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Sunday, 31 August 2014

Ultra Mega Power Projects: For the desired GDP growth in India

Last updated: January 20, 2017

Formidable Challenges in Indian Power Sector:

India has achieved significant generation capacity addition in the last 50 years. Despite of this it continues to face formidable challenges in bridging the gap between demand and supply. It needs to add another 170 GW of installed generation capacity in the next decade to get the desired 9% growth in GDP and this can be achieved only through large capacity power projects. 

Ultra Mega Power Project:

In view of this, the Government of India has come up with the concept of Ultra Mega Power Project (UMPP). These coal powered, super-critical technology based power projects, each with a capacity of 4 GW or more and each unit of 660 MW or 800 MW is a series of ambitious power projects planned by the Indian Government. So far 16 UMPPs have been envisaged in various states including Gujarat, Andhra Pradesh, Chhattisgarh, Jharkhand, Karnataka, Madhya Pradesh, Maharashtra, Orissa and Tamil Nadu. Estimated investment in each UMPP is approximately Rs 20,000 to 30,000 crores.

Super-critical Thermal power plants:

The term “super-critical” is used for power plants operating at pressure above critical pressure; i.e. plants operating above 225.56 kg/cm2 and 374.15 oC are called super-critical thermal power plants. Central Electricity Authority (CEA) has evaluated super-critical technology from the technical and economical point of view and has recommended the same for Indian thermal power plants. Super-critical thermal generating units of 660 MW (steam pressure of 247 kg/cm2 and temperature of 535/563 oC) and 800 MW (temperature of 565/593 oC) is proposed for all future thermal power plants.

Super-critical Technology:

Power plants based on super-critical technology has the advantage of lower CO2, NOX, and SOX emission per kWh of electricity produced in comparison to sub-critical power plants. As per the Government decision, in the 13th FYP only super-critical technology based thermal power plants would be set up in India.

The average tariff for these projects is in the range of  Rs 2-3 per unit which is much lower than the recent tariffs. The projects are awarded to developers on tariff-based International Competitive Bidding (ICB) on a Build-Own-Operate (BOO) basis. CEA is the technical partner and Power Finance Corporation (PFC) is the nodal agency for getting the basic infrastructure like land, water supply, environment clearances, etc. In order to enhance investors’ confidence, and reduce risk perception, PFC incorporates Special Purpose Vehicles (SPVs) for each UMPP to undertake the bidding process on behalf of the beneficiary states. Apart from bid process, the purpose of the SPVs is to obtain various clearances for the projects.

Significant UMPP:

The first UMPP, developed by Tata Power at Mundra, Gujarat has been commissioned and contributes 4,000 MW (8 x 800 MW) of power to the Western grid. Sasan UMPP, a 3,960 MW (6 x 660 MW) pit-head power plant is located in Madhya Pradesh. The project has been allocated three captive coal mine blocks; with an envisaged production of 25 million tonnes of coal per annum. When completed, this UMPP become the largest integrated coal-cum-power plant in the country involving almost 10,000 acres of land of which almost 7,000 acres would be coal mines.
The project was awarded to Reliance Power through ICB process in August 2007. The estimated project cost is over Rs. 27,000 crores (US$ 4.2 billion). Sasan is the first ever integrated-power cum coal mine project with current operational capacity of 2640 MW. First unit of 660 MW was commissioned in March 2013, second unit in January 2014, third unit in April 2014 and fourth unit in May 2014. 5th Unit is synchronized with grid and commissioning to be declared shortly. 6th and last unit is in advanced stage of commissioning and expected to be commissioned in the next couple of months. 

Power generated from the plant would be sold in Madhya Pradesh, Punjab, Uttar Pradesh, Delhi, Haryana, Rajasthan and Uttarakhand states of India at a levelized tariff of 1.196 INR/ kWh. The low tariff of the project is primarily because of the low cost of generation due to its pit head location and captive mines. Because of the advanced 'super-critical' boiler technology, the operating efficiency is higher and emissions are reduced, thereby making it a less polluting thermal power plant.

The Tilaiya UMPP also by Reliance Power, is another integrated pit

pit-head power plant with an aggregate capacity of 4 GW located at  

As on March 2014, India had 13.9 GW of installed generation capacity based on super-critical technology; of which Adani Power has commissioned the maximum of 6.6 GW (10 units of 660 MW) with plant location at Mundra, Tiroda (Maharashtra) and Kawai (Rajasthan) . The 3 x 660 MW Sipat-I is the only UMPP in the public sector owned by NTPC, the rest have been commissioned by private sector.
electricalmonitor news bureau

Saturday, 30 August 2014

Basics of Shunt Reactive Compensation

Purpose of providing Reactive Compensation:

The purpose of providing reactive compensation is to change the natural electrical characteristics of a transmission line. Shunt connected capacitors are used to maintain the voltage of the transmission system at desired levels during the loaded condition whereas shunt connected reactors are employed to reduce line overvoltages under light load or no-load conditions.

