nepal substations and loads

POWER EVACUATION SYSTEM STUDY FOR SELECTED HYDROPOWER PROJECTS IN WESTERN

NEPAL

DISSERTATION

Submitted in partial fulfillment of the requirements of Master of Engineering in Electrical Power Engineering

Manohar Shrestha

Department of Electrical and Electronics Engineering

School of Engineering Kathmandu University

December 2005

POWER EVACUATION SYSTEM STUDY FOR SELECTED HYDROPOWER PROJECTS IN WESTERN

NEPAL

DISSERTATION

Submitted in partial fulfillment of the requirements of Master of Engineering in Electrical Power Engineering

By:

Manohar Shrestha

Under supervision of:

Mr. Surya Prasad Adhikari Planning and Design Engineer

Engineering Department Butwal Power Company Ltd.

and

Mr. Lalt Bickram Rana Assistant Professor

Department of Electrical and Electronics Engineering School of Engineering

Kathmandu University

Department of Electrical and Electronics Engineering

School of Engineering Kathmandu University

December 2005

ACKNOWLEDGEMENT

I would like to express sincere and profound gratitude to our Project Supervisors

Mr. Surya Pd. Adhikari and Mr. Lalit B. Rana for helping me to complete this

project with valuable guidance whenever I faced problem during the course of

dissertation.

I would also like to express my hearty thanks to Dr. Bhupendra Bimal Chhetri,

HOD electronics and electrical department, KU, for providing necessary material

and uninterrupted access to computer lab for project work.

Special thanks go to Mr. D.D Joshi, M.D AutoCarto Pvt. Ltd. for providing relevant

data required for the study and Er. Kiroj Shrestha, Western Grid Office, NEA for

helping to get existing present data of Western Nepal from Western Central Office,

NEA.

At last, I am very much thankful to my classmates and colleagues whose sincere

efforts have inspired me to be with them in the pursuit of academic goals.

ABSTRACT

Electricity Power Evacuation from small hydro power plant is emerging as challenge for

the entire entrepreneur who wishes to enter in the field of hydro power sector. The

increasing load demand and availability of power market around the clock in Nepal has

evoke many capitalist to invest in hydro power sector. This thesis studies the present and

will identify future power evacuation system performance in certain area of Lamjung

district from different power plants Khudi (KHP) 3.5 MW, Lower Nyadi (LNHP), 4.5 MW

and Lower Khudi (LKHP), 2 MW. The thesis studies existing and proposed power

evacuation system and carries out detail study of an existing transmission line and conduct

detail study of power evacuation systems from KHP, LNHP and LKHP. The thesis also

studies the performance of distribution system for Lamjung district.

The methodology adopted for carrying out evacuation study is based on following:

Collection of data regarding existing and proposed electrical system.

Preparation of program/software for technical and financial analysis of

evacuation system

Identification of different transmission line alternatives and selection of best

option.

Study performance of evacuation sys tem.

Study performance of distribution system.

For studying power evacuation system transmission capacity, available transmission

margin and transmission are taken into consideration. For distribution system performance

study computer programs are developed. Spreadsheet for calculation of transmission line

performance and Carl1.0 (Load flow software for radial distribution network) for studying

distribution feeders has been updated.

TABLE OF CONTENTS

GLOSSARY OF ABBREVIATIONS i LIST OF FIGURES ii LIST OF TABLES iii CHAPTER 1 INTRODUCTION 1

1.1 General 1 1.2 Objective 1 1.3 Background 2 1.4 Performance standard for Grid 2

CHAPTER 2 EXISTING ELECTRICAL SYSTEM IN STUDY AREA 4

2.1 Existing power plants in western Nepal 4 2.2 Under Study Small Hydro Power Plant in Western Nepal 4 2.3 Existing Grid transmission system in western Nepal 5 2.4 Existing Electrical Network in Some District of Western Nepal. 6

CHAPTER 3 METHODOLOGY 11

3.1 Data Collection 11 3.2 Transmission line alternative 12 3.3 Available Transmission Capacity 13 3.4 Transmission Margin 13 3.5 Performance of Transmission line 13 3.6 Distribution system planning 13 3.7 Spread Sheet Calculation for Conductor selection and Voltage [2] 14 3.8 Carl 1.0 18 3.9 Netbas Simulation 18 3.10 Evacuation System for KHP, LNHP and LKHP. 19

CHAPTER 4 RESULTS AND DISCUSSIONS 20

4.1 Existing System Result 20 4.2 KHP Evacuation System 25 4.3 Results of LNHP Evacuation System 33 4.4 KHP and LNHP Evacuation system 34 4.5 System with KHP, LNHP and LKHP 41 4.6 KHP, LNHP, LKHP and Chame substation 42 4.7 Load flow analysis of four feeders of Udipur S/S 43

CHAPTER 5 CONCLUSION AND RECOMMENDATION 45 REFERENCES 48 APPENDICES Appendix A: Transmission line Design Procedure Appendix B: Load Flow Analysis in Electric Power distribution Appendix C: SLD of Existing Electrical Network Appendix D: Spread Sheet Results Appendix E: Netbas Results Appendix F: Carl1.0 Results Appendix G: List All Power source and Cost

i

GLOSSARY OF ABBREVIATIONS

Abbreviation Full-Form First in Page INPS Integrated Nepal Power System KHP Khudi Hydro Power LNHP Lower Nyadi Hydro Power Plant LKHP Lower Khudi Hydro Power Plant NEA Nepal Electricity Authority 2 JHP Jumdi Hydro Power 2 BPC Butwal Power Company 2 DOED Department of Electricity Department 5 SHPP Small Hydro Power Project 5 WI Winrock International 5 VDC Village Development Committee 8 LEDCO Lamjung Electricity Development Company 9 ACSR Aluminum Conductor with Steel Reinforcement 9 USC US Cent 15 S/S Substation 21 KSw/S Khudi Switching Station 26 USS Udipur Substation 31 DuSS Dumre Substation 31 AkSS AnbuKhaireni 31 DaSS Damauli Substation 31

ii

LIST OF FIGURES

Figure No. Caption Page

2.1 5 MVA 33/11 kV Udipur Substation 10

3.1 Conductor optimization sheet using spreadsheet 17

4.1 Existing Electrical System of Lamjung District 20

4.2 Conductor selection for KHP evacuation 26

4.3 KHP evacuation system 27

4.4 Conductor optimization chart for LNHP only 34

4.5 Conductor and voltage chart for KHP and LNHP 36

4.6 KHP and LNHP evacuation system 37

4.7 KHP, NHP and LKHP evacuation system 42

4.8 Evacuation system with Chame load 43

iii

LIST OF TABLES

Table No. Caption Page 2.1 Small Hydro Power Plants of Western Nepal 4 2.2 SHP projects (1-10 MW) in Western Nepal 5 2.3 Existing 132 kV Transmission Line of Western Nepal 6 2.4 Feeder Status of 5 MVA, 33/11 kV Udipur S/S 10 4.1 Full S/S load, Existing System 21 4.2 70% S/S load Existing System 21 4.3 50% S/S load Existing System 22 4.4 30% S/S load Existing System 22 4.5 10% S/S load Existing System 23 4.6 100% S/S load with 'Wolf' Existing System 23 4.7 80% S/S load with 'Wolf' Existing System 24 4.8 50% S/S load 'Wolf' Existing System 24 4.9 Spread Sheet calculation for KHP evacuation system (0.9 km) 25 4.10 Spread Sheet calculation for KHP evacuation system (14.9km) 26 4.11 Full load, KHP evacuation System 27 4.12 70% load, KHP evacuation System 28 4.13 50% load, KHP evacuation System 28 4.14 30% load KHP evacuation System 29 4.15 10% load KHP evacuation System 29 4.16 100% load with 'Wolf' KHP evacuation System 29 4.17 50% load with 'Wolf' KHP evacuation System 30 4.18 100% S/S load, effect in existing system with KHP 31 4.19 70% S/S load, effect in existing system with KHP 31 4.20 50% S/S load, effect in existing system with KHP 32 4.21 30% S/S load, effect in existing system with KHP 32 4.22 10% S/S load, effect in existing system with KHP 33 4.23 LNHP evacuation System 33 4.24 LNHP and KHP 33 kV transmission line 35 4.25 LNHP and KHP 66 kV transmission line 35 4.26 100% substation load, KHP and LNHP power evacuation 38 4.27 70% substation load, KHP and LNHP power evacuation 38 4.28 50% substation load, KHP and LNHP power evacuation 39 4.29 30% substation load, KHP and LNHP power evacuation 39 4.30 10% substation load, KHP and LNHP, power evacuation 39 4.31 100% load, effect in existing system, KHP &LNHP evacuation 40 4.32 70% load, effect in existing system, KHP &LNHP evacuation 41 4.33 50% load, effect in existing system, KHP &LNHP evacuation 41 4.34 System Performance with KHP, LNHP and LKHP 42 4.35 System performances with KHP, LNHP, LKHP and Chame Substation. 43 4.36 Load flow result of four feeders of Udipur S/S. 44

Chapter 1 Introduction

1

CHAPTER 1

Introduction 1.1 General

Nepal, with its very difficult geographic structure, grid expansion to remote area has been very

costly approach for rural electrification as well as to extend for small hydropower

interconnection. Mainly these areas are planned based on the electricity distribution purposes.

This thesis tries to develop the methodology especially for evacuating power from small

hydropower plant in western Nepal by focusing on grid connection as well as local

consumption using existing infrastructure.

