The four turbines at Mangdechu (File picture on MHPA website)

Oil leak, Computer issues and water nozzle trouble impact all four turbines of the brand new Mangdechu project

The issues if not resolved threatens to derail power production from Bhutan’s highest tariff earning project

On September 28th one of the four units of the 720 MW Mangdechu Hydroelectric Project had to be suspended and put offline.

The brake system of the turbine applied itself when the turbine was in full speed generating 180 MW. Normally the break is only applied when the turbine is 10 to 15 percent of its full speed.

The force of the brake and turbine meeting was so great that the brake pad finished altogether and generated a lot of black carbon particles which in turn entered the generator above blackening it inside.

The system is still out of commission with a trial run being done only on November 7.

It now appears that the problem is not just with one of the turbines but there are common issues with all four generating units which have been supplied by the Bharat Heavy Electrical Limited (BHEL) under a total electro-mechanical equipment package of around Nu 8 bn.

There are apparently three main issues with the electro mechanical equipment supplied by BHEL. The equipment are essentially the four power generating turbines of 180 MW each and other electrical components around them.

The first issue is of the lubricating oil leaking out of the Bearing System in two locations that surrounds the generator above and turbine below. The bearing system is drowned in lubricating oil and this provides support and lubrication to the rotating components of the turbine and the generator.

Another issue is of the water Nozzle Injector which regulates the amount of water that hits the peltons that turns the turbine to generate electricity. The more the nozzle opens the more water will come out and more power will be generated.

The water nozzle has been behaving erratically which is causing concern among project officials. It sometimes works and sometimes does not work. That nozzle injector is controlled through a Governor which is the control system which also has problems.

The third issue which is related to the above is the Computer Controls and Monitoring Systems provided by BHEL which is equivalent to the brain and nervous system of the electro-mechanical equipment. This automated computer system takes in feedback and information from around 3,000 sensors including the turbines and either displays them or takes action.

This critical computer system is giving problems as its sensors are not functioning properly by giving erroneous reading or not giving readings at all. The sensor is part of the automation to take the feedback and signals from the machines and other parts and it informs the computer.  Among other things, sensor checks the temperature of the turbine, water flow, flow of cooling water, oil temperature, oil level and many other functions.

With the frequent failure of the Computer Controls System the Mangdechu staff are operating the plant using manual commands. Each turbine will require 25 manual commands in a stage wise process to start and run.

It has been learnt that trouble started from day one itself when the first unit was commissioned on 16th June 2019 and continued even after the final turbine was inaugurated on 17th August.

BHEL has been given time till December 15, 2019 by the project to make the changes and repairs and resolve the issue.

The BHEL equipment have a one-year liability period but since the equipment were faulty from the start the defect liability period has not been started by the project which will only do so once the full repairs or replacements are done.

The issues, if not addressed satisfactory by BHEL, threatens to hamper production from the entire project.

While the project lost revenue due to the September shutdown the only saving grace right now is that the water flow has dropped to 29.5 cubic meters which means that around two units are enough for generation as each unit needs 35 cubic meters for full generation.

However, if the issue is not fixed by May next year once the river level starts rising then there could be huge revenue losses for the project.

Not first time for BHEL

However, this is not the first time that BHEL equipment has had quality issues.

In the 1020 MW Tala project the agreement was that BHEL would provide an automated SCADA system (Supervisory Control and Data Acquisition) which is a computer system that collects real time information, analyzes it and takes action.

This means that the person should be able to run a power plant even sitting in an office away from the site.

However, BHEL’s SCADA system soon failed in the Tala project and BHEL was unable to fix it with the result that the Tala system is now based on the manual system that requires more people to monitor and run the plant.

One problem also was that the defect liability period of the equipment was already over by the time the project was handed over by the Tala project authority.

According to experts, BHEL has been supplying electro-mechanical equipment to Bhutan’s hydro projects from around 30 years ago with Kurichu, Chukha and Tala, but the equipment do not see much innovation and its installation and workmanship is also not up to the mark.

By comparison, the Generator Transformer supplied by General Electric India or the Gas Insulated Switch supplied by Hyosung from South Korea are of much higher quality.

The incident of the brake automatically applying itself, which is very dangerous by itself, did not happen for the first time in Mangdechu but had also happened in Kurichu and Tala with BHEL equipment.

Revenue implications

This issue could not have come at a worse time as the 12th plan and the Civil Service pay hike is heavily dependent on revenue from the Mangdechu project.

Mangdechu project is expected to generate 3 billion units in a year and at the Nu 4.12 per unit tariff this means around Nu 12.36 bn in annual revenue of which around half will go to loan repayment.

As per the Pay Commission report the direct revenue from Mangdechu (minus tax and deductions) is Nu 19.625 bn from 2019-2023. The total pay and allowances including civil services and other autonomous institutions like Royal University of Bhutan could go up to Nu 20 bn in the same four-year period.

BHEL’s Monopoly Position

BHEL which is a Public Sector Undertaking (PSU) company owned by the Indian government is the monopoly electro-mechanical equipment supplier from India and it apart form Mangdechu had got contracts to supply equipment to Punatsangchu I and II projects.

Bhutan in the past had made unsuccessful efforts to allow private companies to compete apart from BHEL.

In the fourth Punatsangchu Hydroelectric Project Authority (PHPA) meeting in 26th December 2008 Bhutan first pushed for the relaxation of the eligibility criteria in the electro-mechanical suppliers to accommodate participation of competitive bidders like Alstom India, Andritz India and Voith Siemens which are private companies.

The proposal from Bhutan was to have other bidders apart from BHEL to participate in the Punatsangchu II project and Mangdechu.

However, during the 5th PHPA meeting held in 16th March 2009 at New Delhi, the representatives from the Central Electricity Authority (CEA) of India strongly supported BHEL as the only qualified bidder for the contract as per the understanding between the two governments and eventually resolved that the participation of other competitors, may be considered in the future.

The CEA’s tough stand came from the fact that Bhutan was building the project with Indian grant and loan and so was under pressure to accept the monopoly equipment supplier even though it had performed poorly in Tala.

Controversially, BHEL had also hired a newly created Bhutanese company Bhutan Ventures Trading (BVT) in 2009 and agreed to give a commission of Nu 197.897 mn to the company for getting the monopoly order for Mangdechu and Punatsangchu II in 2012.

As per the ACC investigation BVT claimed that it only received Nu 18.80 mn in total while BHEL on its part despite requests from Bhutan has not yet agreed to cancel the total commission which may have gone or is going to other unknown people.

Except for a leak in an Adit Tunnel which was fixed, the civil works of the projects like the dam, head race tunnel and powerhouse has not given any issues.

The Mangdechu project was constructed at Nu 50.12 bn.

The Indian Ambassador, Ruchira Kamboj said that a BHEL team has resolved the issue of oil spillage.

She said that despite some teething problems the project is a success (see story on pg 3).

About Tenzing Lamsang

One comment

  1. This is not only worrying but alarming. One can accept certain teething problems but such explanation is not acceptable for defect in design and manufacturing. The concerned departments should carry thorough investigations on past and present performances for future decisions. It is Technical matter and should be clear and transparent without any PYA for future benefits and to avoid pitfalls. Truth must come out for benefits of everyone.

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