Faults & failures

At this crucial time when the government needs to stabilise itself economically and politically, the massive electricity load-shedding is likely to resurface across the country during the coming summer season, adding to other numerous enormous challenges facing the country.

Seemingly, the grave situation will primarily result due to accumulated circular debt of Rs1.3 trillion in the power sector the government would be unable to clear within a short span of time, though there are a variety of other factors too complicating the energy crisis.

During May 2018 electricity shortfall was in the range of 6,000-7,000MW, though officially a deficit of 3,600MW was admitted. The average shortfall in the same month was 20,000MW, whereas the electricity generation remained static at about 14,000MW.

Likewise, during June the demand increased to 25,000MW against a power generation of maximum 19,440MW, resulting in a shortfall of 5,560MW. However, the shortfall on June 26 touched a record high level of over 9,000MW in spite of government claims of having added 11,461MW to system from new sources.

The annual growth in demand of electricity has been 10 percent that further worsens the problem of power crisis. Unless drastic measures are taken by the government to address the issue, in the present scenario there seems to be no significant respite for the consumers. The scheduled and unscheduled load-shedding and forced outages are not only have a negative impact on industrial and trade activities but they also cripple routine civic life causing strong protests and political unrest.

Obviously, the government can ill-afford the projected situation. Besides financial constraints and power transmission limitations, the generation capacity at national level is not being fully utilised at present.

Generation companies’ (GENCOs) thermal power plants are not being operated according to their availability and capacity factors, resulting in much less generation during the years. Understandably, the thermal Independent Power Producers resort to operating their units at lower capacity due to non-payment by distribution companies and restricting the use of costly furnace oil for generation. The worsening situation is likely to prevail. Of late, an increased role of water resources for economic growth has led to a renewed focus on the hydroelectric power generation. In this backdrop there will be more dependence in future on optimal utilisation of available hydropower generation capacity.

However, it is surprising that a few hydropower plants (HPPs), including Chashma, Jinnah, and Khan Khwar, were not operating at their respective design capacity factors during last summer, in spite of high-flow season and much better hydrology, which resulted in loss of millions of units (kWh) of low-cost energy.

It is learnt that two units of Chashma HPP ( 2x23MW) and three of Jinnah HPP ( 3x 12MW) are still out of operation for the last three years due to mechanical problems in the respective turbines and poor maintenance management system of Water and Power Development Authority (WAPDA). Similarly, one unit of Khan Khwar (37MW) remained out of operation for several months simply because of non-availability of some minor parts for its governor system. Surprisingly, National Electric Power Regulatory Authority, being the power regulating authority, has not taken notice of gross negligence and mismanagement on the part of the WAPDA that has also resulted in loss of billions of rupees to the national exchequer.

The economic operating life of a hydropower plant is averaged as 30 years, under normal conditions of operation & maintenance (O&M). After this period power station requires rehabilitation and/or replacement of major and critical components. The WAPDA engineers, recognised as having competence of international standards on O&M, have been operating old hydropower stations satisfactorily for much longer periods such as medium and large HPPs of Warsak, Mangla, and Tarbela, as well as small units installed five or six decades ago like Rasul (constructed in 1951), Kurram Garhi (1957), Chichoki Malian (1959), Shadiwal (1961), Nandipur hydro and Dargai, etc.

All these power plants are based on the Western technology as well as sources of supply for hydropower machinery. But, relatively new and recently commissioned power stations, mostly using the Chinese machinery, have experienced serious technical problems even from early stages of their commercial operations.

Typical examples are of Jinnah and Khan Khwar power stations. The 72-MW Khan Khwar project was completed in March 2012, but was shut down in July 2015 due to serious technical faults. There are two Francis turbines each of 34.25MW installed capacity and one Impulse turbine of 3.65MW. All three units were damaged as the supplier did not provide a sand trap to flush-out the bed load and suspended load sediments accumulated in the forebay. After major repairs, overhaul, and replacement of defective components the units were restored for generation in June 2016. Reportedly, the Chinese company has supplied substandard equipment.