Nepal is divided into five development regions, 14 zones and 75 districts. Western

development region is one of the development regions which comprises of three zones,

Lumbini, Dhaulagiri and Gandaki and has 16 districts. The total generating capacity of

interconnected power system of Nepal is 613.557 MW in total, of which about 556.5 MW is

from Hydro Power Stations and 57 MW from Diesel and multi- fuel Power Stations. Obviously

with the emerging scenario of increased power production, expansion of transmission and

distribution system becomes essential. The project thesis, will study power evacuation options

for different small hydropower plant by using the transmission line design program developed

for this purpose and analyze new local market for energy consumption, necessary to evacuate

growth in power production.

This thesis carries out evacuation study to incorporate the major changes in the power scenario

of the western part of Nepal. A power Generation expansion study for different small

hydropower plant is used for the transmission expansion studies. This report carries out

evacuating system study for different selected hydropower plants that will be connected to grid

in the coming years.

1.2 Objective

The major objectives of this thesis is to find out suitable power evacuation system for existing,

under implementation and up coming projects analyzing existing transmission line. The project


2

also focuses on study of the selected existing distribution system in case of local power

evacuation. The areas of work in this thesis consist of:

To select Suitable Small Hydro Power Plant in Western part of Nepal.

To get related data regarding existing electrical network of the area in the vicinity.

To find out transmission line alternatives.

Develop software in spread sheet in EXCEL to find out best transmission alternatives

considering technical aspects.

To study system performance using Netbas Simulation.

To perform distribution system planning using distribution load flow software.

1.3 Background

In addition to government owned power development agencies (like NEA, MOW, WECS, and

EDD) the private power development agency, Butwal Power Company is also actively

participating in Generation, Transmission and Distribution of electrical power to INPS as well

as local consumers. Butwal Power Company Limited (BPC) is the first private sector Power

Company of Nepal. Today BPC is a leading Hydropower developer of the country.

There are many small hydro power plants that have been identified in western part of Nepal

which are under study. Each year few new hydro power generating potential sites are identified

and undergo pre feasibility study followed by feasibility study. After completion of feasibility

study power purchase agreement is signed with Nepal Electricity Authority (NEA). BPC is

involved in developing 3.5 MW Khudi Hydro Power Plant (KHP), and studying feasibility

study for 2 MW Lower Khudi (LKHP) and 2 MW Jhumdi (JHP) Hydro Power project. Power

evacuation design is very necessary to get PPA signed and the design should be based on

performance standard of grid.

1.4 Performance standard for Grid

Objective:

The objective of the Performance Code is to specify the minimum technical standards to ensure

efficient and reliable operation of Grid [1].


3

Power Quality:

To ensure power quality as per NEA Grid Code standard voltage variation, frequency variation

and transmission loss should be as follows:

a. Voltage Variation

The system operator shall ensure that the power supply voltage in the grid at major connection

points during normal operating condition shall not deviate by more than +/- 10% of its normal

value.

b. Frequency Variation

The system operator shall ensure that the fundamental frequency in the system is maintained

between 48.75 Hz. and 51.25 Hz. i.e. +/- 2.5% of 50 Hz, which is the nominal value of

fundamental frequency.

c. Transmission Loss

The grid owner shall ensure that the transmission loss does not exceed 4.5 % of the received

energy.

1.5 Grid Connection Requirement As per NEA Grid Code requirement, generator shall maintain Power Factor between 0.85

lagging and 0.95 leading [1].

Chapter 2. Existing Electrical System in study area

4

CHAPTER 2 Existing Electrical system in Study Area 2.1 Existing power plants in western Nepal

In western region there are three zones and sixteen districts. Electricity service is available in

all districts through INPS grid (in eleven districts) and isolated small hydro power stations (in

remaining 5 districts). In either case the electricity service is made available only in limited

area. The total generation of western region is 260.49 MW and most of the generation plants of

the region are situated in Gandaki Zone. The major hydropower plants in this region are 75

MW Marsyandi, 5.1 MW Andhikhola, 14.8 MW Modikhola, 144 MW Kaligandaki 'A', and 15

MW Gandak. The total installed capacity of major hydropower plants is 253.9 MW. There are

twelve existing small hydro power plants of different sizes in western region with total

installed capacity of 6590 kW [2].

Table 2.1: Small Hydro Power Plants of Western Nepal

SNo. Zone District Power Plant Installed Capacity

(kW)

Year of Commissioning Developer

1 Gandaki Kaski Phewa 1088 1967 NEA 2 Lumbini Rupandehi Tinau 1024 1978 NEA 3 Dhaulagiri Baglung Baglung 200 1981 NEA 4 Dhaulagiri Mustang Jomsom 240 1983 NEA 5 Gandaki Syrrgja Syanja 80 1984 NEA 6 Gandaki Kaski Seti 1500 1985 NEA 7 Gandaki Manang Chame 45 1987 NEA 8 Gandaki Manang Manang 80 1988 NEA 9 Gandaki Gorkha Arughat 150 1990 NEA 10 Dhaulagiri Myagdi Tatopani-I 1000 1991 NEA 11 Dhaulagiri Myagdi Tatopani-II 1000 1995 NEA 12 Gandaki Lamjung Sangekhola 183 2002 SPC

Note: SPC=Sange Power Company; source: System planning, NEA

2.2 Under Study Small Hydro Power Plant in Western Nepal

It is worth mentioning here that many Independent Power Producers (IPP) are showing strong

interest in the development of small hydro power plant in Nepal. In western region only, there


5

are altogether 24 new small hydro power plants have been identified by private promoters. List

of Identified Small Hydro Power Plants identified by private promoters are tabulated below.

Table2.2: Small Hydro Power Projects (1-10 MW) in Western Nepal

SN. Project Name Project

Location Promoter Installed Capacity

(MW) Information Source

1 Bhimkhola Baglung Butwal Power Company 3.1 DOED

2 Bijayapur 1 Kaski Bhagwati HP Development Company (P) Ltd 2 DOED/SHPP

3 Daraudi Gorkha Shreerup Hydropower Pvt.Ltd. 5 DOED

4 Dharam Khola Baglung The Gorkha Hydropower P Ltd. 5 BPC

5 Dudh Khola Manang Swet Bhairb Pvt Ltd. 10 DOED

6 Dordi I Lamjung Shah Consult Pvt. Ltd. 8 DOED

7 Ghami Khola Mustang Cosmic Hydropower Pvt Ltd 2.5 DODE

8 Jumdikhola Gulmi Butwal Power Company Ltd. 2 DOED

9 Karuwa Kaski Jhyamolongma Hydropower Dev. Co.(P) Ltd. 6 DOED

10 Khudi Lamjung Lamjung Electricity Development Co. P Ltd 3.6 SHPP/WI

11 Kotre Kaski Machhapuchhre HP Development Company 3 SHPP/WI

12 Lower Myagdi Myagdi Nect Center Pvt.Ltd & Him Consult 5 DOED

13 Madkyu Khola SHP

Kaski Arjun Prashad Paudyal 5 DOED

14 Madi 1 Hydro Kaski Annapurna Group P/ltd. 10 BPC

15 Mardi Khola Kaski Gandaki hydro power Development P. Ltd. 3 DOED

16 Mardi Khola MD-1 Kaski N/A 10 BPC

17 Nyadi II Lamjung Baverian Hydropower Nepal P Ltd 4.9 SHPP/WI

18 Pati Khola SHP Parbat Unified HP Pvt Ltd. 1.5 DOED

19 Paudi Khola SHP Lamjung N/A 1.5 DOED

20 Ridi Khola Gulmi Ridi Hydropower Development Co.Pvt.Ltd 1.8 DOED

21 Seti hydropower Kaski Seti Hydropower Development Co. (P) Ltd 10 SHPP/WI

22 Shardi Khola SHP Kaski Sarimati Deepal Poudel 1.7 DOED

23 Upper Dharam A SHP

Baglung Ghumte Hydropower Pvt Ltd 4.5 DOED

24 Upper Seti - 1 Kaski Seti Hydropower Development Co. (P) Ltd 3 DOED

2.3 Existing Grid transmission system in western Nepal

The available grid transmission voltage in western region is only 132 kV and sub transmission

voltage is 33 kV. Grid transmission line is connected from east to west through Bardghat,

Butwal and Shivapur areas and from north to south through Pokahara area. Bardghat is one of

the major grid substations in south western part having power sources from Gandak, 15 MW

power station and National Grid. Bardhaghat is connected to Bharatpur by 132 kV single


6

circuit transmission line in the east, with Butwal by 132 kV double circuit transmission line in

the west and with Gandak power station by 132 kV double circuit transmission line. Butwal is

another major junction of south-western part of the National Grid having power sources from

National Grid, Andhi Khola, Tinau, Gandak, and Kali Gandaki 'A' power station. Butwal is

connected with Bardhghat by 132 kV single circuit transmission line in the east, with Shivapur

by 132 kV single circuit transmission line in the west and with Kali Gandaki 'A' power station

by 132 kV double circuit transmission line. Shivapur (Chanauta) is also major junction of

south-western part of the National Grid having power sources from INPS. This S/S is

connected with Butwal S/S in the east and Lamahi S/S in the west by 132 kV single circuit

transmission line. Pokhara S/S is connected to Bharatpur via Damauli in the south and is

connected to Modi in the north. The existing transmission lines of western region are tabulated

below.

Table 2.3: Existing 132 kV Transmission Line of Western Nepal

Area Voltage Level

No. of Circuit Conductor Code Line Length (km)

Lamahi--Shivpur 132 single Bear 51 Shivpur--Butwal 132 single Bear 61 Butwal--Bardghat 132 double Bear 43 Bardghat--Gandak 132 single Panther 14 Bardghat--Bharatpur 132 single Panther 70 Bharatpur--Damauli 132 single Wolf 39 Damauli--Pokhara 132 Single Wolf 46 Pokhara--Modi 132 Single Bear 37 Bharatpur--Marsyangdi 132 Single Duck 25 Marsyangdi--Suichatar I 132 Single Duck 83

Source: System Planning, NEA

Substations in Pokhara, Damauli, Bardghat, Butwal and Chanauta areas are the main power

sources for western region [2].

