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Shaping Up the National Grid

Venugopal Pillai ,  Tuesday, April 14, 2015, 14:29 Hrs  [IST]

The XIII Plan period (2017 to 2022) is expected to see hectic activity in the power transmission segment as India endeavours to efficiently transmit the huge power generation capacity build-up that has taken place in the recent Plan periods. This special story by Venugopal Pillai gives an overview of activities relating to interregional lines for transfer of power, popularly known as the National Grid.

April-1.pngThe XIII Plan period (2017-22) is going to be very significant with respect to power transmission. While the focus on the preceding Plan periods has been on augmenting generation capacity, the XIII Plan period will be a phase where the focus will clearly shift from power generation to power transmission. Within power transmission, much work is expected in the National Grid, which will be responsible for seamless and synchronous transfer of power from India’s five regions—north, east, west, south and northeast. Fortification of the National Grid will of course need to be matched by setting up transmission infrastructure within the states. Hence, there will be concurrent effort by Power Grid Corporation of India Ltd for the National Grid, and state transmission utilities for intra-state grids. At both these levels, active participation from the private sector is expected via several PPP modalities.

Currently, India has 261 GW of power generation capacity installed including around 32 GW from renewable energy sources. During the XII Plan period, about 49 GW was added up to December 2014. It is expected that by the end of the XII Plan period (March 31, 2017), India will have a total of 367 GW of installed capacity. In the XIII Plan period, new additions of around 102 GW are expected that will take the country’s aggregate to 469 GW as of March 31, 2022. The XIII Plan period will also see induction of power from neighbours like Bhutan and Nepal. India would also be exporting electricity to Pakistan and Sri Lanka.

The present interregional capacity is around 40,050 mw and by the end of the XII Plan period (March 2017), this is likely to go up to 73,850 mw. The XIII Plan period is slated to be the most hectic with an estimated addition of 52,800 mw to the National Grid capacity. By March 2022, the total transfer capacity of the National Grid will be in the region of 126,650 mw. A striking observation to make here is that the quantum of interregional power transfer in relation to the total power generation capacity is expected to improve dramatically over the years. Currently, 15 per cent of the total installed capacity is available for interregional transfer. However, this proportion will be seen rising gradually to reach 20 per cent by March 2017 and 27 per cent by March 2022. This also demonstrates how in the years ahead, the thrust area in the power sector will shift from generation to transmission.
The following sections look at critical aspects like fund requirement, shift in technology and the role of private sector.

Fund requirement in XIII Plan
In the XIII Plan period (FY18 to FY22), around 62,800 ckm of transmission lines, 1,500 mw of HVDC terminal capacity and 128,000 MVA of transformation capacity is envisaged. This relates to voltage of 400kV or above. A majority of this system will be implemented as inter-state transmission system. Based on the current cost, the total cost of construction is estimated to be Rs.1,60,000 crore. Besides, another Rs.1,00,000 crore will be spent on transmission infrastructure of 220kV or below, which will be at the state level. The total requirement of the power transmission sector in the XIII Plan period therefore works out to Rs.2,60,000 crore.

Emerging Technology
In the XIII Plan and beyond, India’s power transmission sector is expected to see the induction of modern technology. The core transmission infrastructure will be based on 765kV level as against 400kV today. As of March 2012, India had 5,250 ckm of 765kV lines that represented 4.9 per cent of the total high-voltage lines (400kV and above). In March 2017, the end of the ongoing XII Plan period, this proportion is expected to rise to 22 per cent. By the end of the XIII Plan period, this metric will have grown to 31 per cent.

Apart from just improving the voltage level, there will also be technological advancements that would include VSC-based HVDC technology, dynamic reactive compensation, PMU/PDC-based synchrophasor technology, wide area monitoring systems (WAMS), phase-shifting transformers and series reactors. Most importantly, India would most likely be the first country to have 1,200kV power transmission lines on commercial scale. This voltage level is today the highest anywhere in the world. India is testing 1,200kV technology through a pilot 1-km line built at Bina in Madhya Pradesh.

