Conductor Selection Study

For

Some aged 132kV transmission lines of PGCB

(Revised)

November 2015

Power Grid Company of Bangladesh Ltd.

Conductor selection study for some aged 132kV transmission lines of PGCB (updated)

Preamble: This study is performed to identify the techno-economically appropriate solution for the reconductoring of Ashuganj-Ghorasal-Narshingdi-Bhulta-Haripur-Sonargaon-Daudkandi-Comilla (N)-Comilla(S)-Feni 132kV double circuit transmission line. Except some newly built LILO connections, most of this transmission line is one of the oldest and most aged parts of Bangladesh National Grid.

Figure 1 : Google Map Preview of Study Area

Ashuganj

Marjal

Ghorashal

Narshingdi

Daudkandi

Shonargaon

Haripur

Madhobdi

Bhulta_Old

Bhulta_New

Rupshi

Muradnagar

Comilla(N)

Comilla(S)

Chouddogram

Feni

Feni(New)

Legends:

Existing Substation

Planned Substation

132kV LineUnder Study

Study Methodology: The study is modeled and performed in CYME (power system analysis software). Initially the loading levels of different line segments are observed for year 2021, 2025, 2030 & 2035. Some highly loaded line segments are then exclusively selected for further studies. Addition of parallel branches where and

when required and uses of higher capacity conductors from year 2021 are taken as options. Transmission losses for these options are then evaluated. Later economic analysis is made on the available results.

Load Flow Study:

Based on line loading found from load flow study (Table-2), several options are selected for further studies where the highly loaded lines will not have contingency in near future. The highly loaded parts are proposed to be either renovated by higher rating conductors or adding parallel circuits of similar capacity (i.e.; ACSR Grosbeak) when and where needed. As per PGCB system planning standard this measures are required to ensure reliable power supply (by ensuring N-1 security criteria) to the study area. Thus renovation of the whole line by ACSR Grosbeak is not technically feasible.

Table-1: Study Options

SN Options Description

1 TACSR Highly loaded segments will be renovated by higher capacity TACSR Grosbeak and other parts will be renovated by ACSR Grosbeak

2 ACCC Highly loaded segments will be renovated by higher capacity ACCC Grosbeak and other parts will be renovated by ACSR Grosbeak

3 Parallel line/cable The aged part of the line will be renovated by ACSR Grosbeak and highly loaded segments will have one additional parallel line/cable to reduce loading level.

Table-2: Line Loading Scenario (Considering all lines are renovated by ACSR Grosbeak)

From Bus To Bus km % Loading Parallel Line

Addition Year Reconductoring

Requirement 2021 2025 2030 2035 Haripur Rupshi 8 51% 58% 64% 70% 2021

Higher Capacity Rupshi Bhulta New 4 15% 31% 49% 67% 2030

Bhulta Bhulta New 5 13% 19% 22% 24% Not Required Bhulta Madhobdi 8 22% 35% 46% 60% Not Required* Normal

Capacity (ACSR Grosbeak)

Madhobdi Narsingdi 12 7% 17% 25% 31% Not Required Ghorshal Narsingdi 18 12% 13% 15% 19% Not Required Ghorshal Marjal 30 10% 10% 11% 13% Not Required Higher

Capacity Marjal Ashuganj 15 34% 50% 64% 79% 2021 Haripur Sonargaon 15 23% 37% 50% 64% Not Required**

Normal Capacity (ACSR

Grosbeak)

Sonargaon Daudkandi 62 10% 10% 10% 9% Not Required Daudkandi Muradnagar 35 12% 22% 30% 40% Not Required Comilla (N) Muradnagar 20 17% 24% 29% 34% Not Required Comilla (N) Comilla (S) 16 5% 8% 11% 14% Not Required Comilla (S) Chauddagram 30 1% 5% 9% 14% Not Required

Chauddagram Feni (New) 36 44% 60% 74% 87% 2021 Higher Capacity Feni Feni (New) 5 16% 23% 28% 31% Not Required

*Loading of this line can be reduced by keeping Bhulta_Bhulta New segment open from 2030 onwards. **PGCB management does not want to consider upgrading this line segment by higher capacity conductor in this study as most of the part of this line is newly built and until 2030 there will be no contingency problems in this line. However older part of this line will be renovated by ACSR Grosbeak.

Figure 2: Line Loading Scenario

Table-3: Renovations of the following line segments are proposed by Higher capacity TACSR Grosbeak or ACCC Grosbeak

SN Branch Name km 1 Haripur_ Rupshi 8 2 Rupshi_ Bhulta New 4 3 Bhulta_ Bhulta New 5 4 Ghorashal_ Marjal 30 5 Marjal_ Ashuganj 15 6 Chouddogram_ Feni (New) 36 7 Feni_ Feni (New) 5

Table-4: Addition of a parallel line/cable are proposed for these following line segments

SN Name of the Branch Length km

No. of Existing Ckt.

