Transmission Planning including National Grid
India is trying to expand electric power generation capacity, as current generation is seriously below peak demand. Although about 80% of the population has access to electricity, power outages are common, and the unreliability of electricity supplies is severe enough to constitute a constraint on the country’s overall economic development. The government had targeted capacity increases of 100,000 megawatts (MW) over the next ten years.
While India currently does not have a unified national power grid, the country plans to link the India’s state electricity boards (SEB) grids eventually, and has set up a state company, Powergrid, to oversee the unification. India also plans to establish national and state level regulatory bodies to set tariffs and promote competition.
The India’s government approved a large number of “mega-projects,” defined as plants with capacity of more than 1,000 MW for thermal plants and more than 500 MW for hydroelectric plants, from the mid-to-late-1990s, but project approvals have often not led to construction.
The Dabhol plant, valued at $2.9 billion, is the largest single foreign investment in India. The Indian government is attempting to implement reforms which would increase the financial strength of the SEBs in an attempt to attract capital back to electricity generation projects. New legislation on power sector reform was approved by the Indian cabinet in February 2002, and is to be introduced in the parliament.
Developments in power sector emphasize the need for accelerated implementation of National Power Grid on priority to enable scheduled/ unscheduled exchange of power as well as for providing open access to encourage competition in power market.
In view of above, nationwide synchronous power grid, interconnecting all the five regional grids, has been established with the commissioning of 765kV S/c Raichur – Sholapur line on December 31, 2013. POWERGRID is strengthening its transmission network to establish inter-State and inter-regional links for enhancing the capacity of National Grid in a time bound manner to ensure optimal utilization of uneven distribution of energy resources. In FY 2015-16, 12,400 MW of Inter- regional transmission capacity has been commissioned by POWERGRID and it is expected to implement 12,300 MW in FY 2016-17.
In a potential game-changer, South India finally joined the national electricity grid, completing the integration of the entire country into one seamless network for delivering power to consumers. Not only did it provide relief to the power-short southern region, it will also improve transmission and facilitate better management of demand, ensuring the stability of the electricity grid. Easier availability of power could also lead to lower tariffs in Andhra Pradesh, Karnataka, Kerala, Tamil Nadu and Puducherry.
Together with a proposal to separate the so-called carriage-and-content operations of existing power distribution companies, the move has the potential to bring about a structural transformation of the power sector. Of the five regional grids in the country—northern, southern, eastern, north-eastern and western—only the southern one had not been connected to the national grid.
With this interconnection, the Indian power system has entered into a new era and become one of the largest operating synchronous grids in the world with about 232 GW (gigawatts) of installed power generation capacity. This will provide a huge benefit as it will help in the reduction of electricity cost which are high due to the transmission constraint.
While large and medium component suppliers have captive diesel power plants, generating electricity from diesel is at least three times more expensive than buying it from the state. Therefore, while buying from the national grid will be expensive, at least it will not be a expensive as generating power from diesel gensets. If there is adequate connectivity, it will result in better availability resulting in lesser power cuts, helping us. The development will also help in grid stability and “work as a better shock absorber”. A grid collapse is the worst case scenario for any transmission utility.
The creation of an integrated national grid will also help towards interlinking countries of the South Asian Association for Regional Cooperation (SAARC) that groups India, Pakistan, Nepal, Bhutan, Bangladesh, Sri Lanka, Afghanistan and the Maldives. The SAARC grid envisages meeting electricity demand in the region. India already has power grid links with Bhutan, Nepal and Bangladesh, and plans to develop power transmission links with Myanmar and Sri Lanka.
Adopting new technologies in indian transmission system
Electricity sector in India is growing at rapid pace. During the current year 2017-18 (Upto 31.07.2017), the Peak Demand is about 159.8 GW and the Installed Capacity is 330.1 GW with generation mix of Thermal (66.8%), Hydro (13.5%), Renewable (17.7%) and Nuclear (2.1%).
The natural resources for electricity generation in India are unevenly dispersed and concentrated in a few pockets. Hydro resources are located in the Himalayan foothills, North Eastern Region (NER). Coal reserves are concentrated in Jharkhand, Odisha, West Bengal, Chhattisgarh, parts of Madhya Pradesh, whereas lignite is located in Tamil Nadu and Gujarat. Also lot of power station, generating from Gas and renewable energy sources like Solar, Wind etc. have been installed in various parts of country.
Powergrid Corporation of India Limited (POWERGRID), a Central Transmission Utilities (CTU), is responsible for planning inter-state transmission system (ISTS). Similarly there are State Transmission Utilities (STU) (namely State Transco/ SEBs) responsible for the development of Intra State Transmission System.
An extensive network of Transmission lines has been developed over the years for evacuating power produced by different electricity generating stations and distributing the same to the consumers. Depending upon the quantum of power and the distance involved, lines of appropriate voltages are laid. The nominal Extra High Voltage lines in vogue are ± 800 kV HVDC & 765kV, 400 kV, 230/220 kV, 110 kV and 66kV AC lines. These have been installed by all the SEBs, and by Generation, Transmission & Distribution utilities including those in Central Sector.
8,366 circuit kilometres (ckm) of transmission lines have been commissioned during 2017-18 (April-July 2017). This is 36.2% of the annual target of 23,086 ckm fixed for 2017-18. Similarly, 30,050 MVA of transformation capacity of substations has been added during 2017-18 (April-July 2017) which constitutes 55.7% of the annual target of 53,978 MVA fixed for 2017-18.
The capacity of transmission system of 220 kV and above voltage levels, in the country as on 31st July 2017 was 3,76,217 ckm of transmission lines and 7,70,815 MVA of transformation capacity of Substations. As on 31st July 2017, the total transmission capacity of the inter-regional links is 76,550 MW.
The transmission lines are operated in accordance with Regulations/standards of Central Electricity Authority (CEA) / Central Electricity Regulatory Commission (CERC) / State Electricity Regulatory Commissions(SERC).However, in certain cases, the loading on transmission lines may have to be restricted keeping in view the voltage stability, angular stability, loop flows, load flow pattern and grid security.Power surplus States have been inter-alia, able to supply their surplus power to power deficit State Utilities across the country except for some congestion in supply of power to Southern Region.
Power System Operation Corporation Limited (POSOCO), is managing the National and Regional grid from National Load Despatch Centre (NLDC) and its five Regional Load DespatchCentres (RLDC) through state-of-the-art unified load dispatch &communication facilities.