The voltage sag is largest at the midpoint for an uncompensated transmission line. Thus, the optimum location to place a shunt compensator is at the midpoint. Also, the compensator at the midpoint segments the line into two equal sections for each of which the maximum transmittable power is the same. The midpoint shunt compensation can significantly increase the transmittable power but the reactive power demand on the compensator increases rapidly with the increase in transmitted power.

Multiple shunt compensators can be placed on the transmission line located equidistance from each other. With the increase in number of compensators and hence the segments of the line, the voltage profile of the line approaches a flat profile. Theoretically the power which can be transferred over a transmission line doubles with each doubling of the segment. Such a system however would become too complex and costly.

Machine Angle Oscillation in Under-damped Power System:

In an under-damped power system, a small disturbance may cause the machine angle to oscillate around its steady-state value at the natural frequency of the entire electro-mechanical system. This oscillation of angle results in a corresponding sustained power oscillation. By appropriate variations in the shunt reactive compensation and hence in the voltage of the transmission line, the accelerating and decelerating swings of the disturbed machine or machines can be neutralized. 

When the oscillating generator accelerates and the machine angle increases, the electric power transferred must be increased to compensate for the excess mechanical input power. On the other hand the power transmitted must be reduced to counter the reduced mechanical input when the generator decelerates and the angle decreases. 

Thus, with appropriate and fast controls, shunt reactive compensation is able to change the power flow in a system during and following dynamic disturbances. This increases the transient stability and damps the power oscillations. Hence reactive or VAr compensation is used for voltage regulation at the midpoint or at some intermediate locations in the transmission line and at the end of a radial transmission line to avoid voltage instability, to increase transient stability and to damp power oscillations.

Ref: Hingorani and Gyugyi, “Understanding FACTS”, John Wiley & Sons, UK

Friday, 29 August 2014

Solar Energy: Crucial Component of India’s Energy Portfolio in the Next Decade

Last updated: May 13, 2017

Economic growth and Welfare of a country:

Electrical power is one of the most crucial component for the economic growth and welfare of any country. Adequate electrical infrastructure and its further development is essential for sustained growth in our country also. Indian power sector, one of the most diversified and rapidly growing power sector in the world, generates electricity from conventional sources such as coal, lignite, natural gas, hydro, nuclear power etc. and from non-conventional sources such as wind, solar, biomass etc. 

National Solar Mission:

In order to meet the increasing demand for electricity in the future, huge addition to the existing generation capacity is very much needed. The objective of Jawaharlal Nehru National Solar Mission (JNNSM) is to establish India as a global leader in solar energy by creating conducive conditions for its large scale diffusion across the country. The mission will accomplish its objectives in three phases with the 3rd phase ending by 2022 (the end of 13th FYP). 

Ambitious target of  “Solar India”:

The mission under the brand name “Solar India” set an ambitious target of adding 20 GW of grid connected and 2 GW of off-grid capacity by 2022. The target was later revised in June 2015 and enhanced to 1,00,000 MW by 2022. This 100 GW capacity will comprise of 40 GW of Roof Top Solar PV system and 60 GW large and medium scale grid connected solar power plants. Success in solar energy capacity addition will require a long-term commitment and a sound understanding of local dynamics.

India; the third biggest solar market in the world:

Several studies on electricity demand growth of the country, cost, availability and the environmental factors associated with fossil fuel, declining trend noticed in the cost of solar energy related equipment, awareness among the general mass and government efforts were carried out. Based on these studies, few predict that the solar power generation capacity could well exceed 100 GW by 2022 and India’s solar energy market could be of billions of dollars in the coming decades. Some predict that by 2017-18, India will become the third biggest solar market in the world.

It is expected that the per unit cost of energy generated by conventional power plants and that by solar power plant will be the same by the year 2017-18. In the initial stage the government support and subsidy is going to fuel the promotion of solar energy whereas in the later stages rising demand and favorable economics will drive the mission. 

Mechanism to Boost Solar Energy: 

Mechanism such as Renewable Purchase Obligation (RPO), Renewable Energy Certificate etc. are going to boost up the confidence of investors and the participants. It is also expected that local players are going to dominate the solar energy market with their services which includes project development, installation and distribution.     

Thursday, 28 August 2014

WAMS: A new and emerging technology for efficient electricity grid performance

Last updated 18 January 2017

The current installed capacity of grid interactive Renewable Energy power plants in India is 46.6 GW ( as on Nov 2016); with still more ambitious projects to materialize in the coming decades. Renewable energy generation is intermittent in nature and with its integration to the grid in a large quantum would increase the complexity regarding monitoring and control of a large grid such as the Indian power grid.

