Power Transmission & Distribution in India Industry Information Insights 2014
Power Transmission & Distribution in India
Sep 03, 2014
Short report gives need and scenario of power transmission and distribution sector in India, along with recent statistics.
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Power Transmission &
Distribution in India
Industry Information Insights 2014
Table of Contents
Introduction
Regional and National Grid
Market Structure
Evolution of Transmission Sector
T&D Lines Length
Transmission Capacity
Substation Capacity
Distribution System
Competitive Bidding
Introduction
The huge amount of power generated in a power station is to be transported over a long
distance to load centers to cater power to consumers with the help of transmission line and
transmission towers.
For instance, for a power station generating 120 MW power at 10 kV line to line voltage,
current in the transmission line will be 8660 A. Instead of choosing 10 kV transmission
voltage, if transmission voltage were chosen to be 400 kV, current value in the line would
have been only 261.5 A.
So, the sectional area of the transmission line (copper conductor) will now be much smaller
compared to 10 kV transmission voltage. The cost of conductor will be greatly reduced if
power is transmitted at higher and higher transmission voltage.
The cost of conductor will be greatly reduced if power is transmitted at higher and higher
transmission voltage.
The use of higher voltage (hence lower current in the line) reduces voltage drop in the line
resistance and reactance. Also transmission losses are reduced.
Standard transmission voltages used are 132 kV or 220 kV or 400 kV or 765 kV depending
upon how long the transmission lines are.
After the generator, there is a step up transformer to change the generated voltage (say 10 kV)
to desired transmission voltage (say 400 kV) before transmitting it over a long distance with
the help of transmission lines supported at regular intervals by transmission towers.
While magnitude of current decides the cost of copper, level of voltage decides the cost of
insulators. The idea is, in a spree to reduce the cost of copper one can not indefinitely increase
the level of transmission voltage as cost of insulators will offset the reduction copper cost.
At the load centers voltage level should be brought down at suitable values for supplyingdifferent types of consumers.
Consumers can be categorized as:
• big industries such as steel plants
• medium and small industries
• offices and domestic consumers
Electricity is purchased by different consumers at different voltage level. For example, bigindustries may purchase power at 132 kV, medium and big industries purchase power at 33kV or 11 kV and domestic consumers at rather low voltage of 230 V, single phase.
Thus, 400 kV transmission voltage is to be brought down to different voltage levels beforefinally delivering power to different consumers. This is done by step down transformers.
Substations
Substations are the places where the level of voltage undergoes change with the help of
transformers. Apart from transformers a substation houses switches (called circuit breakers),
meters, relays for protection and other control equipment.
A big substation receives power through incoming lines at some voltage (say 400 kV) changeslevel of voltage (say to 132 kV) using a transformer and then directs it out wards throughoutgoing lines.
At the lowest voltage level of 400 V, generally 3-phase, 4-wire system is adopted for domesticconnections. The fourth wire is called the neutral wire (N) which is taken out from thecommon point of the star connected secondary of the 6 kV/400 V distribution transformer.
Regional and National Grid
Transmission forms a critical link in the power sector value chain. India's power generationcapacities are unevenly dispersed across the country creating an imbalance between thedistribution of power demand and supply centres.
The country has been demarcated into five electrical Regions:
1. Northern (NR)
2. Eastern (ER)
3. Western (WR)
4. Southern (SR)
5. North Eastern (NER)
All the regional grids are synchronously interconnected and operating as single grid knownas Central Grid or National Grid.
Market Structure
Both central and state governments are responsible for the development of power sector inIndia.
POWERGRID is the Central Transmission Utility (CTU) and is responsible for wheeling ofpower generated by Central Generating Utilities (CGUs) and inter-state Mega IndependentPower Producers.
Each of the five regions has a Regional Load Despatch Centre (RLDC), which is the apexbody, as per the Electricity Act 2003, to ensure integrated operation of the power system inthe concerned region.
Additionally, there is an apex body at the national level called the National Load DespatchCentre (NLDC) to ensure integrated power system operation in the country.
