 kV); (c) with HPQC compensation under enhanced operation

voltage (Vdc = 21.8 kV)........................................................................... 128

Fig. 4.7: System performances on 21 MVA load capacity and power factor of

0.9: (a) without compensation; (b) with HPQC compensation under

minimum operation voltage of rated value (Vdc = 18.67 kV); (c) with

HPQC compensation under enhanced operation voltage (Vdc = 25.7

kV). ......................................................................................................... 129

Fig. 4.8: Vector diagram showing operation of HPQC with compensation range

under enhanced operation voltage. ......................................................... 131

Fig. 4.9: Vector diagram showing the operation of HPQC under certain load

power factor. ........................................................................................... 132

Fig. 4.10: A graph showing the compensation range of the HPQC under a

specified kinv value. ................................................................................. 133

Fig. 4.11: Vector diagram showing the operation of HPQC at compensation

range boundaries. .................................................................................... 138

Fig. 4.12: A graph showing the relationship between the HPQC operation

voltage rating kinv against power factor limit PFlimit. .............................. 139

Fig. 4.13: A graph showing the relationship between kinv and rlimit under PFlimit. . 140

Fig. 4.14: Simulated three phase source current unbalance with various load

power factor (kinv=0.66, Vdc=25.7 kV). .................................................. 142

Fig. 4.15: Simulated three phase source power factor (minimum) with various

load power factor (kinv=0.66, Vdc=25.7 kV). .......................................... 142

Fig. 4.16: Simulated three phase source current unbalance with various load

capacity ratings (PFlimit=0.96, kinv=0.66). ............................................... 143

Fig. 4.17: Simulated three phase source power factor with various load capacity

ratings (PFlimit=0.96, kinv=0.66). .............................................................. 143

Fig. 4.18: Some important formulae derived for different purposes in this chapter. 146

Fig. 5.1: Circuit schematic of the co-phase traction power with HPQC hardware

prototype. ................................................................................................ 148

xii

Fig. 5.2: Hardware circuit schematics of co-phase traction power supply

prototype with HPQC ....................................................................................149

Fig. 5.3: Circuit schematics of rectifier RL load model for traction load. ....................150

Fig. 5.4: Circuit schematic of power supply for signal conditioning,

microcontroller and driver circuits.................................................................150

Fig. 5.5: Top view of Wintech TDS2812EVMB board ................................................151

Fig. 5.6: Simplified diagram showing the required input and output signals for

microcontroller in the hardware application. .................................................151

Fig. 5.7: Simplified diagram showing the arrangement of different timers with

different functions. .........................................................................................152

Fig. 5.8: Connections of TDS2812EVMB ADC and PWM pins with other

electronic gadgets...........................................................................................153

Fig. 5.9: Circuit schematic of the signal conditioning circuit used in the

hardware prototype. .......................................................................................154

Fig. 5.10: Appearance of the signal conditioning circuit in hardware prototype. ........155

Fig. 5.11: POWERSEM PSHI23 IGBT Driver ............................................................155

Fig. 5.12 – Pin connections of the IGBT driver PSHI23 .................................................156

Fig. 5.13: Input and output waveforms obtained during testing of IGBT driver. .........157

Fig. 5.14: External appearance design of the hardware prototype. ...............................158

Fig. 5.15: Layout design of the hardware prototype. ....................................................159

Fig. 5.16: Front view of the hardware prototype. .........................................................160

Fig. 5.17: Back view of the hardware prototype. ..........................................................161

Fig. 5.18: Appearance of hardware first layer ..............................................................162

Fig. 5.19: Appearance of hardware second layer. .........................................................162

Fig. 5.20: Appearance of hardware third layer .............................................................163

Fig. 5.21: Appearance of hardware forth layer. ............................................................163

Fig. 5.22: Appearance of the load layer. .......................................................................164

Fig. 5.23: Control block diagram showing the control in hardware application ..........164

Fig. 5.24 – Program control flow chart. ...........................................................................165

xiii

Fig. 5.25: System waveforms for co-phase traction power without compensation:

(a) three phase source voltage; (b) three phase source current; (c) load

current; (d) Vac and Vbc phase compensation current. .......................... 168

Fig. 5.26: Three phase voltage and current data for co-phase traction power

without compensation. ............................................................................ 168

Fig. 5.27: Three phase power data for co-phase traction power without

compensation. ......................................................................................... 169

Fig. 5.28: Three phase source current THD data for co-phase traction power

without compensation. ............................................................................ 169

