LUẬN VĂN CAO HỌC HỆ THỐNG ĐIỆN CẢI THIỆN CHẤT LƯỢNG ĐIỆN ÁP VÀ GIẢM TỔN THẤT TRONG HỆ THỐNG LƯỚI

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