VSC-based HVDC technology: The current technology used in HVDC systems is based on Line Commutated Converters (LCC) that use thyristors. This technology is now considered as the conventional type. The principal drawback of this system is that commutation within the converter is driven by AC voltage of interconnected AC system requiring minimum short circuit level of surrounding AC system. On the other hand, voltage source converter (VSC)-based HVDC transmission technology, which is based on insulated gate bipolar transistors (IGBT), overcomes some of the limitations of conventional HVDC technology. It also provides better reactive power controls and can be helpful in inter connection of weak AC systems, island networks and renewable sources to a main grid. This technology is presently costlier than the LCC-based technology and is still under development stage for bulk-power transmission requirements. In coming twenty years, this technology may become economical and more usable.

Dynamic reactive compensation: In order to maintain voltages in stipulated limits and grid stability, reactive compensation in the form of switchable/controlled bus reactors as well as STATCOM/SVC as dynamic compensators, at strategic locations are required.

Synchrophasor Technology/WAMS: As power grids get more complex, it becomes increasingly important to capture dynamic behaviour of the power system on real time basis, to ensure safety, security and reliability. Application of synchrophasor technology using Phasor Measurement Unit (PMU), integrated with Phasor Data Concentrators (PDC) and high speed wideband fibre optic communication links has emerged to address above critical developments in the grid. This technology enables visualization of magnitude and angle of each phase of three phase voltage/current, frequency, rate of change of frequency, oscillations and angular separation at every few millisecond interval in the control centre. Thus the dynamic behavior of the power system can be observed in near real time at the control centre thereby improving/enhancing situational awareness for the operators and help increasing deliverability of the grid.

April-3.pngPhase-shifting Transformers: Existing transmission systems are often operated and stressed to the limit of their performance capability of their original design in order to maximize asset utilization. To ensure that under these conditions the economical, reliable and secure operation of the grid is maintained, the need for various aspects of power flow management within the power systems is becoming evident. Phase-shifting transformers (PST) help control the real power flow in transmission lines and systems inter-ties. They allow for better utilization of existing networks by balancing the loading in parallel paths. In this regard, it is worth mentioning that three PSTs have been planned in southern and western region of India. Out of this, one PST was commissioned by Bharat Heavy Electricals in December 2014. This indigenously-developed PST, also the country’s first, was deployed at the Kothagudem Thermal Power Station Stage-VI in Telangana State Power Generation Corporation Ltd in Telangana. The 400kV/220kV, 315 MVA rating PST shall be utilized to control and improve the power flow between 400kV and 220kV network in either direction by providing phase shift as per the system requirement.

Series Reactor: Series reactors, either as series bus reactors or series line reactors, are considered for limiting the fault current level. The effect of the series bus reactor is very prominent in controlling the short circuit level of the bus on which it is installed. A series line reactor is very effective when small numbers of identified feeders are contributing maximum short circuit current.

UHVAC Technology: Although 765kV power transmission technology is soon emerging on the Indian landscape, it is universally felt that voltage levels should progressively rise. India’s requirements for long and high-capacity power transmission lines are growing as consumption centres are very far away from generation centres. For instance, east India is a hub for thermal power generation and northeast is that for hydropower. Consumption centres are typically located in the north, west and southern parts of the country. Right of way is a very challenging issue in the Indian context. There will therefore be a conscious effort to have maximum power transmission with minimum geographical footprint. In this context, 1,200kV AC power transmission is a logical step forward. In 2012, a test line at Bina was built with indigenous technology. Commercial 1,200kV lines are expected only by the end of the XIII Plan period. India is also building lower-voltages lines with a provision to easily converting them to 1,200kV at a later stage. The 400kV Wardha-Aurangabad D/C line is a case in point.

Private Participation
The introduction of the tariff-based competitive bidding (TBCB) mechanism marks an important paradigm in India’s electricity sector. In the context of power transmission, and especially interregional lines, the TBCB regime, launched in January 2011, marks the end of the monopoly of Power Grid Corporation of India Ltd as the sole agency for implementing such lines.