2.4 Existing Electrical Network in Some Districts of Western Nepal.

To understand the existing electrical network up to distribution level in the western region data

showing the present distribution status of some of the district is explained below.

1. Palpa

In this district there are altogether 113,361 number of consumer including domestic,

commercial, non-commercial, industrial and others. In this district electrification is done using


7

both 11 kV and 33 kV distribution systems. The total 11 kV distribution line length is 60 km

and 33 kV distribution line lengths are 118 km. Most of the electrified areas are electrified

using 33/0.4 kV, 99 numbers of distribution transformers of various sizes. In this district there

is one area substation of capacity 6/8 MVA with three feeders East feeder (40 nos. of 11/0.4 kV

transformers), Bazaar feeder (10 nos. of 11/0.4 transformers) and West feeder (30 nos. of

11/0.4 transformers). This substation receives power from Andhi Khola hydro power station

and Butwal grid S/S. There are no existing power plants and also no new identified small power

plants undergoing study.

2. Parbat

As per NEA, in Parbat district the total number of consumers including domestic, industrial,

commercial, noncommercial and others is 6,941. In Parbat distribution level voltage is 33 kV

and 33/0.4 kV distribution transformer is used for power distribution to consumers. There is

also 11 kV distribution line in this district and the line length is 26.39 km. The 33 kV

distribution line lengths is 89.79 kV. There is no area substation in Parbat and no grid

substation also. In case of power station, there are no existing power plants. Pati Khola SHP,

1.5 MW is the only small hydro power identified by Unified HP Pvt. Ltd. in this district which

is now undergoing feasibility study.

3. Syanja

According to the information obtained from Syanja Branch, NEA, total number of consumer

including domestic, industrial, commercial, noncommercial and others is 11,200. In this

district Private sector Company, BPC is involved in distributing electricity to about 14,000

numbers of consumers. Total Number of 33/0.4 kV Distribution transformer is 16. In this

district also, distribution has been done in two voltage levels 33 kV and 11 kV. The total line

length of 33 kV distribution line is 18.93 km and the total line length of 11 kV distribution line

is 129.29 km. There are two are area substation under NEA, Badkhola, 33/11 kV, 1.5 MVA

substation and Mirmi, 33/11 kV, 500 kVA substation. There is one existing power station,

Andhi Khola, 5.1 MW, which has 5.3/33 kV substations with three feeders, Walling feeder

with total connected load of 3265 kVA, Galyang feeder with total connected load of 3205 kVA


8

and NEA feeder, which is connected to Butwal grid substation passing through 200-kVA load.

All these feeders feed load in 33 kV voltage level.

4. Gulmi district

The Gulmi District is one of the districts of Lumbini Zone in Western Development Region.

There are altogether 79 VDCs in this district. Tamghas is the district head quarter.

Electrification in Gulmi district is very small compare to its size in terms of geography as well

as demography. Only 24 VDCs out of 79 have been partially electrified from 33 kV sub

transmission line joining 5 MW Andhikhola hydropower plant, 40 (1x10 and 1x30) MVA

Butwal Grid substation and 12 MW Jhimruk hydropower plant.

At present the total number of consumers is 8793 including industrial, commercial and others

are enjoying benefits from electricity service in the district. Based on this, the electrification

ratio of the district is only about 15%.

Sub Transmission and Distribution Lines

There is no area substation in this district. 33 kV line network has been used to distribute

electricity with 33/0.4 kV distribution transformers. The 33 kV line originating from

Andhikhola enters the district at Aslewa, which is 17 km from source and joins 33 kV line of

Butwal Grid substation at Baletaksar at a distance of about 77 km from the source.

This 33 kV line further links the 33 kV subtransmission line from Jhimruk hydropower plant at

Wangla in Arghakhanchi and Tamghas in Gulmi district, forming a looped network of 33 kV,

which covers the load centers of both the districts. The total 33 kV line length in the district is

approximately 158 km. All the existing 33/0.4 kV distribution tappings in the district have been

shown in the single line diagram in Appendix C. This distribution network is consisting of fifty

one (51) 33/0.4 kV distribution transformers of various capacities from 25 KVA to 100 KVA

[3].

In this district, two upcoming small hydro power projects are identified and undergoing study.

Jumdi hydro power (JHP), 2 MW is under feasibility study by Butwal Power Company (BPC)

and Ridhi Khola SHP, 1.8 MW is also under feasibility study carrying out by Ridhi Hydro

Power Development Company.


9

5. Lamjung

Lamjung is one of the districts of Gandaki zone in western development region of Nepal. The

existing electrical network in the Lamjung district is comparatively small. According to 8th

power report, NEA, in Lamjung district only 24 VDCs out of 61 VDCs have partial access to

electricity from a single 1.5 MVA, 33/11 kV substation at Udipur.

About 4600 (year: 2001) numbers of consumer including industrial, commercial, and other

have access to electricity in the district. This data shows that the electrification ratio of about

11% and the total energy consumption is about 1472 MWhr. (Year: 2001).

One distinct electric power generating activity in the district is the 183 kW, small-scale

hydropower plant, which is under operation at Sange (of Taghrin VDC) by a private company,

LEDCO.

Source Substation

In Lamjung there is only one 5 MVA, 11/33 kV area substation at Udipur. Source for this area

substation is 132/33 kV Grid substation at Damauli which is 34.5 km from Udipur. In between

Damauli Grid substation and Udipur substation there is another 5 MVA, 33/11 kV substation at

Dumre from where 20 km long 33 kV transmission line is tapped directly to feed Udipur

substation.

Besisahar headquarter of Lamjung district and the area in the vicinity is electrified from four

different outgoing feeders from Udipur substation. Small part of Tanahu district is also

electrified from this substation. The four feeders are Besisahar, Okhari, Bhote Odar and

Nayagaon.

Sub Transmission and Distribution Lines

In Lamjung district the only sub transmission line is 20 km long Dumre-Udipur 33 kV

overhead line constructed on wooden poles using ACSR conductor 65 sq. mm (equivalent

copper area) Dog.

In case of distribution lines, about 229 km of (including proposed 128 km) 11 kV line is

distributing electricity up to consumer premises. The conductor used in 11 kV distribution line

are ACSR Rabbit and Weasel. There are 115 numbers of 11/0.4 kV distribution

transformer of varying capacities from 25 kVA to 200 kVA including existing and proposed

transformers on four outgoing feeders from Udipur substation. Four out of 105 transformers are

located in Tanahu district. The existing electrical network in Lamjung district is presented in


10

Appendix C. The 11 kV outgoing feeder from Udipur S/S and total connected load in each

feeder of this district is presented below [3].

Figure 2.1: 5 MVA, 33/11 Udipur Substation

Table2.4: Feeder status of 5MVA, 33/11 Udipur substation. Name of Feeders Total No. of Transformer Total kVA Besisahar Feeder 36 1400 Okhari Feeder 17 550 Bhote Odar Feeder 45 2125 Majhgau Feeder 17 575

Total Connected kVA 4650

Power Plants

Khudi, KHP (3.5 MW) is undergoing construction in this district, and is expected to connect

with the NEA Grid at Udipur substation. Lower Nyadi Hydro Power with installed capacity of

4.5 MW is upcoming hydropower which also gets access to grid through 33 kV transmission

line connecting to Udipur substation. Middle Marshyangdi, 70 MW, Hydro power plant is also

under construction and is going to generate power at the end of 2006. Besides these mentioned

hydro power plants there are many other possibility of power generating sites available in this

district. Lower Khudi, 2 MW, and Upper Nyadi 10 MW are already identified and are

undergoing study.

Chapter 3. Methodology

11

CHAPTER 3 Methodology In Nepal, there are immense opportunities in the field of hydro power development. The record

shows that Nepal has theoretical hydro power potential of 83,000 MW out of which 42,000

MW is technically and economically feasible. In Nepal many of Independent Power Producers

(IPP) are showing strong interest in the development of small scale hydropower. Usually for

small hydro Power, power evacuation is becoming great challenge because of difficult

geographic structure and absence of electrical network/grid in the vicinity. Arrangement for

accessing grid substation will make most of the small hydro power plant economically not

feasible so for the small power plant which has enough possibility of local power consumption,

it is required to develop a methodology that will make access to grid as well as satisfy local

power demand. Keeping this in mind, this thesis tries to concentrate in identifying the

evacuation system of Khudi Hydropower (KHP), Nyadi Hydro Power (NHP) and Lower Khudi

Hydropower (LKHP) in western Nepal. Further, detail analysis of evacuation system of Khudi

and Nyadi Hydro Power will be carried out using software developed in spread sheet, Carl

1.0-distribution load flow software and Netbas Simulation.

The methodology adopted for identifying and designing evacuation system is mainly based on

the availability of data for any selected small hydro power. The data collected in this regard

should comprise of information on geography, demography, existing electrical network and

future power expansion plans. After data collection comes analysis part, the analysis part is

divided into two parts viz. technical and financia l. Technical analysis results in feasibility of

selected transmission line alternative regarding technical parameter like voltage, line length,

power to be transmitted, power factor and efficiency. Financial analysis will decide in selection

of one alternative among many technically feasible alternatives.

3.1 Data Collection

From data collection regarding existing electrical network of different district of western

Nepal, help in locating the power house site of new coming small hydro power plants. Exact

location of most of the new under study power plant is not known so knowledge of existing


12

electrical network including 11 kV distribution, 33 kV distribution or sub transmission line,

33/11 kV substation and 132/33/11 kV Grid substation is very essential because ultimately the

power generated must be evacuated there.

