More power outages loom
http://www.theindependent.co.zw/
Thursday, 06 October 2011 16:34
Chris Muronzi
ZIMBABWE is headed for more power outages after several generation units at
the country’s most reliable power station, Kariba, went off owing to
various faults, a Zimbabwe Power Company report to industry says.
According to the report, Kariba, which has largely been operating at full
capacity for the past two years, is struggling.
“During the week ending 25th September the protection on Units 3 and 4
tripped. Unit 4 was isolated from the transformer which it shares with Unit
3. Unit 3 was then brought back into service. After meticulous trouble
shooting, it was found that switchgear and control devices, which were
replaced by another OEM (Original Equipment Manufacturer) during our
maintenance shutdowns earlier this year, had failed. Repairs to these
devices are underway under guidance of the OEM from Europe,” said the
report.
The problems at Kariba Power Station started in June after a failure in the
generator winding of Unit 2.
Copper windings to get Unit 2 back on stream can only be manufactured and
fitted by OEM.
The problem was compounded by a crack that was found in one of the turbine
blades which only the OEM can repair.
“This repair work is underway and is scheduled for completion before
mid-October. In my view the OEM did not, and could not, be encouraged to
respond to our crisis with the urgency demanded by our unique situation or
with the respect that a 30year relationship deserves. Our MD has been in
Europe this week to discuss this with the OEM,” said the report.
ZPC foresees a “significant amount of work” going into stabilising Hwange
Power Station and hopes to float a tender once funding becomes available to
replace key components which have lead times of up to one year.
Hwange, according to the report, lost four Phase One smaller units over the
last week.
“ Unit 1 due to the failure of the “Boiler Feed Pump” which is new and under
warranty, Unit 2 due to a failure of its thrust bearing, Unit 3 due to wear
on its induction fans caused by the under-performing de-ashing system and
Unit 4 due to the failure of its Boiler Feed Pump,” said the report.
The problems at Hwange were worsened after the entire station was taken out
by a surge out of Eskom last Tuesday.
“At the time of writing this statement we now have two Phase Two (larger)
units and one Phase One (smaller) unit feeding the grid. We expect to bring
another unit back overnight (Sunday) and the fifth by Wednesday this week,”
the report said.
Thermal power stations in Bulawayo, Harare and Munyati are also constrained
in maintaining modest outputs due to the availability of coal from
suppliers.
“All three suppliers assure us that their production will improve over the
next two months. Should this not be the case we will have to consolidate and
probably run only two of the three stations,” added the report.
Major retrofitting and component replacement projects will continue over the
next 12 months, the report said.
Wapcos, the Indian company that provides expert advice at Hwange, have
provided an experienced project manager to help oversee these projects at
Hwange.
ZPC hopes the execution of these projects would extend planned outages of
units on a sequential basis next year.
“For example the precipitators (ash handling) on Phase Two will be
retrofitted over the next seven months therefore from the middle of October
until May 2012 and one of the Phase two Units will be offline,” said report.
“At Kariba the system that governs the turbine blades, in sympathy to the
power demand, will be replaced on each unit (six weeks per unit) on a
sequential schedule. This means that from mid-December until September 2012
only five of the six units will be online.”
In addition, ZPC will over the next 12 months some units will also be taken
off line for shorter periods to undertake unit specific upgrades or repairs,
the report added.
“So in summary the power supply regime will for the next 12 months will be
much the same as it has been for the last 12 months – all in a bid to
stabilise and optimise supplies in the medium term,” the report added.
The refurbishment of the 40km pipeline from the Zambezi to the Hwange
station remains a priority and is a one year project. The feasibility study
was completed over two months ago and we await the outcome of possible of
government-to-government funding with the government of India.
While demand for electricity is picking, nothing can be done to augment
output for the next four years when planned power projects come on board.