The NLDC and RLDCs together form a part of the Power System Operation CorporationLimited (POSOCO), which is a wholly owned subsidiary of Power Grid Corporation of IndiaLimited (PGCIL).
Evolution of Transmission Sector
Indian power sector remained closed to private investments till 1991. Power generation wasopened up for private participation in 1991.
The Electricity (Amendment) Act, 1998, defined transmission as a separate activity and led tothe creation of the CTU (currently PGCIL) and STUs.
The Regulatory Commission Act, 1998, mandated the setting up of an independentregulatory mechanism at the central (CERC) and state level (SERCs).
National Tariff Policy 2006 introduced mandatory Tariff Based Competitive Bidding (TBCB)for all transmission projects with the objective of promoting competitive procurement oftransmission services, encouraging greater investment by private players in the transmissionsector and increasing transparency & fairness in the process.
T&D Lines Length
6,939,5297,287,413 7,487,977
7,801,098 7,951,486
8,726,0928,970,112
0
1,000,000
2,000,000
3,000,000
4,000,000
5,000,000
6,000,000
7,000,000
8,000,000
9,000,000
10,000,000
2006-07 2007-08 2008-09 2009-10 2010-11 2011-12 2012-13
ckm
Year
In six years from 2007 to 2013, the power transmission sector registered a growth of4.37% CAGR.
Transmission Capacity
Type Central State JV/Private Total (ckm)500 kV HVDC 5,948 1,504 1,980 9,432765 KV 9,898 837 361 11,096400 kV 79,612 36,179 10,166 125,957220 kV 10,489 133,484 878 144,851Total 291,336
As on 31 March, 2014, transmission capacity is given in the following table:
Substation Capacity
As on 31 March, 2014, substation capacity is given in the following table:
Type Central State JV/Private Total (MVA)765 kV 78,000 2,000 3,000 83,000400 kV 91,775 85,047 630 177,452220 kV 7,716 247,311 1,567 256,594500 kV HVDC 9,500 1,500 2,500 13,500
Distribution System
Power received at a 33 kV substation is first stepped down to 6 kV and with the help of underground cables (called feeder lines), power flow is directed to different directions.
At the last level, step down transformers are used to step down the voltage form 6 kV to 400V. These transformers are called distribution transformers with 400 V, star connectedsecondary. Such transformers are generally mounted on poles in cities beside the roads. Theseare called pole mounted substations.
From the secondary of these transformers 4 terminals (R, Y, B and N) come out. N is calledthe neutral and taken out from the common point of star connected secondary. Voltagebetween any two phases (i.e., R-Y, Y-B and B-R) is 400 V and between any phase and neutralis 230 V.
Residential consumers are supplied with single phase 230 V, 50 Hz. So individual are to besupplied with any one of the phases and neutral.
Distribution companies try to make sure that the loads remain evenly balanced among thephases as far as possible. Roughly one-third of the consumers are supplied from R-N, nextone third from Y-N and the remaining one third from B-N.
Competitive Bidding
The Ministry of Power has mandated that procurement of transmission services in newprojects on the basis of tariff-based competitive bidding.
This is done to encourage private sector participation in the development of electricityinfrastructure and to move towards tariff based competitive regime from the earlier cost-plussystem.
In order to bring in private sector participation, the Ministry of Power has appointed PFC asBid Process Coordinator, for two projects and PFCCL (wholly owned subsidiary of PFC) fornine projects. Out of these eleven projects, four have already been transferred to thesuccessful bidders and the remaining are under process.
Inter-State Transmission Projects
So far, 8 inter-state transmission projects have been allotted on the basis of competitivebidding involving an estimated cost of about INR 14,000 crores.
Projects
System strengthening in Northern & Western Regions for import of power from NorthKaranpura outside NR & WR and also for power evacuation from projects within WR.
Augmentation of Talcher-II Transmission system
Transmission scheme for enabling import of NER-ER surplus power by NR
Transmission scheme for Krishnapatnam UMPP - Synchronous interconnection between SR& WR (Part-B)
Transmission Project “System strengthening common for WR & NR”
Transmission Project “System strengthening for WR”
Transmission System associated with IPPs of Nagapattinam/Cuddalore Area – Package - A
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