Fig. 5.29: System waveforms for co-phase traction power with conventional

RPC (VDC=76V): (a) three phase source voltage; (b) three phase source

current; (c) load current; (d) Vac and Vbc phase compensation current.170

Fig. 5.30: Three phase voltage and current data for co-phase traction power with

conventional RPC compensation (VDC=76V). ........................................ 171

Fig. 5.31: Three phase power data for co-phase traction power with conventional

RPC compensation (VDC=76V). ............................................................. 171


with conventional RPC compensation (VDC=76V). ................................ 171

Fig. 5.33: System waveforms for co-phase traction power with proposed HPQC

(VDC=52V): (a) three phase source voltage; (b) three phase source



proposed HPQC compensation (VDC=52V). ........................................... 173

Fig. 5.35: Three phase power data for co-phase traction power with proposed

HPQC compensation (VDC=52V). .......................................................... 174


with proposed HPQC compensation (VDC=52V). .................................. 174

Fig. 5.37: System waveforms for co-phase traction power with conventional

RPC (VDC=52V): (a) three phase source voltage; (b) three phase source


xiv


conventional RPC compensation (VDC=52V). ........................................ 176

Fig. 5.39: Three phase power data for co-phase traction power with conventional

RPC compensation (VDC=52V). ............................................................. 177


with conventional RPC compensation (VDC=52V). ................................ 177

xv

LIST OF TABLES

Number Page

Table 1.1: Basis for harmonic current limits in IEEE Std. 519-1992 ........................ 9

Table 1.2: Current distortion limits for generation distribution systems (120V

through 69 000V) in IEEE Std. 519-1992 .................................................. 9

Table 1.3: Current distortions limits for generation distribution systems (69 001

V through 161 000 V) IEEE Std. 519-1992 .............................................. 10

Table 1.4: Comparisons among various mentioned compensators (1) .................... 20

Table 1.5: Comparisons among various mentioned compensators (2) .................... 20

Table 2.1: Simulated and theoretical values of different vectors in Fig. 2.6 ........... 35

Table 2.2: Simulated and theoretical values of different vectors in Fig. 2.7 ........... 37

Table 2.3: Simulated and theoretical values of system zero, negative and

positive sequence currents ........................................................................ 38

Table 2.4: Simulated and computed value of PFA and PFB ................................... 39

Table 2.5: Odd harmonic current contents in simulated load current ...................... 41

Table 2.6: Comparisons between computed and simulated load current THD ....... 42

Table 2.7: Comparisons of system performance statistics with and without

compensation (signal analysis) ................................................................. 51

Table 2.8: Statistics of zero, positive and negative sequence vectors with and

without compensation (signal analysis) .................................................... 52

Table 2.9: Statistics of thee phase source current vectors with and without

compensation (signal analysis) ................................................................. 54

Table 2.10: Three phase source current THD for simulation of system with and

without harmonic compensation. .............................................................. 58

Table 2.11: Comparisons of simulated system performance with and without

comprehensive compensation (signal analysis) ........................................ 62


without comprehensive compensation (signal analysis) ........................... 63

xvi

Table 2.13: Statistics of thee phase source current vectors with and without

comprehensive compensation (signal analysis) ........................................ 64

Table 3.1: Parameter design of XLCb for proposed HPQC in simulations. .............. 92

Table 3.2: Simulated results with different DC link voltage in HPQC. .................. 95

Table 3.3: Harmonic current contents (%) in a typical pulse signal ...................... 104

Table 3.4: Harmonic current contents in the harmonic load used in simulation. .. 109

Table 3.5: The RPC circuit parameters used in the simulation verifications......... 110

Table 3.6: The HPQC circuit parameters used in the simulation verifications. .... 111


without comprehensive compensation (signal analysis) ......................... 113

Table 3.8: Statistics of thee phase source current vectors with proposed HPQC

compensation and without any compensation ........................................ 114

Table 3.9: Summarized simulation results of co-phase traction power supply

with nonlinear RL load using conventional RPC and proposed HPQC

compensation. ......................................................................................... 115

Table 3.10: Summarized system statistics in co-phase traction power with

HPQC under operation voltage below minimum (Vdc=22 kV) and at

minimum (Vdc=27 kV) ............................................................................ 117

Table 4.1: Parameter setting under different investigated load conditions. ........... 126

Table 4.2: HPQC circuit parameters used in simulation of operation voltage

rating when load changes. ....................................................................... 127

