LOAD FLOW MODEL FOR UPFC WITH ESS AND ATC DETERMINATION NORHAFIZ BIN SALIM UNIVERSITI TEKNOLOGI MALAYSIA

LOAD FLOW MODEL FOR UPFC WITH ESS AND ATC DETERMINATION NORHAFIZ BIN SALIM UNIVERSITI TEKNOLOGI MALAYSIA

LOAD FLOW MODEL FOR UPFC WITH ESS AND ATC DETERMINATION NORHAFIZ BIN SALIM A project report submitted in partial fulfilment of the requirements for the award of the degree of Master in Engineering (Electrical-Power) Faculty of Electrical Engineering Universiti Teknologi Malaysia NOVEMBER 2009

iii ACKNOWLEDGEMENT All praise, glory and gratitude be to Allah who said in the Holy Qur an that "He who taught (the use of) the pen and taught the man that which he knew not". Peace be upon the Prophet Muhammad SAW, his family, his companions, and all those who followed him until the Day of Judgment. First of all I wish to express my deepest gratitude to my thesis advisor Assoc. Prof. Dr. Mohd Wazir bin Mustafa for his invaluable advice, personal attention, and continuous encouragement throughout my master program at Universiti Teknologi Malaysia. It was a great experience working and learning with him and without his continued support and interest, this thesis would not have been the same as presented here. I am also indebted to Universiti Teknikal Malaysia Melaka (UTeM) for funding my Master study as well. My appreciation is extended to Engr. Prof Dr. Marizan bin Sulaiman as the Dean of FKE at UTeM for giving strong support and encouragement to complete my study. My fellow postgraduate student should also be recognized for their support. My sincere appreciation also extends to all my colleagues and others who have provided assistance at various occasions. Their views and tips are useful indeed. Special and deep thanks to my wonderful parents, brother and sister for their moral suppo rt and motivation. Last but not least, I extend my thanks and appreciation to everyone who helped to get this work done.

iv ABSTRACT A load flow analysis is used for planning and to determine the transmission constraints in the existing networks. The load flow solution gives information about the magnitude and phase angle of the voltage at each bus and real and reactive power flows in each line for given generation, load and transmission network data. By using Flexible AC Transmission System (FACTS) devices namely Unified Power Flow Controller (UPFC) will gives a basic control for transmission line real/reactive power flow and bus voltage/shunt reactive power. UPFC with ESS helps in regulating the power and mitigating the rotor speed instability and damping oscillations. UPFC placement was conducted at each line in the entire network system together with ESS to obtain the most suitable optimum location for most effectiveness performance. The performance of the optimal UPFC and ESS location is checked by applying a fault across a transmission line to which UPFC is connected and the power flow in the line and stability of the system is determined. Available Transfer Capability values indicate allowable highest magnitude of active power (MW) that can be transferred from the source to the sink over and above the already committed uses (base case) of the whole network without exceeding any line thermal loading and bus voltage limits. Finally, simulations were carried out using PSAT software to validate the performance of the UPFC and ESS connected to a transmission line. The effectiveness for UPFC and ESS are demonstrated on IEEE 9 bus and IEEE 24 bus system while for ATC is demonstrated on IEEE 6 bus system and all the results are compared.

v ABSTRAK Analisis aliran beban digunakan untuk merancang dan sekaligus menentukan kekangan penghantaran di dalam rangkaian sediaada. Penyelesaian aliran beban memberikan informasi tentang magnitud dan juga sudut fasa bagi voltan di setiap bas serta aliran kuasa nyata dan kuasa regangan di setiap talian bagi data di rangkaian penjanaan, beban dan penghantaran yang dinyatakan. Dengan menggunakan alatan FACTS iaitu UPFC, kawalan asas bagi aliran kuasa nyata/regangan di dalam talian penghantaran serta voltan bas/kuasa regangan pirau telah dilakukan. UPFC dengan kehadiran ESS dapat membantu dalam pengaturan kuasa serta mengatasi ketakstabilan halaju dan ayunan bagi redaman pada rotor. UPFC ditempatkan di setiap talian pada keseluruhan sistem rangkaian beserta ESS untuk memperoleh lokasi optimum yang paling sesuai bagi membolehkan prestasi yang paling efektif. Untuk menyemak prestasi bagi lokasi optimum UPFC dan ESS, satu kerosakan di kenakan pada talian penghantaran di mana UPFC disambungkan dan seterusnya aliran kuasa pada talian serta kestabilan pada sistem dapat diketahui. Nilai ATC yang dikira menunjukkan magnitud tertinggi bagi kuasa nyata yang masih boleh ditampung oleh talian penghantaran tanpa melangkaui had voltan bas serta had beban talian bagi sistem. Akhir sekali, simulasi telah dilakukan dengan menggunakan perisian PSAT bagi mengesahkan prestasi UPFC dan ESS yang disambung pada talian penghantaran. Keberkesanan UPFC dan ESS ditunjukkan dengan aplikasi pada sistem IEEE dengan 9 bas serta 24 bas manakala bagi ATC, ia didemonstrasikan dengan menggunakan sistem IEEE 6 bas dan seterusnya hasil bagi keseluruhan simulasi dibandingkan.

