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Tổn công suất và sụt điện áp luôn luôn là vấn đề chính liên quan tới giá trị thực của ngành điện lực. Nghiên cứu về những phương pháp giảm tổn thất công suất và cải thiện chất lượng điện áp đã được tiến hành nhiều năm. Trong phương pháp nghiên cứu ngày, tác giả mong muốn hiện tại phương pháp luận được ứng dụng cho lợi ích lưới điện trong nhóm tổn thất điện năng và sụt điện áp. Phương pháp sẽ tìm ra vị trí tối ưu nguồn phân tán và những bộ tụ điện trong hệ thống lưới phân phối. Có hai phần trong nghiên cứu này, phần thứ nhất tìm ra dung lượng tối ưu của nguồn phân tán và vị trí để đạt tổn thất công suất tác dụng bé nhất trong hê thống. Có nhiều nguồn phân tán khác nhau, nguồn phân tán chủ yếu chỉ cung cấp công suất tác dụng và công suất phản kháng, DG cung cấp công suất tác dụng nhưng chi phối cân xứng với công suất phản kháng, chúng được quan tâm tới việc giải quyết những vị trí tối ưu của nguồn phân tán. Phần thứ hai những bộ tụ điện được đặt vị trí tối ưu. Phương pháp luận sẽ được liên hệ với các lộ đường dây của một trạm phân phối trong công ty điện lực Hà Nội. Những lộ đường dây này có mô hình như 40 bus hệ thống và 62 bus hệ thống.
IMPROVING VOLTAGE PROFILE AND REDUCING LOSS IN THE HANOI POWER DISTRIBUTION SYSTEM CONSIDERING DISTRIBUTED GENERATIONS AND CAPACITOR BANKS CẢI THIỆN CHẤT LƯỢNG ĐIỆN ÁP VÀ GIẢM TỔN THẤT TRONG HỆ THỐNG LƯỚI PHÂN PHỐI TP. HÀ NỘI CÓ XEM XÉT ĐẾN NGUỒN PHÂN TÁN VÀ BỘ TỤ A thesis submitted in partial fulfillment of the requirements for the Degree of Master of Engineering in Energy Asian Institute of Technology School of Environment, Resources and Development ii Acknowledgements The author would like to express his deepest gratitude to his advisor, the chairman of the thesis examination committee, Dr. Mithulananthan. N. The author would also like to thank Dr. Weerakorn. O and Prof. Sam R. Shretha for their kindness in serving as members of examination committee and for their valuable suggestions and advice throughout this study. The author wishes to convey his thank to the Electricity of Vietnam for generously granting the scholarship so that he could pursue this valuable master degree. The author also thanks Ha Noi Power Company (HPC) for providing him the opportunity to pursue this valuable master degree, to the staff and officers of HPC, for their assistance during the data collection phase. Many thanks are also sending to the faculty and staff members of Energy Program, especially to Mr. Pukar Mahat, for their help during the study. The author thanks to all of my Vietnamese classmates, Ninh, Dung, Minh, Hieu, for their kindly support. Finally, the author would like to express his deepest appreciation to his family – his parents, his wife, and his son for their utmost support, encouragement and understanding during his study in AIT. iii Abstract Power losses and voltage drop are always major concerns to electricity utility. Study about the methods to reduce power loss and improve voltage profile has been carried for many years. Nowadays, the interest in distributed generation around the world is sharply increasing. DGs are predicted to be a major component of future power system with all the benefits that come with them. If placed properly, they will improve the system in various ways, and of course, reduce power loss and voltage drop. So, it becomes essential to place them in such a way that all parties associated with them will be benefited. In this study, the author would like to present the methodology to improve the utility grid in term of power loss and voltage drop. The method will find out the optimal DG and capacitor banks in distribution system. There are two parts in this study. The first one finds the optimal DG size and the location to minimize real power loss in the system. Different DG types, namely DG supplying real or reactive power only, DG supplying real power but consuming proportionate reactive power, are considered to solve the optimal DG placement problem. In the second part, the capacitor banks are optimally placed. The methodology will be carried out with the primary feeders of one substation