In January 1996, Kuala Langat combined cycle cogeneration power plant in Malaysia entered full combined cycle operation. Developed by independent power producer (IPP) Genting Sanyen Power (GSP) on a fast track basis, this project was an instrumental part of the government’s plans to meet rapidly rising power demand.

Kuala Langat power plant is located within the confines of Genting Sanyen (M) Sdn Bhd’s paper mill complex near Kuala Lumpur. The plant was a result of the company’s business diversification strategy at a time when Malaysia was embarking on a programme of private fast track power projects which also included Lumut and Pasir Gudang power plants. GSP was therefore established to build Kuala Langat.

With power sale revenues a priority, GSP was keen to achieve a high level of reliability and availability from Kuala Langat, and so decided to outsource the operation and maintenance of the plant to ABB Operation & Maintenance Ltd. (ABB O&M). This strategic decision has allowed the company to not only concentrate on its core business but also maximize its investment in the power industry and reduce risk.

Any private power project has certain operational risks, including:

  • Plant availability, as revenues are tied directly to availability

  • Heat rate of the plant governs fuel costs

  • O&M expenses

  • Equipment and plant outage will lead to loss of revenue under the power purchase agreement (PPA).

    ABB O&M aims to reduce these risk factors for the owner through guarantees of power plant availability, capacity and heat rate which it can achieve with its in-house knowledge of the plant equipment. The company offers a fixed price, long term contract, allowing the plant owner to concentrate on core businesses and maximize on its investment.

    Kuala Langat is a prime example of the success of this strategy.

    A fast track project

    Kuala Langat combined cycle cogeneration power plant is located 70 km south of the Malaysian capital. The main engineering, procurement and construction contract was awarded to ABB in January 1994 and the first gas turbine was operating in simple cycle by November 1994, two months ahead of the fast track schedule.

    By the beginning of 1996, the plant was in full commercial operation, supplying power to the grid and steam to the paper mill.

    The combined cycle block is based on three ABB GT13E2 gas turbines and one ABB steam turbine. The paper mill is also equipped with two 21 MW GE Frame 5 turbines which are linked to the steam turbine at the combined cycle power plant via a heat recovery steam generator (HRSG). Overall capacity is therefore 720 MW.

    The GT13E2 is a 50 Hz machine consisting of a 21 stage compressor and a five stage turbine. The design of the 13E2 is based largely on that of the earlier GT13E model but its higher exhaust gas flow rate of 532 kg/s and a higher turbine inlet temperature have given rise to an increased gross power output of 165 MW. The horizontally split casing design of the 13E2 also allows easy accessibility and maintenance and access to the bearings can be achieved without opening the casing.

    Three natural circulation dual pressure HRSGs are used to recover heat from the gas turbines. There is one single pressure HRSG connected to the two GE Frame 5 turbines at Genting’s paper mill. Steam is fed to the 248 MW ABB steam turbine.

    The plant is operated on natural gas, with No. 2 distillate oil used as a back-up fuel. National Utility TNB controls the dispatch of Kuala Langat which is essentially run as a base load operation. Power generated by the plant is delivered to the TNB grid at 275 kV.

    The sale of power from the plant is done under a 21 year power purchase agreement (PPA) between TNB and GSP. Under the PPA, a capacity test is carried out on the plant two times per year to ensure that the declared capacity is being maintained. Provided that declared capacity is 720 MW or more, capacity payments are made, otherwise penalties are imposed. In addition, plant availability must exceed 85 per cent.

    In addition to providing electricity to the grid, Kuala Langat supplies 15 kg/s of process steam at 6 bar to Genting Sanyen’s paper mill under an internal contract between GSP and Genting Sanyen.

    The O&M contract

    ABB Operation & Maint-enance Ltd. is a subsidiary of ABB Power Generation. The unit was established in 1993 as a standalone business and has the global responsibility for ABB’s gas turbine and combined cycle power plants. It currently has over 8000 MW of capacity worldwide under contract, and this is likely to increase with the forecasted growth in private power projects.

    ABB O&M received the contract for Kuala Langat combined cycle power plant at about the same time that ABB Power Generation Ltd. started detailing the engineering, and began its mobilization process almost immediately. Design reviews were held with GSP and ABB Power Generation in order to optimize the plant with respect to O&M. During the first few months, most activity was in the lead centre in Switzerland, but work was soon transferred to Malaysia.

    A new regional centre for O&M services was quickly established there, and the regional and plant managers were able to begin recruiting local personnel as well as considering other plant needs such as spare parts.

    The O&M contract for the plant began in January 1994 and runs for a period of six years starting from the plant’s commercial operation date, after which time it can be renewed. It is a fixed cost contract covering all aspects of power plant operation, maintenance, staffing, training and administration. GSP pays an annual fee and ABB O&M takes on full responsibility for the plant. The contract also contains guarantees for plant availability and performance which are in line with the requirements of the power purchase agreement.

    Under the contract, ABB O&M guarantees an availability of not less than 90 per cent for open cycle operation and 86 per cent for combined cycle operation. There is a bonus/malus system which covers plant availability, capacity and heat rate, giving an incentive to avoid unplanned outages and unnecessary maintenance hours. The contract provides for all consumables and spares required during the six year period. GSP provided the initial spares inventory which is kept on-site, and ABB O&M must maintain this inventory by replacing parts used.

    The O&M contract signed between ABB O&M and Genting Sanyen Power also includes the operation and maintenance of the two GE Frame 5 gas turbines located on the paper mill.