Modern interconnected power transmission network require a close monitoring and control of equipment and grid operation. Even small disturbances, if not detected at an early stage, may lead to widespread and cascading failure of the electrical grid. Accurate and reliable real time sensors are required to make the electric grid a smart one. Smart electricity grid means a more resilient, reliable and capable grid, needed to manage the variable Renewable Energy sources and other intelligent equipments and systems. Currently Supervisory Control and Data Acquisition (SCADA) is widely used by utilities to monitor and control the grid operations. The SCADA measurements are made once every 4 to 10 seconds or so, and is no longer a fast measurement to provide adequate observations.

Because of the widely spread grid and with the advent of open access and electricity market, wide area monitoring and control is the need of the hour. In this scenario, new and emerging technology such as Wide Area Measurement System (WAMS) is needed to enhance the efficiency and performance of the grid. 
"Wide Area Measurement Systems (WAMS) consists of advanced measurement techniques, information and communication tools and operational features that facilitate the monitoring, and control of a more complex interconnected power system, particularly with large penetration of Renewable Energy"
Presently WAMS is used as a complementary system to enhance the real time 'situational awareness' much needed for the safe, efficient and reliable operation of the grid. It requires installation of Phase Measurement Units (PMU) at strategic locations throughout the grid such as power plants and major substations. This technique incorporating synchro-phasor measurements (Phasor measurements that happen at the same time is known as synchro-phasor measurements) facilitates dynamic real time measurements and visualization of the power system which is much needed for the safety and security of the grid.

PMU measurements are taken at nearly 25 to 50 samples per second or even 200 samples per second which is quite high compared to the conventional measurements. Thus, PMU essentially requires a very robust and highly scalable data communication network to facilitate a more clear view and control of the power system. The information from the PMUs is passed on to a Phasor Data Concentrator (PDC) installed at central locations; and further forwarded to the SCADA system. For the fast data transfer high bandwidth communication networks are needed.

Global application of WAMS:

Many utilities in America, Europe, Brazil, China etc. have started developing and using this emerging technology in operating their large electrical grids. China has been using the WAMS technique since 2006 and has installed several hundred PMUs at its key locations.

WAMS technique in Indian Grid:

In India also, the process of installation of PMUs has already began and 8 PMUs already installed and commissioned in the Northern Region (NR). The data to the PDC, located at the Northern Region Load Dispatch Centre (NRLDC), is transferred through fibre optic communication link. From the Phasor data, more accurate information about the load angle at different location of the grid, with updation in few ms, is available. This enhances the capacity of the tools available for grid operation. About 1000 to 1500 PMUs and 30 to 60 PDCs are proposed for installation in the 12th FYP. The State Load Dispatch Centre (SLDC) may have the Master PDCs and the National and Regional Load Dispatch Centres (RLDC) may get the Super PDCs.

1.       “Draft National Electricity Plan”, Vol-II, Transmission, Government of India, Ministry of Power, CEA, 2012.  

2.       Progress update by Ministry of New and Renewable Energy (MNRE), Government of India

Wednesday, 27 August 2014

World’s first multi-terminal UHVDC transmission System in India

Last Updated 25 Dec 2016

India is going to have the world’s first multi-terminal Ultra High Voltage (UHV) DC system. The ± 800 kV, 1728 km long Biswanath-Agra UHV DC transmission system costing 12,000 crore will transmit hydroelectric power from India's northeast region to Agra in Uttar Pradesh.  The line will have a transfer capacity of 8000 MW including a 2000 MW redundancy. Power flow through Pole-I ( or phase-I) of the transmission system has been commenced in Sep. 2015. Commissioning of phase-II of the project is expected in the financial year 2017.

Transfer of bulk power through the so called "chicken neck area":

Northeast region of India has abundant hydro power resources scattered over a wide area. To transfer bulk power thus generated must pass through the so called "chicken neck area," which is a very narrow patch of land with 22 km width  and 18 km of length in the state of West Bengal having borders with Nepal on one side and Bangladesh on the other side. 

UHV DC Transmission: Best option for power evacuation in large quantum

The only option for power evacuation in such a large quantum is UHV transmission lines. The Biswanath-Agra UHV DC transmission project will enable bulk transfer of power uninterruptedly over a long distance with much lower losses (6%), more transmission reliability and stability. 

It will also facilitate inter-state trading of exportable power of State sector generation, evacuation of power from the Central sector power plants and will increase the capacity of National Grid. 

The  Biswanath-Agra UHV DC transmission project is a bi-directional link, which is supposed to help in transferring surplus electrical power from the North-eastern region during monsoon to the Northern and Western region of India. During the winter season, a reverse power flow is expected as the reduced availability of water will hamper the power production in the North-eastern sector.  