vi TABLES OF CONTENTS CHAPTER TITTLE PAGE DECLARATION ii ACKNOWLEDGMENTS iii ABSTRACT iv ABSTRAK v TABLE OF CONTENTS vi LIST OF TABLES x LIST OF FIGURES xi LIST OF SYMBOLS xiii LIST OF ABBREVIATIONS xiv LIST OF APPENDICES xv 1 INTRODUCTION 1 1.1 Introduction 1 1.2 Problem Statement 2 1.3 Objectives 2 1.4 Scope of research 3 1.5 Thesis organization 4

vii 2 FACTS WITH ENERGY STORAGE SYSTEM 5 2.1 Introduction 5 2.2 UPFC Operating Modes 7 2.2.1 Uncontrolled operating mode 8 2.2.2 Inductive or capacitive operating mode 8 2.3 UPFC control interactions 10 2.3.1 Shunt converter 10 2.3.2 Series converter 11 2.4 Energy Storage System 12 2.4.1 Energy storage technology 13 2.4.1.1 Storage Methods 14 2.4.2 Renewable energy storage 14 2.4.2.1 Grid-Tie inverter 15 2.4.2.2 Typical Operation 16 2.4.2.3 Characteristic of Grid-tie Inverter 17 2.4.3 Flywheel energy storage system 19 2.4.3.1 Concept of Operation 19 2.4.4 Flywheels Coupled with Induction Machine 21 2.4.4.1 Circuit Operation 22 2.5 Summary 23 3 NEWTON RAPHSON LOAD FLOW ANALYSIS 24 3.1 Introduction 24 3.2 Load Flow Analysis Method 25 3.3 Power flow Problem 25 3.3.1 Slack bus 28 3.3.2 PQ bus 28 3.3.3 PV bus 28 3.4 Network Model Formulation 29

viii 3.5 Power Flow Control 32 3.6 Newton Raphson Power Flow 34 3.7 Fast Decoupled Load Flow 38 3.8 Summary 39 4 AVAILABLE TRANSFER CAPABILITY 40 4.1 Introduction 40 4.2 Definition of Total Transfer Capability 40 4.3 Total transfer capability determination 41 4.3.1 Margin in TTC 43 4.4 ATC definitions and determination 43 4.4.1 Principles of ATC determination 44 4.4.2 Network response calculation 45 4.4.3 Example of ATC calculation 50 4.5 Summary 51 5 RESULTS AND DISCUSSION 52 5.1 Introduction 52 5.2 ATC for IEEE 6 bus Test System 53 5.2.1 Test System I 53 5.2.2 Base case analysis of transaction 1 and 2 54 5.2.3 Contingency case analysis of outage line 4-5 55 5.3 Base Case 61 5.3.1 Test System II 61 5.4 Faulted Case 64 5.4.1 Test System II 64 5.5 Base and Faulted Case 66 5.5.1 Test System III 66

ix 5.6 Summary 69 6 CONCLUSIONS AND FUTURE WORK 70 6.1 Conclusion 70 6.2 Future Work 71 REFERENCES 73-75 Appendices A-B 76-102

x LIST OF TABLES TABLE NO. TITTLE PAGE 2.1 Energy Storage Methods 14 3.1 Typical overhead transmission line parameters 26 3.2 Load Flow - Bus Types 29 3.3 Elements of Jacobian matrix 37 5.1 Power flow results for transaction 1 in 56 normal condition 5.2 Power flow results for transaction 2 in 57 normal condition 5.3 ATC determination using OPF for transaction 58 1 and 2 in normal condition 5.4 Power flow results for transaction 1 in 59 contingency condition 5.5 ATC determination using OPF for transaction 1 60 in contingency condition 5.6 Power flow results for 9 bus test system 63 5.7 Power flow results for 9 bus test system 65 with 3 phase fault 5.8 Power flow results for 24 bus test system 67 5.9 Power flow results for 24 bus test system 68 with 3 phase fault

xi LIST OF FIGURES FIGURES NO. TITTLE PAGE 2.1 Single-line diagram of transmission line installed 7 with UPFC 2.2 Uncontrolled operating mode 8 2.3 Transformation of 3-D UPFC operating conditions to 9 1-D operating modes 2.4 Electromechanical oscillation modes 9 2.5 The arrangement of UPFC controllers 11 2.6 Modern concept of flywheel application 20 2.7 Basic circuit diagram of FESS 22 3.1 Bus variables V k k, P k and Q k 27 3.2 Single line diagram of a three bus system 29 3.3 Equivalent circuit of the power system 30 3.4 Reduced circuit diagram of Figure 3.3 31 3.5 Generator Thevenin equivalent 33