Located on the Jinnah Barrage, Jinnah hydel power station has an installed capacity of 96MW. The project was initiated in February 2006 and the Chinese were awarded contract on government-to-government basis. First unit had test and trials in January 2012. All eight units were in operation by October 2013. However, three units of 12MW capacity each remained inoperative for couple of years as the substandard design of installed trash racks could not withstand the differential pressure caused due to heavy trash in water, and therefore collapsed. Under-water repair and modification in trash racks of two units, 4 and 8, was completed only last year and then the units were put back into the system.

Unit 1 has been out of operation for the last four years due to damaged speed increaser. Remaining units are operating at less than 40 percent capacity due to damaged structure of the trash racks, high temperature of guide bearings, misalignment, shaft seals failure, and weak insulation of generators’ windings etc. Unfortunately, the power station has never attained its required target of operations at rated load for annual generation.

The USAID-financed Gomal Zam Dam in South Waziristan was commissioned in 2013, but till date the power station could not be operated at its rated capacity of 17MW. It is facing serious operational problems owing to repeated defects-led failures, basically due to flawed design and inferior quality of electromechanical equipment. Reportedly, some of the equipment supplied from China did not conform to contract specifications either. Currently, only one unit is operative, while the second has been out of operation for last three years.

Chashma hydropower plant was commissioned during 2000-2001. It has eight units (a Kaplan turbine of 23MW each), with a combined capacity of 184MW. Two units are closed as major faults were detected in the turbo-generators in past years. Unit 8, being non-operational since 2015, is currently undergoing major repair on the main generator by the machinery supplier, whereas unit 2 is shut down for the last two years or more, on the advice of machinery supplier, as the main turbine shaft had developed cracks that could cause serious damage not only to the unit but, consequentially, to the whole power station.

The 1,410 MW (3x470 MW) Tarbela Fourth Extension was inaugurated on March 10, 2018. At that time Tarbela reservoir was at the dead level of 1,380 ft. This caused huge quantity of mud and silt passed through the tunnel, turbine and deposited between the partially demolished coffer dam and the draft tubes outlets. The coffer dam built for construction work was not completely dismantled till then but demolished partially only up to the level of 327 meters above sea level (MASL), still 15 meters above the level of draft tubes. The area between the draft tubes outlets and the coffer dam thus acted as a silt/sand trap. It was absolutely undesirable to start the powerhouse when the reservoir was at dead level and the coffer dam had not yet been completely dismantled.

After inauguration, unit 17 was kept shutdown but when the reservoir level went up to 1,400 ft, it was put into operation for about one month. The unit was shut down when the reservoir level came down again to dead level. On July 15, when the reservoir was at the dead level, a leakage was observed from the tunnel dewatering valves, installed on penstock of unit 17. The draft tube gates were lowered in unit 17 and turbine dewatered for temporary repair of the leaking valve, without depressurisation or dewatering of the tunnel. After the repair of the dewatering valves, draft tube gates from unit 17 were taken out on July 7.

On July 9, the leakage started from the tunnel dewatering valves of Unit 16. Repair of the same was not possible without dewatering the power tunnel. For this purpose, draft tube gates had to be lowered in all the three units and power tunnel was dewatered. After temporary repair of the leaking valves, when operation of the powerhouse was being restored, it was revealed that the draft tube gates of all the three Units were badly stuck in the silt. It took the WAPDA about three months to release the stuck-up gates and restore operation of the powerhouse. The WAPDA had to suffer a huge generation loss worth billions of rupees simply because of substandard, low quality China-make dewatering valves for the power tunnel.

The first-ever self-financed medium hydel power station in the KP Province, Malakand-III of rated capacity of 81MW owned by the PEDO, has never operated on full capacity as wear and tear of machinery was very fast.

This power station is also equipped with the Chinese equipment which started de-ration (derating) immediately after its commissioning in 2008. The maximum annual generation of Malakand–III is 400 million kWh as compared to its net design capacity of 553 million units per year. Performance of the PEDO projects in the KP, including Renolia 17MW, Daral Khwar 36MW, and Machai 2.5MW, constructed by the Chinese companies is yet to be checked and evaluated. Connection of these projects with national grid is awaited for Power Purchase Agreement with the National Transmission and Dispatch Company.

The writer is a former chairman of State Engineering Corporation