We begin by constructing an overall picture of the electricity sector in India so that you do not look at the power distribution sector in isolation but acquire a wider perspective. An electric supply system has three main components:
It comprises
generating units that produce electricity;
high voltage transmission lines that transport electricity over long distances;
low voltage distribution lines that deliver electricity to consumers;
substations, which are the part of the electricity transmission and distribution system where the voltages are transformed to lower levels for distributing power to end-users; and energy control centres to coordinate the operation of the components.
It comprises
generating units that produce electricity;
high voltage transmission lines that transport electricity over long distances;
low voltage distribution lines that deliver electricity to consumers;
substations, which are the part of the electricity transmission and distribution system where the voltages are transformed to lower levels for distributing power to end-users; and energy control centres to coordinate the operation of the components.
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| A Typical Electric Power Supply System |
We shall discuss about generation and transmission of electricity very briefly in the Indian context and then focus on the power distribution sector.
Power Generation
Do you know what the total electricity generation by power utilities was in 1947? It was a meagre1362 MW. It has increased 100 times in about 60 years Another 14636 MW of captive generating capacity is also connected to the grid.Though there is a significant increase in power generation capacity in the last 60 years, we still have a long way to go. You know that our country is still plagued by severe power shortages. As per official statistics, the total energy Sectoral Overview and Enabling Framework shortage during the year 2005-2006 stood at 8.3% and the peak shortage was 12.3% during the same period.
Power Generation
Do you know what the total electricity generation by power utilities was in 1947? It was a meagre1362 MW. It has increased 100 times in about 60 years Another 14636 MW of captive generating capacity is also connected to the grid.Though there is a significant increase in power generation capacity in the last 60 years, we still have a long way to go. You know that our country is still plagued by severe power shortages. As per official statistics, the total energy Sectoral Overview and Enabling Framework shortage during the year 2005-2006 stood at 8.3% and the peak shortage was 12.3% during the same period.
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| Total Electricity Generation: Actual and Projected |
Inadequate generation capacity is one of the reasons for power shortage.Based on the 16 th EPS projections, over 1,00,000 MW generation capacity is required to be added during the X th and XI th plan period, i.e., by 2012 to bridge the gap between supply and demand of power. Let us look at the power generation sector very briefly to understand the options available to us.Electric power generation in India relies on four basic energy sources:Fossil fuels such as coal, oil and natural gas; Hydroelectricity; Nuclear power; and Renewable energy sources such as bio-fuels, solar, biomass,wind and tidal. As of September, 2006, a bout 66 % of the power generated in India is from coal based thermal power plants. The hydro-electric power plants account for about 26% of total electricity generation, nuclear power plants for about 3% and the remaining 5% comes from renewable energy resources
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| Electric Power Generation Source-Mix in India |
Future Directions
The Government of India has envisaged installed capacity of 2,12,000 MW by the year 2012 to meet its mission of power to all. The large coal reserves in the country provide a ready and economical resource and ensure energy security as of now. Hence, coal has been identified as the mainstay fuel for power generation till 2012. The government has also committed to generate 10% of its power from renewable energy by the year 2012. The overall potential for renewable energy generation is around 1, 72,000 MW. Of this,less than 7000 MW has been realized so far. In fact, the Electricity Act, 2003,about which you will study in the next unit, mandates all State Electricity Regulatory Commissions (SERCs) for fixing a minimum percentage of procurement from renewable energy. The entry of renewable energy can helpus in meeting present peaking power and general shortages.Another step in this direction is the scheme of allowing captive power generation, which refers to generation from a unit set up by an individual, co-operative society or industry for their own consumption. Industries in the manufacturing sector, e.g., cement, aluminium, fertilizers, steel, paper, sugar, etc. have their own captive power plants to supplement the electricity purchased from utilities or for producing energy. This has implications for the utilities as you will learn in the next section.