Difficulty in designing power evacuation system is quite similar for almost all identified new

small hydro power plants. All hydro power station sites are far from major load centers and

obviously far from grid access. So, in this thesis, for studying evacuation system of western

Nepal, Lamjung district is selected because, in Lamjung district there are comparatively

smaller hydropower plants identified by different IPPs and are under going different stages of

study. The small hydropower plants identified in this district are 3.5 MW Khudi Hydro Power

(KHP), 4.5 MW Lower Nyadi Hydro Power (LNHP), 2 MW Lower Khudi Hydro Power

(LKHP) and 10 MW Upper Nyadi Hydro Power Plant (UNHP). Among these, Khudi Hydro

Power Plant has started construction work, and detail study of Lower Nyadi Hydro Power is

under progress. Now, for designing evacuation system for these two hydro power plants, data

based on geography and demography is acquired from topographic map, data regarding all

existing as well as proposed electrical network of whole Lamjung district is taken from 8th

Power Report, NEA, and some of the data related to electrical infrastructure have been updated

with the latest data acquired during field visit of Western Nepal. The existing electrical

network of Lamjung district is presented in Appendix C.

3.2 Transmission line alternative

Topographic Map shows all required information regarding land, water, lakes, pond, rivers,

stream, canals, dams, bridge, mountains, hills, valleys cliffs, towns, cities, roads, boundaries

and other geographic and demographic features. Study of Topographic map gives the

preliminary idea about the transmission line route. Selection of transmission line route is based

on a procedure which should consider restricting factor like safety, engineering and

technology, system planning, environmental, institutional and aesthetics. The transmission

route selection is based on available right of way and results of system analysis. Usually the

route is selected within the country on private right of way in order to obtain most possible

direct route and to stay away from road, buildings, highway etc. After finalizing the

transmission route/s technical and financial analysis is carried out for choosing best alternative


13

if there are many. Detail study for identifying the transmission line route is out of scope of this

thesis. For carrying out technical and financial analysis of the selected transmission line,

program developed on MS excel will be used, followed by Netbas simulation for studying

system performance, finally using available data distribution system planning is carried out

with Carl1.0 (program for load flow calculation of 11 kV radial distribution network).

3.3 Available Transmission Capacity

Transmission Capacity is the maximum power that can be delivered from power generating

station to the distribution station. Transmission capacity depends on line length, size of

conductors and voltage level. While determining transmission capacity of new transmission

system, possibility of addition of new power plant is to be considered. Available Transmission

Capacity (ATC) is difference between transmission margin and present line loading.

3.4 Transmission Margin

Transmission margin is the maximum allowable power that can be transmitted without

violating the transmission line criteria which may be performance standard or control and

protection settings used in primary and secondary distribution substations.

3.5 Performance of Transmission line

Efficiency and Voltage regulation are the key parameters that determine the performance of

transmission line. For any type of transmission line, calculation based on ABCD constants for

determining efficiency and regulation can be done using computer program. If the efficiency

and regulation are not within prescribed value then it is necessary to revise the calculation

using thick conductor cross-section and changing the conductor configuration. In some cases it

may be necessary to use a higher transmission voltage in the revised design. Detail of

transmission line design is presented in Appendix A.

3.6 Distribution system planning

The project will focus on the present distribution system and will work out for future

distribution planning which is the most important parameter required for designing power

evacuation system. Transmission and distribution planning is done so that present and future

power required by local consumer is identified and help in designing required evacuation

system. Distribution planning will be done using load forecasting of study area which includes


14

study of load growth pattern and load flow analysis. This thesis covers the load flow analysis

part only.

3.7 Spread Sheet Calculation for Conductor selection and Voltage [2]

For the selection of optimum conductor size and transmission voltage a program is developed

in spread sheet. The selection is based on capitalized cost per km of transmission line. This

method is mainly applicable to transmission lines that are not subject to load growth. Such

transmission line would be from new power plants to the nearest grid connection point in the

existing system. Another important use of this spread sheet is to "screen" the number of

alternatives down to a manageable level before full system studies are undertaken.

Basic Formula

The selection of transmission lines for the planned power plants in Nepal are based on

economic evaluation of different line/tower solutions over the lifetime of the project. The

optimization takes into account the investment cost, cost of transmission losses and operation

and maintenance costs.

The calculation is performed on a km transmission line basis and is as such not dependent on

the length of the transmission line. The following formulas apply to the calculation:

moLossesInvestmentTotal KKKK &++= [NRs. / km] Eq. 1

DkTRUP

K ELossRated

PeakLosses ....

2

= [kNRs. / Km] Eq. 2

DC

KK MOInvestmentMO .100. && = [NRs. / km] Eq. 3

Where, PeakP =Maximum Transmitted Power [MW], RatedU = Rated AC line Voltage [kV], R =

AC line resistance [? / km], LossT = Loss Duration [hours], Ek = Energy Cost [NRs/kWh], D

= Discount Factor, MOC & = Annual Operation & Maintenance cost [% of initial investment].


15

Plant Loss Duration

The equivalent loss duration is calculated from the plant factors. The equivalent loss duration

should be understood as the time the plant will have to operate on rated capacity in order to

produce the annual losses, and is calculated from:

-+=

2

2

22

87601

21

1.8760

nUtilizationUtilisatioLoss

TTT [Hours] Eq. 4

Energy Cost

The energy cost normally to be used for optimization of transmission line is the long run

marginal cost of generation. In Nepal, it has been agreed that an average incremental cost of

generation better reflects the real value and is therefore used. The average incremental cost of

generation is 6.02 USC/kWh.

Operation & Maintenance

The operation and maintenance cost of transmission line is set to 1.5% of initial investment by

NEA. Typical figures range from 0.5% to 1.5%, and Nepal may be in the upper range of this

due to the recurring monsoon and frequent landslides. An annual operation and maintenance

cost of 1.5% has therefore been used in the optimization.

Annual Outage

Outage means power transmission failure due to unavailability of transmission line during

faulty condition. In Nepal, for 132 kV transmissions line the annual outage is taken as

0.28hrs/km.

Discount Factor

The discount factor represents the discounted value of fixed annual payments of one unit each

year of the lifetime. With 25 years technical lifetime and 10% discount rate, the discount factor

is 9.08.

( )( )

+-+

= NN

iii

DF1

11 Eq. 5

Where, DF is discount factor, i is discount rate in percent, N is Number of compounding

periods in years.


16

Spreadsheet Result:

Input to the spreadsheet program are line length, power factor, voltage level and power to be

transmitted from generation source to distribut ion substation. The program will carry out

transmission line design analysis using selected four different conductors from a given list. The

result is the outcome of technical and financial analysis. For technical analysis the program will

give, voltage regulation, efficiency of line and line loss. Changing either conductor size or

voltage level, the result can be made within required voltage regulation and efficiency.

Financial analysis is based on transmission line cost with selected conductor only. For more

than one conductor satisfying both criteria i.e. voltage regulation and efficiency the best

conductor is selected for minimum KTotal in given in Equation 1.

Input

Input parameters in spread sheet calculation for selecting conductor are power to be delivered

in MW, line length (L) in km and power factor (Cosf ).

Testing criteria

The selected conductor should meet both efficiency and voltage regulation criteria. If one of

these criteria is violated, the conductor is not suitable for the transmission line. As per NEA

Grid Code efficiency should be not less than 95.5% and voltage regulation should be 10 %.

Voltage Regulation

Voltage regulation of a line is the change in voltage at the receiving end when full load at a

given power factor is removed keeping sending end voltage constant.

rfl

rflrnl

V

VVgulation

-=Re% Eq. 6

Where,

Vrnl = magnitude of receiving-end voltage at no load.

Vrfl = magnitude of receiving-end voltage at full load.

Transmission Efficiency

%100*s

Rline P

P=h Eq. 7

Where,

PR = Power to be delivered at receiving end

Ps = Power sent at the sending end


17

Conductor and Voltage Optimzation

300

800

1300

1800

2300

2800

3300

3800

4300

4800

1 Mw 2MW 3MW 4MW 5MW 6 MW 7MW 8 MW

Peak Load [MW]

Cap

ital

ized

Co

st [

kNR

s.]

Weasel_33

Rabbit_33

Beaver_33Dog_33

Tiger_33Wolf_33

Lynx_33Panther_33

Dog_66

Wolf_66Panther_66

Lion_66

Figure 3.1: Conductor optimization sheet using spreadsheet


18

3.8 Carl 1.0

In order to evaluate the performance of a power distribution network and to examine the

effectiveness of proposed alterations to a system in the planning stage, it is essential that a load

flow analysis of the network is carried out. The load flow studies are normally carried out to

determine:

1. The flow of active and reactive power in network branches.

2. Effect of additions or alterations on a system.

3. Optimum system loading conditions.

4. Optimum system losses.

Input

For this software-Carl1.0, the input parameters are related to the 11 kV radial distribution

feeders only. Input data related to 11 kV feeder are; substation capacity (MVA), voltage level

(kV), name of load centers, name of sending end node and receiving end node, distribution load

(kVA of 11/0.4 kV distribution transformer), power factor, length of 11 kV line between

sending end and receiving end of a branch and finally type conductor. This software allows

only three conductor options viz. 'dog, rabbit and weasel because in Nepal, only

conductors dog, rabbit and weasel are used in the distribution level.

Output

The output of the software is directly saved in the MS Excel sheet. The results of load flow are;

total power loss in each branch feeders (sum of loss in all branches), total power flow in each

branch, minimum voltage in percent ; voltage drop in each branch, voltage at each receiving

end, location of node with minimum voltage, length of different type of conductor used, total

power loss of the feeder and total power flow in the feeder.

Using this software conductor selection, feeder load management and voltage regulation can be

done. This software is used just to study the status of local load centers.