Under the TBCB philosophy, PGCIL and private sector entities bid for projects and the developer is selected based on the tariff quoted. It may be mentioned that when PGCIL was the sole agency, it could also quote the project cost based on the “cost-plus” method that guaranteed returns on investment.

Though the official guidelines for TBCB came into effect in January 2011, the Union power ministry proposed to offer interregional transmission lines on tariff-based competitive bidding (Case-II) way back in 2007.

A study done by Electrical Monitor suggests that the involvement of private sector in interregional lines has failed to meet expectations. So far, 19 projects have been awarded under the tariff-based bidding route, up to February 2015. Out of these projects, PGCIL has won six. In the private sector, Sterlite Grid (part of the Vedanta Group) has been most successful, also with six projects. Reliance Power Transmission (part of Anil Ambani Group) has won two and so has Essel Infraprojects Ltd. A consortium of BS Ltd, Patel Engineering and Simplex Infrastructures; L&T-Infrastructure Development Projects Ltd; and Techno Electric Engineering have won one project each (see table).

It is worth observing that Reliance Power has not been bidding for new projects in the wake of problems with its two transmission projects—Talcher II and North Karanpura. Both these projects were awarded in 2010 but there has not been much physical progress. Reports available in public domain indicate that severe cost escalation is deterring Reliance Power from embarking on project implementation. The entity has appealed to CERC for invoking “force majeure” clause while Central Transmission Utility PGCIL has appealed that the transmission licence granted to Reliance Power be revoked. There are further reports of some sequential transmission projects that depend on the completion of these two projects, also being adversely affected. The matter is pending judgement from Central Electricity Regulatory Commission.

Some transmission service providers that Electrical Monitor interacted with are of the opinion that private sector involvement could get better only if there is substantial improvement in the policy environment. Currently, Power Grid Corporation of India is playing the role of both regulator and developer of transmission lines. This gives unfair advantage to PGCIL vis-à-vis private players. Some sections of the industry feel the need for an independent authority on the lines of National Highways Authority of India. This might bring more transparency to the bidding and award process.

There is also discontent amongst private players regarding the nomination route where the Central government obviates the TBCB mechanism and awards projects to PGCIL. A recent case in point is the 800kV HVDC Raigarh-Pugalur project for which PGCIL was nominated as developer. While the government maintained that early project completion was imperative and that the project was technologically complex, the private sector felt that it missed out on a major project. This HVDC bipolar line traversing 2,000km and with a capacity of 6,000 mw is expected to cost at least Rs.15,000 crore.

April-4.pngThe Union Budget 2015-16 has proposed a plug-and-play model for ultra mega power projects with the possibility of extending this model to other infrastructure projects. Under the P-and-P model, the government will ensure that land acquisition and all other pre-project formalities and clearances are in place even before project bidding starts. Power transmission projects, being a land-centric project, often face right-of-way hindrances. If private players are assured of encumbrance-free projects, their interest could revive, at least partially. Currently, there are signs of waning investor interest. Recent interregional projects pending final award have elicited interest from just about four bidders.

There are of course more contentious issues in the tariff-based bidding mechanism route, which need early resolution. For instance, developers could win a project through an aggressive bid, based on certain assumptions. These assumptions sometimes go wrong due to unforeseen factors and it makes the project economically unviable. Developers desist from implementing the now-unviable project, often resulting in a prolonged stalemate.

The setting up of a solid network of interregional lines for synchronous power transfer between regions is an important component of India’s power ambitions. With respect to implementation, a transmission line project is never an easy task; there are bound to be right-of-way issues. The power ministry should resolve issues related to right-of-way and forest clearances. In the next ten years, the interregional power transmission infrastructure will almost double from its present level. Besides, the infrastructure would be much more advanced from a technical perspective. India will need to have enough technical knowhow to make sure that grid uptime is maintained. In the years to come, there will also be a growing supply of power from sources like wind and solar energy. The grid will need to factor this intermittency by suitable balancing technologies. Lastly, the setting up of interregional grids should be complemented by intra-state power transmission networks. State governments should have a policy framework that encourages and sustains private enterprise in state grids.
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