India ranks sixth in the world in terms of electricity generation after the United States of America, China, Japan, Russia and Canada.However, the annual per capita consumption in India, at about 606kWh/Year (2004-2005), is amongst the lowest in the world.A Comparison with China China adds more than 28,000 MW of capacity, on an average,annually. India has been able to add only 4,500 MW annually.China’s T& D losses are less than 10% compared to India’s more than 30%. Almost 97% of China’s households have access to electricity while India trails way behind with less than 50%. The annual per capita consumption in China is 1,255 kWh as compared to India’s 606 kWh. China’s generation capacity has grown from 1,850 MW in 1950 to 508,000 MW in 2005. Compare this with India’s growth shown in Fig.
Transmission and Distribution
In India, the power plants typically produce 50 cycle/second (Hertz),alternating-current (AC) with voltages between 11 kV and 33 kV. Electric power is brought from the power plant to the consumer through an extensive transmission and distribution (T&D) system comprising distribution networks,state grids and regional grids. The various stages of the process are given below:
At the power plant site, the 3-phase voltage is generated and stepped up to a higher voltage for transmission on cables strung on cross-country towers.High voltage (HV) and extra high voltage (EHV) transmission is the next stage to transport A.C. power from the power plant over long distances at voltages like 220 kV, 400 kV and 760 kV. For longer distances and higher powers, higher voltages are economical. In special cases HVDC (high voltage direct current transmission) is preferred.
Sub-transmission network at 132 kV, 110 kV, 66 kV or 33 kV constitutes the next link towards the end user.
Distribution at 11 kV/ 6.6 kV / 3.3 kV constitutes the last link to the consumer, who is connected directly or through step-down transformers. These transformers bring the voltage levels down to 400V for 3-phase, 4 wire secondary distribution. The single phase residential lighting load is connected between any phase and neutral (230 V) and 3-phase load is connected across 3-phase lines directly.
The transmission and distribution network includes sub-stations, lines and distribution transformers. Sub-stations, containing step-down transformers, reduce the voltage for distribution to industrial,commercial and residential customers. These substations and distribution lines are referred to as the distribution system.Transmission lines are usually capable of transmitting large quantities of electrical energy over long distances. They operate at high voltages.
Distribution lines carry limited quantities of power over shorter distances.The State Electricity Boards (SEBs) or state governments (through the state electricity departments) primarily own and operate the distribution networks and state grids. The Power Grid Corporation of India Limited (PGCIL) owns and operates most of the inter-regional transmission lines (forming a part of the national grid) in order to facilitate transfer of surplus power to a deficit region. The entire country has currently been divided into five regions or zones for transmission systems, namely, Northern Region, North-eastern Region,Eastern Region, Southern Region and Western Region. The interconnected transmission system within each region is also called the Regional Grid. Each region or zone has its load control centre.
The establishment of a National Power Grid by the year 2012 is being planned with an inter-regional power transfer capacity of about 37,150 MW. A perspective transmission plan has been evolved for strengthening the regional grids with the objective of establishing a strong and vibrant National Grid to support the envisaged generating capacity addition of 1,00,000 MW . This move is expected to help in optimal development and utilization of coal and hydro resources. It is also aimed at improving the economy, reliability and
quality of power supply. For example, the energy resources in our country are unevenly distributed: the coal resources are abundant in Bihar/Jharkhand,Orissa and West Bengal and hydro resources are mainly concentrated in Northern and North-Eastern Regions. That is, some regions do not have adequate natural resources for setting power plants to meet their future requirements whereas others have abundant natural resources. The National Power Grid as an integrated entity can serve as an effective tool to accommodate energy needs of different regions and transfer electricity from power surplus regions to power deficit regions.
A major portion of the distribution network is controlled by SEBs or their restructured entities and a very small section by private power utilities. As a part of this system, you are responsible for its efficient working. You will agree that a well-managed power distribution network holds the key to consumer satisfaction, a healthy economy and national prosperity.We have so far presented a broad picture of the electricity sector in India. It is unfortunate that in spite of having abundant energy resources and a large pool of highly skilled human capital we are faced with many problems in all three components of the power supply system: generation, transmission and distribution. We list some of these in Table . You may like to add to the list.