xii 4.1 Single line diagram 6-bus test system in normal 46 condition 4.2 Single line diagram 6-bus test system in contingency 48 condition 4.3 Transmission service reservation 51 5.1 Single line diagram of 6-bus test system 53 5.2 Single line diagram of 9 bus test system 61 5.3 Single line diagram of 9 bus test system with 64 3 phase fault 5.4 Single line diagram of 24 bus test system 66

xiii LIST OF SYMBOLS P 1E - P Q Q m m 2E - 1E - 2E - E - E - B - B - - Rotational Speed M - Mass R - Radius k - Inertial Constant Z c - P Q k - k - Real Power flow into UPFC Real Power flow out from UPFC Reactive Power flow into UPFC Reactive Power flow out from UPFC Modulation Ratio of shunt UPFC converter Modulation Phase of shunt UPFC converter Modulation Ratio of series UPFC converter Modulation Phase of series UPFC converter Surge Impedence Real Power Delivered to Bus k Reactive Power Delivered to Bus k ith - Bus Injected into the Transmission System Y bus Z E bus - g - Bus Admittance Matrix Bus Impedance Matrix - Excitation Voltage - Power Angle X g - Positive-Sequence Synchronous Reactance J - Element of Jacobian Matrix

xiv LIST OF ABBREVIATIONS FACTS - Flexible AC Transmission System ESS - Energy Storage System FESS - Flywheel Energy Storage System ATC - Available Transfer Capability TTC - Total Transfer Capability CBM - Capacity Benefit Margin TRM - Transmission Reliability Margin ETC - Existing Transmission Commitments

xv LIST OF APPENDICES APPENDIX TITTLE PAGE A System response with and without UPFC/ESS 76 B Data preparation 92

1 CHAPTER 1 INTRODUCTION 1.1 Introduction Power system analysis is fundamental in the planning, design, and operating stages and its importance cannot be overstated. Electric utility industry is undergoing rapid changes of the electricity market in many countries generally and specifically Malaysia. The demand for flexible power flow control is becoming very attractive by the innovative power electronics technology. The load flow analyses cover reactive power flow and control, optimization techniques, and introduction to Flexible Alternating Current Transmission System (FACTS) controllers, three-phase load flow, and optimal power flow. In terms of power flow control in the transmission network, operator cannot do much traditionally except turning on and off the circuits at their terminal. The parameters and network configuration are almost fixed and dynamically uncontrolled infact it is difficult to cope with system load flow control required especially the speed where those mechanical switched or control equipment definitely one step backward compare with the trend of fast on-line decision making nowdays. In this regard FACTS devices were introduced to be one of power systems development in the coming decade.

2 1.2 Problem Statement i. Power system tends to become unstable at long transmission line when the power flow is heavy. ii. Many compensation devices have its own criteria and limitations:- i. Fixed Capacitor can only provided its own MVAr, manage low power factor correction and need high maintenance ii. Switched Capacitor will create overvoltage, voltage transient and causes harmonic 1.3 Objectives The following are the main objectives for this project; i. To study the Unified Power Flow Controller (UPFC) as one of FACTS devices modeling in power systems. ii. iii. iv. To develop a model of UPFC and ESS in single line diagram for power system steady-state operation. To determine the impact of Available Transfer Capability (ATC) on power system. To verify and analyze the effect of UPFC and Energy Storage System (ESS) in damping oscillation while improving system stability.

3 1.4 Scope of Research A power system may lose stability in the first swing if it is not equipped with proper transient control devices if there are disturbances. UPFC is the one that able to help reduce the flows in heavily loaded lines and improve stability of power systems. The scopes are as follow: i. Review on steady state and transient stability analyses on power system. ii. Develop UPFC with ESS modeling using PSAT in MATLAB for single line diagram of 9 buses test system and large scale system of 24 buses. iii. Study and review of ATC impact in power system. iv. ATC computation using Optimal Power Flow in MATLAB by Newton Raphson Load Flow programming. Finally all test systems will be demonstrated via simulation to illustrate its stability performance.

4 1.5 Thesis Organisation This report is organised in 6 chapter. Following this Chapter 2, introducing the basic operating principles of FACTS device namely UPFC in addition with the present of ESS. Chapter 3 reviewed the Newton Raphson s method in solving load flow analysis which is a backbone of power system analysis and design. Chapter 4 discusses the operating principles adopted in electrical power system with specific focus on the main issues related to ATC determination. Chapter 5 presents the typical results obtained from extensive tests on a 9 buses and 24 buses system and compares their performances or evaluations with those from Newton Raphson s load flow programmed. Chapter 6 concludes the findings of the present research together with some suggestions for further investigations. The Appendix A and Appendix B includes supporting materials for the results obtained.

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