Dr Ambedkar Institute of Technology

Bangalore

REPORT

On

“INDUSTRIAL VISIT TO VARAHI HYDEL POWER

PLANT”

MASTER OF TECHNOLOGY

In

POWER ELECTRONICS

Submitted by

ANAND REDDY B.R.

(1DA10EPE01)

CONTENTS

KPCL OVERVIEW,

OBJECTIVES OF KPCL,

UNDERGROUNG POWER PLANT,

TECHNICAL DETAILS OF THE VARAHI UNDER GROUND POWER

PLANT,

PELTON TURBINE,

Oil-Filled Cable,

VERTICAL MOUNTED ALTERNATOR – TURBINE,

CONTROL OPERATION OF POWER PLANT,

CONCLUSION

KPCL OVERVIEW

For over three decades, the Karnataka Power Corporation has been a prime mover and catalyst behind

key power sector reforms in the state - measures that have spiraled steady growth witnessed in both

industrial and economic areas.

Right from the year of inception, in 1970, KPCL set its sights on “growth from within” meeting

growing industry needs and reaching out to touch the lives of the common man, in more ways than

one.

KPCL today has an installed capacity of 5975.91 MW of hydel, thermal, solar and wind energy, with

9500 MW in the pipeline. The 1720 MW Raichur Thermal Power Station located in Raichur dist is

accredited with ISO 14001-2004 certification for its environment protection measures. From an

industry vantage point, KPCL has raised the bar on the quality of deliverables and is constantly

working at lowering the cost per megawatt - a commendable cost-value equation that has become a

benchmark on the national grid. KPCL’s stock in trade is industry proven - well-established

infrastructure & modern, progressive management concepts and a commitment to excel, helping it

meet the challenges of the rising energy demands of Karnataka.

The leverage point of KPCL initiatives are its resource management strengths – right across planning,

financing and project engineering. KPCL also has a high rating in terms of project completion and

commissioning within the implementation calendar.

OBJECTIVES OF KPCL

KPCL seeks to touch higher vantage points in the world of power engineering. Our formula for

achieving this - start with a world class organization, build-in efficiency and cost control and ensure

that progress is in harmony with the environment.

• Exploring, identifying and developing opportunities in power generation.

• Devising innovative ways of setting up and operating power plants.

• Investing in a resource base of technical competence, systems, processes and capability.

• Empowering people, work teams and the support network to achieve these objectives.

UNDER GOROUND HYDEL POWER PLANT

The river Varahi takes its birth at a height of 730 m in the Western Ghats at Hebbagilu, near Agumbe

in Shimoga District. It joins the Arabian Sea near Kundapur. After a 25 Km initial run, this swift and

powerful river falls 455 m in cascades to form the bellowing Kunchikal falls.

Varahi is Karnataka’s first underground powerhouse – a key milestone in the corporate history of

KPCL.

Initially conceived as a surface power house at the blueprint stage, Varahi was later converted into an

underground Powerhouse. The decision for the change-over was based on three key parameters :

technical, economical and our concern for environment protection. Stage I of the Varahi Hydro

Electric Project has a total installed capacity of 230 MW contributing 1100 MU annually. This

consists of 2 x 115 MW Generating Units at Varahi underground Powerhouse and two 4.5 MW units

in the power house at the Mani Dam site. Provision was made to add two more Units at this power

house of similar capacity (115 MW) & the excavation works were completed during Stage I works

only. Now the construction works of units 3 & 4 each of 115 MW capacity is under progress. These

units are commissioned during November 2008

VARAHI HYDEL POWER PLANT

An underground power station is a type of hydroelectric power station constructed by excavating

the major components (e.g. machine hall, penstocks, and tailrace) from rock, rather than the more

common surface-based construction methods.

Often underground power stations form part of pumped storage hydroelectricity schemes, whose basic

function is to level load: they use cheap or surplus off-peak power to pump water from a lower lake to

an upper lake, then, during peak periods (when electricity prices are often high), the power station

generates power from the water held in the upper lake

TECHNICAL DETAILS OF THE VARAHI UNDER GROUND POWER

PLANT

INSTALLED CAPACITY: 460MW

PEAK LOAD: 215MW

PLANT LOAD FACTOR: 20.59%

UGHPP LAYOUT

CUMMULATIVE MONTHLY GENERATION: 2.273

NO UNITS INSTALLED: 4

EACH UNIT CAPACITY: 115MW

ALTERNATOR: 11KV

POWER TRANSFORMERS: LV SIDE-11KV

HV SIDE-220KV

Load centers:2 n.o.shimoga,

2 n.o.mangalore

Generator voltages, current, line voltages and number of transmission lines:

Station: varahi

Rated current generator terminals: 6715A

Rating of generator transformer:2*130mw

No of line bays: 5 (1 under construction)

Type of turbine: vertical pelton

Rated turbine speed: 250 RPM

WATER CONSUMPTION:MCft/MU:32

Design discharge MCft/MU:77 cuecs per unit

PELTON TURBINE

The water flows along the tangent to the path of the runner. Nozzles direct forceful streams of water

against a series of spoon-shaped buckets mounted around the edge of a wheel. As water flows into the

bucket, the direction of the water velocity changes to follow the contour of the bucket. When the

water-jet contacts the bucket, the water exerts pressure on the bucket and the water is decelerated as it

does a "u-turn" and flows out the other side of the bucket at low velocity. In the process, the water's

momentum is transferred to the turbine. This "impulse" does work on the turbine. For maximum

power and efficiency, the turbine system is designed such that the water-jet velocity is twice the

velocity of the bucket. A very small percentage of the water's original kinetic energy will still remain

in the water; however, this allows the bucket to be emptied at the same rate it is filled, (see

conservation of mass), thus allowing the water flow to continue uninterrupted. Often two buckets are

mounted side-by-side, thus splitting the water jet in half (see photo). This balances the side-load

forces on the wheel, and helps to ensure smooth, efficient momentum transfer of the fluid jet to the

turbine wheel.

PELTON TURBINE CROSS SECTION

Oil-Filled Cable

A high-voltage power cable in which the paper insulation is impregnated with mineral oil

under pressure. An increase in the electric strength of insulation is achieved in oil-filled

cables through the elimination of gas inclusions (voids) within the insulation, which are

potential sites of breakdown, by filling them with oil. During operation of the cable the oil

pressure is maintained by make-up equipment. Oil-filled cables are used to lead power lines

from large power plants or underground hydroelectric power plants to distribution equipment,

where power transmission lines cross water obstacles, in densely builtup areas, and where

power lines extend far into cities with high power

consumption

VERTICAL MOUNTED ALTERNATOR – TURBINE

CONTROL OPERATION OF POWER PLANT

The hydroelectric power stations are undergoing a modernization process for operating optimization.

One of the main ways to improve a hydropower development (hydropower station) is to equip it

with SCADA-type acquisition and control systems the system is based on an

architecture distributed and two hierarchical levels: the process, local level (located in the HPS) and

the territorial dispatching level (located in Hydropower Dispatcher level). The system includes

programmable automatic equipments, intelligent electronic devices, data transmission system and

computers. The monitoring system connects three distinctly different environments.

The substation, where it measures, monitors, controls and digitizes; the Control Room, where it

collects, stores, displays and processes substation data; the Dispatcher Center, where it stores and

displays incoming data. A communications pathway connects the three environments

CONCLUSION

The industrial visit was highly informative and an experience to know the complexities involved in

generation and transmission of electric power.