Table 4.3: Summarized system performances on load capacity of 12 MVA, and

power factor of 0.9. ................................................................................. 130

Table 4.4: Summarized system performances on load capacity of 21 MVA, and

power factor of 0.9. ................................................................................. 130

Table 4.5: Computed compensation range of HPQC for rated load capacity of 15

MVA and power factor of 0.85 under kinv of 0.66. ................................. 134

Table 4.6: Simulated three phase source current unbalance (%) under different

load condition combinations: horizontal (r) and vertical (load power

factor) ...................................................................................................... 135

xvii

Table 4.7: Simulated three phase source power factor (minimum value) under

different load condition combinations: horizontal (r) and vertical (load

power factor) ........................................................................................... 136

Table 4.8: Simulated system performances with different load capacities at load

power factor limit (PFlimit=0.96, kinv=0.66) ............................................. 144

Table 5.1: Tested results of IGBT driver with different duty ratios (1 kHz and 10

kHz)......................................................................................................... 156

Table 5.2: Summarized data of different funciton settings in the experiment. ...... 167

Table 5.3: RPC circuit parameters in co-phase traction power hardware. ............. 170

Table 5.4: HPQC circuit parameters in co-phase traction power hardware. ......... 172

Table 5.5: Comparisons of system compensation performance ............................ 175

Table 5.6: Comparisons of system compensation with RPC (Vdc=52V) and with

proposed HPQC (Vdc=52V) .................................................................... 178

xix

LIST OF ABBREVIATIONS

A. Ampere

AC. Alternating Current

ADC. Analog/Digital Converter

AT. Auto Transformer

BT. Boost Transformer

DC. Direct Current

DSP. Digital Signal Processor

DVR. Dynamic Voltage Restorer

FACTS. Flexible AC Transmission System

FC-TSR. Fixed Capacitor Thyristor Switched Reactor

HAPF. Hybrid Active Power Filter

HPQC. Hybrid Power Quality Compensator

Hz. Hertz

IEEE. Institute of Electrical and Electronics Engineers (USA)

IGBT. Insulated Gate Bipolar Transistor

kHz. Kilohertz

kV. Kilovolt

NS. Neutral Section

PCC. Point of Common Coupling

PF. Power Factor

PWM. Pulse Width Modulation

RPC. Railway Power Compensator

STATCOM. Static Synchronous Compensator

SVC. Static Var Compensator

xx

TCR. Thyristor Controlled Reactor

THD. Total Harmonic Distortions

TSC. Thyristor Switched Capacitor

UPQC. Unified Power Quality Compensator

us. microsecond

V. Volt

VA. Volt-Ampere

VSI. Fixed Capacitor Thyristor Switched Reactor

xxi

ACKNOWLEDGMENTS

The work in this thesis would not have been accomplished without the help from

several individuals. First and foremost I would like to express my sincerest and

heartily gratitude to my supervisors, Prof. Man-Chung Wong, Dr. Ning-Yi Dai and Dr.

Chi-Kong Wong, who have been supporting me throughout the thesis with patience,

guidance and knowledge. They have broadened my vision and brought me into a

challenging and worthwhile realm in power electronics. I attribute the level of my

Master degree to their encouragement and effort. Without them, this thesis could not

have been completed or written.

My project partner, Mr. Wei-Gang Liu, has always been giving me strength and

inspiration. I would like to express my special thanks for his assistance and help in

hardware prototype construction. Without him, the work can hardly be completed.

I would also wish to express my heartily thanks to my seniors, Mr. Chi-Seng Lam and

Mr. Io-Keong Lok, for having continuously aided me with their comments and

experiences. I would also like to give special acknowledgements to my friends and

colleagues, Mr. Wei-Hei Choi (UM), Mr. Xiao-Xi Cui (UM), Dr. Wei Du (TsingHua),

Miss. Miao Liu (UM), Mr. Bo Sun (UM), Dr. Xu Tian (TsingHua), Mr.

Yan-ZhengYang (UM) and Miss Xi Zhang (UM). An extraordinary word of thanks

should be given to Miss. Miao Liu and Miss Xi Zhang for their assistance in

simulation verifications.

I would also like to say thank you to all the friends that I have met. Thank you for

their continuous encouragement and support. They have filled my life with colors and

happiness.

Last, but certainly not the least, I wish to render my utmost gratitude to my parents

and my dear brother, for their constant understanding, endless support, care and

encouragement.

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