Requirement of Additional Ckt.

Year of Ckt. Addition

1 Haripur-Rupshi 8 2 1 2021 2 Rupshi-Bhulta New* 4 2 1 2030 3 Marjal-Ashuganj 15 2 1 2021 4 Chauddagram-Feni(N) 36 2 1 2021

*As this circuit will be required by 2030, underground cable is considered instead of overhead line as the area is a potential industrial growth area and right of way for overhead line is very unlikely to be available.

Figure 3: Option - TACSR or ACCC

Figure 4: Option - Parallel Line/Cable

Table-5: Salient features of conductors used in this study

Conductor DC resistance

at 20° C Weight (lb/1000ft)

Overall Diameter

(inch)

Thermal Capacity

(Amp) at Max Operating

Temperature Ohm/km Ohm/mile ACSR Grosbeak 0.0876 0.1410 875 0.99 629 at 80° C

TACSR Grosbeak 0.0915 0.1473 947 0.99 1091 at 150° C ACCC Grosbeak 0.068 0.1095 842 0.99 1457 at 175° C

Economic Analysis: Based on the above options further load flow studies were performed and line loss found for these options are plotted on the following chart:

Figure 5: Comparative line loss profile from year 2021 to 2035

From the above chart, TACSR is found to be less feasible than other two options. ACCC and addition of parallel line/cable are having very similar loss profiles. The loss profile for ACSR (ACSR Grosbeak) in the above chart is the reference for comparative analysis. Estimation for capital investment for the alternative options is mainly calculated based on the DPP of this project (Enhancement of Capacity of Grid Substations and Transmission Lines for Rural Electrification). Part of the estimation is made with the help of RDPP of a completed project of PGCB.

0

5

10

15

20

25

2020 2025 2030 2035

Loss

(MW

)

ACSR TACSR ACCC Parallel Line

Table-3: Calculation of Additional Capital Cost

Options Scope of Work Unit Unit Cost Cost Present Value* of Capital

(USD) As of 2015 Km

/Nos. USD USD

ACSR Conductor change of 229 km double circuit 132kV line by ACSR Grosbeak 229 $51,199 $11,724,53 $14,707,25 $14,707,258

TACSR

Conductor change of 126 km double circuit 132kV line by new ACSR Grosbeak 126 $51,199 $6,451,055 $8,092,203

$18,330,761 Conductor change of 103 km double

circuit 132kV line by TACSR Grosbeak 103 $79,244 $8,162,116 $10,238,559

ACCC

Conductor change of 126 km double circuit 132kV line by new ACSR Grosbeak 126 $51,199 $6,451,055 $8,092,203

$20,142,513 Conductor change of 103 km double circuit 132kV line by ACCC Grosbeak

103 $93,266 $9,606,434 $12,050,310

Parallel Lines/Cables

Conductor change of 229 km double circuit 132kV line by ACSR Grosbeak 229 $51,199 $11,724,536 $14,707,258

$29,275,167

New 29 km single ckt. 132kV Transmission Line & 6 no. of 132kV bay

29 $179,499 $5,205,475 $6,529,748

6 $284,347 $1,706,082 $2,140,109

New 4 km single ckt. 132kV 800 mm² XLPE U/G Cable & 2 no. of 132kV bay

4 $1,033,299 $4,133,197 $5,184,683

2 $284,347 $568,694 $713,370

*At 12% discount rate

Table-4: Reference Cost (Year 2013)

Component Material

(C&F)

Insurance &

Transportation Installation

Total Unit Price

Lakh BDT

Total Unit Price

Reference

(Lakh BDT) (USD) Reconductoring by ACSR Grosbeak 21.30 0.58 18.06 39.94 $51,199

*

Reconductoring by TACSR Grosbeak (Considered 2.0 times higher than ACSR)

42.60 1.15 18.06 61.81 $79,244

Reconductoring by ACCC Grosbeak (Considered 2.5 times higher than ACSR)

53.25 1.44 18.06 72.75 $93,266

132kV Single Ckt. line on double ckt. tower 74.79 2.02 63.20 140.01 $179,499

132kV Bay Extension 166.32 4.49 50.98 221.79 $284,347 132kV Single Ckt. 800 mm² XLPE U/G Cable 530.34 14.32 261.31 805.97 $1,033,299 **

*Enhancement of Capacity of Grid Substations and Transmission Lines for Rural Electrification Project (DPP) **Aminbazar Old Airport Project (Revised DPP)

Table-5: Requirement of additional investment for different study options

Options

Capital requirement for line renovation

If this study was not performed

Capital requirement For different study options

($USD)