One converter station will be in Assam, and the second in West Bengal, both will have a capacity of 3000 MW each. The other end of the HVDC line will terminate at Agra, which is it's third station. The Agra station will have a capacity 0f 6000 MW, where two bipolar converters will be connected in parallel. The converter station will have a 33% continuous overload rating. The 800 kV equipment yard at Agra will be indoor, which is happening for the first time. 

Design, Supply and Installation responsibility:

ABB and Bharat Heavy Electricals Ltd. (BHEL) are responsible for the design, supply and installation of the three HVDC converter stations. 

Other significant 800 kV bi-polar, HVDC transmission line:

Contract has been awarded to build the phase-II of the Champa-Kurukshetra, 800 kV bi-polar, 1365 km long HVDC transmission line by POWERGRID. This line will have a capacity of 3000 MW and will transfer power produced by the thermal power plants of Chhatisgarh state to Kurukshetra in North India. The phase-II link will run in parallel to the currently under construction phase-I link of the same capacity.       


Last up-dated 16 January 2017

" The Gas Insulated Substation Technology was introduced for the first time in 1968 and is widely used today because of its significant advantages."
Today's power system insists for a more efficient and reliable solution to handle the new challenges. Power Transmission and Distribution in densely populated urban area is a great challenge because of land availability, and low noise and electromagnetic limitations. With the development in technology and enough improvement in substation and switch-gear design, Gas Insulated Lines (GIL) and Gas Insulated Substations (GIS) are finding increasing use under these conditions. These sub-stations are more safe and reliable, requires less maintenance, and have a longer life. They are highly adaptable to individual requirements.  

How they are different from Conventional Sub-stations?

In a GIS, major equipment such as circuit breakers, CTs, PTs, isolators, bus-bars etc are enclosed in a sealed environment of Sulphur Hexafluoride (SF6) gas. Due to the excellent dielectric properties of SF6 gas, the clearance required between phase to phase and phase to earth is much smaller and hence the design is compact. The enclosure is made up of Aluminium which is light in weight and is non-corrosive. Reduced weight of enclosure leads to reduced load on foundations/ floors and thereby reduces the cost also.

Relative merits of Gas insulated substations:

Gas insulated substations have an estimated lifespan of more than 50 years. They have high mechanical stability and resistance to arcing, and hence offers a high degree of personal safety. As these sub-stations are very compact, even larger units of relatively higher voltages are easy to handle during transportation and installation. They can be shipped as completely assembled units, pre-filled with SF6 gas. The control interfaces of these sub-stations enable the connection to any analog or digital control, protection and monitoring system.  

Scope of Gas insulated substations in India

The scope and future of Gas insulated substations in India is quite promising considering the rapid growth in power sector. Bulk power is transmitted at 400/765 kV and still higher voltage to come, the scope and opportunity for GIS is quite substantial. 

GIS, which are available in voltage range of 72.5 kV to 765 kV, is preferred for hydro-power plants and coastal area substations because of its compact and enclosed design and low maintenance requirements. In these substations, additional protection against thunderstorm, lightning, static discharge etc is not required. The footprint of a typical GIS is about 10 times less than the conventional air insulated sub-station. Because of the ever increasing land cost, GIS has now become a commercially viable solution in India. 

Prominent Gas insulated substations Projects in the Country

Recently Alstom T&D India (globally known as Alstom Grid) has been awarded to supply two 400/220/66 kV Gas insulated substations at Wangtoo and Gumma in Himachal Pradesh. The scope of the project covers the design, manufacturing, testing and commissioning of the GIS. The same company has been awarded a contract by Power Grid Corporation of India to design, manufacture, install and commission two Gas insulated sub-stations at Betul in M.P. and Navsari in Gujarat. These 400/220 kV substations will help to evacuate the power generated at Mouda STPP and Kakrapar Atomic PP. Alstom T&D India is manufacturing Gas insulated substations in India since 2009.

Similarly another Energy Sector industry L&T construction, in collaboration with Korean company, has successfully commissioned India's first 765 kV gas insulated sub-station in Pune, Maharashtra in 2015. This particular sub-station will enhance the grid connectivity and power transmission in Western India.  

Tuesday, 26 August 2014

STATCOM for Indian Grid: Advanced state-of-the-art Solution for Dynamic Reactive Compensation

Reactive Power balance in a Power System:

The reactive power balance in a power system varies with time. This variation in reactive power balance may bring in voltage variation or even voltage collapse. Dynamic i.e. the fast reactive power support, in the power system is very critical to maintain the system reliability. It helps to recover the voltage following a system disturbance.

To provide dynamic reactive capability, one of the following type of devices is needed.

  1. Static VAR compensator (SVC), or
  2. Static Synchronous Compensator (STATCOM), or
  3. Synchronous Condenser.

STATCOM belongs to the family of FACTS devices and is capable of providing both capacitive and inductive reactive power. It continuously provides the reactive power according to the voltage variations and thus helps to maintain the grid stability.

