Friday, March 18, 2016

Sri Lanka coal plants need back-up generators for safe shutdown: Minister

ECONOMYNEXT - Sri Lanka's state-run Ceylon Electricity Board may have to install back-up power to safely shut down and re-start its coal plants and end multi-day delays now seen after emergency shutdowns during blackouts, Deputy Power Minister Ajith Perera said.
After a country-wide power outage Sunday, triggered by a failure at a transformer, the utility is enforcing 7-hour power cuts as much as five days later as it struggled to re-start at least two of its three 300 MegaWatt coal plants.
The plants had to cool for three days for CEB technicians to access the machines and replace diaphragms in the boilers which ruptured for emergency steam release.
"The plants require power to run their cooling systems," Perera said. "When the generators trip out of the system there has to be power to cool them down. But there are no auxiliary generators at Norochcholai.
"We are now thinking of buying generators for auxiliary power."
 A so-called 300 MegaWatt power plant will typically export about 270MW of power and use about 30MW to run itself, which is called the house load.
A bulk of the power goes for feed pumps which take water to the boilers, where steam is raised and then superheated and are carried to turbines which in turn drive the generators.
When generators stop working, and the national grid is down, the coal power station has no power to safely cool the plants or operate feed water pumps to keep boilers safe, and the diaphragms rupture to protect equipment.
"Please don't ask me why the (auxiliary) generators were not built in the first place," Perera said.
The coal power station in Norochcholai in Puttalam was designed and built by China on a 1350 million dollar loan after environmentalist and the Catholic Church opposed the construction of a Japanese funded plant built to CEB specifications.
Ex-President Mahinda Rajapaksa gave the go ahead for the plant and CEB engineers, who were thwarted in their bid to build cheap coal plants since the 1980s by religious and environmental lobbies, agreed to the plant despite reservations.
The plants have since helped save billions of rupees every week and has already resulted in lower tariffs for everyone as well as uninterrupted power during the dry season.
The coal plants are generating power for less than 5 rupees a kilowatt hour compared to 17 rupees for the cheapest liquid fuel plant running on residual oil.
Sources familiar with the matter say that officials are also looking to see whether at least one of the three plants could be kept running at lower operating level (de-loaded) to provide 'houseload' to safely shutdown the other two plants in the future.
Coal plants are expected to be base load plants, which, once started run for the better part of the year (about 9-10 months) without shut down and at maximum output. In Sri Lanka the plants also reduce output in the night.
Power sector analysts say in many countries it is unheard of for grid failures to occur and it may not be happening in China.
Sri Lanka also has an archaic system control centre and the agency has been struggling to procure modern computerized system for years.
Observers say it is amazing that CEB engineers are able to keep the grid running as they do and more importantly getting it up after a blackout with no real-time information available.
"I was surprised when I saw the control centre, it was very old," Deputy Minister Perera said. "There is a construction delay in the National System Control Centre."
Before construction delays the award of the contract itself dragged on when a losing bidder appealed against the original award to an India unit of Alstom.
The award finally went back to Alstom T & D in India but it has still not finished. A fibre optic cable system which would go with the control system, awarded separately to a Japanese contractor had been completed.
Sri Lanka Telecom faced similar delays in awarding cable laying contracts until it was privatized in the mid-1990s ending 10-year waiting lists for phones.
There are also other techniques to protect against nationwide blackouts and generator tripping such as islanding.
India's Mumbai, which is supplied by Tata Power, and fortunately escaped expropriation by the rulers in 1950s has been able to keep itself energized by an islanding scheme, despite the state-run Maharashtra around the city plunging the state into blackouts regularly.
Tata Power is credited by some as being a key reason behind Mumbai becoming and staying the commercial capital of India.

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