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Articles |
Hydropower stations being
refurbished and modernised
BY : ENGINEER HUSSAIN AHMAD
SIDDIQUI
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ARTICLE (March 18 2010): Total installed capacity of hydroelectric power
plants in Pakistan is 6,474 MW, which contributes about 33% to the combined
installed generation capacity of all resources. During the financial year
ending 30th June 2007, hydro energy generation of 31,846 GWh was dispersed
through the national grid, at a cost ranging from Paisa 35 to paisa 167 per
kWh unit for different power stations.
A significant number of the existent power stations are very old, almost
30-40 years, though a few small hydropower plants were even commissioned as
early as in 1925 and 1938, and all are still operative. Generally, the
manufacturers of generating units prescribe a useful life of hydropower
station as 30 years, depending on the operating conditions.
But, total replacement of installed machinery after completion of its
lifecycle is not considered techno-economically feasible as it entails huge
capital outlay. Nonetheless, the power stations, generally, have potential
for achieving higher efficiency and, in most cases, increased output too.
Hence, fundamental rehabilitation and refurbishment of the electromechanical
equipment and system of existing plant is carried out, which enhances
plant's operating life by another 20 years or more. This is achieved by
incurring a nominal cost, comparing to installing new generating sets.
Hydropower is a well proven and advanced technology, with modern power
plants providing the most efficient power generation ie up to 90%, the
lowest operating costs and longest plant life as compared to any other
energy resource.
Pakistan Water and Power Development Authority (Wapda) is strongly committed
to sustainable development of hydropower, at an accelerated pace, in order
to secure national power supply to meet the growing demand. While work on
its various new hydropower projects is in progress at varied ongoing stages
of construction, development and planning, Wapda is alive to the need of
undertaking rehabilitation, up-gradation and modernisation of turbines,
generators and allied equipment at its major power station installations.
An extensive programme to renovate, upgrade and up-rate the major power
stations, with total capital expenditure of billions of dollars, has been
worked out to be implemented, progressively, during the next five years.
This is in addition to carrying out annual maintenance, replacement of
spares/components and periodic general overhauls of the machines installed,
which remains an ongoing regular exercise.
The plan primarily aims at improving availability of power stations through
enhancement of the turbo-generators' output and efficiency, ensuring
reliable and economic power generation.
Latest technological advancements in metallurgy, instrumentation and
controls, insulation materials for electrical equipment and quality control
techniques, etc have made the modern equipment much better in performance
and efficiency as compared to those installed in the power houses decades
ago.
Increasing the capacity and energy output is possible either by carrying out
modifications in existing turbine runners or by replacing with up-graded
runners. Likewise, modern generator development, such as optimal cooling,
design innovations and adopting lower class F insulations, has resulted in
greater generator efficiency. Recent technical and safety improvements
corresponding to the automation technology focuses on protection, excitation
and enhancement of human-machine interfaces.
Mangla power station has an installed generation capacity of 1,000 MW. Ten
generating units each of 100 MW were commissioned during the period July
1967 to July 1994. Though the power station has been operating largely
trouble-free, the quality and reliability of the original electro-mechanical
equipment has deteriorated and is no longer of satisfaction. Efficiency has
reduced from the designed values of the respective equipment installed. It
is therefore, envisaged to undertake refurbishment and rehabilitation.
Also, it is considered feasible to effectively enhance power station
capacity from the present 1,000 MW to 1,250 MW, whereas improved power
potential up to 1,500 MW cumulative capacity can be attained with the recent
completion of Mangla Dam Raising Project. WAPDA is currently in the process
of appointing international consultants, who would determine the most viable
option for up-gradation and refurbishment of all the installed generating
units, as well as achieving greater capacity of the existing power station.
Warsak power station, regarded as the pioneering medium-size hydropower
project in the country, has an installed capacity of 243 MW. Four generating
units of 40 MW each were commissioned in 1960, whereas its extension,
carried out in 1980-81, has resulted in installation of another two units,
each of over 41 MW capacity.
First phase of rehabilitation of power station was undertaken during the
period from 1996 to 2006, to restore full generating capacity of 243 MW.
However, further ageing of electromechanical equipment, problems in civil
works and sedimentation has now caused a net loss of 30 MW in power
generation. This has necessitated undertaking the second phase of
refurbishment and rehabilitation. Wapda has invited the EOI (expression of
interest) for consultancy services to seek the most cost-efficient solution
to restore and maintain the ability of power station to full generation
capacity of 243 MW. The refurbishment and modernisation plan also covers
rehabilitation of civil works and sedimentation management at the power
house.
The largest hydropower station at Tarbela has 14 units, of cumulative
installed capacity of 3,478 MW, in full operation. Four units of capacity
175 MW each were commissioned in 1977; another 6 units of 175 MW each during
1982-85, whereas the latest 4 units of 432 MW each were commissioned during
1992-93. The equipment has started showing signs of ageing. Selective
up-grading and updating of the power station, based on the current
international standards of safety and performance, is therefore, planned.
Despite obsolescence, all the existing hydropower stations have been giving
excellent continuous service, under the given conditions and limitations. It
has been made possible due to Wapda, having a strong backup of professionals
and skilled manpower. Wapda engineers have shown very high levels of
commitment and responsibility during breakdowns and accidents that occurred
in recent past.
At times, on-site emergent repairs were undertaken without any foreign
assistance, restoring power generation within the shortest possible time.
Still, this is the high time that refurbishment and modernisation of power
stations be undertaken at a large scale, with due emphasis on strengthening
of its human resources by imparting advanced training.
Hydropower, the most economic form of renewable energy, which is
environmental-friendly too, meets about 20% of the world's electricity
requirements. The demand for hydropower is increasing globally and Pakistan
is no exception. To optimise existing operations and maintenance of
hydropower stations is a salutary measure in this direction.
Concerted efforts, however, should be made by Wapda to the expeditious
implementation of the planned refurbishment and modernisation, aiming at
accomplishing it within the stipulated timeframe and at reasonable cost.
(The writer is former Chairman of State Engineering Corporation, Ministry of
Industries and Production.)
Copyright Business Recorder, 2010
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