Principal Components and Working of STATCOM:

The principal components of  STATCOM are:
  1. the PWM Converter,
  2. the Coupling Reactor, and
  3. the DC Capacitor.
The converter topology depends on the rated voltage and power. STATCOM is usually a Voltage Source Converter (VSC) based compensator, but can be implemented using both the voltage or current source approach. The reactive power at the output depends on its terminal voltage. The device behaves as an inductor in case the AC system voltage is higher. The coupling reactor absorbs the instantaneous voltage difference between the grid voltage and the converter voltage. If the output voltage of the STATCOM is higher than the AC voltage at the point of connection, the STATCOM behaves as a capacitor. In either mode the reactance of the STATCOM can be varied continuously.

The coupling reactor also reduces the current harmonic distortion and helps to stabilize the switching frequency. These reactors are designed considering the maximum allowable current harmonics or the control scheme to be implemented. The DC capacitor maintains a constant DC voltage equal to the reference value. The selection of capacitor is based on the maximum allowable voltage harmonic distortion and the maximum tolerance value of DC voltage fluctuations. 

Advantages of STATCOM over SVC:

STATCOMs were preferred over Static VAR compensator (SVC) because of their faster response, reduced space requirement, and advanced technology.  The STATCOM has a much faster response than the SVC mainly because of the fast switching provided by the Insulated Gate Bipolar Transistor (IGBTs) of the VSC.  

The STATCOM also has better reactive power support at low AC voltages than the SVC, as the reactive power produced by a STATCOM decreases linearly with the AC voltage whereas in case of SVC the reactive power produced is proportional to the square of the AC voltage.  

STATCOM may also be combined with mechanically switched reactors and capacitors for the reactive power compensation under steady state. Installing STATCOMs  at one or more points in a power system helps in maintaining a smooth and stable voltage profile under varying operating conditions, thus enhancing the power transfer ability of the transmission system. 

Dynamic Reactive Compensation of Indian grid:

Power Grid Corporation of India Limited (POWERGRID), the Central Transmission Utility (CTU) of India, is responsible for planning, implementation and operation and maintenance of Inter-state Transmission System. It is also engaged in the operation of National and Regional Power Grids. 

POWERGRID currently owns and operates about 1,38,850 circuit kilometres of Extra High Voltage (E.H.V.) AC and DC Transmission lines throughout the country. It has 217 EHV AC and HVDC substations with a transformation capacity exceeding 2,88, 500 MVA. These transmission lines and systems transfers nearly half of the electrical energy produced in the country.  

POWERGRID, has a very good and proven track record. Its consistency rate is about 99% achieved through adopting global standards and deployment of hi-tech operation and maintenance practises. The Corporation after having interaction with various utilities and manufacturers, has decided to install STATCOM for the dynamic reactive compensation of Indian grid. It has proposed to install STATCOM of ± 200 and ± 300 MVAr at 13 locations in the WR, NR, ER, and SR of the Indian Power System.  

To further assist on the Flexible AC Transmission Systems (FACTS) and High Voltage Direct Current (HVDC) technology, POWERGRID has appointed Dr. Narain G. Hingorani, a consultant of international repute.

Ref: Study Report on Dynamic Reactive Compensation, POWERGRID

Monday, 25 August 2014

The Indian Desert Power Mission 2050

Peak electricity demand of India is expected to grow to about 1700 GW by the year 2050 as envisaged in the report of Central Electricity Authority (CEA) and the PowerGrid Corp. of India Ltd (POWERGRID); accordingly the power generation has to be enhanced.

Vast potential to install Renewable Energy (RE):

India has large deserts viz. the Thar desert, Rann of Katchh, Ladakh, and Lahul-spiti valley and the total estimated wasteland is approximately 148,000 sq.km. There is a vast potential to install Renewable Energy (RE) power plants such as Wind and Solar in these deserts and wastelands. Upland with or without scrubs, under-utilized/ degraded notified forest land of these deserts are well suited for Renewable generation. Also land in these deserts with accumulation of sand and with rock exposure can be utilized for setting up RE power plants. Only a ten percent of this wasteland i.e. 14800 sq.km has the potential to produce nearly 450 GW from solar and wind generation.


Ministry of New and Renewable Energy (MNRE) has already envisaged setting up large solar power plants, to be called as Ultra Mega Solar Power Projects, in these deserts. The proposed locations are Sambhar (Rajasthan), Kharaghoda (Gujarat), and Leh/ Kargil (J&K). 

Seeing the potential, MNRE has entrusted POWERGRID to assess the RE generation potential in these desert lands and to develop the required infrastructure including the transmission system for a time horizon up to year 2050. The study will also asses the economical potential of RE, demand of power, grid balancing, and the impact of such a large scale integration of renewable power in the local area.  