3.9 Netbas Simulation

This software is developed by Powel Company, Norway. Netbas Simulation is very helpful in

solving load flow ana lysis, short circuit analysis and other power system analysis. In this thesis,

Netbas is used for determining the system performance after connecting a small power plant in


19

the existing electrical network. The comparison between status of existing electrical network

before and after connecting new power plant will definitely help in selecting best evacuation

option for upcoming hydropower plant.

As per grid code, NEA, in Nepal study of system performance is necessary for any new hydro

power plant more than 1 MW, willing to connect to the grid. System performance shall include

the following information:

1. Power flow direction during different time frame, loading conditions.

2. Change in voltage regulation in existing electrical network

3. Change in transmission line loss in existing electrical network.

These required data can be easily determined using Netbas Simulation

3.10 Evacuation System for KHP, LNHP and LKHP.

The methodology described above is used to study evacuation system of KHP, LNHP and

LKHP in Lamjung district. These power plants are under different stages of development. The

present status shows that KHP will come first then LNHP and at last LKHP. For all these power

plants the nearest available existing grid is 33/11 kV, 5 MVA, Udipur substation which is fed

by 132/33 kV grid substation at Damauli, 34.5 km away at Tanahu district. There are no other

options available for power evacuation from these power plants. Therefore, this thesis

concentrates on detail study for evacuating power using existing transmission system for

different loading conditions.

Chapter 4. Results and Discussion

20

CHAPTER 4 Results And Discussions Existing system in Lamjung district is shown below. Udipur substation is 14 km away from

Dumre substation and connected with 33 kV transmission line with conductor 'dog'. Dumre,

Udipur and Anbu Khaireni substations are fed by Damauli 132/33 substation through 14.5 km

long 33 kV transmission line from Damauli S/S to Dumre S/S. Single line diagram of existing

33 kV sub transmission network is shown in figure below.

Figure 4.1: Existing Electrical System of Lamjung District

4.1 Existing System Result

Existing system analysis will help in finding out the present performance and make us able to

compare with different options of addition of hydro power plant or addition of bulk load. Three

area substations Dumre S/S, Udipur S/S and Anbu S/S and one grid substation, Damauli S/S

will be affected by addition of upcoming SHP. Load flow is carried out for different loading

condition.


21

Case I : Full Load

In 100% load, i.e. 15 MVA (sum of full load of three substation, 13.5 MW at 0.9 pf), swing

bus- Damauli substation will generate 14.83 MW including line losses. Maximum voltage drop

is at Udipur which is 13.68 % i.e. voltage at Udipur is only 28.486 kV. In this case Damauli-

Dumre line section is over loaded, 106.23%. The result of Netbas Simulation for full load case

is tabulated below.

Table.4.1: Full Sub Stations Load, Existing System

Conductor Dog

Generation at Damauli (slack bus) 14.83 MW, 8.32 Mvar

Total voltage independent load 13.5 MW, 6.58 Mvar

Total Loss in line sections 1.33 MW, 1.74 Mvar

Total % of transmission Loss 8.97 %

Max. Voltage Drop and location 13.68 %, Udipur

Heaviest loaded line Damauli-Dumre, 106.23%

Case II: 70 % Load

In 70% load, i.e. 10.5 MVA (9.45 MW at 0.9 pf), the swing bus, Damauli substation will

generate 10.045 MW including line losses. Maximum voltage drop is at Udipur which is 9.11%

i.e. voltage at Udipur is only 29.995 kV. In this case Damauli- Dumre section is heaviest loaded

line, 71.22 %. The result of Netbas Simulation for this case is tabulated below.

Table.4.2: 70 % Substations Load, Existing System

Conductor Dog




Total % of transmission Loss 6.35 %




22

Case III: 50 % Load

In this case all three area substations are considered to be operated in half load only. Total

generation in Damauli S/S is 7.04 MW including losses 0.29 MW in all line sections and the

total load of all substations is 6.75 MW. The maximum voltage drop is 6.71 % at Udipur S/S,

which is 30.92 kV. The heaviest loaded line is Damauli-Dumre, 49.6%.

Table 4.3: 50% Substations Load, Existing System

Conductor Dog




Total % of Transmission Loss 4.12 %


Heaviest loaded line Damauli-Dumre,49.6%

Case IV: 30 % Load

In this test case all substations are considered to be running in 30% loading. Total power drawn

from Damauli S/S is 4.15 MW including 0.099 MW losses in all line sections. The maximum

voltage drop is 3.69 % at Udipur which is 31.78 kV. In this case also the heaviest loaded line is

Damauli-Dumre, 29.06%.

Table.4.4: 30 % Substations Load, Existing System

Conductor Dog





Max. Voltage Drop and location 3.69%, Udipur



23

Case V: 10 % Load

In this test case all substations are considered to be running in 10 % loading. Total power drawn

from Damauli S/S is 1.36 MW including 0.01 MW losses in all line sections. The maximum

voltage drop is 1.2 % at Udipur which is 32.605 kV. Table4.5: 10 % Substations Load, Existing System

Conductor Dog





Max. Voltage Drop and location 1.2%, Udipur

Heaviest loaded line Damauli-Dumre,

Case VI: 100% load with Wolf

In full load capacity, with conductor wolf the total system loss is 6.05% which is

unacceptable and the voltage drop is 10.41%, so the existing system will be inefficient even if

conductor wolf is used.

Table 4.6: 100% Substations load with 'wolf', Existing system Conductor Wolf






Heaviest loaded line Damauli-Dumre

Case VII: 80% load with Wolf

In 80% load capacity the total line loss is 4.5% and maximum voltage drop is 8.1%. Generation

at Damauli S/S is 11.31 MW and total substation load is 10.8 MW.


24

Table 4.7: 80% Substations load with 'wolf', Existing system Conductor Wolf




Total % of Transmission Loss 4.5%



Case VIII: 50% load with Wolf, Existing System

In this case the system performance is within acceptable limits. The voltage regulation of

4.88% and total transmission loss of 2.8% with total generation of 6.95 MW at slack bus makes

the system quite normal.

Table 4.8: 50% Substations load with 'Wolf', Existing system Conductor Wolf






Heaviest loaded line Damauli-Dumre,49.0%

Discussion: Existing Electrical Network

Usually the substation capacity is determined from the peak load forecast of 15th year from the

date of its construction. The analysis of system is carried out for different loading condition in

the substations. From load flow analysis using Netbas simulation it is found that transmission

capacity of Damauli-Dumre 33 kV transmission line is 13.5 MW without over loading. Full

capacity of this line cannot be used because of poor voltage regulation (13.68 %) and

transmission loss (8.97 %). From Case III Transmission Margin is 7 MW. If the total load

demand exceeds 50%- case III, then the total transmission loss exceeds 4% and in this case the

total power drawn from Damauli S/S (swing bus) is 7 MW. For Case I, II and III, there is no


25

Available Transmission Capacity in existing system because total line loss is more than 4%. In

case IV the total line loss is only 2.38% so more power can be drawn from Damauli S/S

therefore ATC is 2.54 MW and in case V ATC is 5.68 MW.

As the existing system performance using conductor dog is very inefficient when the load

demand exceeds 50% of total substation capacity. Therefore for better performance conductor

with higher cross section shall be used. Analysis of system performance using conductor wolf

shows that the existing system will be acceptable up to load demand of 80% of total

substation capacity. By changing the existing conductor "Dog" with conductor "Wolf" the

transmission margin can be increased to 11 MW.

4.2 KHP Evacuation System

This section shows the analysis for Khudi Hydro Plant (KHP) power evacuation. As Lower

Nyadi Hydro Project (LNHP) is also coming in near future so the Khudi Switching Station will

connect both power sources and feed down to Damauli S/S through Udipur S/S and Dumre S/S.

First step is to analyze transmission system of KHP up to Khudi Switching station (KSw/S) and

then Udipur S/S using spreadsheet calculation. Transmission line from KHP to Khudi

switching station is only 0.9 km and this line will be used only for transferring power from

KHP to Khudi switching station. From spread sheet calculation in 33 kV voltage level

conductor Beaver, Dog, Wolf and Panther is found to be technically feasible but

financial analysis shows that conductor Wolf is the best having lowest NPV of Investment

(inclusive of losses, O&M and outages over the period of 25 years). The spread sheet result is

tabulated below:

Table 4.9: Spread Sheet Calculation for KHP Evacuation System Technical Part

Conductor Beaver Dog Wolf Panther Line Length (km) 0.9 0.9 0.9 0.9 Receiving End Voltage (kV) 32.95 32.96 32.97 32.97 Voltage Regulation (%) 0.23 0.13 0.1 0.09 Line Losses (kW) 4.80 3.44 2.3 1.72 % transmission loss 0.2 0.1 0.07 0.05 Line Efficiency (%): 99.86 99.9 99.93 99.95 Power Delivered (MW) 3.49 3.49

Economical Part NPV of Investment inclusive of losses, O&M and outages (NRs.'000)

1556 1375 1335 1378


26


300

800

1300

1800

2300

2800

3300

3800

4300

4800

1 Mw 2MW 3MW 4MW 5MW

Peak Load [MW]

Cap

ital

ized

Co

st [k

NR

s.]

Weasel_33Rabbit_33

Beaver_33Dog_33

Tiger_33

Wolf_33Lynx_33

Panther_33

Figure 4.2: Conductor Selection for KHP evacuation

Before LNHP connected to the Khudi Switching Station KHP will get connected in Udipur

Substation through 14km long 33 kV transmission line from Khudi Switching Station to

Udipur S/S. Now in this case the total transmission length is 14.9 km and spread sheet

calculation shows that conductor "Wolf" is best and have lowest NVP of Investment. The

details of spread sheet result are tabulated below.