Total Additional*

Compared to Base Case

ACSR $14,707,258 (Base Case)

$14,707,258 $0 TACSR $18,330,761 $3,623,503 ACCC $20,142,513 $5,435,255

Parallel line/cable $29,275,167 $14,567,909 *This additional amount will be required for the selected study option

Table-6: Comparative energy cost calculation for different study options based on extrapolated data for 20 years time period from Figure-5 between years 2021 to 2035

Options Energy Saved* kWhr

Present Value** of Saved Energy (As of 2015)

@ Average Generation Cost*** 0.06 USD/kWhr

@ Unserved Energy Cost**** 0.407 USD/kWhr

ACSR (Reference) 0 0 0 TACSR -26910720 ($323,661) ($2,195,503) ACCC 81923520 $998,495 $6,773,123

Parallel Lines 79015200 $922,788 $6,259,580 * At 40% loss factor. **At 12% discount rate. ***Average Generation Cost 0.06 USD per kilowatt-hour – BPDB Annual Report 2013-2014 **** Cost of unserved energy: Where the subproject is supplying demand that would otherwise not be met, this is valued at the fuel and variable operating costs of diesel generation for irrigation and commercial customers and at the fuel costs of kerosene lanterns for household customers. For industrial customers, unserved energy is valued at the cost of unplanned outages in industry, which a 2003 study by the United States Agency for International Development calculated as Tk28.21 per kilowatt-hour, and which was updated to 2010 values. For 2011, the weighted average across all groups is Tk31.74 (USD 0.407) per kilowatt-hour. -Power System Efficiency Improvement Project (BAN RRP 37113) ECONOMIC ANALYSIS Considering 1 USD = 78 BDT

Table-7: Benefit cost ratio of different options

Options

Benefit Cost Ratio (Taking Input from Table-5 & 6)

@ Average Generation Cost: 0.06 USD/kWhr

@ Unserved Energy Cost: 0.407USD/kWhr

TACSR -0.06 -0.61 ACCC 0.05 1.25

Parallel line/cable 0.03 0.43

General Assumptions: 1. Average generation cost remains 0.06 USD throughout the study period. 2. Unserved energy cost remains 0.407 USD throughout the study period. 3. Cost of TACSR and ACCC equivalent conductors are respectively 2 times and 2.5 times higher than

ACSR Grosbeak. 4. Cost of environmental & social impacts due to addition of parallel lines and cable are not considered.

Financial Analysis: A financial analysis was made to find out the time of capital recovery for two best options found from economic study [namely ACCC and Parallel line/Cable]. It is found that with a 15 years loan repayment period starting from 2021 with 4% interest rate, considering present value of money and present wheeling charge [0.2791 BDT/kWhr] it takes around 17 years for ACCC option and 33 years for parallel line/cable option to recover the additional loan amount. In this analysis utilization of the additional capacity of studied transmission lines are considered for wheeling income calculation. Load duration curve of last 12 months [Nov 2014 to Oct 2015] is used to scale the future loading pattern of the transmission lines. The following figure shows the cash flow at present value (@12% discount rate) from year 2021 to 2060 due to different options:

Figure 6: Cash flow at present value from year 2021 to 2060 due to different options

$0

$100,000

$200,000

$300,000

$400,000

$500,000

$600,000

$700,000

$800,000

$900,000

$1,000,000

2021

2022

2023

2024

2025

2026

2027

2028

2029

2030

2031

2032

2033

2034

2035

2036

2037

2038

2039

2040

2041

2042

2043

2044

2045

2046

2047

2048

2049

2050

2051

2052

2053

2054

2055

2056

2057

2058

2059

2060

PGCB Income @ Present Wheeling Charge: 0.2791 Tk/kWhr

PGCB Re-payment (Option ACCC)@ 4% Interest rate within 15 years

PGCB Re-payment (Option Parallel)@ 4% Interest rate within 15 years

Benefit Cost Ratio

ACCC 1

Parallel 0.36

Benefit Cost Ratio

ACCC 2.7

Parallel 1

Recommendations:

1. Based on the study results from Table-7, Option ACCC (ACCC Grosbeak equivalent of ACSR Grosbeak)is the most feasible and thereby can be selected for the renovation of the following parts of the studied transmission line:

SN Line Segments: Length (km) 1 Haripur-Bhulta 17 2 Ashuganj-Ghorashal 45 3 Feni-Chouddogram 41 Total 103

2. Remaining part of the line (229-103) km = 126 km can be renovated by ACSR Grosbeak. 3. ACCC class conductors are new products and may require relaxed qualification criteria (i.e.; period of

supply records may not be more than 3/4 years) in the tender documents. This will ensure more number of candidates in the bid.