Wind and Solar Hybrid Model:

Since deserts of Thar, Rann of Kutch also has a good wind flow, hybrid model of Wind and Solar, with 30% wind turbine and 70% Solar generation, is envisaged. The percentage of Solar plant is kept higher because of the greater yield of Solar generation, typically 30-40 MW/ sq.km, which is approximately 4 times higher than the wind output for the same area.  

Researchers conclude that hybrid plants, with wind and solar combination, produce almost double the energy on the same surface area. The model also ensures a steadier power injection into the grid as compared to RE plants with wind turbine or Solar PV alone.  

Environmental Benefits of the Mission:

It is expected that by 2050, generation capacity through RE plants, in these deserts will be approximately 300 GW. The weighted average specific CO2 emission from coal fired power plants is 1.09 ton/MWh as per the National Electricity Plan 2012. Assuming a capacity utilization factor of 25%, these RE plants are expected to substitute nearly half of the fossil fuel generation and shall replace 286 ton of CO2 emission.  

Ref: “Desert Power India-2050”, Integrated Plan for Desert Power Development, Power Grid Corp. of India Ltd, Dec. 2013.

Sunday, 24 August 2014

1200 kV UHV transmission system: For the second most rapidly growing country

" Recent studies by the US department of energy indicate that China, India and Brazil will be the most rapidly growing countries in terms of electrical demand." 

This is clearly echoed in the report, “Working Group on Power”, Government of India, Ministry of Power, 2012, in which the additional generation capacity to be added in the 12th Five Year Plan is stated as 76000 MW. To meet the long term power transfer requirement and for optimal utilization of Right of Way (ROW), large capacity transmission corridors interconnecting the mega power plants and major load centres have been planned. 

Main transmission level in the next Decade:

In the next decade 1200 kV UHV AC system is expected to emerge as the main transmission level in India along with the 800 kV UHV DC system. The power transfer capacity of 1200 kV UHV AC transmission system is expected to be between 6000 to 8000 MW as against nearly 400 MW for a typical 400 kV line.

In this direction work has already began with the laying of foundation stone of Wardha-Aurangabad 1200 kV transmission line in the year 2011 and it is going to be the first 1200 kV transmission line in India and in the world.

1200 kV test station at Bina:

The only 1200 kV test station at Bina in Madhya Pradesh (India) with two 1200 kV bays, one single circuit (S/C) 1200 kV transmission line of 1.1 km length and 0.8 km of 1200 kV double circuit (D/C) line has already been dedicated to the nation in the year 2012. The system parameters of this 1200 kV UHV system were finalized after an extensive simulation study and giving due weightage to cost and size optimization. 

Testing of In-house manufacturing techniques:

Single phase auto-transformers of 333 MVA, 1200 kV each are installed considering the high voltage level and the difficulties encountered during transportation. With the successful charging of bay –I and the lines, India has achieved world’s highest transmission voltage level. Powergrid Corp. of India Ltd. and the consortium of 34 Indian electrical equipment manufacturers have shown to the world their in-house capabilities in developing the 1200 kV transmission technology

For example, 1200 kV capacitor voltage transformer and optical current transformer were manufactured by Alstom, auto-transformers by BHEL, Crompton Greaves, and Vijay Electricals, 1200 kV circuit breaker and surge arrestors by Siemens, 1200 kV isolators by Hivelm Ind etc. 

Upon charging of bay-II, more extensive field tests with the equipment loaded will be carried out. With this 1200 kV substation this small town of Madhya Pradesh (India) will fare prominently on the global power map as it already has 220 kV, 400 kV and 765 kV substations.

This project is a unique example of public-private partnership (PPP) in which all the UHV equipments have been developed indigenously by Indian manufacturers with PowerGrid providing the required basic design and specifications and other resources. This project is a milestone in India’s power transmission sector.

History of UHV transmission system:

Research on UHV transmission system is not new to the world as it started way back in 70’s and 80’s. Experimental UHV lines and substations were built in USA, USSR, Italy, Japan and China to develop the technology. However as the requirement of power transfer was not substantial as seen today in India and China, commercialization of UHV AC system has not taken place at that time. 
" For example, in USSR, a 411 km, 1150 kV Ekibastuz-Kokchotav-Kustanai transmission system was commissioned in 1985. The transmission line was in operation for about two years but after the split of USSR it was operated at 500 kV. "
China’s effort on UHV transmission system is quite advanced. It's preliminary work on UHV AC transmission began in 2004-05. The commercial operation of world’s first 1000 kV UHV AC transmission line at full rated voltage was started in China in the year 2009. The 650 km long Jindongnan-Nanyang-Jingmen line has a transfer capacity of 5000 MW.    

Saturday, 23 August 2014

Swift development of Transmission infrastructure in India: The Joint Venture route

Last Updated: 31 January 2017

Issues with Indian Transmission sector:

Installed generation capacity in India has nearly doubled in the recent times, mainly because of restructuring and deregulation of the power sector and the thrust given to Renewable energy sources. But the transmission sector is way lagging behind the generation, as the former was not given the due consideration. 