Table.4.10: Spread Sheet calculation for KHP Evacuation System Technical Part

Conductor Beaver Dog Wolf Panther Line Length (km) 14.9 14.9 14.9 14.9 Power to be Transmitted (MW) 3.50 3.50 3.5 3.5 Receiving End Voltage (kV) 32.11 32.29 32.44 32.52 Voltage Regulation (%) 2.71 2.16 1.69 1.44 Line Losses (kW) 79.48 56.90 38.16 28.45 % transmission loss 2.21 1.59 1.07 0.8 Line Eficiency (%): 97.79 98.41 98.93 99.2 Power Delivered at the load end (MW) 3.41 3.43 3.45 3.46

Economical Part NPV of Investment inclusive of Losses, O&M and Outages (NRs.000) 25696 22717 22083 22803

For studying the affect of connecting KHP to Udipur S/S Netbas Simulation is used. Power

from KHP will get grid access at Udipur S/S and will feed power to local area through 33/11

Wolf_33


27

kV Udipur S/S. The excess power is transmitted to Dumre S/S and feed power there also and

finally excess power will be transmitted to Grid. Netbas Simulation is carried out for studying

the following system performance under different loading condition of Substations.

Figure 4.3: KHP Evacuation System Case I: Full load

In full load, i.e. 15 MVA (13.5 MW at 0.9 pf), swing bus i.e. Damauli substation will generate

10.73 MW including line losses. Power generation from Khudi Power plant is 3.5 MW.

Maximum voltage drop is at Anbu Khaireni which is 8.66 % i.e. voltage at Anbu Khaireni is

only 30.14 kV. In this case Damauli- Dumre line section is heaviest loaded with 73.58%. The

result of Netbas Simulation for full load case is tabulated below.

Table.4.11: Full Load, KHP Power Evacuation Conductor Dog Generation at Damauli (slack bus) 10.73MW, 4.85 Mvar Total Generation 14.23 MW, 7.7 Mvar Total voltage independent load 13.5 MW, 6.58 Mvar Total Loss in line sections 0.68 MW, 0.9 Mvar % of total transmission line loss 4.77 % Max. Voltage Drop and location 8.66%, AnbuKhareni Heaviest loaded line Damauli-Dumre, 73.58%


28

Case II: 70% load In 70% load, i.e. 10.5 MVA (9.45 MW at 0.9 pf), the swing bus, Damauli substation will

generate 6.27 MW including line losses. Power generation from KHP is 3.5 MW. Maximum

voltage drop is at AnbuKhaireni which is 5.75 % i.e. voltage at AnbuKhaireni is only 31.1 kV.

In this case Damauli- Dumre section is heaviest loaded line, 45.7 %. The result of Netbas

Simulation for this case is tabulated below.

Table.4.12: 70 % Substation Load, KHP Powe r Evacuation Conductor Dog Generation at Damauli (slack bus) 6.27 MW, 3.76 Mvar Total Generation 9.77 MW, 5.15 Mvar Total voltage independent load 9.45 MW, 4.61 Mvar Total Loss in line sections 0.29 MW, 0.38 Mvar % of total transmission line loss 2.97 % Max. Voltage Drop and location 5.75%, AnbuKhareni Heaviest loaded line Damauli-Dumre, 45.7%

Case III: 50% load In this case all three area substations are considered to be operated in half load only. Total

power drawn from Damauli S/S is 3.44 MW including losses 0.16 MW in all line sections and

the total load of all substations is 6.75 MW (at 0.9 pf). Power generation from KHP is 3.5 MW.

The maximum voltage drop is 3.94% at AnbuKhaireni S/S, which is 31.70 kV. The heaviest

loaded line is KHP-Khudi Sw/S, 30.91%.

Table.4.13: 50 % Substation Load, KHP Power Evacuation Conductor Dog Generation at Damauli (slack bus) 3.44 MW, 3.15 Mvar Total Generation 6.94 MW, 3.64 Mvar Total voltage independent load 6.75 MW, 3.3 Mvar Total Loss in line sections 0.16 MW, 0.21 Mvar % of total transmission line loss 2.3 % Max. Voltage Drop and location 3.94 %, AnbuKhaireni Heaviest loaded line KHP-Khudi Sw/S,30.91 %

Case IV: 30% load In this case all substations are considered to be running in 30% loading. Total power drawn

from Damauli S/S is 0.69 MW including 0.11 MW losses in all line sections. Power generation

from KHP is 3.5 MW. Power generation from KHP is 3.5 MW. The maximum voltage drop is

2.21 % at AnbuKhaireni which is 32.27 kV. In this case also the heaviest loaded line is

KHP-Khudi Sw/S, 30.8 %.


29

Table.4.14: 30 % Substation Load, KHP Power Evacuation Conductor Dog Generation at Damauli (slack bus) 0.69 MW, 2.64 Mvar Total Generation (MW) 4.19 MW, 2.26 Mvar Total voltage independent load 4.05 MW, 1.97 Mvar Total Loss in line sections 0.11 MW, 0.15 Mvar % of total transmission loss 2.62 % Max. Voltage Drop and location 2.21%, AnbuKhaireni Heaviest loaded line KHP-Khudi Sw/S, 30.8%

Case V: 10% load In this case all substations are considered to be running in 10 % loading. Total power fed to

Damauli S/S is 1.98 MW including 1.43 MW losses in all line sections. Power generation from

KHP is 3.5 MW. The maximum voltage drop is 0.55 % at AnbuKhaireni which is 32.82 kV. In

this case also the heaviest loaded line is KHP-Khudi Sw/S, 32.39%.

Table.4.15: 10 % Substation Load KHP Power Evacuation Conductor Dog Generation at Damauli (slack bus) -1.98 MW, 2.21 Mvar Total Generation 1.53 MW, 1.0 Mvar Total voltage independent load 1.35 MW, 0.66 Mvar Total Loss in line sections 0.143 MW, 0.19 Mvar % of total transmission line loss 9.34 % Max. Voltage Drop and location 0.55%, AnbuKhaireni Heaviest loaded line KHP-Khudi Sw/s, 32.39%

Case VI: 100% load with conductor wolf

As from economical analysis conductor wolf is the best one. Using this conductor the total

transmission loss is 3.42%. Maximum voltage drop is 7.33% only. The power drawn from

Damauli S/S is 10.52 MW and power generation from KHP is 3.5 MW.

Table.4.16: 100% Load with 'Wolf', KHP power evacuation Conductor Wolf Generation at Damauli (slack bus) 10.52MW, 5.23 Mvar Total Generation (MW) 14.02 MW, 7.62 Mvar Total voltage independent load 13.5 MW, 6.58 Mvar Total Loss in line sections 0.48 MW, 0.84 Mvar % of total transmission loss 3.42 % Max. Voltage Drop and location 7.33%, AnbuKharireni Heaviest loaded line Damauli-Dumre, 73.4%


30

Case VII: 50% load with conductor wolf

In this case using wolf conductor the system performance is very much improved. The total

line loss is only 1.62% and maximum voltage drop is 3.41% at AnbuKhaireni.

Table.4.17: 50% Substation Load with 'Wolf', KHP power evacuation Conductor Wolf Generation at Damauli (slack bus) 3.39 MW, 3.11 Mvar Total Generation (MW) 6.89 MW, 3.62 Mvar Total voltage independent load 6.75 MW, 3.29 Mvar Total Loss in line sections 0.112 MW, 0.196 Mvar % of total transmission loss 1.62 % Max. Voltage Drop and location 3.41%, AnbuKhaireni Heaviest loaded line KHP-Khudi Sw/S, 30.94%

Effect in NEA line:

Udipur S/S is feeding in Lamjung district through outgoing four feeders. Power source for this

S/S is Damauli grid S/S 34.4 km away. KHP, on the other hand is only 14 .9 km away from

Udipur S/S and connecting 33 kV transmission line from KHP to Udipur will change the

existing electrical system. Existing transmission line sections are Udipur S/S to Dumre S/S

(USS to DuSS), Dumre SS to Damauli SS (DuSS to DaSS) and Dumre SS to AkSS (Dumre SS

to Anbu Khaireni SS).

Case I: 100 % loading

With addition of KHP in Udipur S/S line losses in three existing section of NEA has improved

also voltage drop in these sections has greatly reduced. The total losses in these line sections

reduce from 1.326 MW to 0.606 MW. The maximum voltage drop in Dumre Damauli section

has also improved from 10.29 % to 6.61 %. The result shows that if KHP is connected then

Udipur, Anbu Khaireni and Damauli S/Ss can be run in full load without violating the voltage

regulation and efficiency limits. The result from Netbas Simulation is tabulated below.


31

Table.4.18: 100% Substation Load, effect in existing system with KHP. SNo Section Length,

km Previous Line Loss (kW)

New Line Loss (kW)

Previous V Drop %

New V Drop %

1 USS to DuSS

20 170.06 7.88 5.03 0.408

2 DuSS to DaSS

14.5 1058.17 507.74 10.29 6.61

3 DuSS to AkSS

12 97.92 91.13 2.92 2.69

Total 1326.15 606.75 Case II: 70% loading

After addition of power from KHP in Udipur S/S line losses in three existing section of NEA

has improved. Voltage drop in these sections has greatly reduced. The total losses in these lines

sections reduce from 0.594 MW to 0.238 MW. The maximum voltage drop in Dumre

Damauli section has also improved from 6.63 % to 4.26 %. The result shows that if KHP is

connected then Udipur S/S, Anbu Khaireni S/Ss and Damauli S/S can be run without violating

the voltage regulation and efficiency limits. The result from Netbas Simulation is tabulated

below.

Table.4.19: 70% Substation Load, effect in existing system with KHP.