    Maintaining output

    At Kuala Langat, the frequency and scope of the maintenance schedule for the plant is determined by the operating regime for the gas turbines which are rated for operation up to 8760 h/year and up to an average of 25 starts per year. Medium and major gas turbine inspections are carried out every 6000 hours during scheduled outages.

    The operating experience of today’s GT13E2 fleet is over 100 000 fired hours in simple and combined cycle applications. The simplified design of the GT13E2 enables its inspection to be carried out in the shortest possible time. A and B inspections are visual inspections which typically require three days including the cool-down period. The C inspections are more lengthy, and involve opening the turbine for preventative and corrective work. The horizontally split casing design of the GT13E2 facilitates this.

    As with all ABB gas turbines, maintenance and repair work, including reblading and rebalancing, is performed on-site. On-site maintenance and repair is a basic feature of ABB turbines and no shipment to specialist facilities is required. This strategy requires a workshop on-site and a comprehensive spares inventory, as well as regional support.

    ABB also supplements its approach to the O&M of the GT13E2s with the use of a predictive, condition-related maintenance programme. This is based on a component lifetime optimization database of the entire GT13 family of gas turbines. Through an equipment operations analysis of this family fleet, operational characteristics and the resulting maintenance requirements for individual GT13E2 units can be profiled.

    This strategy enables accurate forecasting of operating patterns, the development of improved maintenance and parts replacement strategies, and the identification of specific performance upgrade possibilities thus optimizing life cycle costs for the plant owner.

    In November last year, one of the Kuala Langat gas turbine blocks underwent a C inspection. This was completed over a 32 day period and included inspection of the gas turbine, generator and HRSG. It was completed eight days ahead of schedule and no major defects or problems were encountered. Equivalent operating hours of the turbine at the time of the outage was 25 000 hours, and the first row of turbine moving blades was replaced.

    The operational data shown in Tables 1 and 2 illustrate that ABB O&M has been successful in managing the operation of the plant. The plant entered full combined cycle operation in 1996 and for the first 12 months of operation, overall plant availability including the GE Frame 5 machines was 95.4 per cent. Reliability for this period, not including the GE turbines, was over 99 per cent. Similar results have been achieved during 1997 although availability has been slightly lower due to modifications carried out to the gas turbines and the November C inspection.

    On 3 August 1996, a substation fault caused a total blackout in Malaysia. Around 900 MW was shed from the grid leading to a fast and significant drop in frequency. This drop was beyond the protection settings of the turbines and so the response of the turbine control systems was protection.

    Modern combined cycle power plants tend to have a low response capability during grid disturbances. This is largely because gas turbines are operated close to their lean extinction limit in order to keep NOx emissions low.

    By adapting the control equipment and the implementation of a sophisticated fuel distribution concept (FDC), it is possible to add this capability to the units. FDC and new frequency response settings give the generation units a higher frequency response capability.

    The FDC system enables the gas turbines to respond rapidly and immediately to grid disturbances with steep static loading gradients. At Kuala Langat, FDC has achieved a frequency response rate of up to 6 MW/s and improved ramp rates. FDC was installed on two of the GT13E2s at Kuala Langat in 1997, and the third unit will be equipped later this year. This technology has already been tested at Lumut combined cycle plant.

    FDC also provides the following features:

  • Power augmentation achieved through water injection

  • Rapid on-line change over between natural gas and oil at all loads. This can also be programmed to occur automatically if falling gas pressure is detected

  • Additional safety margins against flame-off even during extreme grid disturbances.

    With FDC, the power controller can now make full use of the dynamic capabilities of the gas turbines to function as a grid supporter during a grid emergency, a feature of commercial value to the grid.

    During a capacity test carried out in July 1997, the plant again achieved an output in excess of 720 MW (including the GE Frame 5s). ABB has actually increased the power output of the combined cycle island through the addition of three evaporative coolers.

    Under the all-encompassing O&M contract, there are other management aspects which are also of significant importance in the efficient operation of the plant, for example staffing and training. Training of the personnel not only involves an in-depth knowledge of the equipment but also of the necessary operational processes for operation, maintenance, health and safety.

    Kuala Langat employs a total of 46 local staff and three expatriate managers. Training of the local staff was performed by the O&M crew together with the commissioning personnel using modern teaching modules and simulators. A maximum of four personnel are needed on site to operate the plant, and staff work around five shift cycles.

    Due to the shortage of skilled personnel locally and the extent of in-depth training required, ABB O&M believes that it is economic to employ slightly more staff than is actually required, helping the plant management to avoid personnel shortages.

    If the operation and maintenance contract at Kuala Langat is not renewed after six years, the local staff will be given the opportunity to relocate to other ABB projects elsewhere. ABB O&M’s long term aim is that all of its contracted power plants be managed by its local staff.

    Aggressive strategy

    Prospects for the renewal of the O&M contract at the Kuala Langat power plant are good given the track record of the plant under ABB’s management over the past two years.

    ABB O&M believes that by following its strategy to produce a true “win-win” situation, risks can be minimized for the owner and revenues guaranteed, even in the region’s current economic climate.

    The company now sees its business developing alongside the private power market, with plant performance guarantees becoming increasingly aggressive as plant owners accept increasing levels of risk in the competitive market.

    Table 1. Kuala Langat operations data, 16 January 1996 to 31 December 1996
    Table 2. Kuala Langat operations results, year to end August 1997