Some of the major obstacles in the development of transmission infrastructure in the country has been the difficulty in acquiring land, delayed forest clearances, and the government monopoly. 

Transmission unavailability has resulted in major load-sheddings in various areas, despite of surplus energy in certain regions. This has led to unsold generation capacity, low market prices and low plant load factor.
“The Electricity Laws (Amendment) Act 1998” treats transmission as a distinct activity in India and has made provisions for private sector investment in transmission system. In order to activate resources from private sector, Government of India issued certain guidelines for private sector participation in transmission sector in the year 2000. 

Methods envisaged for private sector participation in Indian Transmission sector:

One of the methods envisaged for private sector participation in transmission was through Joint Venture, wherein the Central/State Transmission Utilities (CTU/STU) shall own at least 26% equity and the balance shall be contributed by the Joint Venture Partner. 

The second route was all the way through Independent Private Transmission Company (IPTC), wherein 100% equity shall be owned by the private body. The CTU/STU will do the planning and identify approved transmission system or part thereof for implementation and execution by the private sector. 

Ministry of Power has also initiated Tariff Based Competitive Bidding Process for development and strengthening of Transmission system through private sector participation.

The aim is speedy development of transmission infrastructure in India, and to bring in potential investors. Since the power demand is increasing at a faster rate, gestation period of generating plants are reducing now it’s time for the transmission sector in the country to ramp up.

As a pilot project on JV method, Powerlinks Transmission Ltd., a joint venture between the Tata Power Company Ltd. (51%) and Power Grid Corp. of India Ltd. (49%) was selected through International Competitive bidding for the execution of 400 kV D/C transmission line associated with Tala Hydro Project, costing about a thousand plus Crores. The transmission project with a route length of around 1166 km connects Siliguri (West Bengal) and Mandola (Uttar Pradesh). This project which is in operation since 2006 has opened up Public-Private Partnership (PPP) in the transmission sector in India. Success achieved under JV route of private participation has encouraged POWERGRID to identify many more projects under this route.

Friday, 22 August 2014

Experimental setup showing Ferranti effect in Long Power Transmission lines

What is Ferranti Effect?

A long transmission line draws a substantial amount of charging current because of its distributed capacitance. If such a line is open ended or very lightly loaded, the operating voltage increases with the distance along the line and the receiving end voltage is greater than the sending end voltage. This effect is known as “Ferranti Effect”.

Why Ferranti Effect occurs?

Ferranti effect occurs when the charging current drawn by the long transmission line itself is greater than the current drawn by the load at the receiving end. Overvoltage occurs due to the voltage drop across the series inductance of the transmission line because of the flow of leading capacitive current or charging current. Overvoltage at the receiving end because of Ferranti effect can be controlled by using shunt reactor. The lagging reactive current drawn by the shunt reactor compensates for the charging current and hence the increase in voltage at the receiving end is controlled.

Typical values of inductance and capacitance parameters of a 400 kV transmission line are
L = 1.044 mH/km of line length and  C = 12 nF/km of line length. 

Demonstration of Ferranti Effect:

The effect of Ferranti effect can be well demonstrated in a lab using the tube light chokes and capacitors used for domestic fans and coolers connected in series and parallel respectively. The sending end can be provided a 230 V AC or some reduced voltage with the help of an auto transformer and the increase in voltage at the receiving end can be observed with the help of a voltmeter. Figure 1 shows the experimental board prepared to show the Ferranti Effect in the Lab.

Fig.1: Experimental board prepared to show the Ferranti Effect in the Lab.

The over-voltage caused by Ferranti effect can also be demonstrated with the help of MATLAB coding.

Tuesday, 19 August 2014

Transmission Infrastructure requirement for integration of large scale Renewable Energy

Last Updated 16 jan 2017

Tremendous potential of Renewable Energy 

Reports suggest that India has tremendous potential of un-tapped Renewable Energy (RE) sources. Our large deserts of Thar, Rann of Katchh etc are suitable enough for large Wind and Solar power plants. Solar alone has a potential greater than 750 GW. Indian Energy Security Scenario predicts a possibility of achieving 889 GW through Wind and Solar power by 2047. Generation capabilities of small hydro and Biomass is yet to be included. Amazing figures by any standards, is not it?

Why we are so madly behind Renewable Energy Sources?

Now the question is why we are so madly behind the Renewable Energy Sources? Yes certainly the International pressure is there to reduce the Carbon footprint, so that we can save our planet. 

Apart from that we can reduce the revenue outflow because of coal imports. Huge coal imports (over 1 lakh crore in 2014-15) are also a cause for un-reliable power supply. Since the prices of coal we import are higher, un-regulated and therefore quite volatile at times. Electricity Distribution companies, already under financial crunch, are unable to purchase power at escalated tariff at many occasions, resort to un-scheduled power cuts. 