SNo Section Length, km

Previous Line Loss

New Line Loss

Previous V Drop

New V Drop

1 USS to DuSS

20 75.15 1.17 3.17 1.91

2 DuSS to DaSS

14.5 475.6 195.75 6.63 4.26

3 DuSS to AkSS

12 43.95 41.94 1.85 1.76

Total 594.7 238.86 Case III: 50 % loading




Damauli section has also improved from 4.51% to 2.84 %. The result shows that if KHP is

connected then Udipur S/S, Anbu Khaireni S/Ss and Damauli S/S can be run in without


32

violating the voltage regulation and efficiency limits. The result from Netbas Simulation is

tabulated below.

Table.4.20: 50% Substation Load, effect in existing system with KHP.


Previous Line Loss

New Line Loss

Previous V Drop

New V Drop

1 USS to DuSS

20 36.09 10.93 2.13 0.05

2 DuSS to DaSS

14.5 230.59 79.61 4.51 2.84

3 DuSS to AkSS

12 21.29 20.6 1.25 1.21

Total 287.97 111.14 Case IV: 30 % Loading




Damauli section has also improved from 2.58 % to 1.53 %. The result shows that if KHP is

connected then Udipur S/S, Anbu Khaireni S/Ss and Damauli S/S can be run in without

violating the voltage regulation and efficiency limits. The result from Netbas Simulation is

tabulated below.

Table.4.21: 30% Substation Load, effect in existing system with KHP


Previous Line Loss

New Line Loss

Previous V Drop

New V Drop

1 USS to DuSS

20 12.29 30.32 1.19 0.21

2 DuSS to DaSS

14.5 79.22 27.24 2.58 1.53

3 DuSS to AkSS

12 7.31 7.15 0.71 0.71

Total 98.82 64.71 Case V: 10 % Loading



sections increase from 0.01 MW to 0.091 MW. The maximum voltage drop in

DumreDamauli section has also improved from 0.82 % to 0.33 %. Unlike other cases the


33

result shows that in lightly loaded condition system performance is better with out KHP. The

result from Netbas Simulation is tabulated below.

Table 4.22: 10% Substation Load, effect in existing system with KHP.

S.No Section Length, km

Previous Line Loss

New Line Loss

Previous V Drop

New V Drop

1 USS to DuSS

20 1.3 58.17 0.38 0.37

2 DuSS to DaSS

14.5 8.43 32.14 0.82 0.33

3 DuSS to AkSS

12 0.78 0.77 0.23 0.29

Total 10.31 91.48

4.3 Results of LNHP Evacuation System

LNHP to Khudi switching station is about 7 km and this is the only alternative to evacuate

power to grid. Power generation from LNHP is 4.5 MW. This power has to be evacuated to

nearest available grid and that would be Udipur S/S which is 14 km away from Khudi

switching station. New 33 kV, 7 km long transmission line is needed for power evacuation.

From spreadsheet calculation station following results is obtained.

Table 4.23: LNHP evacuation system Conductor Beaver Dog Wolf Panther Efficiency 98.65 99.03 99.35 99.51 Voltage Regulation 1.63 1.3 1.02 0.87 % of transmission loss 1.35 0.97 0.65 0.49 NPV of Investment 16,780 14,163 12,854 12,664

Details of spread sheet calculation are presented in Appendix D. Conductors "Panther" is

recommended because of lowest investment.


34


Panther_33Panther_33

Panther_33Panther_33

Panther_33

300

800

1300

1800

2300

2800

3300

3800

4300

4800

1 Mw 2MW 3MW 4MW 5MW

Peak Load [MW]

Cap

italiz

ed C

ost

[kN

Rs.

] Weasel_33Rabbit_33Beaver_33Dog_33Tiger_33Wolf_33Lynx_33Panther_33

Figure 4.4: Conductor Optimization chart for LNHP only

Discussion:

From technical analysis conductors beaver, dog, wolf and Panther all are acceptable but

from conductor optimization chart in Figure 6: for evacuating power of 4.5 MW conductor

Panther will be economical.

4.4 KHP and LNHP Evacuation system

Power Evacuation from Khudi Hydro Power and Nyadi Hydro Power will be more fruitful if

certain portion of power can be consumed locally. The priority is given for local consumption

because such small hydro power plant located very far from grid access. After connecting NHP

and KHP at Khudi switching station the total power will be directly fed to 5 MVA, 33/11

Udipur substation through 14 km long 33 kV new transmission line and excess power after

satisfying local demand in Udipur substation will be fed to Dumre Substation through 20 km

long existing 33 kV transmission line and the rest at 132/33/11 kV, Damauli Grid Substation

through 14.5 km long 33 kV existing transmission line. From spread sheet calculation for

power transmission in 33 kV level and 66 kV level from Khudi Switching station to Udipur

Substation following results are obtained.


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Table 4.24: LNHP and KHP 14 km long 33 kV transmission line Conductor Employed Dog Wolf Panther Lion

Line Length (km) 14 14 14 14 Power to be Transmitted (MW) 8 8 8 8

Receiving End Voltage (kV) 31.27 31.65 31.84 31.91

Voltage Regulation (%) 5.24 4.10 3.51 3.31 Line Losses (kW) 353.54 237.06 176.77 157.23

% transmission loss 3.77 2.56 1.92 1.71

Line Eficiency (%): 96.23 97.44 98.08 98.29 Power Delivered at the load end (MW) 8.62 8.74 8.80 8.82

NPV of Investment inclusive of Losses, O&M and Outages. (NRs.000) 78,395 60,528 52,264 50,009

Table 4.25: LNHP and KHP 14 km long 66 kV transmission line Conductor Employed Dog Wolf Panther Lion Line Length (km) 14 14 14 14 Power to be Transmitted (MW) 8 8 8 8

Receiving End Voltage (kV) 65.10 65.29 65.39 65.42 Voltage Regulation (%) 1.37 1.08 0.93 0.88 Line Losses (kW) 88.38 59.27 44.19 39.31 % transmission loss 0.97 0.65 0.48 0.43 Line Eficiency (%): 99.03 99.35 99.52 99.57 Power Delivered at the load end (MW) 8.89 8.92 8.93 8.94

NPV of Investment inclusive of Losses, O&M and Outages. (NRs.000) 44,876 42,255 41,883 42,185

In this case conductor dog, wolf , panther and lion all can be used because all satisfy the

prescribed technical criteria but if better efficiency and voltage regulation is to be considered

then higher conductor is to be chosen. From conductor optimization chart 66kV conductor

'Panther' is the best option for power evacuation.


36


Panther_66

300

800

1300

1800

2300

2800

3300

3800

4300

4800

1 Mw 2MW 3MW 4MW 5MW 6 MW 7MW 8 MW 9 MW

Peak Load [MW]

Cap

ital

ized

Co

st [

kNR

s.]

Weasel_33

Rabbit_33

Beaver_33Dog_33

Tiger_33Wolf_33

Lynx_33Panther_33

Dog_66

Wolf_66Panther_66

Lion_66

Figure 4.5: Conductor and Voltage selection for KHP and LNHP


37

Discussion:

Although for transmitting 15 MW power from KSw/S to Udipur S/S 66 kV, conductor

'Panther' is most economical, it is only for transmission line. If 66 kV is chosen the

substation cost will make the NPV of Investment greater than transmission system with

conductor 'Dog'.

Netbas Result:

Netbas Simulation gives us the clear picture of system performance during full load, normal

load and off load. For analyzing existing system performance load flow is carried out for

100% load, 50% load and 10% load of substation capacity. The result is presented below

Figure 4.6: KHP and LNHP evacuation system

Case I: Full Load In full load, i.e. 15 MVA (13.5 MW at 0.9 pf), swing bus i.e. Damauli substation will

generate 6.33 MW including line losses. Power generation from KHP and LNHP are 3.5

MW, 4.5 MW respectively. Maximum voltage drop is at Anbu Khaireni which is 7.95 % i.e.

voltage at Anbu Khaireni is only 30.37 kV. In this case Damauli- Dumre section is heaviest


38

loaded line with 57.35 %. The result of Netbas Simulation for full load case is tabulated

below.

Table.4.26: 100% substation load, KHP and LNHP power evacuation Conductor Dog Generation at Damauli (slack bus) 6.33 MW, 6.68 MVAR Total Generation 14.33 MW, 7.33 MVAR Total voltage independent load 13.5 MW, 6.53 MVAR Total Loss in line sections 0.739 MW, 0.971 MVAR % of Total Transmission Loss 5.15% Max. Voltage Drop and location 7.95%, AnbuKhaireni Heaviest loaded line Damauli-Dumre, 57.53%

Case II: 70% load

In 70% load, i.e. 10.5 MVA (9.45 MW at 0.9 pf), the swing bus, Damauli substation will

generate 2.15 MW including line losses. Power generation from KHP and LNHP are 3.5

MW and 4.5 MW respectively. Maximum voltage drop is at AnbuKhaireni which is 5.38%

i.e. voltage at AnbuKhaireni is only 31.22 kV. In this case Khudi Sw/S-Udipur S/S section

is heaviest loaded line, 49.91%. The result of Netbas Simulation for this case is tabulated

below.

Table 4.27: 70% substation load, KHP and LNHP power evacuation

Conductor Dog Generation at Damauli (slack bus) 2.15 MW, 6.14 MVAR Total Generation 10.15 MW, 5.73 MVAR Total voltage independent load 9.45 MW, 4.58 MVAR Total Loss in line sections 0.607 MW, 0.796 MVAR % of Total Transmission Loss 5.98% Max. Voltage Drop and location 5.38%, AnbuKhaireni Heaviest loaded line Khudi Sw/S-Udipur SS, 49.91%

Case III: 50% load

In this case all three area substations are considered to be operated in half load only. Total

power fed to Damauli S/S is 0.53 MW including losses 0.63 MW in all line sections and the

total load of all substations is 6.75 MW (at 0.9 pf). Power generation from KHP and LNHP

are 8 MW. The maximum voltage drop is 3.76% at AnbuKhaireni, which is 31.76 kV. The

heaviest loaded line is Khudi Sw/S-Udipur S/S, 50.62%.


