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

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 ii

4.2 HPQC Operation Voltage and Compensation Range ...................................130 4.2.1

Theoretical Studies......................................................................131

4.2.2

Simulation Verifications .............................................................134

4.3 HPQC Operation Voltage and Load Limitations ..........................................137 4.3.1

Theoretical Studies......................................................................137

4.3.2

Simulation Verifications .............................................................141

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

iii

iv

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 v

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 vi

Fig. 2.19:

Revised simplified model of proposed co-phase traction power system with HPQC compensation including harmonic contents. .........................55

Fig. 2.20:

Simplified control block diagrams for investigation of ideal system harmonics compensation performance .....................................................57

Fig. 2.21:

Comparisons of co-phase traction power source current (top) without compensation; (bottom) with ideal compensation current signal (harmonic) .................................................................................................57

Fig. 2.22:

Control block diagram showing the computation details of comprehensive compensation of system unbalance, reactive power and harmonics ..................................................................................................58

Fig. 2.23:

Simplified control block diagrams for investigation of ideal system with comprehensive compensation performance ......................................61

Fig. 2.24:

Comparisons of co-phase traction power source current (top) without compensation; (bottom) with ideal compensation current signal (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 vii

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 viii

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 ix

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 x

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

xi

Fig. 5.2:

Hardware circuit schematics of co-phase traction power supply prototype with HPQC ....................................................................................149

Fig. 5.3: Fig. 5.4:

Circuit schematics of rectifier RL load model for traction load. ....................150 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

xii

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

Fig. 5.32:

Three phase source current THD data for co-phase traction power 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 current; (c) load current; (d) Vac and Vbc phase compensation current.173

Fig. 5.34:

Three phase voltage and current data for co-phase traction power with 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

Fig. 5.36:

Three phase source current THD data for co-phase traction power 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 current; (c) load current; (d) Vac and Vbc phase compensation current.176

xiii

Fig. 5.38:

Three phase voltage and current data for co-phase traction power with 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

Fig. 5.40:

Three phase source current THD data for co-phase traction power with conventional RPC compensation (VDC=52V).................................177

xiv

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 Table 2.12:

Statistics of zero, positive and negative sequence vectors with and

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

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

Table 3.7:

Statistics of zero, positive and negative sequence vectors with and 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

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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

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xviii

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 xix

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

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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. xxi