Achieving 175 GW of RE by 2022 is the new target set by Indian Government. It is expected that achieving the set targets in next 5-6 years is going to cut the coal imports significantly. Thus to achieve a sustainable growth, energy security is of paramount importance. Promoting and implementing RE sources can help to mitigate the power sustainability issues.   

Potentially Rich States

Several Indian states having enormous potential of RE expansion, e.g. Tamil Nadu, Rajasthan, Karnataka, Andhra Pradesh, Gujarat, Maharashtra, J & K and Himachal Pradesh. Various policy and regulatory initiatives along with fiscal incentives have attracted further interest in developing RE generation and the sale of energy thereof. About 41000 MW of RE capacity addition is envisaged in the 12th FYP, thus the installed capacity of RE generation will be about 66000 MW by the year 2016-17.

Transmission Infrastructure Requirements

Transmission system plays a crucial role to facilitate smooth flow of electricity produced at the various RE power plants in a more economical, reliable and efficient manner. Till now the quantum of RE power was small and it was supposed that connectivity with local grid would be sufficient for its consumption. 

Now with this big leap forward in RE generation, the surplus energy from RE rich states have to be transferred to other states. Recent report by Power Grid Corp. India Ltd. stresses on the transmission infrastructure and other related services required for the integration of large scale renewable energy capacity addition. 

With the increase in the share of RE sources on the Power System, the complexity regarding monitoring and control of the grid also increasesVarious up-gradations in grid design, technology and operation protocols have to be implemented to minimize and manage the impacts of generation uncertainty and variability.   

In the year 2013, Government of India formulated a dedicated transmission network expansion program for RE under the National Green Corridor Program (NGCP). With a proposed cost of 43,000 INR, the transmission corridor is supposed to transfer the energy produced from different RE power plants across the country. In the first phase of the project, inter-state transmission network,  inter-connecting the above mentioned RE rich states, will be strengthened. Phase II will connect the various solar parks proposed throughout the nation.

The program also focuses on the establishment of Renewable Energy Management (RMC), and advanced forecasting techniques to mitigate the effects because of intermittent and variable nature of RE.     

Monday, 18 August 2014

UHV Transmission in India

Last updated: January 21, 2017

Indian power system is poised to grow at an accelerated pace. The qualitative and quantitative development of the power sector will be the key factor in country's socio-economic growth. Recent studies by US Department of Energy indicate that India will be the second most rapidly growing country, only after China, in terms of electrical demand.
"The peak demand is expected to grow more than 500 GW by 2026." 
North-east region of India has abundant hydro power resources. More than half the power stations are still thermal power plants. Renewable Energy (RE) sector is also progressing at a rapid pace. Indian Energy Scenario predicts a possibility of 889 GW through RE sources by year 2047. Deserts of Thar, Rann of Katchh are suitable for large wind and solar power plants. 
" By 2027 the installed generation capacity is supposed to touch 700 GW."
Power generation centres are typically Eastern and North-eastern regions, whereas the load centres are scattered across the country. Power evacuation in such a quantum over long distances is really a challenge for the Indian power engineers. Transmission of bulk amount of power over long distances can be accomplished most economically using Ultra High Voltage (U.H.V.) transmission lines. An increase in transmission voltage results in reduced electrical losses, increased transmission efficiency, improved voltage regulation and reduced conductor material. 

In addition, getting Right of Way (RoW) for transmission lines passing through forest areas and private land has been a critical issue in our country. Several transmission projects are getting delayed because of objections from handful of land owners.

Thus, to meet the bulk power transfer requirement and for optimal utilization of Right of Way, large capacity transmission corridors, of Ultra High Voltage (UHV) level, interconnecting the generating resources with load-centres are being planned.
"UHV generally means AC voltages of 1000 kV or more and for DC transmission system it is 800 kV or more." 
1200 kV AC transmission system is being envisaged as the next transmission voltage. Further in this direction, a 1200 kV test station near Bina in the state of Madhya Pradesh (India) along with 1200 kV test lines has been set up to study the characteristics of UHV system under actual conditions. It is expected that in a couple of years we will be able to take our commercial power transmission to the 1200 kV level. 

Also UHV DC transmission system is promoted to facilitate transfer of power from major power plants and to increase the capacity of National Grid. Execution of 1728 km long 800 kV bi-polar Biswanath-Agra DC transmission system worth 12,000 crore INR is a step forward in this direction.

Challenges related to UHV transmission:

Certain challenges related to UHV transmission are to be undertaken. For example, sudden loss of a UHV transmission link may result in serious stability issues. Corona loss at such enormous voltage will be quite high. Also the high electromagnetic fields of these UHV lines may seriously impact the health and environment.