Transmission and Distribution
In India, the power plants typically produce 50 cycle/second (Hertz),alternating-current (AC) with voltages between 11 kV and 33 kV. Electric power is brought from the power plant to the consumer through an extensive transmission and distribution (T&D) system comprising distribution networks,state grids and regional grids. The various stages of the process are given below:
At the power plant site, the 3-phase voltage is generated and stepped up to a higher voltage for transmission on cables strung on cross-country towers.High voltage (HV) and extra high voltage (EHV) transmission is the next stage to transport A.C. power from the power plant over long distances at voltages like 220 kV, 400 kV and 760 kV. For longer distances and higher powers, higher voltages are economical. In special cases HVDC (high voltage direct current transmission) is preferred.
Sub-transmission network at 132 kV, 110 kV, 66 kV or 33 kV constitutes the next link towards the end user.
Distribution at 11 kV/ 6.6 kV / 3.3 kV constitutes the last link to the consumer, who is connected directly or through step-down transformers. These transformers bring the voltage levels down to 400V for 3-phase, 4 wire secondary distribution. The single phase residential lighting load is connected between any phase and neutral (230 V) and 3-phase load is connected across 3-phase lines directly.
The transmission and distribution network includes sub-stations, lines and distribution transformers. Sub-stations, containing step-down transformers, reduce the voltage for distribution to industrial,commercial and residential customers. These substations and distribution lines are referred to as the distribution system.Transmission lines are usually capable of transmitting large quantities of electrical energy over long distances. They operate at high voltages.
Distribution lines carry limited quantities of power over shorter distances.The State Electricity Boards (SEBs) or state governments (through the state electricity departments) primarily own and operate the distribution networks and state grids. The Power Grid Corporation of India Limited (PGCIL) owns and operates most of the inter-regional transmission lines (forming a part of the national grid) in order to facilitate transfer of surplus power to a deficit region. The entire country has currently been divided into five regions or zones for transmission systems, namely, Northern Region, North-eastern Region,Eastern Region, Southern Region and Western Region. The interconnected transmission system within each region is also called the Regional Grid. Each region or zone has its load control centre.
The establishment of a National Power Grid by the year 2012 is being planned with an inter-regional power transfer capacity of about 37,150 MW. A perspective transmission plan has been evolved for strengthening the regional grids with the objective of establishing a strong and vibrant National Grid to support the envisaged generating capacity addition of 1,00,000 MW . This move is expected to help in optimal development and utilization of coal and hydro resources. It is also aimed at improving the economy, reliability and
quality of power supply. For example, the energy resources in our country are unevenly distributed: the coal resources are abundant in Bihar/Jharkhand,Orissa and West Bengal and hydro resources are mainly concentrated in Northern and North-Eastern Regions. That is, some regions do not have adequate natural resources for setting power plants to meet their future requirements whereas others have abundant natural resources. The National Power Grid as an integrated entity can serve as an effective tool to accommodate energy needs of different regions and transfer electricity from power surplus regions to power deficit regions.
A major portion of the distribution network is controlled by SEBs or their restructured entities and a very small section by private power utilities. As a part of this system, you are responsible for its efficient working. You will agree that a well-managed power distribution network holds the key to consumer satisfaction, a healthy economy and national prosperity.We have so far presented a broad picture of the electricity sector in India. It is unfortunate that in spite of having abundant energy resources and a large pool of highly skilled human capital we are faced with many problems in all three components of the power supply system: generation, transmission and distribution. We list some of these in Table . You may like to add to the list.
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| Problems in the Generation, Transmission and Distribution Segments of the Power Sector |
The end users of electricity like households, farmers, commercial establishments and industries confront many problems such as frequent
power cuts (both scheduled and unscheduled), faulty metering and inflated billing. Erratic voltage and low or high supply frequency have further added to the power woes' of the consumer. Further, people in a large number of avillages and small towns have limited or no access to electricity.
power cuts (both scheduled and unscheduled), faulty metering and inflated billing. Erratic voltage and low or high supply frequency have further added to the power woes' of the consumer. Further, people in a large number of avillages and small towns have limited or no access to electricity.
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