in Ha Noi Power Company. These feeders are modeled as 40 bus system and 62 bus systems. iv List of abbreviations CAPO – Optimal Capacitor placement DG – Distributed Generation EVN – Electricity of Viet Nam E2 – Long Bien distribution substation HPC – Ha Noi Power Company kWh – kilowatt hour kW – kilowatt kV, V – kilovolt, volt kVAr – kilovar kVA – kilovolt ampe km – kilometer MW – megawatt PSS/ADEPT – Power System Simulator – Advance Distribution Engineering Productivity Tool pf – power factor pu – per unit v Tables of Contents Chapter Title Page Title i Acknowledgements ii Abstract iii List of abbreviations iv Tables of Contents v List of tables ix 1. Introduction 1 1. Mở đầu Error! Bookmark not defined. 1.1 Background 1 1.2 Statement of problem 2 1.3 Objectives of Study 2 1.4 Scope and limitations 3 1.5 Expected results 3 2. Literature review 5 2.1 Distribution network power loss 5 2.2 Distributed Generation 6 2.2.1 Development of Applications DGs 6 2.2.2 Benefits of DG 7 2.2.3 Distribution Generation Technologies 8 2.2.4 Standard Sizes of Distributed Generation on Market 11 2.3 Distribution Power Flow Algorithms 12 2.4 Shunt Capacitor Placement 14 2.5 DG Placement Techniques 15 3. Distribution Load Flow 17 3.1 Distribution System Characteristics 17 3.2 Modeling system elements 18 3.2.1 Line Modeling 18 3.2.2 Load Modeling 19 3.2.3 Shunt Capacitor Modeling 20 3.2.4 Distributed Generation Modeling 20 3.2.5 Distribution Transformer 21 3.2.6 Network Indexing 21 3.3 Load Flow Algorithm 22 3.3.1 Backward Sweep 22 3.3.2 Forward Sweep 22 3.3.3 Stopping Criteria 23 4. Optimal Placement of the Distributed Generation 25 4. Vị trí tối ưu của nguồn phân tán Error! Bookmark not defined. vi 4.1 Optimal DG Placement to Reduce Loss 25 4.2 Optimal DG placement when DG Supply Real Power Only 25 4.3 Optimal DG placement when DG Supply Reactive Power Only 27 4.4 Optimal DG placement when DG supply P and consumes Q 27 5. Methodology 29 5. Phương pháp luận Error! Bookmark not defined. 5.1 Overview of methodology 29 5.2 Optimal DG placement to reduce system real power loss 30 Software Tools 31 5.3 Optimal Capacitor Placement Using PSS/ADEPT Application 33 5.3.1 About the PSS/ADEPT Software 33 5.3.2 Analyze Network in PSS/ADEPT 33 5.3.3 Load Flow Analysis in PSS/ADEPT 34 5.3.4 Calculating Capacitor Placement 35 5.4 System data 37 6. Results and conclusions 38 6.1 Optimal Distributed Generation 38 6.1.1 Results of Radial Feeder 983-E2 38 1. Type 1: DG supply real power only: 38 2. Type 2: DG supply real power and consume reactive power: 40 6.1.2 Results of Radial Feeder 979-E2 42 1. Type 1: DG supply real power only: 42 2. Type 2: DG supply real power and consume reactive power: 45 6.2 Optimal Capacitor Placement 47 6.2.1 Results of Radial Feeder 983-E2 48 1. Results of Load flow analysis 48 2. Results of CAPO 48 6.2.2 Results of Radial Feeder 979-E2 50 1. Results of Load flow analysis 50 2. Results of CAPO 51 7. Conclusions 54 7.1 Conclusions 54 7.2 Further study 54 References 55 Appendix A Phụ lục A Appendix B Phụ lục B Appendix C Phụ lục C vii List of figures Figure Title Page Figure 3-1: Model of a line section for single phase (π) representation. 18 Figure 3-2: Model of a line section. 19 Figure 3-3: General form of 3-phase transformer model. 21 Figure 3-4: Numbering of buses and branches. 22 Figure 3-5: Basic steps in the iterative algorithm. 24 Figure 5-1: The flow chart of works. 30 Figure 5-2: Flow chart to find the optimal DG size and the location to reduce loss in the system 31 Figure 6-1: Optimal DG size at each bus type 1 case 983-E2 38 Figure 6-2: Real power loss when DG installed at each bus with optial size type 1 case 983-E2 39 Figure 6-3: Voltage profile type 1 case 983-E2 40 Figure 6-4: Optimal DG size for type 2 case 983-E2 40 Figure 6-5: Real power loss when DG installed at each bus with optial size type 2 case 983-E2 41 Figure 6-6: Voltage profile before and after DG installed type 2 case 983-E2 42 Figure 6-7: Optimal DG size at each bus type 1 case 979-E2 43 Figure 6-8: Real power loss when DG installed at each bus with optial size type 1 case 979-E2 44 Figure 6-9: Voltage profile before and after