39

Table 4.28: 50% substation load, KHP and LNHP power evacuation Conductor Dog Generation at Damauli (slack bus) -0.53 MW, 5.87 MVAR Total Generation 7.47 MW, 4.45 MVAR Total voltage independent load 6.75 MW, 3.27 MVAR

Total Loss in line sections 0.63 MW, 0.823 MVAR % of Total Transmission Loss 7.8% Max. Voltage Drop and location 3.76%, Anbu Heaviest loaded line Khudi Sw/sUSS, 50.62 %

Case IV: 30% load In this case all substations are considered to be running in 30% loading. Total power fed to

Damauli S/S is 3.13 MW including 0.0.724 MW losses in all line sections. Power

generation from KHP and LNHP are 3.5 MW and 4.5 MW respectively. The maximum

voltage drop is 2.2 % at AnbuKhaireni which is 32.27 kV. In this case also the heaviest

loaded line is Khudi Sw/S-Udipur S/S, 52 %.

Table 4.29: 30% substation load, KHP and LNHP power evacuation Conductor Dog Generation at Damauli (slack bus) -3.13 MW, 5.67 MVAR Total Generation 4.87 MW, 3.3 MVAR Total voltage independent load 4.05 MW, 1.96 MVAR

Total Loss in line sections 0.724 MW, 0.95 MVAR % of Total Transmission Loss 9.05% Max. Voltage Drop and location 2.2%, AnbuKhaireni Heaviest loaded line Khudi Sw/S-Udipur S/S, 52.01%

Case V: 10% load

In this case all substations are considered to be running in 10 % loading. Total power fed to

Damauli S/S is 5.66 MW including 0.89 MW losses in all line sections. Power generation

from KHP and LNHP are 3.5 and 4.5 MW respectively. The maximum voltage drop is 0.71

% at AnbuKhaireni which is 32.76 kV. In this case also the heaviest loaded line is Khudi

Sw/S-Udipur S/S, 53.96%.

Table 4.30: 10% substation load, KHP and LNHP, power evacuation Conductor Dog Generation at Damauli (slack bus) -5.66 MW, 5.54 MVAR Total Generation 2.34 MW, 2.24 MVAR Total voltage independent load 1.35 MW, 0.65 MVAR

Total Loss in line sections 0.89 MW, 1.17 MVAR % of total Transmission Loss 11.125%** Max. Voltage Drop and location 0.71 %, AnbuKhaireni Heaviest loaded line KH-1 KH-3, 53.96 %


40

Discussion

Using spreadsheet calculation it is found that, to transmit 6.65 MW from Khudi Sw/S to

Damauli S/S, conductor 'Bear' will make total transmission loss reduced to 4.0 %, if it is

used to transmit power from Khudi Sw/S to Damauli S/S. Loss in 14 km line section to

transmit 8 MW from Khudi Sw/s to Udipur S/S is 44.19 kW, loss in 20 km line section to

transmit 7.55 MW from Udipur S/S to Dumre S/S is 142.43 kW and loss in 14.5 km long

transmission from Dumre S/S to Damauli S/S is 80.11 kW resulting total transmission loss

of 266.13 kW.

Effect in NEA line

Case I: 100 % loading

With addition of KHP and LNHP in Udipur S/S, line losses in three existing section of NEA

has improved; also voltage drop in these sections has greatly reduced. The total losses in

these line sections reduce from 1.32 MW to 0.63 MW. The maximum voltage drop in

Dumre Damauli section has also improved from 10.29 % to 2.6 %. The result shows that

if KHP and LNHP are connected then Udipur, Anbu Khaireni and Damauli S/Ss can be run

in full load without violating the voltage regulation and efficiency limits. The result from

Netbas Simulation is tabulated below.

Table 4.31: 100% load, effect in existing system, KHP &LNHP evacuation SNo Section Length,

km Previous Line Loss (kW)

New Line Loss (kW)

Previous V Drop %

New V Drop %

1 USS to DuSS

20 170.06 229.9 5.03 0.45%

2 DuSS to DaSS

14.5 1058.17 309.8 10.29 2.6%

3 DuSS to AkSS

12 97.92 89.41 2.92 2.64%

Total 1326.15 629.11 Case II: 70% loading

After addition of power generated from KHP and LNHP in Udipur S/S line losses in three

existing section of NEA has improved. Voltage drop in these sections has greatly reduced.

The total % of transmission losses in these lines sections reduce from 6.3% to 3.6%. The

result from Netbas Simulation is tabulated below.


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Table 4.32: 70% load, effect in existing system, KHP &LNHP evacuation SNo Section Length,

km Previous Line Loss kw

New Line Loss, kw

1 USS to DuSS 20 75.15 146.57 2 DuSS to DaSS 14.5 475.6 154.47 3 DuSS to AkSS 12 43.95 41.46

Total 594.7 342.5 Case III: 50 % loading

After addition of power from KHP and LNHP in Udipur S/S line losses in three existing

section of NEA has improved. Voltage drop in these sections has greatly reduced and with

acceptable limit. The total losses in these lines sections increases from 0.288 MW to 0.63

MW. The result from Netbas Simulation is tabulated below.

Table.4.33: 50% load, effect in existing system, KHP &LNHP evacuation SNo Section Length, km Previous Line

Loss, kw New Line Loss, kw

1 USS to DuSS 20 36.09 207.77 2 DuSS to DaSS 14.5 230.59 126.95 3 DuSS to AkSS 12 21.29 20.45

Total 287.97 355.17

Discussion

After addition of power generated from KHP and LNHP the performance of existing line of

NEA (from Damauli S/S to Udipur S/S) has improved for 70% and 100% loading case but

for load 50% and less performance is worse because all the excess power has to be fed to

Damauli S/S which 34.5 km away from Udipur S/S.

4.5 System with KHP, LNHP and LKHP

There is possibility of coming another Hydro Power 500 m away from KSw/S (Khudi

switching station). This new power plant is Lower Khudi Hydro Plant with capacity of 2

MW. There is only one option for evacuating power from LKHP at KSw/S. The system

performance using Netbas Simulation shows that addition of this power plant will make

existing system inefficient. In full load case total transmission loss is 5.33% and maximum

voltage drop is 7.37% at Anbu Khaireni.


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Figure 4.7: KHP, LNHP and LKHP evacuation system

Table.4.34: System Performance with KHP, LNHP and LKHP

Substation Loading (%)

Total Generation,MW

Total loss in line sections MW MVar

% of total transmission loss

Max. Voltage drop, location

100 15 0.8 1.048 5.33% 7.37%, AnbuKhaireni 70 10.5 0.901 1.182 8.64% 5.2%, AnbuKhaireni 50 10 1.022 8.64 % 3.81 % 30 10 1.223 12.23 % 2.48 %

Discussion

From above table, only in full load case existing system looks fine but in lightly loaded

condition the system will be worse. Using conductor 'Lion' in new section KSw/S-USS the

total transmission loss can be reduced to 4.68%.

4.6 KHP, LNHP, LKHP and Chame substation

Chame substation is located in Manang district. In Chame the proposed substation size is 1.5 MVA. This S/S is 50 km away from Khudi switching station. Using transmission voltage 33 kV with conductor 'dog' the system performance is checked in NETBAS simulation and is tabulated below.


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Figure 4.8: Evacuation system with Chame load

Table 4.35 System performances with KHP, LNHP, LKHP and Chame substation

Substations Total loading (%)

Total Generation, MW

Total loss in line sections MW

% of total transmission loss

Max. Voltage drop, location (%)

100 15.67 0.75 4.7% 7.34%, Anbu 70 10 0.88 8.77% 3.76%, Anbu 50 10 0.994 9.94 2.39% 30 10 1.22 12.22% 2.48%

Discussion:

In full load, only 5.67 MW power is drawn from Damauli S/S and total generation from

three power plants is 10 MW. From NETBAS calculation the highest loss of 1.22 MW will

occur during 30% of total substation loading i.e. 4.05 kW and the transmission loss in

percentage is 12.22 %. Maximum voltage drop of 7.34 % is at AnbuKaireni.

4.7 Load flow analysis of four feeders of Udipur S/S

Power evacuation from Nyadi Hydro Power (NHP) and Khudi Hydro Power (KHP), to

local consumer is possible with four outgoing feeders of 5 MVA, 33/11 Udipur substation.

The four feeders are Besisahar, Bhoteodar, Okhari and MajhGau with total connected load

(TCL) of 1050 kVA, 1950 kVA, 550 kVA and 450 kVA respectively. Load flow analysis

of these feeders using Carl1.0 for peak load time gives the clear picture of local power flow.


44

The result of load flow analysis of each feeder is given below. Detail result is presented in

Appendix F.

Table.4.36: Load flow result of four feeders of Udipur S/S.

Conductor, km Feeder Name

Total

Connected

Load

(kVA)

Total

Power fed

(kW)

Active

Power

Loss

(kW)

Reactive

Power

Loss

(kVar)

Minimum

Voltage

(%) Dog Rabbit Weasel

Besisahar 1050 973.59 33.39 39.01 93.56 13.4 6.72 16.8

Bhoteodar 1950 1660 100.33 80.48 90.21 16.5 15.9 34.9

Okhari 550 443.68 3.68 2.08 98.9 0 9 18

MajhGau 450 388.39 5.89 3.33 97.38 0 12 20

Discussion:

From load flow analysis of four feeders it is found that feeder Bhoteodar is worst of all,

having minimum voltage (at farthest end) of 90.21% and total feeder loss of 6.04%. This

feeder uses 16.5 km of conductor 'dog', 15.9 km

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