DG installed type 1 case 979-E2 45 Figure 6-10: Optimal DG size at each bus type 2 case 979-E2 46 Figure 6-11: Real power loss when DG installed at each bus with optial size type 2 case 979-E2 46 Figure 6-12: Voltage profile before and after DG installed type 2 case 979-E2 47 Figure 6-13: Voltage profile of feeder 983E2 before capacitor placement - plotted by PSS/ADEPT 48 Figure 6-14: Voltage profile before and after capacitors placement by CAPO 50 Figure 6-15: Voltage profile of feeder 979E2 before capacitor placement 51 viii Figure 6-16: Voltage profile of feeder 979E2 before and after capacitor placement by CAPO 52 ix List of tables Table Title Page Table 2-1: Available capacities of DG for various technologies 11 Table 6-1: Ranking of buses for loss reduction type 1 case 983-E2 ( Appendix B) 39 Table 6-2: Ranking of buses for loss reduction type 1 case 983-E2 (Appendix B) 41 Table 6-3: Ranking of bus for loss redution type 1 case 979-E2 44 Table 6-4: Ranking of bus for loss redution type 2 case 979-E2 46 Table 6-5: Compare the results of case 983-E2 52 Table 6-6: Compare the results of case 979-E2 52 1 1. Introduction 1.1 Background Electric power distribution system engineering has been designed to deal with problems related to the rapidly expanding distribution system, load management and reduction of distribution loss. Voltage drop and power loss are major concerns for utilities as they limit the load ability of feeders and reduce revenue. All utility have found and applied the optimal method to improve voltage drop and power loss. Traditionally, there are many options available for reducing loss and voltage drops such as network reconfiguration, load balancing, introduction of higher voltage level, reconductoring, and capacitor installation. Among them, capacitor placement is one of most economical options for loss reduction, especially in distribution systems of developing countries. Recently, the application of small generators, called Distributed Generation (DG) has been considered to address the issue of loss reduction in distribution system. DGs have some advantages to replace capacitor banks in order to improve voltage profile and power loss. DGs can supply both real and reactive power. DGs can also keep the voltage at some buses in stable by adjusting reactive power smoothly and automatically. However, DGs also have some disadvantages such as coordination protection, high initial cost… This would be lead to a question that which option would be the best among all the alternatives available? Distributed Generation (DG) includes the application of small generators, typically ranging in capacity from few kW to as high as 10,000 kW, scattered throughout a power system, to provide the electric power needed by electrical customers[1]. Distributed Generation (DG) uses small-scale power generation technologies to generate electricity in close proximity to its utilization point. DG technology portfolios typically include small or micro hydro power plants, wind turbines, photovoltaic, fuel cells, reciprocating engines, combustion gas turbines and micro turbines. This study presents the methodology to find the best solution for improving voltage drops and power loss in distribution system. The first part presents a method using MATLAB software to develop a program that finds optimal DG sizes and the locations to take part in the distribution networks in order to improve voltage profile and minimize loss. The second part uses PSS/ADEPT software to find the optimal capacitor banks placement . voltage drops of the existing main primary distribution system of HPC. 2. To develop a program that find optimal DG size and location to minimize power loss and improving voltage profile in the. reciprocating engines, combustion gas turbines and micro turbines. This study presents the methodology to find the best solution for improving voltage drops and power loss in distribution system. The. Modeling system elements 18 3 .2. 1 Line Modeling 18 3 .2. 2 Load Modeling 19 3 .2. 3 Shunt Capacitor Modeling 20 3 .2. 4 Distributed Generation Modeling 20 3 .2. 5 Distribution Transformer 21 3 .2. 6 Network Indexing